Sorry to break this long, peaceful silence here, but there's couple of new time dilation papers in arXiv by Crawford:
No Evidence of Time Dilation in Gamma-Ray Burst Data
Observations of type 1a supernovae are consistent with a static universe

Edited: there was a wrong word...

Thank you for breaking the fast, Ari :)

That second paper is pretty interesting...

Crawford said:

The essential point is that the absolute magnitudes are calculated using concordance cosmology and hence the selection of candidates is dependent on the luminosity-distance modulus given by concordance cosmology.

Crawford said:

Thus if a distant supernova is chosen to have the standard absolute magnitude using concordance cosmology then its true absolute magnitude will be weaker and its width will be wider.

That seems to make the light curves in the mainstream papers we have been seeing rather a self-fulfilling prophecy, making the time dilation a result of an assumption of the chosen magnitudes.

Of course, he's pushing his own(?) Curvature Cosmology, which I must admit I have never heard of.

Still, if the paper turns out to ring true, that makes for a very interesting explanation of the SN1a 'time dilations', which have been one of the more 'unassailable' items in the mainstream toolbox.

I was more interested in the first paper. I didn't know there were so many studies done on GRB time dilation issue already.

Ari said:

I was more interested in the first paper.

*laugh* Well, I was on my way to bed, and it's the supernovae phenomena that have always been interesting to me ;)

Crawford said:

The standard understanding, starting with Norris (2002) and Bloom et al. (2003), is that time dilation is present but because of an inverse relationship between luminosity and time measures it cannot be seen in the raw data.

Sounds a little like the explanation used to explain away Hubble's static-universe-conformal luminosity curves.

That's the nasty thing in cosmology - interdependent values that themselves might have a straight or curved relationship from which you are trying to derive a straight or curved relationship of something else, and selection effects are nigh rampant.

Crawford said:

Time dilation provides a much stronger test of universal expansion than the Hubble redshift of frequencies.

Good point, and certainly a contributor as to why people are so interested is these phenomena.

Ari said:

I didn't know there were so many studies done on GRB time dilation issue already.

I'm surprised that we don't hear about them more.

Question: does Crawford have a hope of getting these published? I mean, the methodology seems sound, but he self-references his book and other pre-prints in his GRB paper, which seems a big no-no.

One thing that's interesting about these folks with some specific other cosmologies that they're trying to push is that, as long as they're not crazy, they can look at the data from a little further back to see whether the assumptions and selections that are being made are independent confirmations of concordance cosmology or not. Without that perspective, I can see how it might be difficult to see how concordance cosmology actually just feeds into the experiment in some cases, making the conclusions not the independent confirmations that they might seem.

It's been an interesting last few years in astronomy and cosmology, I must say.

QSO's fail to show time dilation.   GRB fail to show time dilation.   The objects are behaving very badly for BBT expectations.   Somebody needs to remind them that the universe is expanding.

Dave said:

QSO's fail to show time dilation.   GRB fail to show time dilation.   The objects are behaving very badly for BBT expectations.   Somebody needs to remind them that the universe is expanding.

There's probably some dark space in there that doesn't react to expansion...

We have to remember that some studies show time dilation in GRB's while some studies don't show it, so I think the question is still open.

Just a by-the-way: Crawford's book (they all have to have books these days? :) has a 25-page preview on the publisher's web site here below the description.

It sounds like tired-light-meets-general-relativity in a way. I might pick up the book at some point - especially since it's not as pricy as Narlikar and Burbridge's book was.

On the topic of Narlikar and Burbridge's book, Facts and Speculations in Cosmology, my relatives actually bought that for me off my wish list. Having read Hoyle's earlier book, this was basically in many ways a retread in more understandable language, and still pushes just QSSC in a fairly small summary near the end, so a little disappointing in that regard.

I wish there was a book that would do a survey of cosmologies, including Big Bang variants apart from concordance. (Or, if there is such a book, that someone would tell me :)