Re: [asa] Cosmologists questioning the Copernican principle?

It's not just hype - from the standpoint of the standard paradigm that I
mentioned dark energy is a serious problem & serious physicists are trying
to solve it. But they may be looking for a solution to a non-problem
because the paradigm may be wrong.

In the early days of relativistic cosmology homogeneity and isotropy were
assumed, both for "Copernican reasons" - hence the unfortunate term
"cosmological principle" - & as a simplfying assumption. But the article's
statement that "Without the simplifying assumptions of homogeneity and
isotropy, Einstein's fiendishly complex equations proved impossible to
solve" is nonsense. There are relatively simple solutions without those
assumptions, some of which have long been known, & those with spherical
symmetry would be of particular interest for a "void" model. Of course
everybody knows that the universe isn't strictly homogeneous & isotropic, so
the simple (Friedmann-Lemaitre) models are at best a first approximation to
the real universe.

A small correction to my earlier post - the last figure should be 10^120,
not 120%.

Shalom
George
http://home.neo.rr.com/scitheologyglm
----- Original Message -----
From: "Iain Strachan" <igd.strachan@gmail.com>
To: "George Murphy" <GMURPHY10@neo.rr.com>
Cc: "ASA" <asa@calvin.edu>
Sent: Tuesday, November 25, 2008 9:48 AM
Subject: Re: [asa] Cosmologists questioning the Copernican principle?

> Thanks for the reply, which should provide me more material to look up
> about this fascinating subject.
>
> However, in your opinion, do you think that the New Scientist is just
> indulging in journalistic hype in order to make a sensationalist
> article? (It is pretty sensational nowadays to give any credance to
> the idea that the earth, or at least the solar system or our galaxy
> are at the centre of the universe). Interestingly, to get round the
> "specialness" of the position, one of the people on the Richard
> Dawkins forum proposed a "crunchie bar" model, where our "bubble" is
> just one of many in a honeycomb; however given the vast size of the
> void, it still appears to be a coincidence if the earth is so close to
> the middle of one of the bubbles.
>
> Iain
>
> On Tue, Nov 25, 2008 at 1:11 PM, George Murphy <GMURPHY10@neo.rr.com>
> wrote:
>> Much of the puzzlement that theoretical cosmologists express these days
>> in
>> connection with the accelerating expansion of the universe is due to a
>> takeover of the field by physicists whose background is in nuclear &
>> particle physics & quantum field theory rather than general relativity.
>> It
>> may in fact be that the acceleration has nothing to do with quantum
>> vacuum
>> energy but is rather the result of a small but nonzero cosmological
>> constant
>> which is in fact a fundamental constant of nature, a possibility allowed
>> by
>> traditional general relativity. (& of course the old story of Einstein
>> introducing it for the wrong reason & then saying it was his "greatest
>> blunder" will be trotted out - but so what? Maybe he was wrong - as a
>> number of respected GRT folks always insisted.)
>>
>> This still leaves unanswered the question of how the huge quantum vacuum
>> energy which would lead to a huge cosmological constant gets suppressed.
>> But
>> we already know that somehow a fraction (10^120 - 1)/(10^120) of it is
>> suppressed, so it's not a big stretch to say that all of it is. & it's
>> likely that the cosmological "constant" isn't really constant, but it's
>> better to start with an estimate that's off by a factor of oirder unity
>> than
>> by one that's off by a factor of ~120%.
>>
>> Shalom
>> George
>> http://home.neo.rr.com/scitheologyglm
>> ----- Original Message ----- From: "Iain Strachan"
>> <igd.strachan@gmail.com>
>> To: "ASA" <asa@calvin.edu>
>> Sent: Tuesday, November 25, 2008 3:50 AM
>> Subject: [asa] Cosmologists questioning the Copernican principle?
>>
>>
>>> I was quite surprised to see the following New Scientist article:
>>>
>>>
>>> http://www.newscientist.com/article/mg20026821.200-is-earth-at-the-heart-of-a-giant-cosmic-void.html?full=true
>>>
>>> The gist of the argument is as follows. Dark energy has been proposed
>>> as an explanation of the apparent accelerating expansion of the
>>> universe (as illustrated by distant type 1A supernovae being fainter
>>> than expected). However (as I understand it from the article) the
>>> theoretical predictions of the quantity of Dark energy are out by 120
>>> orders of magnitude, implying an incredible degree of fine tuning.
>>>
>>> The alternative (for which the article describes potential experiments
>>> to test the theory) is to propose that the earth is in the centre of
>>> an enormous cosmological "void" ( comparatively sparsely populated
>>> region of space) surrounded by denser material. It should be noted
>>> that this "void" contains most of the observable universe! This would
>>> violate the Copernican principle of the earth being in no special
>>> place in the cosmos, but would exhibit isotropy ( universe appears the
>>> same in all directions - uniformity of the Cosmic Microwave Background
>>> Radiation), while requiring the earth to be near the centre (thus
>>> violating the homogeneity assumption - the structure of the universe
>>> varies with distance from the centre). One quote from the article
>>> seems to sum it up well; we live in a very improbable universe, and
>>> the new proposal trades one improbability (Dark Energy) for another
>>> (Earth near the centre).
>>>
>>> I would have thought that Young Earth Creationists would be very
>>> excited about this. However, I emailed a former colleague who is a
>>> YEC & he was less than excited; the article had been passed round
>>> creationist circles, but there was not much comment. He felt that the
>>> New Scientist article, as always, was too hyped up. (However, there
>>> are also positive discussions of it on the Richard Dawkins website as
>>> well).
>>>
>>> I'm not a cosmologist, but it appears to me that to invoke some
>>> mysterious form of energy, the nature of which we don't know, and
>>> state that it comprises around three-quarters of the material in the
>>> universe, in order to explain some observations that don't fit with
>>> the standard model seems a little like a desperate fix and just shows
>>> how little we really know. Perhaps some cosmologists on the list can
>>> explain if there is other, independent evidence for the existence of
>>> dark energy. Otherwise to invoke something we know nothing about to
>>> explain observations we can't otherwise explain seems about on a par
>>> with the Intelligent Design argument (which I think is a cop-out).
>>>
>>> What do others think? I know the New Scientist is given to hype. Is
>>> this just another case of it?
>>>
>>>
>>> Iain
>>> --
>>> -----------
>>> Non timeo sed caveo
>>>
>>> -----------
>>>
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>
>
> --
> -----------
> Non timeo sed caveo
>
> -----------
>
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Received on Tue Nov 25 10:43:52 2008