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SciAm: Astronomers are NOT dismissing dark matter!

3-D impression of dark matter via Hubble

From Dan Scolnic and Adam G. Riess at Scientific American:

You might have read otherwise in some headlines lately, but don’t be misled

The recent paper that has generated headlines used a catalog of Type Ia supernovae collected by the community (including us) which has been analyzed numerous times before. But the authors used a different method of implementing the corrections—and we believe this undercuts the accuracy of their results. They assume that the mean properties of supernovae from each of the samples used to measure the expansion history are the same, even though they have been shown to be different and past analyses have accounted for these differences. However, even ignoring these differences, the authors still find that there is roughly a 99.7 percent chance that the universe is accelerating—very different from what the headlines suggest.

Isn’t the big problem that we haven’t actually found any dark matter? It’s a matter of faith, in a way.

We now know that dark energy, which is what we believe causes the expansion of the universe to accelerate, makes up 70 percent of the universe, with matter constituting the rest. The nature of dark energy is still one of the largest mysteries of all of astrophysics. But there has been no active debate about whether dark energy exists and none about whether the universe is accelerating since this picture was cemented a decade ago. More.

There is some dissent about dark energy too, actually.

Headline writers do often jump to conclusions but many may be getting restless about why thse entities never seem to turn up.

See also: Rob Sheldon: The universe is expanding at an accelerating rate. Or IS it? One gets the sense that Prof Sarkar is trying not to step on toes as he explains why the Nobel should never have been awarded for dark energy.

Rob Sheldon: How do dark energy and dark matter relate to ID?

Dark matter: Skeptics wanted


Anti-dark energy theories are burnt toast?

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Conventional view:

Wow! SciAm gets a blog from one of the 2011 Nobel prize winners to rebut the paper. Talk about getting out the big guns! And what does he say? He repeats the paper's 3-sigma result as a 99.7% certainty. In other words, he is taking the criticism as valid and simply restating it for us plebians who don't know what 3-sigma means. But you know what? It isn't us plebians that invented the 5-sigma rule for discoveries, it was physicists. So he is as much as admitting that the paper is right, and that his own Nobel prize is undeserved by two sigmas. And lest someone accuse me of "not being an actual cosmologist", I will cite the arXiv paper that came out this week criticizing this same paper: Rubin and Hayden's https://arxiv.org/abs/1610.08972 R&H cite another co-winner of the 2011 Nobel as their consultant, Saul Perlmutter. And what was their critique of the U Cambridge paper? That the statistics used a Gaussian prior instead cherrypicking the parameters to agree with the dark energy hypothesis. In other words, the only way to prove 5 sigma for the dark energy model was to force the model to dim at large distances. Rubin and Hayden had to assume the very thing they wanted to prove. So far I've read 2 critiques from 2 of the Nobel prize winners, and if that is the best they can do, then they are as much admitting that there isn't a 5-sigma discovery in this data set.Robert Sheldon
October 28, 2016
09:25 AM

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