How Far Back Goes Big Bang Science?

[swamidass (S. Joshua Swamidass)]

@PdotdQ

I have not read Sabine’s paper so I do not know how justifiable it is. However I have read McGaugh et al.'s paper that was the impetus for her theory in great detail.

It is interesting primarily because it is a no-parameter model that fits the data. That is interesting, and surprising.

I also find it mind bending that she argues that the Bullet Cluster is strong evidence against Dark Matter. Of course, in this, she is exactly opposite of Ethan Seigel. I’m really curious who is ultimately going to be shown correct.

The Bullet Cluster as Evidence against Dark Matter

This is my assessment. Do you think it is off?

@swamidass

But if no one ever finds anything, perhaps modified gravity models will start to become more mainstream.

One challenge is that some proposals for dark matter rival string theory in lying outside the realm of experimental observability. We may never be able to detect them…

This paragraph from Sabine seems important:

Dark matter was a convenient invention. It could be distributed in just the right amounts wherever necessary and that way the data of every galaxy and galaxy cluster could be custom-fit. But while dark matter worked well to fit the data, it failed to explain how regular the modification of the gravitational pull seemed to be. On the other hand, a modification of gravity was difficult to work with, especially for handling the dynamics of the early universe, which was much easier to explain with particle dark matter.

It seems a major missing piece for MOND or emergent gravity is an account of the early universal that can make sense of cosmic background radiation. I wonder if dark matter particles can be explained as an emergent “particle” (like phonons in sound, or holes in semiconductors), they might be able click things together.

I also want to draw attention to this article. It is a really nice study. I’m impressed by how good a description this is of how science progressed from the point of view of a scientist working with a phenominal graduate student:

It was an accident I even wrote a paper about this. I was supposed to be working on something entirely different – an FQXi project on space-time defects – and thought that maybe Verlinde’s long-range entanglement might make for non-local links. It didn’t. But papers must be written, so I typed up my notes on how to blend Verlinde’s idea together with good, old, general relativity.
…
But next thing I know I have a student who wants to work on modified gravity. He’s a smart young man. Indeed, I now think he is a genius. See, while I kept blathering about the awesomeness of McGaugh et al ’s recent data on the radial acceleration relation, he had the brilliant idea of plotting the prediction from my model over the data.
…
I’m not sure what to make out of this. The derivation is so ridiculously simple that Kindergarten math will do it. I’m almost annoyed I didn’t have to spend some weeks cracking non-linear partial differential equations because then at least I’d feel like I did something. Now I feel like the proverbial blind chick that found a grain.