Tuesday, 31 December 2013

AN ASTRONOMER'S VIEW OF THE UNIVERSE, Short Answers.

1.           Why is it improbable that one particular star will ever come close to
another?
The whole host of stars is roving about in space. A few form groups which journey in company, but the bulk are introverted voyagers and they travel through a spacious universe that it is almost inconceivable scarcity for a star to come anywhere near to another star. For the most part each voyages in loneliness. In a level model in which the stars are ships, the average ship will be well over a million miles from its nearest neighbour, from that it is easy to understand why a ship rarely finds another within calling distance.

2.           What is Jeans's explanation of how the planets came to be formed from the sun?
The sun is intensely hot for life to be able to obtain or keep a grip on it. So also no doubt were the driven out fragments of the sun when they were first thrown off. With the passage of time, they cooled, until now they have but little inherent heat left. In course of time, we know not how, when, or why, these fragments gave birth to life. It started in simple organisms but from these modest beginnings emerged a stream of life which, advancing through greater sophistication.

3.           How does a planet, such as the earth, derive its warmth?
The earth, which started life as a hot mass of gas, has gradually cooled, until it has now about touched bottom. It has almost no heat beyond that which it receives from the sun. This just about balances the amount it radiates away into space, so that it would stay at its present temperature for ever if external conditions did not change, and any changes in its condition will be forced on it by, changes occurring outside. These changes may be either gradual or catastrophic. A new study reveals that only about half of our planet's internal heat stems from natural radioactivity. The rest is ancient heat left over from when Earth first combined with a hot ball of gas, dust, and other material.

4.           What does Jeans imagine the first forms of life on earth to have been like?
Jeans did not know how, when, or why, one of these cooling fragments gave birth to life. It started in simple organisms whose vital capacities consisted of little beyond reproduction and death. The constituents of a living body are perfectly ordinary chemical atoms — carbon, hydrogen, oxygen, nitrogen, and so on. Every kind of atom necessary for life must have existed in the new born earth. Gradually, a group of atoms might happen to arrange themselves in the way in which they are arranged in the living cell.

5.           Why are our first impressions of an astronomer's picture of the universe likely to make us feel that humanity is insignificant?
Our impression of an astronomer’s picture of the universe made us feel that humanity is insignificant because the majority of stars are so large that hundreds of thousands of earths could be packed inside each. Here and there we come upon a giant star large enough to contain millions of earths. And the total number of stars in the universe is probably something like the total number of grains of sand on all the seashores of the world. This is the littleness of our home in the universe. If we attempt to discover the purpose of the universe which surrounds our home in space and time, our first impression is something akin similar to terror. We find the universe terrifying because of vast meaningless distances, our extreme loneliness, and it appears to be indifferent to us. Our sentiments, objectives and achieve­ments; art and religion, all seem equally foreign to cosmic plan.

6.           How does Jeans justify his assertion that the universe appears to be actively hostile to life like our own?
For the most part, empty space is so cold that all life in it would be frozen. Most of the matter in space is so hot which make life impossible; space is crossed, and astronomical bodies continually bombarded, by radiation of a variety of kinds, much of which is probably hostile to, or even destructive of, our life. Jeans justified his statement by stating the above facts. Thus, the universe appears to be actively hostile to life like our own.

7.           Why does a planetary system seems to be the only kind of environment on which life could originate?
Life can only exist inside a narrow temperate zone. Outside these zones life would be frozen; inside, it would be shriveled up. These zones within which life is possible constitute less than a thousand million millionth part of the whole of space. And even inside them, life must be of very rare occurrence, for it is so unusual for suns to throw off planets, that probably only about one star in 100,000 has a planet revolving round it in the small zone in which life is possible.

8.           What is the temperature of most of the space?
We can think of space as a vast gathering of fires spotted all through space. Away from the fires there is this unimaginable cold of hundreds of degrees of frost; close up to them is a temperature of thousands of degrees, at which all solids melt, all liquids boil.

9.           Why does it seem incredible to Jeans that the universe was designed primarily on produce life like our own?
It seems incredible that the universe can have been designed primarily to produce life like our own; had it been so, surely we might have expected to find a better proportion between the mechanism and the product. At first glance, life seems to be an utterly unimportant by product. We living things are somehow off the main line. Life can only exist inside a narrow temperate zone. Outside these zones life would be frozen; inside, it would be withered up. At a rough computation, these zones within which life is possible, all added together, constitute less than the smallest part of the universe. Even inside them, life must be of very rare occurrence.

10.  Why is the origin of life still a riddle to the scientist?
We do not know if suitable physical conditions are sufficient in themselves to produce life. According to one school of thought, the earth gradually cooled, it was natural, and unavoidable, that life should come. Another holds that after one accident had brought the earth into being, a second was necessary to produce life. The constituents of a living body are ordinary chemical atoms, carbon, hydrogen, oxygen, nitrogen and so on. Every kind of atom necessary for life must have existed in the new born earth. At intervals, a group of atoms might happen to arrange themselves in the way in which they are arranged in the living cell. Indeed, given sufficient time, they would be certain to do so. But would they then be a living cell? Is it merely atoms, or is it atoms plus life? Or, to put it in another way, could a skilful chemist create life out of the necessary atoms and then make it go? We do not know the answer.

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