I’ve somehow lost the reference to Dicke and the coasting universe. Does anyone have an idea where I can find it? I’m sure that I read it online somewhere, IIRC in a popular or semi-popular article (or perhaps a book), as there were pictures of scientists in it.

]]>For our response to Ned’s critique of our method (which has also been alluded to by Riess & Scolnic, and amplified on by Rubin & Hayden) please see: https://4gravitons.wordpress.com/2016/11/11/a-response-from-nielsen-guffanti-and-sarkar/#comments

I have just seen the previous posts by John Peacock and can only agree that cosmology is now at the stage when unknown unknowns are what matter. I would argue further that this has been the case all along – simply because astronomical observations are not the same as controllable laboratory measurements! Both are equally necessary however to make progress in our understanding – so let us aspire to the same level of rigour and intellectual honesty in both arenas.

]]>One can solve problems only if they really are problems.

]]>But I hope you will agree that it is by trying to solve such coincidence problems, rather than simply living with it, that science has grown.

]]>*“About the second part of the comment – I wonder why you believe that we must have such a synchronicity problem? Avelino and Kirshner just says that there is synchronicity problem in the Lambda-CDM model.”*

First, a model has to fit all the data, or at least all correct data, not just the supernova data. Second, one can ask which synchronicity problem is more severe. Third, if you think there is a synchronicity problem, read Bianchi and Rovelli. Also, explain why the coincident angular sizes of the Sun and Moon—a much more spectacular coincidence, which also holds only for a relatively short time around the present—does not need an explanation.

]]>Thank you for the comment. About the Milne model, it is correct – it is discussed for more than half a century. I was mentioning this misconception that a constant expansion rate is possible always only in a Milne model.

About the second part of the comment – I wonder why you believe that we must have such a synchronicity problem? Avelino and Kirshner just says that there is synchronicity problem in the Lambda-CDM model.

This model (“The coasting model) has been discussed for over 50 years, not just since 2001. The main problem with it is that it just doesn’t fit the totality of the data.

It’s also the case that the coasting phase of the model is transient. We have to live at the precise point when the acceleration is zero.

]]>This model (“The coasting model) has been discussed for over 50 years, not just since 2001. The main problem with it is that it just doesn’t fit the data.

It’s also the case that the coasting phase of the model is transient. We have to live at the precise point when the acceleration is zero.

]]>[1610.09885] Realistic coasting cosmology from the Milne model .

Use of Bayesian theory in comparing cosmological models is now widely discussed. It may be interesting to know that such a work was done way back in 2001 itself and published in a Physical Review D paper. The result was the same as the recent claim: that the supernova data do not provide strong evidence in favour of an accelerating universe, when compared to a `non-accelerating coasting model’ while using Bayesian theory.

http://journals.aps.org/prd/abstract/10.1103/PhysRevD.65.043506

This result was confirmed again in The Astrophysical Journal (ApJ) in 2005.

http://iopscience.iop.org/article/10.1086/432111/meta

The abstract of this paper tells it all:

In this paper, using a significantly improved version of the model-independent, cosmographic approach to cosmology, we address an important question: was there a decelerating past for the universe? To answer this, Bayes’s probability theory is employed, which is the most appropriate tool for quantifying our knowledge when it changes through the acquisition of new data. The cosmographic approach helps to sort out the models in which the universe was always accelerating from those in which it decelerated for at least some time in the period of interest. The Bayesian model comparison technique is used to discriminate these rival hypotheses with the aid of recent releases of supernova data. We also attempt to provide and improve another example of Bayesian model comparison, performed between some Friedmann models, using the same data. Our conclusion, which is consistent with other approaches, is that the apparent magnitude-redshift data alone cannot discriminate these competing hypotheses. We also argue that the lessons learned using Bayesian theory are extremely valuable to avoid frequent U-turns in cosmology.

]]>“Has dark energy had its day?”

https://thecuriousastronomer.wordpress.com/2016/11/03/has-dark-energy-had-its-day/

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