Re: Expansion = inverse contraction?

From: Russell Standish <>
Date: Mon, 15 Dec 2003 09:21:20 +1100

I'm not sure you're phrasing this correctly. What you mean is to ask
whether our measuring sticks are contracting rather than space
expanding. Since the metre is defined by a certain number of
wavelengths of light radiated by a particular element, this would be
equivalent to asking whether certain atomic properties (e, c, hbar etc
- are changing over time).

However, I'm not sure that there is any meaningful way to ask
questions about change to "measuring sticks", only to dimensionless
ratios such as the fine structure constant (which has changed by a
small amount over the life of the universe).


On Sun, Dec 14, 2003 at 12:25:12PM +1100, Colin wrote:
> Something that occurs to me that I haven't seen any explicit discussion
> about and thought someone in the list may have come across it somewhere.
> In cosmology we traditionally think of the universe as expanding from
> the point of view of any position within it. In our minds it is getting
> bigger and bigger.
> I am asking why I haven't ever seen anyone discuss the inverse
> proposition .ie. That what may be happeneing is that this expansion is
> only an appearance and that it may be that spacetime is actually
> contracting. If it were contracting then from within everything would
> appear to be expanding as we shrink and shrink to nothing.
> This is not a 'big crunch'. This is an inverse-bang. 2nd law/fwd time
> etc still functions as usual.
> Is there something built into the models that forbids this that I simply
> haven't got?
> Or is it meaningless to make the distinction?
> Cheers
> Colin Hales

A/Prof Russell Standish            	 Director
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Received on Sun Dec 14 2003 - 17:25:09 PST

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