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CAMbRiDgE UNivERsity PREssCambridge, New york, Melbourne, Madrid, Cape town, singapore, são Paolo, Delhi, Dubai, tokyoPublished in the United states of America by Cambridge University Press, New yorkwww.cambridge.orginformation on this title: www.cambridge.org/9781108005661© in this compilation Cambridge University Press 2009Tis edition frst published 1930Tis digitally printed version 2009isbN 978-1-108-00566-1Tis book reproduces the text of the original edition. Te content and language refect the beliefs, practices and terminology of their time, and have not been updated.Cambridge University Press wishes to make clear that the reissue of out-of-copyright books not originally published by Cambridge does not imply any knowledge or advocacy of the reissue project on the part of the original publisher.
[...]... and they see only their own shadows, or the other shadows which the fire throws on the opposite wall of the cave? True, he said; how could they see anything but the shadows if they were never allowed to move their heads? And of the objects which are being carried in like manner they would only see the shadows? Yes, he said To them, I said, the truth would be literally nothing but the shadows of the. .. planets must meet the same inglorious end Physics tells the same story as astronomy For, independently of all astronomical considerations, the general physical principle known as the second law of thermodynamics predicts that there can be but one end to the universe a "heat-death" in which the total energy of the universe is uniformly distributed, and all the substance of the universe is at the same temperature... radiation in the process In 1917, Einstein investigated what may be described as the statistics of these jumps Some are of course caused by the radiation itself and the heat of the filament But these are not enough to account for the whole of the radiation emitted by the filament Einstein found that there must be other jumps as well, and that these must occur spontaneously, like the disintegration of the radium... one The sun and the other stars we see in the sky are all intensely hot—far too hot for life to be able to obtain or retain a footing on them So also no doubt were the ejected fragments of the sun when they were first thrown off Gradually they cooled, until now they have but little intrinsic heat left, their warmth being derived almost entirely from the radiation which the sun pours down upon them... cave, which has a mouth open towards the light and reaching all along the cave; here they have been from their childhood, and have their legs and necks chained so that they cannot move, and can only see before them, being prevented by the chains from turning round their heads Above and behind them a fire is blazing at a distance, and between the fire and the prisoners there is a raised way; and you will... possibilities in the universe he had created—in brief, space was of three dimensions so that there could be sailors This and the argument outlined above seem to be much on a level, because life as a whole and the tying of 10 THE DYING SUN knots are pretty much on a level in that neither of them forms more than an utterly insignificant fraction of the total activity of the material universe So much for the surprising... situation is that the balance is very easily upset Primitive man, living in the temperate zone of the earth, must have watched the ice-age descending on his home with something like terror; each year the glaciers came farther down into the valleys; each winter the sun seemed less able to provide the warmth needed for life To him, as to us, the universe must have seemed hostile to life We of these later days,... happened to come within hailing distance of the sun Just as the sun and moon raise tides on the earth, so this second star must have raised tides JMU I 2 THE DYING SUN on the surface of the sun But they would be very different from the puny tides which the small mass of the moon raises in our oceans; a huge tidal wave must have travelled over the surface of the sun, ultimately forming a mountain of prodigious... beings Thefinalestablishment of this law as the primary guiding principle in nature was the triumph of the seventeenth century, the great century of Galileo and Newton Apparitions in the sky were shewn to result merely from the universal laws of optics; comets, which had hitherto been regarded as portents of the fall of empires or the death of kings, were proved to have their motions prescribed by the. .. stars in the universe is probably something like the total number of grains of sand on all the seashores of the world Such is the littleness of our home in space when measured up against the total substance of the universe This vast multitude of stars are wandering about in space A few form groups which journey in company, but the majority are solitary travellers And they travel through a universe . and professionals, either for the source material they contain, or as landmarks in the history of their academic discipline. Drawing from the world-renowned collections in the Cambridge University. towards the light and reaching all along the cave; here they have been from their child- hood, and have their legs and necks chained so that they cannot move, and can only see before them, being. appear over the wall? You have shown me a strange image, and they are strange prisoners. Like ourselves, I replied; and they see only their own shadows, or the other shadows which the fire