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From: nather@ut-sally.UUCP (Ed Nather)
Newsgroups: net.arch
Subject: Re: electrons as a bound on memory size
Message-ID: <5778@ut-sally.UUCP>
Date: Tue, 23-Sep-86 10:40:05 EDT
Article-I.D.: ut-sally.5778
Posted: Tue Sep 23 10:40:05 1986
Date-Received: Tue, 23-Sep-86 22:20:27 EDT
References: <15505@ucbvax.BERKELEY.EDU> <5100124@ccvaxa> <972@cit-vax.Caltech.Edu> <541@cubsvax.UUCP>
Organization: U. Texas CS Dept., Austin, Texas
Lines: 45
Summary: primordial universe & information

In article <541@cubsvax.UUCP>, peters@cubsvax.UUCP (Peter S. Shenkin) writes:
> Let's say it takes 10 kT to
> encode a bit at an acceptable signal-to-noise level;  then the
> number of bits one can encode is (1e54/4e-22)=~2e75;  that is, (2 x 10^75).
> 
> Note that as the universe cools down, it gets cheaper to convey a bit, so
> that the number of bits it is possible to store is continually going up!
> (I pass over any difference between storing and conveying information,
> because how could you use stored information if it weren't conveyed?)
> This would seem to imply (perhaps stretching things a bit, but what the hell --
> you only live once!) that at the moment of the big bang there was no information
> present in the universe (since T was infinite, I believe).
> 

Well, probably not infinite but large enough so the point stands pretty well
anyway.  Your point is interesting in the context of the "communication"
problem in the early universe.  Briefly, it arises if you go so far back
toward the Big Bang that the whole universe becomes very tiny -- and the
time after time zero is correspondingly small.  The standard argument says
that the individual parts of the universe didn't have time to communicate with
each other (assuming the speed of light then was what it is now) so how did
they all know to assume the same conditions?  The 3 degree "fireball" radiation
is remarkably uniform as we now see it, so communication MUST have been
possible.  So maybe we can't extrapolate back to that time "linearly" --
maybe the expansion from time zero wasn't uniform, at the present rate, but
the initial expansion was "inflated" (exponential) and started slower, but
speeded up to the rate we see today "after the communication took place."

If this seems implausible to you, welcome to 1986!  But it is the most widely
accepted cosmological model available today.  The "inflationary universe"
model was developed to explain away the inability of the differing parts of
the very early universe to communicate (and interact, so the system came to
thermal equilibrium).

Your point suggests an alternative explanation, which I find interesting:
maybe the different parts of the early universe really had nothing much to
say to each other!  If so, the "communication" problem simply disappears.

{If we get a Nobel prize for this, we split it 50/50.  OK?}

-- 
Ed Nather
Astronomy Dept, U of Texas @ Austin
{allegra,ihnp4}!{noao,ut-sally}!utastro!nather
nather@astro.AS.UTEXAS.EDU