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Dark matter. Sounds like a catch all designed to make a math model work properly.
You would like this https://www.youtube.com/watch?v=PbmJkMhmrVI
Do you think solutions to dark matter are tied up in a unified GR + quantum mechanics theory?
The experimental observation did not reveal Dark Matter. Nobody has seen or proven Dark Matter, actually. That's why it is called Dark Matter. The observation just showed that the math model was flawed, and they invented "Dark Matter" to make up for it.
My personal take is that they will one day add the right correction factor that should have been in the fomulas all the time.
Just like with E=mc² not being completely correct. It's actually E²=m²c⁴ + p²c². The p²c² is not adding much, but it is still there.
I know that it is not a simple scale thing here. So it might be something else. My bet is that is has something to do with angular momentum,
I'm no astrophysicist - I just design computer chips. But this issue of "We need dark matter" came up with rotating galaxies, didn't it? So I'd look into that direction if there is a potential connection. Classic bug hunting technique.
The Bullet Cluster, among several other systems, are very strong evidence that dark matter is actual baryonic matter that does not experience significant (or any) electromagnetic interactions. What we see when we look at these kinds of systems is that there is all evidence of STUFF there, but we cannot see the stuff. It's not an indication of a poorly-performing math model missing a function term.
It would be like if we saw ripples in the water like we know exist around a rock. But we don't see a rock. Sure, MAYBE we just fundamentally need to rewrite our basic rules of fluid mechanics to be able to create these exact ripples. But the more probable explanation is that there's a rock we can't see, and falsifying that theory will require just HEAPS of evidence.
The evidence we have suggests overwhelmingly that there is actual stuff that has mass that we simply do not have the tools to observe. Which isn't all that surprising given that we are only JUST starting to build instruments to observe cosmological phenomena using stuff other than photons of light.
How would you know the difference? All the evidence of "STUFF" being there is obviously gravity based, as no other factors are involved. So that "STUFF" has a number of parameters that can be determined from the postulation of it's existence: It should be baryonic to have the mass, and it should be stable, or one would probably observe energetic events related to state changes. Another point is: if it has mass, why does it not just clump together? I guess one can also rule out that it is charged, or one might see electromagnetic interactions. Did I miss a key parameter? Did I misunderstand anything here?
So do you know of any 3 (or maybe even 5 or 7) quarks baryon that would fit the pattern? The amount of combinations is limited, and CERN and others have created so many different particles over time that something of that kind that is actually stable should have made an appearance? Or are there any theoretical works on what kind of particle this could be, matching the pattern?
And, by the way, I would not call it a "poor performing" math model, as it covers quite a lot of the world we can observe. I deliberately used the term "incomplete".
We observe patterns of behavior -- orbits, movement, gravitational lensing -- that are exactly what we would see if, for example, there were great clouds of matter or other galaxies in those places. But we don't see the hydrogen gas. We see non-uniform distributions of dark matter mass that imply there is not simply some consistent calculation error, but rather that there is dark matter that is not uniformly distributed. Again, read up on the Bullet Cluster because it shows a VERY clear example of what I am talking about, where the regular, electromagnetically-interacting matter behaves one way but the apparent shadow of dark matter behaves in a different way that is consistent with lack of electromagnetic interactions.
We've also discovered things like ultradiffiuse galaxies -- likely remnants from ancient collisions -- that have apparently been stripped of their dark matter. MOND cannot explain these observations because these galaxies essentially behave in a Newtonian manner that would be impossible in a MOND framework.
Why does stuff clump together? For all non-dark matter, the answer is electromagnetism. Outside of the extreme cases of neutron stars and black holes, where gravity overwhelms and defeats electromagnetism and the nuclear forces theoretically take over to create degeneracy pressure, electromagnetism is the reason things clump. Absent electromagnetism, what would cause clumping? Essentially nothing, stuff would whizz straight through other stuff and go into orbits. Potentially HUGE orbits, which is why there's so many theories around dark matter "halos". Maybe if there were DIRECT collisions of theoretical DM particles, that might cause an energy-releasing event -- this is one of the things current dark matter detectors are looking for and may yet find within the upcoming years.
Yep, and more than a handful Many that make specific predictions we can test for and so are testing for. For example, you could look at axions, which are a theoretical particle predicted by an entirely different theory that may be a good fit for the dark matter particle.
Which would still not rule out anything else...
That non-uniformity though, yes, this is a good point for a "dark matter exists" hypothesis. Although I would still word it differently: Not "We see non-uniform distributions of dark matter mass" but "We see a non-uniform mass-like effect". I've learned that keeping the terms as neutral as possible, or it might exert too much pressure on the thought process to go in just one direction.
Which is basically an extreme case on "not uniformly distributed".
That is acceptable. I was not "selling" MOND here (or any other theory), btw, I'm just wondering what kind of possibilities are there to explain all those observations. "An invisible mass nobody has observed except for it's gravity effect" sounded a bit thin of a leg to stand on there, while incomplete models are a rather widespread phenomenon.
Gravity? I mean, we are talking about something that has gravity. Did planets form because of electromagnetism?
Indeed. Try that with the wannabe-sciences like economics...
Well, at least they share the common trait of not being found yet... ;-)
I don't have a bias against new particles. For me as a non astrophysicist, just another theory having a big hole was simply more likely. And the theory of gravity breaks anyway when it approaches quantum theory, why shouldn't it be broken elsewhere, too?
But I can easily accept the information given here, primarily the case with uneven distribution, which is a good case for something being there. Now you just have to nail the particle down.
Sounds like the retired engineer that has a theory cliché.
No, I'm just wondering about the reasoning for something that has not been observed except for it's gravity effects. I mean, physics has loads of incomplete models, so for me, just another incomplete model looks more likely than some phantom particles that nobody can explain.
Modifying the theory of gravity to fit the data might be useful even if it's just for modelling purposes. But it doesn't make a theory for sure.
I am also an (non retired) engineer, but alas I have no theory of my own :)))
Yeh, that's how the scientific method works.
Observations don't support a model, or a model doesn't support observations.
Think of a reason why.
Test that hypothesis.
Repeat until you think it's correct. Hopefully other people agree with you.
People are also working on modifying General Relativity and Newtonian Dynamics to try and fix the model, while other people are working on observing dark matter directly (instead of it's effects) to further prove the existing models.
https://youtu.be/3o8kaCUm2V8
We are in the "testing hypothesis" stage. And have been for 50ish years
Yeah, it's legitimate science being done, but some people treat it as sacred and would fight you to no end because they say Dark Matter is some certainty, rather than approaching it with the proper scientific skepticism or with a statistical outlook.
For the most part believers in Dark Matter are cool, but a vocal minority practically worship it as the only possible truth.
The certainty is that there is something there, we just don't know what it is. The name "dark" anything is irrelevant.
If a new hypothetical model showed that either some far off unobserved mass(es) or the currently observable mass can have the gravitational effects that were previously explained by dark matter, or any other far off idea about the nature of gravity at large scale: then there would be evidence there is nothing there. Currently there is no evidence that something is there, just that there are forces and motions that are not understood.
Great example, and this brings up a great point about this topic - there's a difference between what's a scientific pursuit vs. what is current established scientific understanding.
Dark matter is a topic being studied to try to find evidence of it existing, but as of now there's is zero physical evidence that it actually exists.
You’re not wrong. According to the current scientific understanding of the universe, that’s exactly what it is. They just gave it a badass name.
I know, I was so hype a few years ago when a new gravity well model supposedly eliminated the need for Dark Matter, but recently it's been in the news as a scandal that also doesn't fix everything.
Modified Newtonian Dynamics (MOND). It's been the dissenting voice in the modern Great Debate about dark matter.
On one side are the dark matter scientists who think there's a vast category of phenomenon out there FAR beyond our current science. That the universe is far larger and more complex than we currently know, and so we must dedicate ourselves to exploring the unexplored. The other side, the
On the other you have the MOND scientists, who hope they can prevent that horizon from flying away from them by tweaking the math on some physical laws. It basically adds a term to our old physics equations to explain why low acceleration systems experience significantly different forces than the high-acceleration systems with which we are more familiar -- though their explanations for WHY the math ought be tweaked I always found totally unsatisfactory -- to make the current, easy-to-grock laws fit the observations.
With the big problem being that it doesn't work. It explains some galactic motion, but not all. It sometimes fits wide binary star systems kind of OK, but more often doesn't. It completely fails to explain the lensing and motion of huge galactic clusters. At this point, MOND has basically been falsified. Repeatedly, predictions it made have failed.
Dark matter theories -- that is, the theories that say there are who new categories of stuff out there we don't understand at all -- still are the best explanation. That means we're closer to the starting line of understanding the cosmos instead of the finish line many wanted us to be nearing. But I think there's a razor in there somewhere, about trusting the scientist who understands the limits of our knowledge over the one who seems confident we nearly know everything.