Does dark matter actually exist?

[Takket]

Interesting breakdown of several reason papers...... arguing that a small tweak to Newtonian equations might be the reason for unexplained star velocities far from the center of galaxies, and not the forces of an unseen gravitation influencer (dark matter).

More papers are coming and it sounds like more data is required to expand on this theory.

[Beakybird]

1. What about dark energy?

[Shermann]

2. I feel like micro black holes should be the top contender

Why is a mostly theoretical form of energy and matter more plausible than a hypothesis based on normal baryonic matter?

[CloudWatcher]

12. They looked, couldn't find any micro black holes ...

If "dark matter" was because of micro black holes, there would need to be a lot of them. And they would cause enough gravitational lensing of stuff 'behind' them that we could see that they are there. And so far ... no luck finding them. One result:

Dark matter is not made up of tiny black holes

From 190 consecutive images of the Andromeda galaxy taken over seven hours during one clear night, the team scoured the data for potential gravitational lensing events. If dark matter consists of primordial black holes of a given mass, in this case masses lighter than the moon, the researchers expected to find about 1000 events. But after careful analyses, they could only identify one case. The team's results showed primordial black holes can contribute no more than 0.1 per cent of all dark matter mass. Therefore, it is unlikely the theory is true.

https://www.sciencedaily.com/releases/2019/04/190402113042.htm

[Wounded Bear]

3. Good stuff! Thanks for the link! nt

[GreenWave]

4. I await the day when someone fesses up. "Gosh not everything is 3 dimensional."

Then it is back to the multidimensional drawing board.

[mopinko]

6. ngt has his doubts-

i’ve seen a couple vids on the topic.

[SCantiGOP]

9. Call it "dark stuff"?

Where’s Einstein when we need him.

[keithbvadu2]

7. I just can't keep up with all this new stuff.

It is fascinating to read this stuff but it is way beyond my understanding of the astrophysics.

[pwb]

8. It is time I answered this question.

It is not Dark Matter, it is Dark Light.

[LastDemocratInSC]

10. "More data is required to expand on this theory."

It sounds more like a hypothesis than a theory. Plenty of work ahead to get it to the theory stage, and I'm sure it will be interesting to watch the process.

[Igel]

11. I've seen a few reports arguing for MOND.

They're neat, bundled, and resolve a piece of the data. Sometimes the underlying hypothesis is tweaked to make it work--which is fine for a hypothesis, that's what we do as we get more data to disconfirm one prediction but want to improve on the hypothesis.

But if it works there, it has the same problem that the "tweaks" produce: instead of a single hypothesis there's a range of hypotheses in the same bin but which make different predictions in specific contexts. No one handles all the data without some pretty unprincipled changes to the equations underpinning the thing.

Then again MOND and its numerous flavors is really too incomplete to call a good "theory", so it's hard to completely rule it out. Work continues.

Note there are a number of papers out there that look at examples where MOND requires really extensive work and loopholes to make it work. One-sided gravitational distributions of matter or even gravitational lensing that MOND can't account for so far using analysis with regular matter, even black holes, without some truly exceptional and one-off exceptions. The kind of thing that a good theory should rule out. Like I said, work continues.

I may have to teach dark matter in my high school class, but I also point out that it's less a theory than a hypothesis, "We can't explain this so let's make up some crap to make it work". Again, a nice hypothesis, and work continues.