With light traveling at a constant speed how would this not be a measure of distance?

That's sort of a non sequitur. But a good thing to clarify.

It is the general theory of relativity (gtr) that allows us to precisely model most any expanding universe scenario we choose.... which is a major change from before, when the background "space" for all actions was a simplified, non-changing, neutral setting. Au Contraire, the background appears to be just as dynamic as the objects within it.

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Everyone is entitled to his own opinion, but not his own facts.

You could certainly convert it to a measure of distance, mutiplying time by c. But that distance doesn't tell you much, on cosmological scales, because of the expansion of space during the flight of the photon. To come up with a distance at time of emission, or a distance at time of reception, you need to plug the observed cosmological redshift into the specific model of the Universe you're using.
Local observers will, as you say, always find the speed of light to be a constant, but local observers at rest in their own part of the metric are receding from other local observers at rest elsewhere in the metric. So this means the rate at which a photon approaches us, as it crosses cosmological distances, is not a constant.

Grant Hutchison

1. The inverse square law for distant type 1a supernovae can only be inferred if it is corrected for viewing angle, since the fireballs are inherently asymmetric, (Kesteven, Caswell,see:http://adsabs.harvard.edu/abs/1987A&A...183..118K)..and the luminosity is not constant per steradian. Determining viewing angles for the most distant 1a's, even with Hubble, is tricky at best. Inferring new physics before determining the population of viewing angles for the most distant supernovae requires caution.
2. One also has to question the merit of solving the simultaneous problems of smoothness and lumpiness in the universe. The CMBR is experimentally measured "smooth"...varying scant millikelvins across the sky, inferring that the plasma that created it was pretty homogeneous. Several experiments confirm this, as many have pointed out. But the universe is "lumpy"...stars, galaxies, clusters of galaxies, superclusters of galaxies, great attractors...on a huge scale. The resolution to the two homogeneity/inhomogeneity issues was the proposed ad hoc solution of inflation....a superluminal expansion of spacetime itself, by first Guth, and then Linde. If that happened, as proposed, then much of the cosmological phenomenology cascades out of it...but there is neither experimental evidence that any volume of space can do that, from any particle phyics experiment...nor is there any reason why the timing of the expansion should begin at any arbitray moment after the BB expansion began, or any reason why it should have arbitraily ended some time later, conveniently allowing a solution to the smooth/lumpy problem.None.
3. I've offered cans of inflationary spacetime for sale, so that you can add a little bit to your gasoline tank, and your SUV/Maserati will then have the benefit of gases expanding superluminally in your combustion chamber, with no apparent loss of energy, in violation of every particle physics experiment ever seen...so that you can get several million miles per gallon at least. Nobody buys my additive, and it's hurting new car sales something awful.
4. We must also remember that the "axis of evil" seen by Tegmark in the polarization data has as yet no explanation either...Why does the plane of our homey little solar system line up with the axial symmetry seen in the WMAP polarization data, with a statistical chance of less than 1/10,000?
5. Now the latest issue of Astronomy Now, June 2008, p.10 has a claim for an annual modulation in the number of events seen in the DAMA/LIBRA experiment. They believe that the Earth moving "upstream" and "downstream" through a "sea" of dark matter particles, traveling 280 km/sec when "fast" and 220 km/sec when "slow" in it's motion around the galactic center attenuated by it's Keplerian orbit around the sun, causes their modulations in observed NaI scintillation counts. I hope they're not forgetting the changing neutral current cross-sections, which vary as the square of the average energy (Ultimate Neutrino Page), and Doppler shift during the Earth's annual journey, making a 12 month oscillation in the data.
6. Edit: There is also the issue of the anomalous lack of a sufficient Sunyaev-Zeldovitch effect...a "shadow" on the CMB if it is entirely cosmological in origin...from local galaxies. see:http://arxiv.org/abs/astro-ph/0703470
7. Edit: There is evidence for large scale angular correlations of quasar polarization vectors in regions as large as ~ 1 Gpc size at z~1.
The mean polarization changes with redshift, and is statistically significant at > 99.9% in a sample of 355 quasars . This effect seems strongest along an axis close to the observed CMB dipole , and Tegmark's "axis of evil". These alignments are amonst the largest structures in the universe, possibly questioning fundamental assertions of large-scale cosmological isotropy..(read as no BB) see:http://arxiv.org/abs/astro-ph/0507274 pete


see:http://people.roma2.infn.it/~dama/web/home.html

see:http://cupp.oulu.fi/neutrino/nd-cross.html

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A third rate theory forbids
A second rate theory explains after the fact
A first rate theory predicts...A. Lomonosov

I'm wasn't speaking gtr when i said that, Merely stating that distances we measure are only relative at the time we measure them. Just like measuring continental drift, every year you measure it - it moves but the measurement is widely accepted for what it is today even though 1 billion years later it will be drastically different.