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From: john@frog.UUCP (John Woods)
Newsgroups: net.physics
Subject: Re: Questions about fundamental constants, gravity, electrons
Message-ID: <277@frog.UUCP>
Date: Tue, 20-Aug-85 14:01:13 EDT
Article-I.D.: frog.277
Posted: Tue Aug 20 14:01:13 1985
Date-Received: Sat, 24-Aug-85 18:28:48 EDT
References: <495@sri-arpa.ARPA>
Organization: Charles River Data Systems, Framingham MA
Lines: 84

>    In place of some of the stupid questions that have recently been 
> discussed, I'll pose some (perhaps equally stupid) questions:
>
Your questions were refreshing non-stupid!
> 
>    From time to time I hear or read about speculations that the values of
> the fundamental constants *could* be different now than they were 10**n
> years ago (given a suitably large value of n, as long as it is after the 
> big bang plus one minute).  Is this complete idiocy, or do some physicists
> take the possibility seriously?
> 
Many physicists take this question quite seriously.  However, it turns out
that they are fairly confident that (at least several) constants have been
constant for at least several million years:  they found this natural nuclear
reactor in France, a deposit of uranium ore in spongy rock.  Every time it
rains, the water acts as a moderator, and spontaneous fission happens.  By
now,  the deposit is fairly well depleted of fissile uranium, but by analyzing
the abundances of various isotopes present, they have determined that this
thing has been going, more or less constantly, for (I think) several hundred
million years.

Why is this interesting?  The absorption of a slow neutron by U-235 is the
result of a resonance effect (which overcomes the normal tendancy of the
neutron to just bounce off), and this resonance is somewhat of a chance
conspiracy of (in effect) several of the fundamental constants, which
determine the eigenstates of the U-235 nucleus.  These functions that
determine these eigenstates are very sensitive to changes in these
"constants", and it turns out that if the constants were much different at
all, U-235 would not be fissionable.  However, this pile of U-235 has been
fissioning constantly for hundreds of millions of years, placing the maximum
rate of change at something incredibly low (assuming of course that the values
did not change incredibly suddently microseconds before the molten rock
cooled).

>    What about speculations that the values of the fundamental constants
> *could* be different in another part of the universe?  There seem to be 
> two possibilites, either that there is a continuous, gradual change, or that
> there is an abrupt change at "domain walls" separating various regions of
> the universe.  The claim is made that we could not detect such variations
> since all of our measurements of distant phenomena are made locally, and
> hence are subject to transformations due to local conditions.  Should these
> speculations be ignored, or do they have some merit?
> 
These speculations do have merit, but (I believe) most physicists adopt the
hypothesis that everything is the same everywhere because (1) it is easy,
(2) it makes it possible to get work done, and (3) what few subtle clues they
can obtain without going out there indicate that the assumption is reasonable.

>    Accepting for the moment that the value of one of the fundamental
> constants (pick one!) could be changed, would it vary independently of the
> others or would some of the other constants change too?  What are the
> relationships between the so-called "fundamental" constants, if any?  Which
> of them seem to have unconstrained and hence "arbitrary" values?
> 
I don't know.  My guess is that, since "fundamental constants" are an artifact
of explanation rather than root causes, whatever happens to change one of them
might or might not change others.

>    Has anyone heard more concerning the formulation of gravity as a push
> from infinity (analogous to the pressure inside a balloon) which is
> attenuated by mass instead of its more common formulation as a pull between
> masses?
>
I haven't heard of this one.

>    I've heard that there may only be one electron in the whole universe,
> which explains why all of the electrons we observe have exactly the same
> charge and mass.  Does anyone understand how one gets the observed universe
> which appears to have *lots* of electrons from just one particle?  What 
> about the two electron spin states, and positrons (just one anti-electron 
> in the whole universe?)?  Or is the one-electron theory full of holes
> (sorry about that--I couldn't resist!)?
> 
As a guess, this sounds more like someone couldn't handle the idea of
postulating something distateful (a humongous number of indistinguishable
things) and postulated something complicated (poor, busy electron!).
I rather take the view that electrons are just explanations -- perhaps there
are little critters running around "down there", but they appear to be rather
perverse creatures--hence I try to avoid ascribing "common-sense" attributes
to them.  If you prefer, I avoid insanity by going quietly mad... :-)


--
John Woods, Charles River Data Systems, Framingham MA, (617) 626-1101
...!decvax!frog!john, ...!mit-eddie!jfw, jfw%mit-ccc@MIT-XX.ARPA