Thread by @DudeDarkmatter

Dark Matter Hunters Pivot After Years of Failed Searches - WIRED

“Pivot” is an interesting choice of words. Sorta implies that one is pivoting from one thing (WIMPS) to something else. In which case the “something else” needs to be specified. apple.news/AfFMHcOI9QlK8e…

The whole dark matter search community reminds me of Daffy Duck in the episode quoted from IMDb here. [shockingly, I do not instantly find a gif of Daffy falling off said cliff.]

Reading this article does not inspire confidence. Sounds more like they’re poised to make the same mistakes all over again. Having spent decades in a fruitless search for WIMPs motivated by the WIMP miracle - an irrelevant numerical coincidence - might they decide to learn more?

I am about to say some very strong things about particle physicists, particularly as it pertains to the search for dark matter. These are generalizations. There are certainly individuals who defy the stereotype. But there is also a pretty clear stereotype.

The stereotypical particle physicist has only a cartoon understanding of the astronomical evidence for dark matter.

I have lost count of the number of physics seminars I’ve attended that start with a nominal nod to the evidence - be the evidence is entirely astronomical - usually a slide with a flat rotation curve, a picture of the bullet cluster, and/or the CMB power spectrum.

Then they’re off and running. Having established, to their apparent satisfaction, that dark matter exists, they dive straight into whatever experiment they’re working hard on, or (if a theorist), whatever whacky twist they have on old and discredited ideas (e.g., supersymmetry).

The experimentalists have made phenomenal progress in detecting nothing. The limits are quite sobering. At some point, you gotta ask if we’re barking up the wrong tree. We passed that point many years ago.
astroweb.case.edu/ssm/darkmatter…

In all of those seminars, I’m usually the only person in the room who has written referee papers on all the different lines of astronomical evidence that people involved in dark matter searches are fond of citing.

There’s a lot more to the evidence than what it gets boiled down to: “rotation curves are flat therefor we need dark matter.” The corollary is “we with the Big Brains will take it from here. No need for further input from stupid astronomers.”

They’re not shy about hiding their contempt for the field that gave them 100% of the evidence that motivates the expensive experimental searches that many have made into their lifetime projects. What could an astronomer possibly teach them about dark matter?

Have the gall to point out that the devil is in the details often leads to dismissal of theee details as irrelevant “gastrophysics” - a term consciously coined to deride any details they were ignorant of and too intellectually lazy to come to grips with.

But there are lots of facts that aren’t details. It isn’t just that rotation curves are flat. It is also that the flat part of the rotation curve correlated with the baryonic mass of the galaxy (Tully-Fisher). It isn’t just that you need dark matter as you go farther out...

it is that the amount of dark matter depends on the distribution of baryons. This is true both globally - lower surface brightness galaxies are systematically more dark dominated (the central density relation) and locally - the gravitation potential of the baryons is predictive

of the total gravitational potential (including dark matter - the radial acceleration relation. And those are just systematics for rotating galaxies. Don’t get me started on dwarf satellites, which show these effects and more, like how they’re dynamics are altered by proximity

to their giant hosts. The point is that there is a lot more information available now than when we developed the WIMP paradigm. These observational facts did not inform the development of the paradigm. We weren’t playing with a full deck of cards. Had we been, we mighta come up

with something else. So it is good (and high time) that we think outside to bottomless & apparently empty WIMP box. On the other hand, many of the ideas I see being mooted have also been developed in apparent ignorance of many relevant facts. That just guarantees repeated failure

So if you want to play the dark matter detection game, you owe it to yourself to learn more astrophysics than you will get from the typical graduate physics curriculum. Indeed, addressing this knowledge gap was one motivation I had for developing an entire course on dark matter.

The need was already clear a decade ago. astroweb.case.edu/ssm/333f13/
I had a moment of doubt the first time I taught it: is there really enough material for an entire semester course devoted entirely to dark matter?

#yes

At this point, I find it hard to cover all the empirical evidence, let alone discuss all the hypotheses. An additional course with the same title could be taught from the perspective of particle physics and have almost no overlap with the course I teach. And therein lies rub.

The fields seem to be diverging into different sub-paradigms rather than converging on a solution.

Note that nowhere in here have I even mentioned MOND. That’s advanced tuition. Even after a whole semester, I usually only have barely any time to mention it.

And yes, I’ve written many papers & reviews for serious scientists:
arxiv.org/abs/1404.7525
arxiv.org/abs/1412.3767
arxiv.org/abs/1112.3960
arxiv.org/abs/astro-ph/0…
arxiv.org/abs/1610.08981
arxiv.org/abs/1607.02145
arxiv.org/abs/1808.00971
arxiv.org/abs/1808.00271
Etc.