The Collapse Of The Universe And The

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The Collapse Of The Universe And The Reversal Of Time Essay, Research Paper The Collapse of the Universe and the Reversal of Time Cosmologists today do not agree on whether the universe will expand forever, or will eventually recollapse. And among those who subscribe to the latter view, there is disagreement over the nature of the collapse. Some believe it will be a mirror image of the big bang, so that any intelligent creatures living during the second half of the universe’s life will sense time moving in the reverse direction, and view us as living in their future. This paper presents no solutions, but attempts to analyse the possibilities rationally. COSMOLOGICAL KNOWLEDGE Writers on cosmology appear to speak with authority on the history of the universe. They describe

its earliest moments in great detail, and discuss its present structure and future large scale development. But many of their pronouncements have to take the form, “If such-and-such is true, then so-and-so. And if not, then …” In fact our quantitative knowledge of the universe is very incomplete. True, we know the approximate distances of many celestial objects, both near and far, and we know the age of the universe fairly accurately. Although from time to time the different ways of calculating this age have produced results which appear inconsistent with the known ages of the earth and the stars, there is now general agreement that the big bang occurred between 10 and 20 billion years ago. But estimates of the present size of the universe, or the amount of matter and

radiation it contains, differ widely, and any predictions we wish to make depend critically on these quantities. Indeed there is disagreement over whether these magnitudes are finite or infinite; surely this is the most devastating uncertainty anyone can imagine! For a variety of reasons, which are not presented here, I believe that the quantity of matter in the universe, and its dimensions in space and time, must all be finite. The reader will find a discussion of this assertion in another paper on the present site, entitled Infinity. In the rest of this essay, therefore, we assume that the total amount of matter and radiation has some definite finite value, and that the universe has a finite volume. (This volume, of course, may not correspond with that of the visible universe;

the expansion results in a “horizon” beyond which we cannot see because of the finite speed of light.) And because I believe the lifetime of the universe must also be finite, the following discussion assumes that the expansion we observe today will eventually be followed by a similar period of contraction, leading to a “big crunch”, and the end of everything including space and time themselves. TIME In considering questions such as this it is essential to rid ourselves of the false impressions of time which our human limitations seem to impose upon us. This matter is discussed in detail in the author’s book Time, Science and Philosophy, which the reader is encouraged to study. Briefly, this book maintains that the idea of a “now” is a purely subjective phenomenon,

existing only within the human mind, with nothing corresponding to it in the outside world. It follows that the impression of a moving time is false; there is nothing objective to move, and nothing with respect to which it could move. Above all we must rid ourselves of the belief that the future is in some way less determined than the past; if the borderline between past and future is illusory, then so must be the distinction between the two regions of time which it is supposed to separate. The only reason we believe the future to be still undecided while the past is immutable is that we can remember the one and not the other. To avoid these prejudices we must picture the history of the universe not as a three-dimensional stage on which things change, but as a static