Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site ames.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!vax135!cornell!uw-beaver!tektronix!zehntel!dual!ames!barry From: barry@ames.UUCP (Kenn Barry) Newsgroups: net.religion,net.philosophy Subject: Re: Gd and causality Message-ID: <949@ames.UUCP> Date: Sun, 21-Apr-85 18:42:13 EST Article-I.D.: ames.949 Posted: Sun Apr 21 18:42:13 1985 Date-Received: Wed, 24-Apr-85 03:04:18 EST References: <1385@aecom.UUCP> <812@bunker.UUCP> Distribution: net Organization: NASA-Ames Research Center, Mtn. View, CA Lines: 86 Xref: watmath net.religion:6725 net.philosophy:1707 I was quite struck by the synchronicity of Misha's article on causality appearing at about the same time mine did (on net.religion). Because of the similarities, I'm going to inject my nose into this debate. >> = Misha Berger > = Gary Samuelson >> Everything in this universe (once you get above Plank's >> constant and Schroedinger) has a cause. > >First big assumption, which not everyone will accept. Why the >two exceptions? If you allow two, there may be more. Good point. As I argued in my article, cause-and-effect clearly lacks the necessary generality and explanatory power to "explain" the fact of our existance. >> Every cause preceeds its effects. > >Second big assumption. How do you know that time has such a >unidirectional nature? Right again, but I don't think this is really a second assumption, just the first assumption in a new guise. >> This would leave me with one of two conclusions; either >> 1- the universe (I mean space-time, which might have preceeded >> the big-bang. What caused the big-bang, anyway?) is infinitely >> old, or > >The statement "space-time is infinitely old (or may be)" is circular. >You cannot measure the age of time, since time is the measure >of age. Time has "always" existed, pretty much by definition. Well, the terminology gets confusing, here. In a way, you're right: to say that time has "always" existed must be true, by definition. Yet, we still speak of the universe as being 20 billion years old, and since time may not have any meaning apart from the universe, it may also be correct to say that time "started" 20 billion years ago. How do we phrase this? >> 2- there was a cause which is not of this universe that started >> the whole thing. >> Now, if the net entropy of the universe never decreases, >> wouldn't an infinitely old universe have to be infinitely entropous? >> If the entropy stayed constant for a stretch, we again have to ask >> what *caused* the present trend to start? > >A quantity can be strictly increasing without becoming infinite, >if it approaches some value asymptotically. E.g. f(x) = 1 - 1/x >is strictly increasing, but will never exceed 1. Even if entropy >were infinite, that would not be a problem, in at least two cases. >First, if the universe is infinitely large, then it could be infinitely >entropous and infinitely non-entropous simultaneously. Second, if >the universe is infinitely divisible, there could be an infinite amount >of entropy in a finite space. Traditional arithmetic doesn't work well >with infinities (aka transfinite numbers). For example, there are an >infinite number of even numbers, yet not all numbers are even. Similarly, >there could be an infinite amount of entropy, yet not all is entropy. I see a couple of problems, here. For one thing, current astrophysics strongly suggests that our universe is *not* infinite, either in space or in time. And particle physics is even more firm in rejecting an infinitely divisible universe. So I think Misha's points are relevant to the universe we seem to actually inhabit. Nor would infinities invalidate the second law of thermodynamics. It is true that an infinitely large universe would take an infinite amount of time to completely run down, but it could reach a good approximation of this state in finite time. If energy differentials only exist over *very* large distances, no really interesting energy transfers can take place, and the universe will be, in all but the most technical sense, dark, cold, and dead, dead, dead. What needs explaining, if we suppose an infinitely old universe, is how our universe could be at such a *low* state of entropy after an infinite length of time. When we trace back the present rates of entropy, we find ourselves at the singularity point only 20 billion years ago. Whether there was nothing before this, or some earlier form of reality, *something* unique must have happened some few billion years ago, to put us where we find ourselves today. So I think Misha's question (and mine) remains unanswered: how does one explain the origin of the apparently finite universe we find ourselves in, without concluding that cause-and-effect is not an adequate principle for dealing with the beginning of our universe? - From the Crow's Nest - Kenn Barry NASA-Ames Research Center Moffett Field, CA ------------------------------------------------------------------------------- USENET: {ihnp4,vortex,dual,hao,menlo70,hplabs}!ames!barry