Re: hubble's constantly expanding universe

From: N:dlzc D:aol T:com \(dlzc\) (net_at_nospam.com)
Date: 12/28/04 

Date: Mon, 27 Dec 2004 17:35:32 -0700

Dear Tom Roberts:

"Tom Roberts" <tjroberts@lucent.com> wrote in message
news:cqp9ev$4f1@netnews.proxy.lucent.com...
> DavidBowman wrote:
>> As you know, space itself is expanding as the universe continues to
>> grow after the big bang. This expansion causes the distance between
>> everything to increase with time. The greater the distance between
>> things, the faster they move apart due to new empty space being created
>> between them. [...]
>
> But any bound system will remain the same size, in terms of a standard of
> length provided by quantum phenomena (e.g. count the number of Pt atoms
> in a Platinum ruler to measure length). The reason bound systems remain
> the same size is that their Lagrangians do not change, and the existence
> of an absolute sale of length from quantum physics requires such bound
> systems to remain the same size.
>
> So even without gravity, your body, the earth and moon, etc. would all
> remain the same size (to the extent they are held together via
> quantum-mechanical electromagnetic forces). Of course without gravity the
> moon would not be bound to the earth, or earth to sun, and probably no
> such objects would ever form....
>
> Classical theories of physics, such as GR and classical electrodynamics,
> have no intrinsic length scale. Quantum mechanics does. In a non-quantum
> world such expansion of the universe would be unobservable. But we do
> indeed live in a quantum world, and can observe the cosmological
> expansion of our universe.

Tom, I only have two quibbles with what you have said (paragraph 1 and 2).
Real physical objects don't suffer well as length standards. Recession
over and above momentum transfer from the Earth to the Moon, has been
observed between the Earth and the Moon. Gravity is not truly a force, so
"gravitationally bound" might not mean a whole lot, no?

You cited platinum for a length standard (just as a "for instance" I'm
sure). The platinum mass standard is stored in a vacuum, because it would
otherwise *accumulate* mass by absorbing hydrogen into the metal matrix.
As with the platinum-iridium and Invar length standards...
URL:http://nvl.nist.gov/pub/nistpubs/jres/104/3/html/j43bee.htm
... perhaps no "zero growth" material exists. [As a sidelight to anyone
"watching", the steel standard *shrunk* about as fast as the Invar and PtIr
standards grew.] Earth does not appear to be expanding (or contracting) at
anything near this rate (1 part in 10^8 annually). And this says nothing
about real material's ability to accumulate physical damage.

As to gravitationally bound Moon-to-Earth, you may have better access to
reviews of documents like:
URL:http://arxiv.org/PS_cache/astro-ph/pdf/0302/0302008.pdf
... he believes he has found a local value for expansion that is about half
that of the "post-acceleration" value that has been established.

I am prepared to be reamed, if you think I am muddying the water here...

David A. Smith

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