Category Archives: Phenomena of Nature
“And the things of various colours that He has created for you in the earth, in them is a Sign for those who keep the working of the Divine laws before them”.
As stated earlier, the first living bodies on earth were single cells. These gradually evolved into animals and plants that we see now. The world today thus consists of unicellular as well as multicellular organisms, the basic unit being a cell. Every cell differs from the other in certain respects. Moreover the chemical constituents of a cell are changing every moment. New materials enter a cell. Reactions within a cell change the incoming materials into new compounds, some of which are redistributed within the cell substance, others including the waste products leave the cell. These changes are continuous. But inspite of all the differences between cells and changes within cells, there are certain basic features which are common to all of them. Functions of a cell are based on the properties of its chemical constituents.
BASIC CHEMICAL CONSTITUENTS OF A CELL
95 per cent of the weight of a cell consists of four elements; oxygen 62 per cent, carbon 20 per cent, hydrogen 10 per cent and nitrogen 3 per cent. The rest 5 per cent of the weight of a cell consists of thirty other elements, including calcium, iron, sodium, potassium, magnesium, iodine, phosphorus, chlorine and sulphur as the main ingredients. In addition trace elements are present in particular types of cells. All the elements described above are present in the oceans. The cells having originated in the oceans, their contents and composition are a reflection of the oceanic water.
Minerals. All minerals present in a cell are present in the form of solution, except calcium salts which are present in the form of crystals around individual bone forming cells. Another element namely silicon is also present in crystal form in the outer cells of certain grasses.
Organic Components. As noted already, these are Carbohydrates (which include sugars and polysaccharides) fats, proteins, nitrogen-bases drivatives which include adenoL’iie phosphates and nucleic acids. Like minerals, some of the organic substances form hard parts, for example wood, horn and chitin (the external covering of insects).
Carbohydrates. These, as we know, consist of carbon, hydrogen and oxygen. A carbohydrate with five carbons (C5H10O5) is called pentose. Common example is ribose. That with six carbons (C6H12O6) is called Hexose. Common examples are glucose, fructose and galactose. Sugars such as Pentose or Hexose are called monosaccharides as each represents a single sugar unit. Two monosaccharides joined together form a Disaccharide, a double sugar. Example is cane-sugar which is a combination of glucose and fructose. Two or more disaccharide molecules combine to make a polysaccharide. Examples are cellulose, glycogen etc.
Fats. As seen already, fats are formed by combination of one glycerine molecule and three fatty acid molecules. Like coal or petrol in an engine, fats serve as fuel in cells. They also form boundary membrances of cells where they contribute to controlling the movements of materials into and out of cells*
Proteins. Are polymers of Amino acids. A protein may contain any type, any number and any sequence ofamino-acids. Proteins may be categorised as Fibrous and Globular. Fibrous Proteins are relatively insoluble in water and provide the building materials for the structural framework of cells. Fats, carbohydrates and other materials get secondarily deposited in it.
Protein formation being under the control of nucleic adds, every organism has got specific types of proteins. Thus if protein from one organism is transferred to the body of another organism, it acts as a foreign body and produces disease. For , example bacteria give rise to disease when they infect a host. Proteins of one animal when grafted into another, do not heal into place.
Nucleic acids. As we know, these are nudeotide polymers. Nucleotide is a phosphate of a nitrogen-base plus simple sugar pentose. Pentose may be either Ribose or Deoxyribose, the latter containing one oxygen atom less than ribose. On this basis we may distinguish between Ribose-nucleic-acids (RNA) and Deoxyribose-nudeic-adds (DNA). DNA forms genes and RNA functions as an intermediary between genes and the sites of protein synthesis in a cell.
* Formerly fat was considered to be metabolically inactive substance. (For example, in human body it was supposed to be a reservior from which the body could draw calories during starvation or similar conditions. Its main day to day function was one of insulation against temperature changes and mechanical protection of underlying structures against minor trauma. We were also familiar with the aesthetic aspects of fat But it was not considered as an organ in its own right It is nbw known that fat plays a unique and central role in the economy of energy, a fact of which we were ignorant several years ago. To use an analogy, just as the capital of a bank cannot be allowed to be idle, so resources stored in the fatly tissue are not to be regarded as inactive or inert To extend the analogy, although the amount of capital represented by fat may be constant, there is a continuous borrowing and lending of funds, with the result that, provided the weight remains constant, a zero balance is struck.
Other constituents of cell. In addition to fats, carbohydrates, proteins, nucleic acids and Adenosine-phosphates which form the bulk of living matter, a cell contains hundreds of other organic substances. These are present in minute quantities and yet they may be extremely important for the maintenance of life. One category of these substances is known as pigments. Besides their aesthetic aspect in the living world, pigments perform various extremely important roles.
Pigments. Three types are particularly significant-
One group includes pigments known as Tetrapyrrols. A pyrrol contains a skeleton of five atoms of carbon and nitrogen arranged in a ring. Four such rings joined together form a tetrapyrrol. Tetrapyrrols of this type include red, blue, green and other varieties of pigments found, for example, in algae, in the shells of robin and other bird eggs and in mammalian faeces and urine
Fig.24.-PIGMENTS. (Chemical Structure)
In other tetrapyrrols, the four pyrrol rings are joined to form a larger ring in turn and in the centre of this larger ring is usually present a single atom of metal. A major pigment of this type is green chlorophyll, the central metal atom here being of magnesium. This is present in photosynthetic organisms. In another important type of ring-like tetrapyrrol, the central atom is iron and such pigments are red; for example, haemoglobin, the red oxygen-transporting substance in the blood of many animals (man and vertebrates generally).
(b) A second large group of pigments in organisms comprises carotenoids. They produce red, orange, yellow and brown colours. They are long chains of carbon atoms, with carbon rings attached at both ends of the chain. Two subgroups of carotenoids are the Carotenes and the Xanthophylls. Carotenes have a general formula C40 H55 and Vitamin A is its derivative. Named after the carrot in which carotenes are abundant, the pigments also occur widely in all leaves and are reponsible for the red, yellow or cream white colours of, for example, tomatoes, pumpkins, egg yolk, butter, milk and other plant and animal products.
Xanthophylls contain oxygen in addition to carbon and hydrogen. They are also widely distributed. A common Xanthophyll of leaves is lutien (C40H56O2), which is responsible for the yellow colours in autumn foliage( ).
(c) A third major group of pigments comprises the Anthocyanins formed among plants but not animals. An anthocyanin molecule is composed of several rings of atoms, the ring being joined in complex ways. They produce the deep reds and blues of plants as in many flowers, fruits and roots (e.g., beet-root). They are also manufactured in autumn foliage where they account for red colouration. They are water soluble whereas carotenoids and chlorophylls are fat soluble.
Most conspicuous in animals but not in plants is Melanin. It is responsible for yellow-brown, brown and black animal colours. Thus it occurs abundantly in hair, skin, in the inner layers of eyes and also in the interior membrances of some animals. Melanin is a chemical derivative of the amino acid tyrosine. Specialised pigment cells produce melanin, which accumulates in granules within such cells. If only a few melanin granules are present, the cell appears to be yellowish or brownish in colour. A black colour is produced by dense masses of granules.
The Holy Quran says:
“And the things of various colours that He has created for you in the earth, in them is a Sign for those who keep the working of the Divine Laws before them”.
“Do you not see that Allah sends down rains from above and leads it through springs in the Earth? Then He causes to grow therewith produce of various colours. Then it withers and turns yellow. Then He makes it dry up and crumble away. Truly in this is a message to men of understanding”.
These are the wonderful ways of the working of Divine laws in the physical world. We note how the same Carbon, Nitrogen, Hydrogen and Oxygen atoms in a molecule with change in their number and arrangement pattern, produce a variety of pigments. How the inclusion of a single atom of magnesium in a formula produces green colour, and the inclusion of an atom of iron produces red colour. How the addition of oxygen to carbon and hydrogen atoms (C40H56O2) produces lutien, a yellow pigment of autumn foliage ( ) and so on.
Meaning of colour. It would be worthwhile in this connection to describe what we mean when we say that so an and so object has got so and so a colour. For example, we know that a plant is green because it contains a green pigment called chlorophyll. Why does chlorophyll look green?
For this let us recall the electromagnetic radiation, already described in Chapter IV. The constituents of electromagnetic spectrum which are of different wave-lengths extend from radio-waves to cosmic rays. The wave-length decreases from radio-waves, through infrared rays, light rays, ultraviolet rays, X-rays, gamma rays, to cosmic rays. Thus radio-waves are longest and least energetic and cosmic rays are shortest and most energetic. The light rays or the visible spectrum which is a part of the electro-magnetic spectrum described above is again composed of rays of different wavelengths. They range from violet, through indigo, blue, green, yellow, orange, to red in increasing lengths. Thus violet is shortest and most energetic, and red is longest and least energetic.
Colour is not an inherent property of an object. It is a sensation produced by stimulation of optic nerves by particular light vibrations and its interpretation by brain cells. When light from a self-luminous source falls on a particular object the light rays may be absorbed, or transmitted, or reflected by it. The transmitted or reflected rays when they fall into our eyes, are carried by optic nerves to optic lobe area of brain which interprets these vibrations as colour. (Fig. 25).
Fig.25.-LIGHT RAYS. (Light rays reaching an object may be partly reflected, partly absorbed and partly transmitted.)
An object which absorbs all types of light rays (from violet to red) falling on it would be invisible. A black object approaches this theoretical condition very closely. An object which transmits all light rays, would be completely transparent and would thus be invisible. And an object which reflects all light would appear in the colour of light falling on it.
Thus the colour of an object depends on what type of light rays are absorbed, transmitted or reflected. Just as a radio-receiver is sensitive only to a portion of electromagnetic spectrum known as radio-waves, so the human eye is sensitive only to a portion known as visible spectrum or light rays. The optic lobe of the brain is so constructed that it interprets the shortest most energetic light waves as colour violet and the longest least energetic as colour red. Light waves of intermediate increasing wave-lengths are inerpreted as indigo, blue, green, yellow and orange respectively. Viewed together in a properly mixed beam such as sunlight the whole spectrum of visible waves is interpreted as white.
The subjective nature of colour is revealed in colour blind persons. These people can identify certain colours and not others. The defect here lies in the visual mechanism of the viewer and not in the object viewed.
We may conclude therefore that the light waves which chlorophyll reflects and transmits, and which make chlorophyll appear green to us, have intermediate length and energy content; and that the light waves which chlorophyll absorbs must be the other components of the visible spectrum, namely, the long red waves and the short blue-violet waves.
Similarly the colours of plants, animals, rocks, minerals and in fact of all the living and non-living objects around us varies with their respective chemical and physical structure and consequently upon the rays of solar spectrum that each of them reflects, transmits or absorbs. What a beautiful arrangement, for the display of beautiful colours in this beautiful world.
The scientists who explore nature and gain knowledge of natural phenomena are termed ‘Ulema’ by the Holy Quran:
“Do you not see that Allah sends down rains from above? With it We then bring out produces of various colours. And in the mountains are newly created strata of rocks, white and red of various shades of colour, and intensely black. And so amongst men and crawling creatures and cattle are they of various colours. Those who posses the knowledge of these sciences ( ) really appreciate the mighty powers of the laws of Allah. They know that His law is omnipotent and provides protection for those who abide by it”.
The word in the above verse is significant. Usually it is translated as “tracts”. But actually it means the newly created strata of the Earth’s crust.
means ‘new, or ‘newly created’.
Let us recall that most sedimentary rocks were formed by erosion of other rocks. The action of air and water causes exposed rocks to crumble and the rainwater gradually moves the pieces downhill. After movement has ceased, some substance in solution in water deposits a cementing material which holds the pieces together to form a rock. If the pieces are large, we call it Conglomerate. Pieces about the size of sand grains form a sandstone. When the mass is like a fine smooth powder, the rock becomes a shale. The normal succession of sedimentary rocks is conglomerate, sandstone, shale and limestone. The limestone which is made principally of the shells of marine animals is formed only in clear water, and indicates the presence of very sluggish streams preceding the rock formation that could not carry even small particles. The sedimentary rocks may be turned into metamorphic rocks under the influence of heat, pressure, water and motion. Thus shale became slate, granite became gneiss, limestone became marble and sandstone became quartz. The changes involve recrystallisation and the formation of new minerals. Rocks are made up of minerals, and minerals themselves are composed of one or more of the natural elements. The compounds of different elements, e.g., carbon, copper, iron, aluminium, calcium etc., produce different colours. The colours of rock strata are further influenced by other factors. For example, limestone is white in colour,
but when quite near the shores, mud may be mixed with it to give it a grey colour. Metamorphosis may change colours: for example, sedimentary coal is brown in colour, and when subjected to heat and pressure bituminous coals are formed which are dull-black in colour.
In the above-said verse (15:28), the display of various colours in the newly formed strata of the Earth’s crust is referred to. Moreover this is the only verse in the Holy Quran where the word is used, and here it is used for those who possess knowledge of natural phenomena.
OTHER CONSTITUENTS OF CELLS
In addition to the above constituents of cells there are other complex substances, such as derivatives of corbohydrates which form cells of animals and plants; and lipid derivatives, such as waxes which form covering films in plants; or cutin and sebrin which function as water-proofing and evaporation-resisting materials. Similarly, ralated to fats are the sterols, complex ring structures which form the molecular framework of a number of vitamins and of animal hormones which play major functional roles.
Weathering also affects the colouration of newly sedimentary rocks. Rocks exposed to weather for a long time assume a different colour. The chief agents responsible for weathering of rocks are (1) Air (2) water (3) Temperature changes and (4) plants and animals. The methods by which they cause changes are of two kinds;
mechanical and chemical. It is only chemicals which cause change of colour. Air alone has no -effect on rocks but air and water together are the chief agents of weathering. Oxygen and carbon dioxide are the gases of the air which with water cause important chemical changes in rocks of all kinds. Oxygen and water attack the iron found as a constituent of many dark coloured minerals, changing it to ferric oxide (rust). That accounts for the yellow, brown and red colours of most rocks and soils. The carbonaceous materias of plants also cause change in the colour of soils. The red colour is due to oxidised iron, produced by the chemical weathering of some rocks. There are two classes of iron compounds, ferric and ferrous. The ferric are red, yellow and brown in colour. Ferrous compounds are almost colourless. Hence a reduction of ferric to ferrous compounds by the carbonacous material of the humus, results in a change from red soils to colourless and finally black soils.
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“He Who created you from inorganic matter”.
Composition of the Stars and Planets. A star is a globe of incandescent gas. It may be assumed that a star condenses out of interstellar material which is mainly hydrogen. As it contracts and the internal temperature rises, nuclear reactions begin. As stated earlier, the hydrogen nuclei fuse to form helium nuclei with a slight loss of mass and release of energy. The supply of hydrogen being not inexhaustible, drastic changes take place eventually. There are two distinct types of stellar population. Population I, consists pre-dominantly of very hot bluish or white stars, as well as interstellar gas and dust. Population II, the brightest stars are red giants with little interstellar material. Red stars are later stage of evolution. Here the interstellar material has been used up in the formation of fresh stars. It is suggested that with the passage of time, the sun will become a red star of larger diameter and greater luminosity than at present so that earth will become too hot to support life. At a still later stage this may be followed up by a rapid collapse of the sun into a very small dense star, radiating feebly because of continued gravitational contraction, like the companion of Sirius (double star).
Solar System. As already noted in Chapter II, several hypotheses concerning the origin of solar system have been proposed, such as Nebular hypothesis of Laplace, the Planetesimal hypothesis, the Tidal Disruption theory of Jeans and Jeffreys. The view now widely accepted is that the solar system is the result of excessive rotation of a gaseous ball which was made up of free atoms. Hydrogen atoms were probably more abundant and the other heavier types were present in lesser quantities. The sun was formed when most of the atomic gas, hence most of the hydrogen, gravitated towards the center of the ball. Even today the sun is composed mostly of hydrogen atoms. A swirling belt of gas remained outside. Eddies formed in this belt and in the course of time it broke up into a few smaller clouds. These spinning spheres of glowing gaseous clouds were probably the early planets.
THE STORY OF
Chemical Evolution on the Earth (in relation to the Appearance of Life).
Thus to begin with, the Earth was probably a glowing mass of free hydrogen and other types of atoms, which eventually became sorted out according to weight Heavy ones such as Iron and Nickel settled down in the center of the Earth where they are still present. lighter atoms such as Silicon and Aluminium formed a middle layer. The very lightest such as Hydrogen, Nitrogen, Oxygen an Carbon, collected , collected in the outermost layer (Fig. 13).
|fig. 13.—the eLEMENTS COMPOSING THE EARTH
The elements became sorted out according to weight. Heaviest ones sank into the centre, relatively light ones formed the middle shell and extremely light ones formed the outer shell.
Temperatures must have been too high in the beginning for atoms to become linked together in the form of stable compounds, as the bonds would have been broken as fast as they might have formed, but under the influence of the cold of cosmic space, the earth began to cool down gradually. With the passage of time as the temperature of the earth became low enough, relatively stable compounds came into existence. Compounds thus formed multiplied and free atoms disappeared.
As noted above, the outer layer of the gaseous ball that made the early earth consisted mainly of Hydrogen, Oxygen, Nitrogen and Carbon atoms. As it cooled down enough to allow the formation of compounds, these four types of atoms played an outstanding role. As a result, even today 95% or so of the substance of all living matter consists of just these 4 elements.
On the basis of their known chemical properties, these elements presumably became linked into some half a dozen compounds as below:
The first three of these compounds came into existence not only on the Earth but on the other planets as well. For example, enormous amounts of water, methane and ammonia of undoubtedly abiogenic origin, are present today on the surface of the planet Jupiter in the form of thick permanently frozen solids. Methane and ammonia are also present on Saturn, Uranus and Neptune. Apparently these compounds must have been formed there as on Earth, but being too far away from the sun the surfaces of these planets probably froze before any further bonds could possibly occur. On the hot earth, however, the early compounds could interact further and give rise to new compounds later on.
Origin of First Mountain Ranges and Collection of First Compounds in Sea Water. As the hot gas ball of the Earth, gradually cooled down temperatures became low enough to allow some of the gases to liquefy and some of the liquids in turn to solidify. While passing from the liquid to the solid state, the very dense solids, like iron and nickel, sank into the liquid and as stated already, settled down in the center of the earth; while others floated like great icebergs, some sticking out of the liquid higher than the others, like cork and wood floating in the water because of the specific gravity being different in each case (Fig.l4a). We know that the earth’s crust is composed chiefly of two kinds of rocks, known as granite and basalt. The granite with a specific gravity of 2.7 and the basalt with a specific gravity of 3.0, both floated in the liquid earth mass whose specific gravity was 5.7. But granite stuck out further like cork in water while basalt floated like wood (Fig.l4b). Consequently, when the entire surface had cooled down to a solid, it must have been irregular, with
Fig.l46.”Masses of Canaanite and Basalt floating in liquid rock or Magma.
granite standing higher than the basalt. Thus the middle shell of lighter substances in the gas ball of the earth (Fig. 13) gradually solidified to become the earth’s crust, and the wrinkles and folds so formed gave rise to first mountain ranges. Surrounding this crust was the outer atmospheric covering which at temperatures then prevailing still remained gaseous. Up to this stage water was only present in the atmosphere in the form of clouds which surrounded the earth’s crust, for probably hundreds of miles above its surface. As the temperature of the solid earth underneath was too high, water could not stay there in liquid form. As soon as it touched the surface of the earth, it evaporated immediately. But as the earth’s crust became cool enough to allow liquid water to stay on, rains started. There was a continuous downpour for hundreds of years. Rivers flowed down from the heights of early mountains and water collected in the depressed areas to form the early seas (Fig. 14c). Atmospheric gases-methane, ammonia, carbon, dioxide and hydrogen cyanide-were washed down from the atmosphere into oceans. Salts and minerals also collected in the ocean water. These were obtained from three different sources, firstly from the land surfaces brought down by the rivers, secondly from the sea-shores, dissolved by the violent tides, thirdly from the Fig. 14c. “Early seas formed over basalt interior of the earth brought by
the molten lava bursting into the seas. This dissolving of gases and minerals into the ocean water was an important event with regard to the origin of life on the Earth.
ROLE OF FIRST COMPOUNDS IN THE ORIGIN OF LIFE
Role of Water. Life is not possible without water and water has always been the most important single component of living matter. It makes 60 to 90 per cent of the weight of living organisms, being more abundant in young cells or young organisms than the older ones, and in lower aquatic animals than in higher terrestrial types. Three-fourths of the earths surface today is covered with water and this is of great importance in the economy of living objects. It plays a fundamental role in life (a) in its being the best solvent for inorganic substances and for many organic compounds; (b) it favours the dissociation of electrolytes dissolved in it; (c) it has high surface tension; (d) it has got great fluidity; (e) it has a great capacity to absorb heat. It is thus an excellent medium for chemical reactions to take place. Moreover water was originally the only good source of hydrogen and oxygen. Both of these elements form the basis of building material of living bodies. But as noted already, free atoms of hydrogen and oxygen became unavailable soon after the origin of the earth. Water molecules then became the chief source of supply of these atoms. Even today water is the only usable source of hydrogen and one of the important sources of oxygen. Water thus took the role of a key which opened the door to life. The gases and minerals dissolved in the ocean water reacted with each other and with the water itself to form the early organic compounds and the subsequent chemical evolution led to the emergence of most complex organic compounds which became the precursors of the units of life. The point shall be amply illustrated in the following pages. After the life started on the earth, water still maintained its fundamental role in its control.
The Holy Quran says:-
“And We made from water everything living”.
“And He kept His control post (of life) on water”.
Role of carbon. The chief actor on the stage of life set by water was Carbon which is a versatile element, with convalence of four, i.e., it can link with four atoms of same or of different kinds. Apart from this, carbon atoms may link up directly to other carbon atoms to form chains of varying lengths. Such as: But these are not open chains, they form parts or fractions of whole molecules in which various other atoms or groups of atoms are attached to the carbon. For example if carbons of two or more methane molecules are joined into a chain, their hydrogen atoms will be bonded to carbon as follows:-
No other element approaches the self bonding capacity displayed by carbon.1” The compounds like methane in the early oceans must have reacted with other compounds present there, giving rise to a large variety of carbon containing compounds. This happened to be a very important event in the evolutionary history of living matter, because carbon compounds provided the basis for the synthesis of numerous molecules which constituted the structural framework of living bodies, the carbon compounds are thus known as Organic Compounds.
‘Silicon can do this but only up to a limited degree. It can, however, give huge structures when bonded through oxygen atoms as: But silicon is not found intensively in living organisms.
COMPOUNDS OF CARBON
Among the numerous organic molecules which came into existence in the early seas, five categories became especially significant from the point of view of later developments
These are (1) Sugars (2) Glycerines (3) Fatty acids (4) Amino acids and (5) Nitrogen bases. The structural make up of these compounds is shown in (Fig. 15). Note that in each case a carbon skeleton, either a chain or a ring, forms the basis of the compound and that various group patterns of hydrogen, oxygen and nitrogen are linked to it.
- Sugar. — Sugars are short chains of carbon; 6 or 6 are common in organic matter. Other elements are H and 0. Sugars with five carbons are Pentose, those with 6 carbons are Hexose.
- Glycerines. – Glycerines are chains of three carbon atoms. Other elements are same as in sugars, i.e, H and 0.
- Fatty Acids. – Fatty acids are chains of carbon atoms 2-20, other atoms are H and 0. Carboxyl group COOH is at the end
- Amino Acids. – They also contain COOH group. In addition contain NH2 (amino group). Both groups are attached to carbon; also attached is a carbon skeleton (R) which varies in structure considerably.
- Nitrogen Bases. – There are two major sub-groups, PURINES and PYRIMTOINES. Both contain ring structures of C and N; ring being single in pyrimidines and double in purines.
Sugars. Here carbon skeleton is a short chain which has five or six carbon atoms and they are particularly common in living matter. C5 sugar is called Pentose, an important example is ribose (C5H10O5 ). C6 sugar is called Hexose, example is glucose (C5H10O5 ). In sugars as in other carbohydrates the only elements attached to carbon are hydrogen and oxygen.
Glycerines. Also contain the same elements as sugar i.e., Carbon, Hydrogen, and Oxygen; but contain three carbon atoms in a chain.
Fatty acid. They also contain the same three elements as sugar and glycerine but carbon chain may vary from 2-20 or even more atoms. One end of a fatty acid molecule always terminates in COOH group called the carboxyl group which gives the molecule its acid properties.
Amino-Acids. Like other acids they also contain carboxyl group and in addition carry NH2 or amino group. Both the carboxyl and amino groups are bonded to a carbon atom. To this atom is also attached a chain or ring of carbon skeleton.
Nitrogen bases. Nitrogen is also invariably present in Nitrogen bases which include two major groups Pyrimidines and the Purines. In both of them the molecular skeleton is always a ring containing carbon as well as nitrogen atoms, the ring being single in Pyrimidines and double in Purines.
Under conditions that prevailed in the primitive earth and on the basis of structural configurations it is presumed that the above five categories of organic compounds might have been formed as follows:-
Presence of cyanide could have provided useful material for Carbon and Nitrogen Rings.
Oparin in his book, ‘The Origin of Life’ proposed that earth in its early stages had a reducing atmosphere of Methane, Ammonia, Water and Hydrogen, and that organic compounds might be formed under these conditions. The hypothesis was accepted and followed successively by famous scientists like Urey and Bernal, and in 1953 was submitted to rigid experimental control by Stanley L. Miller in the Chemical Laboratory of the University of Chicago in U.S.A. Miller constructed a special apparatus in which for a longest period of time (one week) was produced an electric discharge in an atmosphere constituted precisely by aqueous vapours, methane, and ammonia. The water circulated continuously in changing states, from the liquid state in the boiling flask to the gaseous state in correspondence to the electrodes, and then again for condensation in the liquid state in the flask. It was observed from the first day that the water was light yellow in colour and then turned decidedly to dark red at the end of a week. It was evident that the colour depended on some organic compounds formed during the experiments. These compounds were submitted to a very precise chemical analysis and were identified as Amino acids.
Source of activation energy and reaction energy for the above Reactions. Two different sources of energy were undoubtedly available on the primitive earth. One of these was the powerful electric discharge in lightning which must have occurred almost continuously in the early cloud-laden atmosphere. Secondly, although light rays could not pass through water vapours forming dense clouds around the earth for a long time, high energy radiations of the sun, such as Ultraviolet rays, X-rays and others could however pass through them. The energy from these two sources could have either acted directly on the gas molecules of the atmosphere and the resulting compounds could then have been washed down by rains into the seas. Or the reactions could have taken place in the waters of the oceans where methane and all other necessary ingredients were present in solution.
The early organic compounds described above, subsequently made possible the synthesis of macromolecules with unique chemical properties.
LATER ORGANIC COMPOUNDS
Presumably five major and several minor groups of new molecules emerged from the interactions of early organic compounds. Later, these came to have particular significance in the origin of life. The five major groups were:(l) Adenosine Phosphates (2) Polysaccharides (3) Fats (4)Proteins (5)and Nucleic acids.
Adenosine-Phosphates. These belong to a highly important class of compounds known as Nucleosides. A nucleoside molecule is a combination of a simple sugar and nitrogen base. For example:
Ribose (Pentose sugar) + Adenine (Pyrimidine)= Adenosine (Nucleoside)
Various kinds of sugars and Nitrogen bases in the early seas must have combined to form various nucleosides, including Adenosine. Plenty of phosphates could also be available in sea water which when combined with adenosine formed
Adenosine + 1 Phosphate = Adenosine Monophosphate(AMP)
Nucleotides- Nucleotides ( Adenosine + 2 Phosphates = Adenosine Diphosphate (ADP)
Adenosine + 3 Phosphates = Adenosine Triphosphate (ATP)
Biologically occurring derivatives of phosphorus play a Key role in the energy transactions of living organisms. ATP is a ‘high energy compound’. The expression ‘high energy compound’ or ‘high energy bond’, as used in biochemistry, has a meaning quite different from the physio-chemical significance of high energy bond. As noted early, in physical chemistry a ‘high energy bond’ is one which requires large amount of thermochemical energy for dissociation. In biochemistry, on the other hand, the expression ‘high energy bond’ refers to the large free energy emissions associated with definite reactions of that bond such as hydrolysis or group transfer.
ATP (Adenosine triphosphate) has got one phosphate group more than ADP (Adenosine diphosphate). The addition of this third phosphate group to ADP requires a great deal of energy which may be provided by various energy yielding reactions, particularly decomposition reactions of organic material like sugars and fatty acids. The ATP so produced is a rich source of energy. If the bond between the second and third phosphate groups is broken, the energy released becomes available for the support of other chemical reactions. ATP thus serves as an intermediate product, it traps energy from one source and makes it available for a different reaction. This has got a great significance in the living matter today. For example the carbohydrates in the animal tissue cells, such as muscle cells, are utilised as a direct source of energy which is liberated when glycogen or glucose is broken down through a long series of phosphorylated intermediates and finally oxidised to carbon dioxide and water. Possibly, ATP has been the basic unit of energy transfer throughout the ages even before living matter existed. Solar energy continued to supply energy for reactions but AdenOsine phosphates provided an alternative to it as a readily usable chemical energy source which could produce reactions independent of solar energy. This phenomenon had an important role in the origin of life because reactions involving the synthesis of complex organic compounds in living bodies cannot avail energy from physical sources directly. They require chemical energy and this is supplied mainly by ATP.
Polysaccharides. These are combinations of a few or many monosaccharide molecules. Polysaccharides may be composed of a single kind of monosaccharides (simple sugars), as in the case of Glycogen which contains several thousands glucose units; or Cellulose in which 2000 units are contained: or they may be composed of two or more kinds of monosaccharides.
The chemical process in which molecular units of similar or identical types are synthesized into a single larger molecule is known as Polymerisation.
Properties of Polysaccharides. (1) Building materials. (2) Energy source.
Fats. These are combinations of glycerine and fatty acids.
1 Glycerine molecule + 3 Fatty acid molecules = 1 FAT molecule.
Properties of Fats. (1) Building material. (2) Energy source.
There are many varieties of Fats depending on the types of fatty acids taking part in their synthesis. Living matter could not have come into existence with fats, polysaccharides and ATP alone in the early seas. Its origin became possible as the result of formation of protein and nucleic acid macromolecules.
Proteins. These are polymers of amino-acids. Some two dozen different types of amino-acids exist and any or all of these may be present in a protein in any number and any sequence. In many proteins as many as 100,000 or more amino-acids may be present. At the cellular and subcellular levels proteins provided building block units of far grater diversity as compared to polysaccharides, fats, water and other inorganic materials. Just as a chain of several hundred links can be looped and twisted into innumerable three dimensional shapes, so may a chain of protein be looped, coiled and twisted into a very large number of molecular shapes. It was due to proteins that a most complex and well finished structure as that of a living organism became possible.
The structure of proteins enabled them to function as enzymes and thus increased the speed of biological reactions tremendously. Reactions which could have taken centuries before the origin of proteins, could now occur within minutes and seconds. Proteins not only enhanced the speed of reactions but they also controlled the types of reactions that could occur in living matter.
Nucleic acids. In the early phase of the molecular evolution only simple molecules were formed. Later, more complex molecules such as amino-acids and proteins came into existence. In the more advanced phases of this period, it is believed that there appeared a molecule with two entirely new properties-(l) The ability systematically to direct the formation of copies of itself from an array of simpler building blocks. (2) And the property of acquiring new chemical configurations without loss of ability to reproduce. These properties, self-duplication and mutation, are characteristics of all living systems and they may therefore be said to provide an objective basis for defining the living state. This molecule was Nucleic acid.
Nucleic acids are high polymers of nucleotides. (Nitrogen Base + Simple Sugar + Phosphates) n = Nucleic Acid, where ‘n’ indicates large number. Nucleic acid molecules are as large or even larger than the most complex proteins. There are innumerable structural varieties of Nucleic adds. Any number and any sequence of nucleotides may be present in its molecule.
We may explain further the properties of nucleic add described above:-(l) Nucleic acids are carriers of biological information in a structural code. The following shall illustrate-when a person speaks P-A-K-I-S-T-A-N, it gives us the information that he says Pakistan. But the above letters together make the word Pakistan only when they are spoken in the above sequence. Similarly the sequence of nudeotides in a given nucleic acid carries information or a set of instructions how to build proteins. The nucleotides sequence determines what kinds of amino-acids will make up a protein and in what order they will be linked together. Thus the specific configurations of differently structured proteins depend on the specific arrangement of the nucleotides in a nucleic acid molecule. (Fig. 16) shows information code and protein synthesis. If ‘1-2-3-4-5 represents a portion of a nucleic chain, the structural characteristics of the nucleotide segment 1-2 could be such that only amino acid ‘a’ could attach there. Similarly only amino acid ‘b’ might be able to attach to the nucleotide segment 2-3 and amino acid ‘c’ to the segment 3-4 etc. If then the amino acids become linked together and form a protein, the sequence of amino acids will have been determined by the coded information contained within the nucleic acid chain.
Thus in all living organisms today, proteins are synthesized according to building instructions contained in nucleic acids. This is of great importance because proteins provide the building blocks and
Fig. 16-Nucleic acid provides information code for building protein molecules.
also function as enzymes which control all reactions in living matter. In short all the life processes are ultimately controlled by Nucleic acids.
(2) Auto-reproduction-Depending on the above information carrying property is the unique property of Auto reproduction or duplication. The molecules of nucleic acids are able to synthesize new molecules perfectly identical to the model. The process is similar to the control of protein-synthesis by nucleic acid. In the building of proteins, the raw material was amino acids and here the raw material is nucleotides. Thus a nucleic acid molecule is able to reproduce itself without the aid of any other controlling agency. (Fig. 17) indicates the process of nucleic add reproduction, (A) A preexisting nucleic acid molecule (Shaded) surrounded by raw materials (i.e., nudeotides) needed for the construction of a nucleic acid duplicate.
- B) A nucleotide of a given type has affinity for a corresponding. component of a nucleic acid. The respective nucleotides therefore get attached in matching sequence to the pre-existing nucleic acid. (C) The nucleotides having taken up their positions link up with Another. (D) The new nucleic acid. molecule so created separates from the original model. Model and replicas are identical in composition.
The first nucleic acid probably came into existence through random polymerization of random nucleotides. But once the first nucleic acid appeared, it multiplied by the process of duplication. Thus reproductivity which is a peculiar characteristic of living beings, actually started at the molecular level, before the origin of first living units. The information code for the synthesis of particular proteins passed on from one generation of nucleic acid to the other, so that each generation could recreate the protein types of its ancestors.
(3) Mutation-Related to the property of Auto-reproduction is another unique property of nucleic acid which later became the characteristic of life. It is the property of acquiring new configuration without loss of ability to reproduce. Molecules of nucleic acids are most stable. They are not easily affected by the physical and chemical forces operating on the earth, as most compounds do. But occasionally certain chemical and physical agents such as ultraviolet rays succeed in producing minor changes in their structures. These changes may be (a) the alteration in structure of one of the component nucleotides, (Fig.l8a); (b) Or a short sequence of
nucleotide chain may be detached from the rest of the chain at one particulate place and reunite at a different place; or in an inverted position; or
Fig. 18a. -NUCLEIC ACID. MUTAION
the sequence may be correct, but during reproduction a wrong type of nucleotide gets attached at an otherwise correct position. (Fig. 18b).
Whereas metabolic errors or deviations in other compounds are constantly erased or repaired by the turnover process, the errors in nucleic acid synthesis become permanent. The altered nucleic acid becomes stable and later reproduces the changed condition which is transmitted from one generation to the other. Such stable alterations are called Mutations.
Fig. 186.-OTHER ERRORS IN MUTATION.
Thus nucleic acids on the early earth not only reproduced their own kind but some of the descendent molecules became different from their ancestors. These differences accumulated through successive generations, so that entirely different and varied types came into existence.
As the nucleic acid molecules changed with the passage of time, the protein molecules whose synthesis depended on nucleic acid, changed accordingly, giving rise to new and diverse types of proteins. And proteins being the building blocks, diverse types of organisms came into being.
Thus the chemistry of the earth took entirely a new turn with the origin of nucleic acids. They carried genetic information from one generation of molecules to the other and controlled the protein synthesis accordingly. Moreover nucleic acid maintained its stability despite acquiring new chemical configurations. Some of the chemical processes on the earth thus ceased to occur at random and became strictly controlled both as regards their permanence as well as change.
A summary of Later Organic Compounds is given below in (Fig. 19)
- Adenosine Phosphates
- Nucleic acids.
(1) Adenosine phosphates (Nuclcotides).
Ribose (Pentose sugar) + Adenine (Purine)= Adenosine (Nucleosidcs).
Adenosine + 1 Phosphate = Adenosine Monophosphate(AMP) Nucleotides
Adenosine + 2 Phosphates = Adenosine Diphosphate(ADP)
Adenosine + 3 Phosphates = Adenosine Triphosphate(ATP)
Properties-1. Energy Trappers and Energy Donors.
Source of Energy-Decomposition of sugars and fats.
(2) Fats-1 Glycerine molecule+3 fatty acid molecules = 1 fat molecule.
Properties-(1) Building materials. (2) Energy source.
There are many varieties depending on types of fatty acids.
(3) Polysaccharides-Polymers of sugar molecules. Energy source-ATP.
Example-Glycogen contains several thousand molecules of simple sugar. Properties-d) Building materials. (2) Energy source.
(4) Proteins-Polymers of amino acids.
100,000 or more amino acids may be present in a protein molecule. Some two dozen types of amino acids arc known. Any number, any type and any sequence may be present in a protein molecule. .Properties-(1) Building materials. (2) Enzymes.
(5) Nucleic Acids-Polymers of nucleotides. Some molecules are as large or even larger than protein.
Properties-W Information code. (2) Reproduction. (3) Mutation.
Fig. 19.-LATER ORGANIC COMPOUNDS (SUMMARY)
The events described so far constitute molecular evolution. To describe briefly seven types of chemicals originated gradually in due course of time and accumulated in the early oceans:-
Inorganic Substances-(1) Water (2) Minerals.
Organic Substances-(1) Adenosine phosphates (2) Carbohydrates (3) Fats (4) Proteins and (5) Nucleic acids.
The subsequent events may be described as Prebiological stage of chemical evolution i.e., the actual formation of first living units or cells from the above. compounds.
PREBIOLOGICAL PHASE OF CHEMICAL EVOLUTION.
(Birth pangs of life on the earth)
Cells are the basic living units. They are microscopic watery drops which contain many types of organic and inorganic compounds. With the origin of cells the chemical evolution still continued, molecules still continued to produce new molecules, but out of the organic molecules emerged entirely a different creation, with the properties of life. This happened to be a most important landmark in the evolutionary history of the earth.
It is estimated that the first cells appeared 200 million years ago. The details of origin of first cells is not clear. The following is a general outline of the sequence of events which led to cell formation, consistent with the laws of physics and chemistry known today.
Origin of Cells. The first cells may have been produced in the following ways:-
Somehow or other the organic compounds described above assembled into small cohesive drops and by virtue of the properties of the aggregated material, life began to appear in these drops. The first question arises as to how could the aggregation of these organic compounds occur. The sea water in which they were present was too dilute a medium in which they could keep proper concentrations. Moreover it was difficult for all the necessary ingredients to assemble all at a time and stay in that condition for a sufficiently long period, because after chance contact the mighty waves of the sea were sufficient to disperse them again. Therefore it is much more likely that the assemblage of various molecules occurred at the sea shore, where they could stick to appropriate surfaces on solid ground.
ADSORPTION or PROPERTY OF STICKINESS is a surface phenomenon in physical chemistry and molecules of sugars, fats and proteins get adsorbed to various surfaces. Nucleic acid molecules are also very much adsorbable. On the other hand, fine particles of sand and clay are excellent adsorbing materials and plenty of them must have been present along the sea shore. Most probably some of the molecules got adsorbed into clay at random, at different places. More molecules of the same or different types might have been added later. Thus there was ample chance for all the key molecules to assemble inside the tiny little spaces in clay where they could form adequate concentrations to react with each other. The reactions could have been accelerated in the tidal zones, by evaporation of water.
It is not necessary that all the complex organic compounds such as polysaccharides, fats, proteins and nucleic acids were first formed in the ocean water and then. aggregated into clay. Rather it is more likely that simple organic compounds such as sugars, fatty acids, amino-acids and nucleotides got adsorbed into day where the macromolecules of proteins and nucleic acids etc. got synthesized, because their synthesis required the close proximity of the necessary ingredients and the energy sources.
It has been experimentally demonstrated that if concentrated mixtures of amino acids are heated under NEAR DRY CONDITIONS, protein like compounds are formed. Similarly mixtures of other appropriate starting compounds heated under almost dry conditions can yield products having some of the characteristics of nucleic acids. The tiny pockets in clay therefore provided favourable environments for the concentration and mutual reactions between raw material molecules. Once the nucleic acids were formed, they must have been followed by protein synthesis and some of the proteins enzymes led to the formation of Polysaccharides and tats etc.
Mixtures containing fats and proteins have got the property of forming surface films. It is a common experience that if a cup of boiled milk or a plate of hot custard are allowed to cool, a thin film forms at the surface. Certain proteins have also got the property of forming precipitates out of solution which turn into granules or (threadlike structures). For example, during bleeding, fibrinogen in the blood plasma gets converted into fibrin (a threadlike structure) and a clot is formed. Polysaccharides, like cellulose (in plants), also can make films or fibrils. Thus some of the organic compounds in the tiny pockets in clay must have constructed external boundary membranes and internal network of fibrils in which the members of the assembly, i.e., water, minerals, ATP, Polysaccharides, fats, proteins and nucleic acids got enclosed. The individual units so formed came to be known as cells. Being protected by external membranes they could remain as separate individuals, even if they were washed into the sea later.
The first cells on earth must have come into existence in various parts of the world and their origin must have been preceded by numerous trials and errors. For a long time the right type of raw material molecules could not have aggregated together; or even after aggregation they may not have been in correct proportion; or if they fulfilled all the requirements for reactions to occur and proceed in the right direction, they could have been washed into the sea before the synthesis of end products could be completed. On the other hand the mixtures of raw materials, instead of remaining in the state of near dryness for an adequate period, could have dried up completely; or if all went well, up to the stage of cell formation, the cells themselves might have dried up and destroyed inside their places of birth by the heat of the sun. Yet after so many false starts and incomplete endings which continued for millions of years, some of the cells could leave the clay, to safely enter the sea water. With the conditions prevailing on the earth and the kind of materials that had accumulated in the early oceans, the origin of first cells was not a matter of chance but a matter of time.
It is not necessary that the above description corresponds in details to the actual events that took place in the remote past but such processes that could result in cell formation are plausible within the scientific domain of physics and chemistry.
The above description regarding the origin of life is based on the research work, by the world scientists during the last several decades. The evolutionary history beginning with unicellular organisms up to the appearance of Man shall be described later, but we must state at this juncture what the Holy Quran said fourteen hundred years ago, about this phase of chemical evolution passing on to biological and ultimately leading to the emergence of Man.
Let us point out at the outset that the Holy Quran is self explanatory and clarifies itself by presenting a subject in various ways and in different contexts, so as to make things easily understandable. Thus it is said:
“We have explained to mankind by displaying different aspects of things in this Quran, with every kind of similitude.”
It has been explained already in this chapter, the phase of chemical evolution leading to the emergence of life cells which form the initial stage of Biological evolution and which ultimately led to the appearance of man on the stage of life: As we have noticed life originated from the inorganic materials of the earth. The Quran says
“It is He who created you from dust (inorganic matter)”.
The role of the first compounds in the origin of life, of which water has been the most important single component have been explained. Water as said earlier, took the role of key which opened the door to life. The Quran says:
“And it is He who has created man from water”.
It means that the presence of two essential elements water and inorganic material of which the carbon was most important, took the basic role in the emergence of life. The Quran says:
“It is He who created you from clay”, i.e. the combination of water and other inorganic materials.
A wrong notion is prevalent that the Creator first prepared the mould of man out of clay, gave it life and named him Adam. Then He bisected the side of his body and got out of it his a female companion. From then onwards started the progeny of man. This is in fact a Biblical story which our commentators have monkeyishly copied, due to their ignorance of the scientific facts of chemical evolution followed by biological evolution, each one of which lasted for millions of years.
According to the Holy Quran, life came into existence not from a lumpsum of day but from the extracts of clay which gradually reached the stage of man. The Quran says:
“And We created man from the extracts of day”.
What is this extract of day? It is the compounds of carbon which eventually evolved in to the later organic compounds such as Adenosine phosphates, polysacharides, fats, proteins and Nucleic Acids in the company of minerals.
As stated earlier, the organic material in the sea water stuck to the clay present on sea shores and formed a preliminary step in the creation of life. This combination however could not occur without the property of adsorption present in the molecules of organic compounds. The clay on the sea-shore was the excellent adsorbing material; the same property being also present in the fats and proteins etc. The Quran says:
“Verily We created them out of sticky clay”.
As stated earlier, concentrated mixtures of Amino Acids when heated to near dryness, protein like compounds are formed. Similarity mixtures of other appropriate starting compounds, when heated under almost dry condition, can yield products having some of the characteristics of Nucleic Acids. This condition of near dryness could occur at such sea shores which were not affected by frequent tidal waves, for quite some time.
The Quran says:
“And verily We created man from old physically altered mud which after a lapse of time reached the stage of near dryness”.
“Most of the commentators have wrongly interpreted the word in verse (15:26) above as ‘putrified mud’. It is an established fact that decay was unknown on the earth before the orgin of bacteria which are living objects. The word actually means “old mud which with the passage of time had undergone physical and chemical changes; not putrifaction which is a biological phenomenon”.
“He created man from mud nearly as dry as pottery (the stage of near dryness).
Thus in the verses described above the Quran provided significant pointers to the origin of life, in its own particular way: from earth (or inorganic matter); from water; from clay (or wet earth); from sticky adsorbent clay; not clay as a whole but from extracts of clay i.e., its active principles which were the precursors of the units of life; from old mud subjected to physical and chemical changes; from mud which reached the stage of near dryness
The above was proclaimed in the 7th century A.D., by one who did not know how to read and write before revelation came to him. How beautifully the story of the creation of life was disclosed, at a time when human knowledge was extremely rudimentary. Even in the present age of advancement, how many people are there, other than the scientists, who know these facts?
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The distribution of tasks in the universe. (51:4)
The planning and readjustment of the contents of the universe. (79:5)
All objects in nature consist of chemicals. Even the living objects originated from chemicals. There are 92 different known elements which form the ‘building bricks’ of the universe. These ‘bricks’ can be transformed one into another. Mendeleev (1834-1907), a Russian scientist, discovered the Periodic law which is a statement of the fact that “properties of chemical elements are periodic functions of their atomic weights”. That is, when they are arranged in order of their atomic numbers, elements having similar chemical and physical properties occur at regular intervals. Table of chemical substances illustrating the Periodic law is known as the Mendeleev Table (F-‘-
Fig.lO-.A PART OF THE MENDELEEV TABLE
The elements are arranged in this Table from No. 1 to No. 92, in order of their atomic weights. The elements in turn consist of tiny particles called atoms. An atom is the smallest complete unit of an element. For example, a carbon atom is the basic unit of the element carbon. Each element is given a chemical symbol. For example, the symbol of carbon is C and that of oxygen is 0. Under certain degrees of temperature, pressure and concentration, all atoms except a few are liable to attach to and remain linked to certain other atoms. Such combinations of two or more atoms are called compounds. The binding forces which keep the atoms in a compound linked together are called Chemical Bonds. Each compound has a particular chemical name and a particular formula, which indicate what kinds and what numbers of atoms are present in that particular compound. For example, carbon dixoide is technically the compound of carbon and oxygen and is represented as CO2 i.e., one atom of carbon is linked with two atoms of oxygen.
How are the chemical bonds between atoms produced? The atoms of all elements are constructed out of components collectively known as fundamental elementary particles which are of 3 types: Protons, Neutrons and Electrons. Protons and Neutrons are situated in the centre of an atom and are collectively known as Atomic Nucleus. Electrons revolve round the nucleus. (Fig. 11A). A Proton has a Mass (Weight) which is the same for all protons and is given the arbitrary unit Value 1. Neutron is the same as the Proton with no charge and thus its Mass is also 1. Mass of an Electron is 1/1800 and thus it is negligible. So the total mass of a whole atom is concentrated in its nucleus.
The mass of an atomic nucleus, i.e., the number of protons and neutrons present determine the Atomic Weight. For example, the simplest type of atom is that of Hydrogen. Its nucleus consists of a single proton and there is a single electron on the outside; neutron is absent. Since the nucleus of hydrogen has a mass of 1, its atomic weight is said to be 1. Next higher element is Helium. Its atomic weight is four and its nucleus contains 2 protons and 2 neutrons. Thus the atomic weights from element No. 1, i.e.. Hydrogen to element No. 92, i.e., Uranium, go on rising stop by step. Uranium is the heaviest of all elements. Its atomic weight is 238. Under certain conditions elements are interconvertible.
In addition to their mass, the elementary particles, of an atom also have certain electrical properties. Neutrons, as the name indicates, are electrically neutral. Protons are electrically positive, i.e., each proton carries one unit of positive electric charge. Electrons are electro-negative, each unit carrying one unit of negative charge. In each normal atom the number of protons is exactly equal to the number of Electrons. For example, the Oxygen atom has got eight protons positively charged and eight electrons negatively charged. Similarly in one atom of Sodium there are 11 positively charged protons and 11 negatively charged electrons. It means that the positive and negative charges in an atom are equal and thus an atom as a whole is electrically neutral.
Number of Electrons (or Protons) in an atom defines its Atomic Number. Thus hydrogen has Atomic No. 1, uranium has Atomic No. 92.
The electrons of an atom move around the nucleus at a speed of the order of 100,000 miles per second. An atom is thus like a miniature solar system. The nucleus is comparable to the central sun and electrons are comparable to the planets. Just as gravitational forces keep the planets in orbits around the sun, so also do forces of electric attraction keep the negatively charged electrons in atomic orbits around the positively charged nucleus. Moreover, just as the planetary orbits are situated at specific distances from the sun, so also are the electrons’ orbits located at specific distances from the atomic nucleus. The paths of the electrons at these distances may be said to mark out specific shells one outside the other known as Quantum Shells. Each shell can hold only a fixed maximum number of electrons. The first shell closest to the atomic nucleus can hold a maximum of 2 electrons the second shell a maximum of 8 electrons. Known maximums also characterise all other shells. In the case of a Hydrogen atom the single electron normally orbits in the first shell. As this shell could hold two electrons, Hydrogen is said to have an ‘incomplete’ or ‘open’ shell. By contrast an atom of Helium possesses two electrons both orbiting the first shell. In this instance the shell holds the maximum possible number of electrons and it is said to be ‘complete’ or ‘closed’. (Fig. 11B). In an atom of Oxygen 8 orbital electrons are present. Two of these fill the first shell and the remaining six occupy the second. Since the second shell could hold 8 electrons, this shell of Oxygen is open. In atoms generally electrons fill the orbital shells from the innermost outwards. Thus depending on the particular number of electrons present in a given atom, the outermost shell is either complete or incomplete. An atom is electronically and chemically stable only when all of its electron quantum shells are complete. A Helium atom possessing just the two electrons necessary to complete the first shell, is electronically entirely stable. It is also quite inert chemically, that is, it is unable to react with other atoms. Similar is the case with elements like Neon, Argon, Krypton, Xenon and Radon called inactive or inert gases. In the atoms of all other elements the outermost shells are incomplete and such atoms are electronically unstable. If appropriate kind and appropriate number of such atoms come into mutual contact, their incomplete outer shells may make them undergo a chemical reaction. The result of such a reaction is the formation of chemical bonds between the atoms, i.e., a chemical compound is produced. Thus the chemical properties of atoms are determined by their outermost quantum shells.
Ions. Every atom has a tendency to complete its outer shell and so to become electronically stable and this is the underlying cause for chemical interactions among atoms.
Now let us see how an originally incomplete shell becomes complete. (Fig. 11C). Consider an atom of Chlorine. Of the 17 orbital electrons, 2 form the first complete shell, 8 a second complete shell and remaining seven an incomplete third shell. Thus a Chlorine atom can satisfy its strong tendency for completing its shells by gaining one more electron in its outer shell. Consider now an atom of Sodium. Of the 11 electrons present in this atom, 2 form a first complete shell, 8 a second complete shell and the remaining one lies in a highly incomplete third shell. If this atom were to lose its single electron in the third shell, practically its second shell would then become the outermost shell. Thus the atom would become complete and stable.
In other words Chlorine is unstable because it has one electron short and Sodium is unstable because it has one electron surplus, in their outermost shells respectively. In view of this both atoms could become stable simultaneously, if a single atom is transferred from one atom to the other. Actually this can happen under certain appropriate conditions, and such a reaction is called an Electron-Transfer reaction.
Such a reaction may take place between more than two atoms; and the electrons transferred may be more than one. In electron transfer among two or more atoms, those atoms which loss electrons are called Electron Donors and those which gain them are called Electron Acceptors. Now why should an atom, say for instance, of Sodium always be a donor and that of Chlorine an acceptor. This is because 7 negatively charged electrons of Chlorine and their oppositely charged nucleus are attracted towards each other with a much stronger force than the one between a single negatively charged electron of Sodium and its nucleus. Thus it is exceedingly difficult to dislodge as many as seven electrons in one batch. Hence Chlorine will always act as an acceptor. Thus with two suitable atoms close to each other, the one containing a lesser number of electrons in the outer shell will become an electron donor and the one containing a larger number will become an electron acceptor. We may note that electron donors are commonly known as Metals and electron acceptors as Non-Metals.
As electrons are negatively charged, their transfer from one atom to another results in important electrical changes. Let us again take for example the transfer reaction between Sodium and Chlorine atoms. An atom of Sodium is electrically neutral because it contains eleven positively charged protons and eleven negatively charged electrons. After one electron is transferred from Sodium to Chlorine atom, the Sodium atom becomes positively charged. Similarly the Chlorine atom which was neutral before transfer took place, became negatively charged after it received an additional electron from Sodium. Atoms or groups of atoms carrying electric charges are called Ions. Substances with opposite electrical charges are attached to each other through electrostatic force. Thus the oppositely charged ions are actually bound together to form Ionic-Compounds.
The number of bonds that an ion forms with others, indicates the valence of the ions. Thus Sodium is said to have a positive valence of 1. Similarly Carbon ion has a positive valence of 4. This applies only to the number of bonds actually formed. Whole atoms have valence of Zero. They have potential valences which become actual through gain or loss of electrons.
Molecules. An atom with an incomplete outer shell may satisfy its tendency to become stable in a different way. An acceptor may not have a suitable donor nearby for interaction but it may have other atoms of its own kind available. In such an event an atom say of Chlorine shall complete its outer shell by reacting with another Chlorine atom (Fig. 11D). When in close contact, each one of the two Chlorine atoms tries to pull strongly an additional electron from the other. But in this mutual pull neither of the two atoms is able to detach an electron from the other. This is so because the force of attraction between the nucleus and electrons of one atom is equal to the force of attraction between the nucleus and the electrons of the other atom. Thus a mutual pull continues, each atom holding its own electrons, as well as trying to pull an additional electron from the other. This results in the two atoms holding each other together and at the same time sharing one pair of electrons. In this way each atom completes its outer shell by keeping under its influence 7 electrons in its own outer shell and one electron in the outer shell of the other atom. Each atom behaves as if it actually possessed 8 electrons in its outer shell. More than one pair of atoms may take part in this sharing process. Atoms such as Carbon, Oxygen and Nitrogen always share electrons, as contrary to such atoms as Sodium and Magnesium which always transfer electrons. The compounds formed as the result of electron-sharing are called Molecules and the reactions producing them are called Molecular reactions.
Just after the origin of the earth, probably free atoms were present all over. Later on they formed compounds. With certain exceptions free atoms are not to be found now. They are in the form of ionic and molecular compounds.
The energy of a body is its capacity for doing Work. It is measured by the amount of Work which a body under a given condition can perform.
Forms of energy. Since mechanical energy, heat, light, sound and electricity are capable of doing work under suitable conditions, they are considered as different forms of energy.
Kinds of energy. The energy is of two kinds. (1) The Kinetic energy and (2) the Potential energy.
Kinetic energy. The kinetic energy of a body is the energy which it possesses on account of its motion. Examples: A moving railway engine, a bullet fired from a rifle, a stone falling from a height are examples of bodies, which possess kinetic energy.
Potential energy. The potential energy of a body is the energy which it possesses on account of its position or some special situation. It is equal to the amount of work, which the body can perform in coming from its given position or condition to some standard position or condition, called Zero position. Examples: Water stored in elevated reservoir, ice lying on the top of the mountain, brick lying on the roof of the house are examples of bodies that possess potential energy on account of their relatively high position. On the other hand, the runner of a watch, a compressed spring and a bow with its string stretched are examples of bodies that possess potential energy on account of some special condition.
Every compound has a varying degree of energy content, depending on the atoms of which it is composed of and on its pattern of structure. As already noted the atoms in a compound are bound together by mutual electrical pull. These binding forces which hold the atoms together represent Chemical energy or Bond energy. The greater the force of attraction between two atoms or ions, the greater is bond energy or capacity to do work. A chemical bond is not a permanent structure. It may be broken up by an external force pushing apart the component atoms or ions. The amount of work required to break such a chemical bond is also called Bond Energy Once the two atoms or ions get disunited, they are free to unite again with each other or with some other suitable ions.
To start a certain chemical reaction, activating energy is required from an external source. How does this energy act? Take, for instance, heat which is the product of motion. As already described in Chapter HI, all atoms, ions and molecules continuously vibrate at random, making back and forth movements. These movements are felt in the form of heat and measured as temperature. The greater the temperature the more violent the motions; they decrease with the fall of temperature until stop at 273°C. Thus the temperature of a certain substance is proportional to the amount of thermal agitation in its chemical units. With the application of heat from an external source, the thermal agitation increases, and the chemical units collide against each other with a greater frequency. The more they collide, the greater is the possibility of reaction taking place between them. But this happens only up to a certain limit. If the application of heat exceeds that limit, so that the atoms and ions in the compounds become so much agitated that the force of the heat motion becomes more than the force which binds them together, then the bonds that already exists begin to break. Any type of energy other than heat, such as ultraviolet rays, will produce the same two effects i.e., increasing the possibility of bond-making up to a certain limit and the breaking up of existing bonds beyond that limit.
Once a chemical reaction is started, energy is also required to maintain that reaction. The maintenance energy comes from two different sources, depending on the potential bond energy that different compounds possess-(l) From the environments, (2) From the reaction itself. As is more frequently the case, the starting compounds entering a reaction have a total bond energy less than the total bond energy of the resulting compounds. In such an event there is an energy deficit in the reactants which can only be made up from an external source. Such reactions which require energy from an external source are called Endothermic.
On the other hand if the total bond-energy of the starting compounds is greater than the total bond-energy of the resulting compounds, the reaction is self-sustaining i.e., the energy in the starting compounds not only maintains reaction but is also released to the environments. Such reactions are called Exothermic. The burning of petrol is an example. Once it is ignited, the reaction goes on automatically and releases energy which can be used for doing some other work e.g., running a motor. In this case the total potential bond energy of the petrol is greater than the total bond-energy of the end products, which are gases.
Types of reactions between compounds. The chemical properties of a compound depend on the following:-
(1) Arrangement of the component atoms. Two molecules may contain the same set of atoms, but if these are arranged differently the molecules will have different properties. For example—
This difference in the binding properties of otherwise similar molecules is particularly significant in the chemistry of living matter. As we shall see later, how physically and biologically different substances come into existence, simply by change in the arrangement pattern of atoms in a given molecule.
(2) Number and type of the component atoms. The number of atoms being the same, a molecule composed of atoms of high atomic weight will obviously be heavier than a molecule composed of atoms of low atomic weight. In the living world the molecules are mostly composed of oxygen, hydrogen, nitrogen and carbon, which are lighter elements. But the molecular weights of organic molecules are often exceedingly high. This is because an organic molecule is composed of hundreds and thousands of atoms. Here it is the large number and not the atomic weight which makes the organic molecule heavy.
As already noted, the compounds are not permanent structures. If subjected to the impact of appropriate amounts of external energy, they may undergo chemical reactions and become converted into different compounds. In the course of such a reaction, changes occur in the numbers, types or the arrangement of atoms of the participating compounds. Depending on the manner in which the structure of compounds become changed, four general categories of reactions may be distinguished:-
(1) Two or more compounds may add together and form a single larger compound. This is known as Synthesis reaction. For example,
NH3 H2O NH40H
Ammonia + Water = Ammonium Hydro-Oxide
(2) A given compound may break up into two or more smaller ones. This is known as Decomposition reaction, the reverse of Synthesis. For example,
NH40H NH3 H2O
(Ammonium Hydro-Oxide) = (Ammonia) + (Water)
(3) One or more of the atoms or ions of one compound may change places with one or more of the atoms or ions of another compound. This is known as Exchange reaction. For example,
+ — + — + – + —
HCl NaOH HOH NaCI
(Hydrochloric Acid) + (Sodium Hydroxide) = (Water) + (Sodium Chloride)
(4)Lastly, the numbers and types of atoms in a compound may remain the same but the bonding pattern of the atoms changes. This is called a Rearrangement reaction. For example,
Note that in all the four types of reactions the total numbers and types of atoms to the left of the equation are exactly equal to the totals on the right In the reaction as a whole, atoms are neither gained nor lost.
Catalysis. Organic compounds are very complex. Reactions between them require very high activation energy. Thus, theoretically, living processes require very hot environments. But it is a common experience that organic matter is liable to be destroyed when exposed to excessive heat. Then how is it possible for such complex processes to be carried out at a low temperature in which the living matter normally exists. This happens by means of Catalysis. The reactions in living matter are enormously accelerated by catalysts which serve as a supplement to thermal agitation. Various types of catalysts are also present in the non-living world. Special catalysts in the living world which are proteins and are thus very highly complex compounds are known as Enzymes. An enzyme combines with the reacting compounds only temporarily and thus brings them dose to each other. The reacting compounds which fit into the enzyme surface are called Substrates. Reaction between Substrates no more depends on chance collision but it becomes a certainty. Enzymes have definite molecular surfaces and the configuration of these surfaces differ, as the internal structure of the respective proteins of which they are made up of, differs. Thus the nature of surface serves as a key to enzyme reaction. This is evident from (Fig.l2A.) The surfaces of molecules ‘a’ and ‘b’ fit into the surface of enzyme like lock and key. Reaction between ‘a’ and ‘b’ is thus no more a chance but a certainty. This indicates that every enzyme selects its own Substrates. Spatial configuration of different enzymes differs and this accounts for the phenomena of enzyme specificity. It means that a particular enzyme catalyses only a particular reaction. In (Fig.l2B) Reactants ‘a’ and b fit partially into the surface of the enzyme but Reactant ‘c’ does not. Hence the enzyme may speed up reactions involving ‘a’ and ‘b’, but not those involving ‘c’. When the reaction between two subtrates is over, the enzyme molecule ultimately reappears unchanged, free to combine with a new set of substrates. The enzyme thus seves only as a medium and is not itself affected by such reaction.
Every chemical reaction has three basic characteristics. It takes place at a certain speed, it proceeds in a certain direction, and it has a certain duration.
Speed of Reaction. In addition to surrounding temperature and catalysts, the speed of reaction is also affected by the concentration of the reacting compounds present, the greater is their number, the greater the speed. The reaction is thus proportional to the concentration of the participating molecules. This is known as the law of Mass Action.
Direction and Duration of Reaction. This concentration of molecules does no affect speed only, it also affects the direction and duration of reaction.
For example:-1Glycerine + 3 Fatty-Acids = 1 Fat + 3 Water.
If the concentration of glycerine and fatty acid on the left of this equation is more than the concentration of fat and water on the right, the reaction will proceed to the right. On the other hand if the concentration is more on the right i.e., fat and water side, then the reaction will proceed to the left. The reaction shall continue, till a balance in concentration is achieved on either side.
The reaction is affected in two other ways. Firstly if we go on adding glycerine and fatty acid on the left, the reaction shall go on proceeding to the right. Secondly, if we go on removing the fat formed on the right side, the reaction shall again go on proceeding to the right. The latter shall happen rather more particulatiy in those reactions where the products of reaction are either gas or a precipitate.
The forces responsible for the distribution of tasks in nature
The term radiation is used in two senses. Firstly it is the process by which energy is propagated in space in the form of rays. Secondly the rays so propagated are also called Radiations.
Light Rays, Heat Rays, Gamma Rays are some examples of radiations.
Propagation of Radiant energy. Light and other such radiations are considered the result of rapidly alternating displacement current in the medium which gives rise to the magnetic effect. The two fields, namely the electric field and the magnetic, so produced, are inseparable, the one varying proportionately with the other. The variations of one field which give rise to the other, urge each other forward with a finite velocity, which is the velocity of light.
With regard to the origin of Electro-magnetic waves it may be stated that the atoms and molecules of matter contain electric charges, the vibrations of which send out electro-magnetic radiations. These radiations cover a very wide range of frequencies of wave lengths, depending on the quickness of alternation of the displacement currents. As a result we get the following chart of the different types of Electro-magnetic waves:-
Form the above chart it is dear that although these Electromagnetic radiations go by different names, in different regions, they are essentially of the same nature.
The shortest waves are the Cosmic Rays whose origin and nature are not fully known yet.
The next short waves are Gamma Rays which are emitted by the spontaneous disintegration of radioactive atoms.
Next come the X-Rays which are produced by an atomic process when fast moving electrons strike material objects.
The Ultraviolet Rays arise when atoms or molecules are subjected to energetic excitation bombardment with fast moving electrons.
The visible region which affects the human eye (Light Rays) occupies a very small portion of the whole electromagnetic chart. The waves of this region are produced by the vibrations of electric charges within both atoms and molecules.
The longer Infrared Rays which are produced by molecular agitation can be detected by their heating effect.
Finally we get the Wireless Rays which are produced by oscillatory electric circuits.
All these different types of radiations are propagated with the same velocity through space and all of them consist of alternating electric and magnetic fields in mutually perpendicular directions.
There are certain heavy metals like uranium, thorium and radium which give out some kinds of radiations for all time continuously and spontaneously and thereby they are converted into a series of elements of lower atomic number. These elements and their salts which too exhibit this property are known as Radioactive Substances and the phenomena of giving out radiations by them is called Radio-activity. Three types of radiations are given out by radio-active substances:-
- Alpha Rays
- Beta Rays
- Gamma Rays
Alpha Rays. They comprise fast moving positively charged particles of mass, four times heavier than that of hydrogen nucleus. They are known to be nuclei of helium.
Beta Rays. They consist of a stream of electrons, moving with a very high velocity. As such they resemble the cathode rays in nature.
Gamma Rays. They are similar in nature to X-Rays and are. therefore, electro-magnetic waves in ether. Their wave-length is even shorter than X-Rays. They travel with the speed of light and have intense penetrating power. These rays carry neither mass nor charge. They are produced by the sudden stoppage of Beta-Rays, just as the X-Rays are produced by the sudden stoppage of Cathode Rays.
ATOMIC ENERGY OR NUCLEAR ENERGY
According to our common concept, matter and energy belong to two different categories and scientists too regarded them till recently as quite separate from each other. Matter in its own sphere was considered to be such that it could neither be created nor destroyed, by any physical or chemical means. This was the famous law of Conservation of Matter, upon which the whole science of chemistry was based. Energy in its own sphere was also considered to be such, that it could neither be created nor destroyed but only changed in form. In the year 1905, Einstein, the mastermind of modern physics, put forward the revolutionary idea that matter and energy are two aspects of the same stuff and that when matter is destroyed, energy is created in enormous quantity. He not only stated this fact but by his mathematical ingenuity discovered the famous equation E = MC2, which determines the relation between the matter destroyed and the energy created. (M-Mass of matter E-Energy in Ergs: and C-Velocity of light).
How large is the energy produced by the destruction of small mass of matter can be judged from the following example:-
If the consumption of electric energy in a house is 25 units per month, therein the energy produced by the destruction of Igm. of mass shall be sufficient to supply electricity to this house for 1,000,000 months, i.e., for more then 80,000 years. The enormous energy thus created by the destruction of a small mass of matter in the nuclei of atoms of some suitable substance is known as Nuclear Energy or Atomic Energy.
Fission and Fusion. The actual destruction of a small mass of matter and the consequent release of nuclear energy is caused by one of the two processes, the fission and the fusion.
Fission. In fission the nucleus of any suitable atom is split up into two parts by the bombardment of a proton or a neutron. For example, when nucleus of uranium 235 is bombarded with a neutron”‘, it undergoes fission and is split up into two parts, one of which is the nucleus of barium and the other is the nucleus of krypton while 3 neutrons are given off. Counting the exact atomic weights of the elements, including fractions, the total final mass produced is less than the total initial mass. The mass thus destroyed in the reaction is converted into energy.
Nuclear Fusion. The second process of the release of nuclear energy is by fusion; in which two or more nuclei of suitable substances are fused together to form a new nucleus, thereby destroying a certain amount of matter and converting it into energy. For example when two deuterium nuclei (a heavy Hydrogen Nudeus-1H2 ) are fused together, they form an atom of helium nucleus 2He4. In this case also the total final mass is found to be less than the total initial mass.
The solar radiations that supply energy for the maintenance of life on the earth, are produced by nuclear reactions inside the sun. The hydrogen is converted into helium. The actual processes are complex but the basic fact is that during fusion of the hydrogen atom and their conversion into helium, the total final mass produced is less than the total initial mass. The mass thus destroyed is converted into energy waves.
We may thus summarize that electrons of all atoms in the universe move round their respective atomic nucleii at a tremendous speed. Moreover, all atoms, ions and molecules, regardless whether they are in a gas, liquid, or solid state, vibrate uninterruptedly at random, with back and forth movements except at a temperature below -273°C. The ionic or molecular bonds are being made and unmade in every nook and corner of the universe. The energy is being released at one place and supplied at another. Energy in one form is being convered into another. One form of matter is being replaced by another. The matter is being converted into energy and vice versa. A pinchful of matter when disintegrated produces an enormous amount of energy. If this energy is released suddenly in the form of an atom bomb, it would produce a tremendous amount of destruction. But in nature the energy is not released for destructive purpose, the radiation waves do not diminish in one jot the substance of God’s material creation but on the other hand they readjust the shape of the innumerable contents of the universe. Every particle of the universe has got a role to perform. Precious treasures are being shaped inside the oceans and in the depths of the Earth. The solar radiations reach the earth and promote photosynthesis in the vegetable kingdom. Food is thus prepared for the plants and animals. Innumerable other phenomena occur day and night. The making and breaking up processes continue uninterruptedly. All that is surplus is sorted out and all that is capable of survival is gradually raised up from one stage to another. Innumerable species of animals and plants become differentiated. The evolutionary processes are thus carried
‘Generally neutron is used for bombardment as it is not affected by the positive charge on the nucleus.
out constantly, in perfect silence and harmony and this all is due to the radiation waves. The Holy Quran describes the above phenomena in a graceful manner, so as to bring into light the process of Allah’s Rububiyyat
“By the (waves of Radiation) that are sent forth constantly for the benefit (of humanity). Those that turn into powder (all that is incapable of survival): and still those that diffuse and make things differentiated one from the other; and make the law of (construction and destruction) unveiled before the humanity so that one may be able to justify his existence by a positive act or take warning from the destructive effect of a negative act Assuredly that which you are promised must come to pass”.
At yet another place the Holy Quran says:
“By (the radiation waves) that scatter (energy); by the (centrifugal and centripetal forces) that lift heavy weights; by the ease and gentleness with which (energy waves) flow; and by the distribution (of tasks) by command; verily that which you are promised is true”.
We have already seen how the celestial bodies send out energy by nuclear fission or fusion and with what ease and gentleness this radiation flows. How the gravitational forces keep the huge big stars and planets with multimillion tons of mass in position? This pull of gravity is invisible and human knowledge is not yet fully developed to find out how it works. These forces of nature function in a state of perfect ease and gentleness. They distribute tasks at various levels not haphazardly but according to ‘Specific laws’. It is not possible to enumerate the number and distribution of these tasks which are processed in perfect coordination and are evidence of the unity of Allah’s plan.
Two different roots of the word Malaika( ) as it occurs in the Holy Quran, are described in Arabic dictionaries. One is ‘ ‘ which means to send messages. The other is ‘ ’ which means power or energy.
All physical communication between any one point in the universe to another is carried out through the agency of radiation. On the other hand, all energy in the universe becomes manifest through radiation. The radiation waves, therefore, being the source of power and means of communication truly-come under the heading of the term Malaika, in so far as it relates to the physical universe.
Some of the functions of Malaika, as described in the Holy Quran are as follows:-
(1) The distribution of tasks all over the universe- (51:4)-as described above.
(2) The planning and readjustment of the shape of innumerable
contents of the universe-( )
As stated earlier, the making and breaking up of chemical bonds depends on the amount of activation and maintenance energy. With the increase in the mount of energy the bond-making processes increase up to a certain limit; beyond this limit the greater the energy the more the speed and violence with which the bonds break. The radiation waves smoothly sail across the space and being of different wave lengths, one type exceeds the other in potency, penetration and consequent effects on environments which are constantly changing. The whole universe is thus perpetually in a state of commotion. The Holy Quran describes this phenomenon in connection with a greater commotion that lies ahead:
“By (the radiation waves) that undo (the bonds) with violence by penetrating (into Materials), and by those that undo (the bonds) with ease, and by those that smoothly float, one exceeding the other (in producing a particular type of effect) and thus readjust the shape of things (in the universe) by command of their Lord: that one day every thing that is in commotion, will be in violent commotion.
Means of communication other than radiation
The Holy Quran also describes means of communication other than the radiation waves:
“Allah chooses His messengers from amongst the ‘Malaika’ and also from amongst the mankind. Lo! Allah has infinite vision and hearing”.
According to the above verse the means of communication between the Creator and the creation are of two different kinds. Radiation is the link between the Creator and the physical word, including human body; and between the different constituents of the creation itself. The other link is the ‘Divine energy’. This link is between the Creator and the living objects, and in the case of man it occurs through the chosen messengers of God from amongst the human beings. The nature and working of this link is beyond the perception of human beings other than the ‘messengers’ themselves. As regards the reception at the (so to say) “control post” of the Creator, it is perfect and infinite. ( )
The other functions assigned to and performed by Malaika in the realm of are equally beyond human understanding.
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(The defensive mechanism in the nearer heaven which protects life on the earth).
“And We have made the heaven as a roof well guarded, yet do they turn away from the signs which these things (points to)”.
In the above-said verse the Holy Quran points out that the heaven surrounding the earth is a well guarded roof which protects life on the earth. It is one of the most conspicuous signs which impresses upon man that the working of the physical laws as well as the laws given to mankind through revelation, originate from the same source. Yet the non-believers instead of pondering over this significant sign, turn away from it.
At yet another place it is said:
“And We adorned the lower heaven with lamps and (provided therein) Guards. Such are the measures of One Whose might and knowledge are boundless”.
To begin with let us clarify the words . Literally it means the heaven surrounding our earth. But the question arises how far it extends? Does it mean the atmosphere surrounding our earth? Or does it mean the heaven which encloses our solar system? Or does it include the far away heaven of which stars are visible to us?
The Quran says: /
“We have made the earth your floor and the heaven your roof and sent down rains from the heaven”.
In the above said verse the word comprises only trophosphere from which the rain falls down and which extends only seven miles above the surface of the earth. And in the verse (41:12) it is said . “We adorned with lamps”. What is meant
by lamps? Do they mean the stars which are billions of miles away from the earth? Because in that case, shall extend very far away
from us. Or do they mean the planets and their satellites which are members of the solar system? The Quran clarifies itself by presenting a subject in different contexts. Thus it is said:
“We have indeed decked the near heaven with beauty in ‘Kwakib’.
Here the word (plural of ) is used instead of which only mean lamps or luminaries. What is meant by the word ? The meaning of this word has been clarified in still another verse:
“Allah is the light of the heavens and the earth. The parable of His light is as if there were a niche and within it a lamp. The lamp is enclosed in a glass. The glass is as if it were a brilliant, glittering like a pearl”.
It is said further in this verse that it is on account of this glass that it becomes “light upon light”. The Quran has thus made it abundantly dear that ‘Kawakib’ are those heavenly bodies which reflect light like glass and such heavenly bodies which send reflected light on the earth are none but planets.
Meaning of the word (seven)
The word Sabaa, as used in the verse (41:12) above is metaphorical. It does not indicate an exact number but gives an undefined idea of plurality. It is not possible to explain this figure in the present state of our knowledge, because the scientific observation has not revealed, so far, any limits to the universe; and as such our knowledge of the outer space is limited. Lane has mentioned with reference to Bezawi that Arabs use the word seven for plurality. Even in Urdu language certain numbers are used for plurality and they do not indicate an exact number. For example – “I have told
you twenty times”. “I have told hundred times”.
“Beyond the seven seas”, which only mean a long distance.
The-word occurs at various other places in the Holy Quran, in the same sense
“We have built over you many strong heavens”.
“It is He who has created a number of heavens, closely fitting each other”.
‘”Do you not see, Allah has created a number of heavens, closely fitting one another”.
“And We have made above you many tracts”.
The other conspicuous word in the verse (41:12) is “guards”. Before we consider what these guards are and how they protect life on the earth, let us describe briefly the various physical factors involved in this phenomenon. As shall be described later, the sun’s rays consist of high energy radiation such as X-rays and Ultraviolet Rays and low energy radiation such as Heat and Light Rays. High energy radiation is dangerous to life and low energy radiation up to a certain limit is essential for the maintenance of life. When the sun’s radiation reaches nearer to the earth, it is disposed of in three different ways: (a) by reflection (b) by transmission and (c) by absorption. In general, gases are the best transmitters, liquids the best reflectors and solids the best absorbers.
Heat transfer. As regards heat there are three modes of its transfer- (a) conduction, (b) convection and (c) radiation.
Conduction. When a solid is heated at one end, the motion of the molecules increases, they bombard neighboring molecules and give up some of their motion to them. Thus the increased molecular motion which we feel as heat is carried from one end to the other. This is known as conduction. Since increased heat means increased molecular motion, heat causes substances to expand.
Convection. It can take place only in liquids and gases. When a vessel of water is heated from below, the molecules at the bottom of the vessel move more vigorously. The liquid expands and becomes less dense so that an equal volume of colder liquid weighs more than the warmer liquid. The colder heavier liquid drops down and pushes the warmer liquid up. In this way the colder liquid becomes warmer in turn, until the entire contents are warmed. The continuous movement of the warm and cold portions of the liquid creates a convection current. Convection in air is analogous to convection in liquids.
Radiation. It is quite different from conduction and convection; whereas these two can occur only in material medium, radiation can pass through space which is devoid of matter. Conduction and convection are slow but radiation is instantaneous. For example, if we burn up fire in a room it gets warm immediately by heat radiation. On the other hand, with a steam heating system it may take an hour or more for a room to get warm by convection currents. A body radiates heat to every other body which is cooler than itself whether it is in contact with it or not, but conduction and convection currents can take place only between bodies which are in contact with each other.
How the atmosphere is heated. Dense air absorbs more heat than rare air. Carbon dioxide, water vapour and dust absorb heat better than air. When radiation passes through atmosphere, very little is absorbed by its upper layers. As it penetrates farther and farther into the denser, dustier and moister air, more and more of it is absorbed and the air is more and more heated. The air at the bottom is heated not only because of the greater absorbing power of the lower layers but also because of their contact with the warmer land and water surfaces. The heated air expands and rises, the cooler, heavier air above sinks and takes its place. Thus the entire mass of air gets mixed up by convectional currents.
Now let us proceed to describe the term (Guards) as it occurs in
the Holy Quran. The earth’s atmosphere is a blanket of gases surrounding the planet. It enables life to exist on the earth, not only because it contains oxygen so essential to life but also because it provides a protective insulation to the earth. Without this insulation, the temperature would have swung from unbearable cold at night to unbearable hot during the day. Just compare it with the moon which is without an atmosphere. There the day temperature rises to 100oC, as high as that of boiling water; and at night the temperature sinks down to-180oC, as low as that of liquid air. Under these conditions no life can exist.
The earth’s atmosphere probably extends at least one thousand miles from the surface of the earth. The air is not a uniform mass but can be divided into layers, each with its own characteristics (Fig. 7). The lowest strata of atmosphere is called Trophosphere. It extends up to seven miles above the surface of the earth. The convectional currents in the atmosphere take place only in this region. It may thus be described as the region of clouds and weather. The temperature rises steadily from about 15″C (in temperate zones) at sea level, to about 56″C at seven miles, while the air thins out with the increasing height.
Above this, is a ten miles thick layer of Stratosphere. The temperature is more or less uniform in this region and is about 60″C. This is because there is no mixing up of air contents by convection. Thus the gases are supposed to exist in strata. Hence the name stratosphere. At its lower boundary the effects of earth’s weather are not usually felt.
Above the Ionosphere is the outermost layer of atmosphere known as Exosphere. The air in this layer is so ratified that its density is only one million-millionth of that at the ground level. Air particles move freely, some escaping into the near-vacuum of outer space.
From the above it becomes dear that the ‘guards’ ( ) as
described in the Holy Quran are the various factors involved in the protection of life on the Earth and these are distributed in the different layers of the Earth’s atmosphere. Ionosphere forms the first line of defence which guards against the harmful effects of radiation from the solar system and of the cosmic rays which come from beyond the solar system. It serves as a filter through which only those rays of the sun are allowed to pass which serve to maintain life on the earth. Meteors which are members of the solar system itself, also burn up here. Chemosphere is the second line of defence which protects against the excessive heat of solar radiation. Trophosphere is the third line of defence. It serves to provide a protective insulation against the excessive rise and fall of temperature.
According to the Holy Quran the protection is provided against ‘
“We have adorned the nearer heaven with lamps and have made it as missiles to drive away the destructive forces and We have prepared for them the obstacle of fire”.
Above this layer is the layer of Chemosphere, which is 20-30 miles thick. It is mainly an accumulation of ozone gas which is a form of oxygen. When ultraviolet rays are passed through oxygen, ozone is formed, but it is changed back to oxygen by water vapours. The absence of water in the Chemosphere has an important effect on the amount of ozone and this in turn has important effects on the amount of high energy solar radiation received on the earth. Ozone acts in both ways. It protects the earth from high energy solar radiation and prevents the earth radiation to pass out which role is also performed by carbon dioxide. The temperature of Chemosphere is very high as compared with the layers above and below it.
Above this, is the layer of Ionosphere which extends for about 250 miles above the surface of the earth. In the Ionosphere the air particles are electrically charged (ionised) by the sun’s ultraviolet radiation and congregate in four different layers, D, E, Fl and F2. It is these layers which reflect radio waves back to the ground. The temperature increases rapidly from 73°C at the D (lowest) layer to about 1600°C at 200 miles. It is mainly at the lower Ionosphere that meteors from the outer space burn up as they meet the increased air resistance. As already stated, when a meteor enters the Ionosphere it becomes intensely heated by friction against the air particles and destroys itself in the streak of luminosity, known as shooting star. It would have been harmful to life on the earth, if it could pass through the atmosphere. Relatively large bodies known as meteorites, however, are able to complete the journey to the ground without being destroyed, but major falls are rare and there is no authenticated record of any one having been killed by a meteorite.
Cosmic rays are fast moving particles continually entering the upper atmosphere from interplanetary space. Mostly they come from far beyond the solar system and their origin is uncertain. They are extremely penetrating and the heavy primaries may well be dangerous to living matter, but the primaries do not reach the Earth’s surface. They collide with nuclei of atoms in the Ionosphere and yield the harmless secondary cosmic rays.
Above the Ionosphere is the outermost layer of atmosphere known as Exosphere. The air in this layer is so ratified that its density is only one million-millionth of that at the ground level. Air particles move freely, some escaping into the near-vacuum of outer space.
From the above it becomes clear that the ‘guards’ ( ) as
described in the Holy Quran are the various factors involved in the protection of life on the Earth and these are distributed in the different layers of the Earth’s atmosphere. Ionosphere forms the first line of defence which guards against the harmful effects of radiation from the solar system and of the cosmic rays which come from beyond the solar system. It serves as a filter through which only those rays of the sun are allowed to pass which serve to maintain life on the earth. Meteors which are members of the solar system itself, also burn up here. Chemosphere is the second line of defence which protects against the excessive heat of solar radiation. Trophosphere is the third line of defence. It serves to provide a protective insulation against the excessive rise and fall of temperature.
According to the Holy Quran the protection is provided against
“We have adorned the nearer heaven with lamps and have made it as missiles to drive away the destructive forces and We have prepared for them the obstacle of fire”.
The word (root ) means rebellious forces, which may be forces of nature as mentioned in the above said verse, (or the baser sentiments of man himself). As a matter of fact, all forces of nature are rebellious unless they are tamed or bound by measures. For example, an untamed river is rebellious but a river with boundaries raised on its banks becomes beneficial or an asset for mankind.
The arrangement of the lines of defence, one behind the other in order to protect against the rebellious forces, is described as follows:
“By the forces that range themselves in ranks and are so strong in repelling (the opposite ones). And thus proclaim the divine law. Verily, your Allah is One. He is the Sustainer of the heavenly bodies and the earth and all that is between them and provides sustenance at every point of the rising sun. We have indeed decked the nearer heaven with beauty in the planets and have provided guards against all the rebellious forces.
It is said further:
“The rebellions forces can not strain their ears in the direction of divine planning; and become cast away from every side. repulsed for they undergo perpetual obstacle. But such, as stealthily dart away (e.g., meteors), are pursued by a flaming fire of piercing brightness”.
It means that although these rebellious forces try to find their way in, as it is consistent with their nature; yet they are unable to pass the barrier that lies against them by divine planning and adjustment.
“The word used in the verse (37:8) above is translated as the Highest Assembly”. It means the Alam-e-Amar where tasks are assigned to the forces of nature.
The strata of earths atmosphere described above, which serve as guards to protect life on the earth, against the rebellious forces of Cosmic rays, Gamma rays X-rays, Ultraviolet rays, excessive heat and light rays, as well as metrors, are called by the Holy Quran. ‘Burooj’ means forts or fortified spheres. Thus it is said:
“It is He who has set out in the sky fortified spheres and made it fair seeming to beholders. And We have guarded it from rebellious forces. But any that steals hearing (i.e., stealthily and silently darts away without being heard) is pursued by a clear flame of fire”.
Our non-scientist commentators, while explaining the above said verses, have related preposterous stories of some sooth-sayers who used to listen to the working of the ‘highest Assembly. They interpret the word “steal hearing” (15:18) as ‘overhearing which is not correct.
Supposing A speaks and B overhears. In that case B steals the voice of A not his hearing.
Fortified Spheres. Amongst various other sign, the Holy Quran also describes the phenomenon of fortified spheres in ihe nearest heaven (i.e. in Solar System), in support of its truth:-
“By the sky that contains fortified spheres”.
The earth is surrounded by fortified spheres which protect life on the earth, against the rebellious forces of Cosmic rays, Gamma rays, X-rays and Ultra-violet rays. These are named as Trophosphere, Stratosphere, Chemosphere and Ionosphere as stated earlier.
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(The Divine laws that operate in the physical world, as well as those given to mankind through revelation, are equally immutable). The sun and the moon follow courses exactly computed. The stars (in the heaven) and the trees (on the earth) are (equally) subjected to the Divine laws. And the celestial bodies He raised high and put them (in space perfectly) balanced. That you may not transgress the limits (0 mankind!) prescribed by the Creator for the maintenance of balance (in the human society).
THE SOLAR SYSTEM (FIG. 1)
We are living on the Earth which is a member of the Solar System. It is a system controlled by the sun and contains the planets with their satellites, the comets, meteors, asteroids and infer-planetary material.
“And We have made (the sun) the source of heat and light”.
Sun is a star round which the earth and other bodies of the solar system revolve. It is a star of an average size, being 864,000 miles in diameter. Its density is only 1.4 times that of water. It is a source of heat and light to the solar system. The life-giving energy of the sun which is generated by the nuclear collision, raises the temperature inside it to about 36 million degrees Centigrade.
The Planets. There are nine major planets in the system and several thousands tiny planets called asteroids. The planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Jupiter is the sun’s largest dependent planet. Its diameter is roughly 13 times that of the Earth but is no More than a speck by comparison with the sun itself. The sun contains over 99.87 per cent of the entire mass in the solar system. Mercury is nearest to the sun, the average distance being 36 million miles. The planets move at different speeds in separate orbits and varying distances from the sun. So far as it can be said at present, life does not exist on any planet other than the Earth. Mercury is so close to the sun that the temperature on its sunlit side reaches 500°C. Venus though about double the distance from the sun as Mercury, has a surface temperature of 100°C. Of the planets farther than the Earth from the Sun, Jupiter, Saturn, Uranus, Neptune and Pluto are too cold and their atmospheres contain poisonous gases, such as hydrogen, helium and ammonia. It is believed that there is some form of life on the Mars but the air over the planet is very thin and icy, and probably some form of primitive vegetation exists there. Earth is the only member of the sun’s family whose composition and distance from the sun has made possible for life to exist.
As far as it is known today, no other planetary system exists in the universe.
Satellites. These are small or secondary planets revolving round the larger ones. They are too small in relation to their mother planets. The moon is the only satellite of a size comparable to its planet, the Earth.
Asteroids. An asteroid is a minor planet, a small world moving round the sun. Most, though not all, asteroids have orbits which lie between the orbits of Mars and Jupiter. Ceres, the largest, has a diameter of 430 miles. The total number of asteroids in the solar system has been roughly estimated as 45,000.
Comets. ( )
Comet is a member of the solar system moving round the sun in an orbit which is more elliptical than that of a planet. A large comet is made up of relatively small particles surrounded by an envelope of tenuous gas while the tail consists of excessively rarified gas and a fine dust released by solar heat. There are several dozens of known short period comets. Encke’s Comet, for instance, has a period of 3.3 years and has been observed at nearly 50 separate returns. The only bright comet with a period less than a century is Halley’s (Fig. 2) which takes 76 years to complete one journey round the sun, and was visible last time in 1986. Great comets have been extremely rare of late. It seems that comets are short-lived. The Holy Quran describes it as “ ” (81:16), i.e., the heavenly body that regularly moves in its orbit without any hindrance and still goes into hiding for a long period. (the) indicates that it refers to a particular group of heavenly bodies.
Meteors. These are small bodies moving round the sun, in the manner of a dwarf planet. If it enters the upper atmosphere it becomes intensively heated by friction against the air particles and destroys itself in the streak of luminosity known as shooting star. The average shooting star is very small, a few thousandths of a gramme in weight. It is estimated that about 100 million meteors enter the earth’s atmosphere daily.
Inter-Planetary (and inter-stellar) matter: It was formerly believed that the space in-between the stars must be empty, but this is now known to be wrong. There is a large quantity of inter-stellar material; much of it is hydrogen, though other substances also occur.
STARS (FIG. 3)
A star is a globe of incandescent gas. The distance between stars is measured by the methods of trignometrical parallax. Beyond a distance of several hundred light years the parallax becomes too small to be measured and alternative methods have to be employed. One such method is to deduce the star’s real luminosity by examination of its spectrum, when the distance may be computed.
The stars that we see are so far away from us that when we look at them, we look back deep into the past, for we see them not as they are now but often as they were hundreds of years ago. The light we receive from most of them began its journey long before we were born, and from the more distant ones long before man appeared on the Earth. Even light of the sun, a mere 93 million miles away, takes 8 minutes to reach the Earth; from the nearest star, Proxima Centauri in the Southern hemisphere it takes more than four years. The vast distances in space need a measure longer than a mile. Astronomers use the light year which is the distance travelled by light in one year; the distance travelled in one second being 186,300 miles. In these terms Proxima Centauri is four and a one-third light years away from the Earth. The distance from earth to the bright star Altair is about 16 light years, to Vega 26 light years, to Deneb 1500 light years, while some stars of the Milky Way are so far distant that their light takes thousands of light years to reach us. The stars are, therefore, placed at great distances in space not only form the Earth but also from one another.
The stars vary greatly in size. Though the Sun seems large to us, it is no more than an average star in the rest of the heavens. Some stars called super-giants make the sun seem a tiny dwarf. Betelgeux, for instance, could contain not only the Sun and the Earth’s orbit round it but the entire orbit of the planet Mars – an orbit of 284 million miles in diameter. On the other hand, there are stars which are a few thousandths of the sun’s size. Stars vary considerably in brightness and so are graded in different magnitudes. The brightest stars belong to the 1st Magnitude, those slightly less bright to the second, and so on until we reach the sixth magnitude which consists of stars just visible to the naked eye on a very clear night. A star of 1st magnitude is 100 times brighter than a star of the sixth magnitude. Compared with some first-magnitude stars, the sun’s light is very faint. The brightest stars in the sky are not necessarily the nearest to us. Several very faint stars are in fact nearer to the earth than the most bright ones.
GALAXY OR STAR SYSTEM (FIG. 4)
The stars are arranged in groups or systems called Galaxies. The galaxy of which the sun with its family of planets is a member, appears to consist of 100,000 million stars, gaseous Nebulae* and an immense quantity of interstellar material. Seen edge-on from outside, the Milky Way system looks like a fairly flat disc with a thick cloud of stars near and around the center. Seen at right angles, it looks like a Catherine-wheel with numerous spiral arms of varying size going out from the center. The sun lies in one of these arms. It is so far away from the center that it needs about 200 million years to complete one orbit round the “hub” of the Catherine-wheel,Calculated on the basis of the sun’s estimated age, it can have made only about 20 complete circuits. The diameter of the galaxy is 1,000,000 light years and the thickness 10,000 light years. The sun lies about 25,000 to 30,000 light years from the galactic nucleus.
Scientific observation has as yet revealed no limits to the universe and has so far probed only a fraction of it, yet to travel to the frontier of that observed fraction, even at the speed of light, would take 6,000 million years. The different bodies and structures in the universe, all of which appear to be receding from us, range from single galaxies to mammoth clusters containing as many as 500 galaxies. Although the cluster of galaxies, to which our galaxy belongs is comparatively small (it has only 14 members), our galaxy itself, the Milky Way system, ranks among the larger of the known stellar systems. There are thousands of millions of galaxies of varying sizes and structures. The most distant one, whose distance has so far been determined with any degree of accuracy, lies perhaps at 5,000 million light years.
‘Nebula is a cloud of interstellar matter. It is generally assumed that galactic nebulae are regions in which fresh stars are being created. If a nebula contains suitable stars, it shines either by exertation, by reflection, or by both; if not it shows up as a dark mass blotting out the light of more distant stars.
THE PLANET EARTH THE HOME OF
MAN – ITS STRUCTURE (FIG. 5)
Let us at the outset describe briefly the nature and properties of the materials that make up the Earth’s surface. In its original gaseous state, we believe there were only the chemical elements. As these gases cooled down, some elements combined with others, forming compounds, e.g., water is a compound. A simple element or compound found in the earth, but not formed by plants or animals is called a Mineral e.g., Quartz – a mineral, composed of the elements silicon and oxygen. A rock consists, chiefly of mixtures of minerals; Granite, for example, is a rock composed of at least three minerals, quartz, feldspar and mica. Some rocks consist of only one mineral, e.g., limestone; it is called a rock because it forms whole areas of the surface of the earth. Kinds of Rocks – We believe that the original gases that formed the earth, cooled down to become liquids first and solids later. Any rock derived from the molten condition, we call it Igneous. The loose material carried down by rivers and deposited on the continential shelf as sediment becomes consolidated into rocks: such rocks we call Sedimentary rocks. Both these kinds
Fig.5 COR OF EARTH
1 1 CRUST 2. MANTLE
2 3 SULPHIDE & OXIDE SHELL
4 OUTER CORE 5 INNER CORE
of rocks, igneous and sedimentary, when subjected to the action of water, heat, pressure, movement and other forces, are changed into what we call, Metamorphic rocks. The surface layer of the earth in which are situated the continents, oceans and mountains is called the Earth’s Crust. It is composed of all the three kinds of rocks-igneous, sedimentary and metamorphic.
The continental parts of the earth’s crust are composed of rocks of many different compositions which as a whole have a density and composition of granite. The granite layer is called Sial because of the predominance of silica and aluminium in its composition. Underneath the granite layer is a denser layer which has an average density and composition similar to that of the common black volcanic lava known as basalt. The basaltic layer (termed Sima because of its richness in magnesium) directly underlines the ocean floor, and here forms the thinnest part of the earth’s crust. In continental areas the granite and basaltic layers together reach an average thickness of about three miles. The best clues to what lies beneath the Earth’s exterior are provided by records of earthquake shocks. Shock waves passing through the earth are found to change their direction and speed at certain level which are known asdiscontinuities. The first major discontinuity is at the base of the basaltic layer where the latter rests on the Mantle – the second layer of the earth. At this level a marked change in the velocity of earthquake waves takes place. This may be due to a change in the chemical nature of the rocks or merely a change in their physical state.
The Mantle extends to a depth of 1,800 miles where a second major discontinuity marks the beginning of Outer Core — the third layer of the earth. The material near the inner edge of the Mantle is two to three times as heavy as the surface rocks.
The Outer Core is 1,310 miles thick and is probably formed of heavy metals (iron and nickel) in molten form.
The next layer, the Inner-Core or the innermost layer of the earth, 850 miles thick, is believed to consist of the same material as the outer core but in a solid state. Knowledge that the earth could not consist entirely of the surface rocks, came first from the planets’ weight measured by its pull of gravity, for these materials are too light to account for a total mass of 6,600 million million million tons.
Movements of the earth’s crust. Movements of the earth’s crust take place both gradual and sudden. There is much evidence in hand to show that every part of the earth’s crust has moved at one time or the other. The finding of the skeleton of a whale in the glacial gravels near Lake Champlain and the remains of other massive animals in the sedimentary rocks of mountains can mean only one thing: these areas were once under sea water. The ancient temple of Jupiter Serapis at Pozzuoli, near Pompeii, is known to have been on dry land A.D. 235. When it was rediscovered in 1749, the bases of its remaining upright columns were buried in marine sediments to a depth of twelve feet above the floor of the temple.
Some of the changes in the earth’s crust must have been due to sinking of the ocean bottom, which would permit the water to run off the land; others to the accumulation of vast amounts of sediment, eroded from the land and deposited in the sea, which would cause the water to overflow the land; still others to a glacial epoch, which precipitated the water, evaporated from the ocean, as snow instead of water. It has been estimated that if the ice sheets of the earth today were all melted, it would raise the level of the oceans about 80 feet. There have been many times when entire continents were uplifted or depressed.
The theory of Isostasy. The cause of the periodic uplift and depression ‘is said to be as follows:- The sediments eroded from the mountains are deposited by rivers on the continental shelf. This causes the removal of the load from the land segment which becomes lighter; on the other hand it makes the ocean segment heavier. The rock underneath the crust is solid but very hot; and there is reason to believe that it is plastic. Thus a slow adjustment takes place, pushing down the ocean segment and forcing up the granite land segment. This re-elevation of land segment is again followed by erosion and thus a cycle of its uplift and depression continues.
Besides these movements of the earth’s crust which are usually imperceptible, requiring millions of years, there are rapid movements which originate from the forces that work in the depths of the earth’s interior. The constant movements in the depth of the earth mount in intensity from time to time, culminating in Orogenies, profound disturbances in the earth’s crust, which give rise to great mountain ranges. The early stage of an orogeny is down-warping of the crust and formation of a sea-filled basin in which great thicknesses of sedimentary rock accumulate. Later the sides of the basin gradually move towards each other and the bottom moves up. The sedimentary rocks caught in this vice are folded and slid over each other piling up into a great mountain chain. The fractures along which the sliding takes place are called Thrusts or Thrust Faults (Fig. 6). Heat and pressure in the depths of the down-warp – the roots of the mountain range — metamorphose the sedimentary rocks and allow molten granite rocks to form. This rises under great pressure, either crystallizing on the way up to give ‘intrusions’ or drilling an outlet in the Earth’s surface to pour as volcanic lava and ashes. As soon as the folded rocks
B C d
Fig. 6: —THRUST FAULTS.
(A) Fault Block. (B) Normal Fault, (C) Reversed Fault. (D) Tear Fault.
- Overfold. 2. Reversed Fault. 3. Normal Fault. 4. Horst.
- Step-faulted rift-valley. 6. Folding. 7. Fault-block mountains.
appear above the surface of the sea, the destructive action of wind, rain, frost and waves begins. Eventually the mountains succumb; layers of sediment are deposited in places over the eroded rocks and a surface of low relief with meandering rivers is all that is left.
Thus in the jigsaw of rocks that form the earth’s surface, the pieces are slowly and endlessly being rearranged.
HOW THE UNIVERSE CAME INTO EXISTENCE
In the words of Sir Eddington, “We can have no conception how it all began in the past. But at some stage we imagine the void to have been filled with matter rarefied beyond most tenuous nebulae, the atoms sparcely strewn hither and thither in formless disorder. Then gradually the power of gravitation is felt. Centers of condensation begin to establish themselves and draw in other matter. The first partitions are star systems, such as our galactic system. Sub-condensations separate the star clouds or clusters; these divide again to give the stars. This process of evolution has not reached the same development in all parts. We observe nebulae and clusters in different stages of advance. Some stars are still highly diffused, others are concentrated like the sun with density greater than water; others, still more advanced, have struck to unimaginable density. But no doubt can be entertained that the genesis of the stars is a single process of evolution which has passed and is passing over a primordial distribution.
Formerly it was speculated that the birth of a star was an individual event, like the birth of an animal. From time to time, two long extinct stars would collide and be turned into vapours by the energy of the collision; condensation would follow and life as a luminous body would begin all over again. We can scarcely affirm that that shall never occur and that the sun is not destined to have a second or third innings; but it is clear from the various trends among the stars that the present stage of existence of the sidereal universe is the first innings. Groups of stars are formed Which move across the sky with common propel motion; they must have had a single origin and cannot have been formed by casual collision.
Formation of Planetary System. As far as our present knowledge goes, our planetary system is unique in the universe, though it may be difficult to assume that nowhere else in the universe has nature repeated the strange experiment which she has performed on the earth.
On examining the stars with a telescope we find that a good number of stars which appear single to the eye are actually two stars close together. When telescope fails to separate them, the spectroscope often reveals two stars in orbital revolution round each other. At least one star in three is double. The most obvious cause of division of stars is excessive rotation. As the gaseous globe contracts, it spins faster, until a time may come when it can no longer hold together and some kind of relief must be found. It has been assumed that the planetary system has come into existence in a similar way. According to the Nebular hypothesis of Laplace, the sun gained relief by throwing off successively rings of matter which have formed the planets. It might be held that the ejection of a planetary system and the fission into a double star are alternative solutions of the problem arising from excessive rotation, the star taking one course or the other according to circumstances. But we know myriads of double stars and of only one planetary system; but in any case it is beyond our power to detect other planetary systems if they exist. Research work by other scientists indicate that rotational break up produces a double star and never a system of planets. The solar system is not a typical product of development of a star; it is not even a common variety of development, it is a freak.
By elimination of alternatives, it appears that a configuration resembling the solar system would only be formed if at a certain stage of condensation an unusual accident had occurred. According to Jeans the accident was the close approach of another star casually pursuing its way through space. This star must have passed within a distance not far outside the orbit of Neptune; it must not have passed rapidly but have slowly overtaken or been overtaken by the sun. By tidal distortion it raised big protuberances on the sun and caused it to spurt out filaments of matter which have condensed to form planets. This was long time ago. The intruding star has since gone on its way and mingled with the others; its legacy of a system of planets remains, including a globe habitable by man”. (The Nature of the Physical World).
According to the evolutionary theory all the material in the universe was formerly concentrated in what may be termed a ‘Primeval Atom’, so that the universe was created at one particular moment and will eventually die. Supporters of the steady state theory, on the other hand, maintain that the universe has always existed and will exist for ever and that fresh matter is continuously being formed. Present observational evidence seems to favour the former hypothesis rather than the latter.
As regards the origin of the universe, the Holy Quran declared fourteen hundred years ago:
“Do not the unbelievers see that the heavenly bodies and the earth were joined together (as one unit of creation), before We clove them asunder? And We made from water every living thing: will they not believe?”
The Scale of Time. The creation of man started about one million years ago while the existence of the earth is estimated to be 5,000 million years. The sun must have been burning still longer, living on its own matter which dissolves bit by bit into radiation. So tremendous is the radiation rate of the sun’s energy that it loses some four million tons in weight every second. According to the theoretical time scale which seems best supported by astronomical evidence, the beginning of sun as a luminous star must be dated five billion (5.1012 ) years ago. On the other hand, despite the tremendous rate of loss on account of radiation, it may continue as a star of increasing feebleness for at least another 16,000 million years. The theory of subatomic energy has prolonged the life of a star from millions to billions of years and we may speculate on processes of rejuvenation which might prolong the existence of the sidereal universe from billions to trillions of years.
As already described, to begin with the Earth and the celestial bodies were all one mass and later broke into pieces. (21:30). At a still later stage the solar system which was one compact mass, got separated into the sun (the main mass) and the planets. The most obvious cause of it being the excessive rotation of the sun which gained relief by the separation and recession of the planetary pieces, the Earth being one of them. The Holy Quran says:
“And after that We threw out the Earth”.
This process of recession still continues as far as the galaxies are concerned. The spectra of galaxies show red-shifts which means that there is an apparent shift of all the spectral lines towards the red or long wave end of the spectrum. This indicates motion of RECESSION. It seems that each group of galaxies is moving away from each other group, so that the entire observable universe is expanding. The only galaxies which are not racing away from us are those of the local group. It has been found that the farther away the galaxies are, the greater is their velocity of recession. The scientists have observed only recently that the universe is expanding. It is marvellous that the holy Quran pointed out towards this fact 1400 years earlier when it was said:
“With power and skill. We did construct the heaven. Verily We are expanding it”.
THE BALANCE ( )
The stars and the extrastellar bodies in a galaxy, or the members of a group of galaxies, are held together by the pull of gravity. Gravitation is the universal attraction of every particle of matter for every other particle; the force is proportional directly to the product of the masses of bodies and inversely to the square of distance between them. For example, in the solar system, the sun by its pull of gravity keeps the planets under control, in spite of their comparative smallness and the enormous distances that separate them from the sun and from one another. Similarly the sun-and the other 100,000 million stars belonging to the Milky Way are kept under control by the galactic nucleus.
The relative position of a group of celestial bodies, say for instance, the solar system, is kept steady by means of two forces. Firstly, the pull of gravity on account of which the planets are pulled towards the sun and secondly the speed with which these planets move round the sun. These centrifugal (force pulling away from the center) and centripetal (force pulling towards the center) forces, are so balanced that they keep the relative position of the sun and the planets steady. Thus the celestial bodies with billions of tons of weight are kept in position without any visible pillars. The Holy Quran says:
“Allah is One Who raised the celestial bodies without any visible pillars and is established on the throne of authority”.
“He created the heavenly bodies without any pillars that you can see”.
“The celestial bodies He has raised high and He has set up a balance (in between them)”.
The Holy Quran introduces this mathematical balance maintained between the heavenly bodies, as a guidance for mankind and asks human beings to act justly to each other and to observe balance in all their actions and never to tansgress due balance in anything.
“In order that you may not transgress (due) balance”.
Just as a small imbalance between the centrifugal and centripetal forces may be the cause of destruction of a system of heavenly bodies, so does an injustice in the human affairs disrupts the smooth running of the human society.
The movement of any star or a planet takes place in a definite orbit around its gravitational nucleus. For example, in the case of solar system the gravitational nucleus is in the sun, and the planets revolve round the sun in their respective orbits with an utmost precision (Fig. 2).
Actually the orbits of the planets are elliptical. The closer a planet is to the sun, the faster it moves. For instance. Mercury, at an average distance of 36 million miles from the sun, moving at a speed of 30 miles per sec., takes 88 days to revolve round the sun; while the Earth the average distance of which from the sun is 93
Fig. 8. JOHANNES KEPPLER
Fig. 9. KEPPLER’S HOUSE
(Model showing laws of planetary motion, is at the bottom)
million miles, needs exactly one year to complete its orbit, travelling at a speed of IS.F miles per second. Pluto, the most distant known planet about 3666 million miles from the sun takes 248 years, moving at a speed of mere 3 miles per second. The German astronomer Johanres Keppler, (Fig. 8) first gave the laws of planetary motion between the years 1609 and 1619 A.D. The Astronomia Nova published in 1609 is Keppler’s most important work. Keppler concluded after painstaking calculations that the principles concerning the movement of the planets which had been recognised since the time of Aristotle should be abandoned. They do not revolve round the sun in circular orbits but in elliptical orbits and their velocity is not constant over the entire course. Keppler succeeded in establishing the laws of planetary motion which were in complete accordance with the observations which had been made. The laws are as follows:
(1) The orbits of the planets are elliptical, the sun lying at one of the faces of the ellipse.
(2) The radius vector i.e., the line joining the center of the planet to the center of the sun sweeps out equal areas in equal times.
(3) The square of the revolution periods of any two planets is proportional to the cubes of their mean distance from the sun.
Fig. 9 shows Keppler’s House, with Model showing laws of planetary motion.
The planets not only move in their respective orbits round the sun but also each one undergoes an axial rotation around its own axis. Take for example the moon. The moon is generally regarded as earth’s satellite but on the whole it seems preferable to term the earth-moon system a double planet. The orbit of the moon is markedly elliptical and is always concave to the sun. The distance from the Earth ranges between 221,460 miles perigee (point in the orbit of moon or planet which is nearest to the earth) and 252,700 miles apogee (point in orbit of moon or planets farthest from the earth), the range giving a mean of 238,840 miles. The revolution period is 27 days, 7 hours and 43 minutes, and this is also the period of axial rotation. But since the rotational period is constant, while the velocity in orbit changes (see Keppler’s laws of planetary mission; which apply to a planet and its companion, as well as to a planet in relation with the sun), the position in the orbit and the amount of rotation become regularly ‘out of step’; the moon seems to rock very slowly to and fro, uncovering first one limb and then the other.
The Holy Quran says:
“And the moon, We have measured for her its stages, till she returns like the old (and withered) lower part of date stalk”.
The Holy Quran described the movements of the planets and the stars in those dark ages when people mostly believed the earth to be stationary. The Holy Quran described the earth as a cradle i.e., an object which regularly moves and at the same time provides ease and comfort:
“Have We not made earth a cradle and the mountains as pegs”?
“He created the celestial bodies without pillars that you can see. He set on the earth mountains standing firm, so that (the earth) moves with you”.
As regard the orbits the Holy Quran says:
“It is He Who created the night and the day and the sun and the moon. All (heavenly bodies swim along, each in its orbit.”
The movement inside the respective orbits is so accurately timed that the heavenly bodies do not collide with one another:
“It is not permitted to the sun to overtake the moon, nor can the night outstrip the day. Each (just swim along in (its own) orbit”.
So accurate are the movements of the heavenly bodies that we base the calculation of time on the position of the sun and the moon in their respective orbits:
“It is He Who made the sun, the source of light and the moon a reflected light and measured out stages for her that you may know the number of years and the count (of time). This is nothing but a part of His constructive design”.
“It is He Who cleaveth the daybreak (from the dark). He made the night for rest and tranquillity and the sun and the moon for the reckoning (of time)”.
Our calendars are mostly based on the relative position of the earth and the sun and the consequent seasonal incidence on the earth. There are, however, other phenomena on the earth whose reckoning of time, coincides with the movements of the moon. For instance, the human fetal life coincides with the lunar months. The stay of a normal human fetus inside the mother’s uterus is 280 days i.e., ten lunar months. As already stated, the revolution period of moon is about 28 days and same is the period of menstrual cycle in a woman. The tidal waves of the sea are well known to be related to the movements of the moon.
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(6 : 1)
The entire creation of the universe and the various aspects of life on the earth are so attractive and captivating, for one who uses his intellect and vision, that he spontaneously expresses his feelings of praise for the One Who created the heavens and the earth, and made the darkness and the light (of revelation).
The Holy Quran describes Allah as (6 :14), which means that Allah is one Who created the heavens and the earth for the first time when there was nothing in the universe. At another place the Holy Quran says;
(2 : 117) “He is the originator of the heavens and the earth. When He decrees a plan. He says to it BE and it is.”
Again it is said:
(36 : 82) “His law of creation is such that when He intends a thing, His decree is BE and it is.”
The underlying idea in the above verses is that Divine intentions and decisions are in fact an integral part of God’s process of creation. The Holy Quran has used two different words for creation. They rather indicate the two different stages of creation. One is Amr, the other is Khalq. Khalq means to create a new object from the existing constituents. This is where an object appears in its manifest form. But prior to this is a stage where an object is still in the process of ‘becoming’. This planning stage is described by the Holy Quran as Alam-e-Amr. What is the nature of this planning “and how it is carried out is beyond human imagination.
This is also described by the Holy Quran as Masliiyyat of Allah which nobody can question.
(14 : 27) “Allah acts according to His will”. Here ‘will’ does not mean whims and wishes. It means a set of laws.
(21 : 23) “He cannot be questioned for His acts.”
For example, fire burns. Why fire is given the burning property, nobody can question. Why the inner ‘shell’ of an atom has got two electrons, nobody can question.
The word Amr, as it occurs in various other contexts in the Holy Quran, requires further elucidation. It means a guidance, or guidance by command. There are two other aspects of this guidance. Firstly, the laws governing the phenomena of nature. These are also called Amr. For example the Holy Quran says:
(7 : 54) “The sun, the moon and the stars are subservient to His (command) law.”
Another beautiful example where the Holy Quran uses the word Amr for the laws governing the phenomena of nature is the floating of ships on the sea. We find in the world of Science that a body wholly or partially immersed in a fluid, suffers loss of weight, equal to the weight of the fluid displaced (Archimede’s principle). If the weight of the body is greater than the weight of the fluid displaced, it sinks. If the weight of the body is less than the fluid displaced, it floats. When a body is floating on the surface of a fluid, a portion of the body is immersed in the fluid, so that the weight of the fluid displaced by the immersed portion is equal to the weight of the entire floating body. This is the law according to which the ship floats on the water. The Holy Quran says:
(22:65) “Do you not see that the law of God has made subject to you all that is on the earth; and the ships that sail through the sea by His (Amr) law. He withholds the celestial bodies from falling on the earth, except according to His law.”
Another phenomenon of nature described in the above verse, is that the celestial bodies do not fall on the earth. This, as shall be explained later, is due to the balance between the centripetal force of gravity and centrifugal force of rotation. If ever the balance between these forces is disturbed at any stage of evolution, the celestial bodies are liable to collide against each other; and that also will be according to a certain law.
Thus, as stated above, the initiative of Divine laws was absolute and unquestionable. Now, the execution of these laws is carried out within specified patterns. This is known as Taqdir.
(33 : 38) “The Divine laws are bound by certain measures.”
(65 : 3) “Allah has made a specific pattern for everything that exists.”
A mango seed shall always grow into a mango tree. This is its Taqdir. Thus, after the initial planning, the execution of these laws has been channelised. The more we explore nature, the more we gain knowledge of these laws. But our knowledge is confined only to the extent of finding out how these laws work. Why do they work as such, we do not know.
Secondly, the laws that govern human affairs and were given to mankind through God’s messengers are also called Amr. These laws are today lying in safe custody inside the Holy Quran only. They govern the rise and fall of nations and also the development of the personality of an individual, and are known as . The Holy Quran says:
(8:42) “But Allah had decided to execute a plan that had to be carried out, so that he who perishes must have an obvious cause of his death and he who survives must have an obvious cause of his survival. And verily Allah is one Who is All-hearing and All-knowing.”
We may summarise that the guidance or guidance by command of God works in three different ways: (1) The first being the planning of certain schemes and the initiation of laws that govern the execution of these schemes. (2) The second being the actual execution of these schemes according to the above laws; all the phenomena of nature are thus controlled by these laws and all animate and inanimate objects in nature are bound to obey them, the animals obey them by instinct. (3) The third being the laws concerning humanity given to mankind through revelation, with the difference that human beings are imbued with the faculty of ”freedom of choice and will.” They are thus given an option whether to obey these laws or not, the result, however, being either construction or destruction according to how the human beings act.
The fact that the law-giver is one and the laws governing the phenomena of nature and those governing the human affairs originate from the same source, and that there is a unity of purpose in the creation of the universe, is described in the Holy Quran over and over again, in so many different ways. That the most obvious and attractive phenomena of nature and the most wonderful capabilities of human personality are all governed from the same source, is beautifully described in the following verses:
(91 :1-10) “By the sun and its brightness and by the moon as she follows him. By the day as it shows up the sun’s glory and by the night as it conceals it. By the heavenly bodies and their (wonderful) structures. By the earth and its (wide) expanse. By the human personality and the order and equilibrium given to it and the (wonderful) way in which the possibilities of its disintegration and protection therefrom have been ingrained therein. All these laws governing the phenomena of nature as well as those that govern the human personality are witness to the fact that truly the one who develops his personality (by his right conduct) does succeed, and the one who disintegrates it by his misdeeds, fails.”
Immutability of Divine Laws
The Holy Quran says:(6 : 34) ….. ….. “Nobody can change the laws of God.” Not even the messenger of God.
(3:127)…. (O Messenger of God!) you are not given the authority to change the laws of God.”
(30 : 30)…. …. “Allah’s process of creation never changes.”
(17 : 77) … “You do not find a change in the working of our (Divine) laws.”
(35 : 43) … …“So you can never find a change in the working of the Divine Laws.” This magnificent proclamation by the Holy Quran, fourteen hundred years ago, when a concept of law hardly existed, now forms the basis of all scientific research and is the essence of (the law that every effect has got a cause). All the past, present and future scientific research is indebted to this fundamental. All the wonderful adventures in the outer space today are the outcome of a confidence in the immutability of the laws of nature.
God’s Creation is Perfect
The Holy Quran says:
(67 : 3-4) “It is He Who created several heavens closely fitting one another. No want of proportion will you see in the creation of one Who created things within a specified pattern. So turn thy vision again. Do you notice any flaw? So again turn thy vision a second time; your vision will come back to you dull and discomforted in a state worn out.”
Against the background described above, now let us proceed to describe the shape and structure of the universe.
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