Quote:
Originally Posted by CraigS
Ok .. so now I've read the complete paper, I'm even more interested.
... so here comes the controversy ... oh no !!  )
"There is however surprisingly little direct evidence that the Universe is expanding. As mentioned in Section 1, searches for time dilation in gamma-ray bursts do not provide a conclusive test. Supernova light curves on the other hand appear to show convincing evidence of time dilation (Foley et al. 2005), which would rule out a non-expanding universe as an explanation for the results presented here for quasar light curves. Although this result has been challenged in an interesting paper by Crawford (2009) on the basis of bias in the sampling procedure, it seems fair to say that the result is still generally accepted."
So,
GRBs => not a conclusive test for universe expansion,
Supernova light curves => convincing evidence of expanding universe (with an outstanding challenge);
Quasar light curves => no dilation but not evidence for a static universe.
So that's a pretty up-to-date summary of where things stand at the moment.
Fascinating !
Cheers |
Pretty much. What most people don't know is that there's more than one BB model. At the last count I think it was somewhere up around 10-20 different models...some more plausible than others, but all pointing to the same conclusion...expansion.
There are problems with all observations, including those of the quasars, as I mentioned in my last post. Even the fact that they've compared the closer quasars to those that are at large values of z is in itself problematical. Simply because the closer quasars are less luminous for good reason....they're a lot older and have different characteristics of accretion and emission than the younger quasars. It's like comparing a 10 year old kid with his/her grandparents. Whilst the basics maybe very similar, it's the details which actually matter. You'll find this out as you read more about the subject