Sorry, but...aren't modified gravity theories gaining some more traction recently? Not enough to say that modified gravity is the most likely explanation for observations, but at least enough to avoid saying that dark matter is "clearly the right explanation"?

edit: I've just realised that some people would describe modified gravity as a specific theory to describe the observational effect of dark matter. Is that what you were doing here?

[–] [email protected] 5 points 11 months ago (1 children)

Maybe it's all because of tiny strings.

Guys

Listen

It's the strings

[–] [email protected] 2 points 11 months ago (1 children)

Ok this gave me a laugh.

But to be serious, isn’t the opposite true? Like, my understanding is that string theory is basically dead, and only getting deader. But I thought modified gravity as explanations for the dark matter observations is seeing a bit of a resurgence lately.

[–] [email protected] 1 points 11 months ago (1 children)

my understanding is that string theory is basically dead, and only getting deader.

Huh... where is this impression from? String theory isn't dead, it's just a very narrow field in which most of the participants specialize in a subset of it that's less concerned with completing it as a whole. It's incredibly difficult work, progress is slow, and it's currently too broad to be applicable to reality (which is important for funding). The tests we can think of to validate the correspondence of math to the physical world are... significantly out of reach due to the energy requirements.

But it's still the leading theory of quantum gravity and there's active work in, say, AdS/CFT correspondence - which shows that string theory can line up to reality and be predictive. It's the best idea we have right now, it's satisfyingly elegant, and it's working as a useful tool at the very least.

There are competing alternatives that get their own research, of course. We should persue them all until a clear victor emerges!

But I thought modified gravity as explanations for the dark matter observations is seeing a bit of a resurgence lately.

Modified gravity, so far, is non-predictive and does not account for things like the bullet merger while also accounting for ultra diffuse galaxies and our observations of the CMBR. All proposed modified gravities have failed to pass experimentation compared to general relativity. Modified Newtonian Dynamics (MOND) fails in the face of light and gravity having the same speed. And even if MOND were to be true, it still requires the presence of (albeit possible baryonic) dark matter to be even considered due to existing mass measurements of galaxies.

So, again, dark matter is simply the best model we have.

[–] [email protected] 1 points 11 months ago (1 children)

I probably overstated the case, but I was mainly going on what this video said about string theory. It’s had no reliable test results, no predictive power. It’s a useful mathematical model, but not actually a good theory to explain the real world.

I don’t even know where I got that idea about modified gravity from. I think I vaguely saw a few headlines about it recently but I didn’t even bother to read the articles they came from, and I somehow allowed that to stick in my brain. My bad.

[–] [email protected] 1 points 11 months ago

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[–] [email protected] 2 points 11 months ago (1 children)

Sorry for not responding earlier, I don't seem to be getting notifications! My other reply further down in the thread hopefully answers all of your (wonderful) questions, though. Have a great day!

[–] [email protected] 2 points 11 months ago

Yeah no worries. I’ve had the same problem with notifications sometimes not appearing. No idea why. Thanks for the feedback though!