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this post was submitted on 22 Dec 2023
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Dark matter. Sounds like a catch all designed to make a math model work properly.
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.
Do you want slightly darker matter? Cause that's how you get slightly darker matter!
Do you think solutions to dark matter are tied up in a unified GR + quantum mechanics theory?
That sounds like it's trying to take large scale phenomena and make them work on the quantum scale. What if the solution is the other way around: make modified quantum mechanics work on the large scale? (I guess those are effectively the same thing. You'd need a quantum gravity theory one way or another. Sorry, layman here. Just spitballin' ideas)
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
"Repeat until you think it’s correct. Hopefully other people agree with you."
Dark Energy has entered the chat.
For those with time to spare: study all you can about neutron stars (including magnetars and quark stars), then go back to "black holes" (especially their event horizons and beyond) and there's a good chance you'll feel like a lot of aspects in BH theories are mythologies written in math - all of it entertaining, nonetheless.
For those who seek extra credit, study zero-point energy before reflecting on cosmic voids, galaxy filaments, galaxies, gravitationally bound celestial systems, quantum chromodynamics and neutrinos. Then, ponder the relativity between neutron stars, zero-point energy and hadron quark sea.
The attempts to measure dark matter directly have gotten incredibly sensitive and still haven't found anything.
All of physics is a "math model". One we attempt to falsify. And when a scientist does prove some part of the model wrong, the community leaps up in celebration and gets to working on the fix or the next.
Dark matter started as exactly a catchall designed to make the model work properly. We started with a very good model, but when observing extreme phenomenon (in this case the orbits of stars of entire galaxies), the model didn't fit. So either there was something we couldn't see to explain the difference ("dark" matter), or else the model was wrong and needed modification.
There's also multiple competing theories for what that dark matter is, exactly. Everything from countless tiny primordial black holes to bizarre, lightyear-sized standing waves in a quantum field. But the best-fitting theories that make the most sense and contradict the fewest observations & models seem to prefer there be some kind of actual particle that interacts just fine with gravity, but very poorly or not at all with electromagnetism. And since we rely on electromagnetism for nearly all of our particle physics experiments that makes whatever this particle is VERY elusive.
Worth observing that once, a huge amount of energy produced by stars was an example of a dark energy. Until we figured out how to detect neutrinos. Then it wasn't dark anymore.
In short, you're exactly right. It's a catch-all to make the math model work properly. And that's not actually a problem.
My personal dark matter theory is that 80% of all stars are surrounded by Dyson Spheres.
Well that’s a fun hypothesis that should be falsifiable. Why not write a paper with some maths predictions? That is a pretty extraordinary claim, but definitely fascinating.
I just read up on it a bit, and there's multiple things disproving my theory:
Respect looking into it further. If you’re into to this sort of stuff, you might like YouTube channel Isaac Arthur.
I wish more people were like you on the internet
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.
There's no scandal. Some people who are leading proponents of MOND theory recently published a new paper using what might be the best scenario we currently have to detect MOND (wide binary stars), and their more precise calculations...are not consistent with MOND. They published evidence against the very theory they were betting on.
https://youtu.be/HlNSvrYygRc?si=otqhH6VINIsCMfiS
The best kind of researchers, I bet that really took a lot of courage to do since it's so far from human nature.
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.
Its observed gravitational effects is evidence. Otherwise nobody would have given it a name.
You would like this https://www.youtube.com/watch?v=PbmJkMhmrVI
I am curious if the opposite of dark matter could be true; while dark matter inside galaxies would explain galactical motion, couldn't the same be explained by something repulsive BETWEEN galaxies? If the latter were the case, it would also explain dark energy.
The observations of systems like the Bullet Cluster imply that dark matter is actual material -- baryonic matter. Stuff that exists in specific locations and has mass. Modifying the math of the physical laws does not explain these observations without absolutely going into contortions where dark matter explains them quite elegantly.
I mean that is pretty much correct. We don’t know what it is, but we can see it’s effect
Even more so Dark Energy
Interesting tidbit for you. You'd think if it was a math model not working properly that could be explained away with adjustments to the model that we'd be wrong looking at all galaxies. And yet there are galaxies out there that appear to be missing dark matter!
https://science.nasa.gov/missions/hubble/mystery-of-galaxys-missing-dark-matter-deepens
https://www.space.com/galaxy-no-dark-matter-cosmic-puzzle
It doesn't solve the problem but, it adds to the intrigue I think.
I'm with you here, I don't understand dark matter and dark energy and the expansion of the universe. We see shit moving all the time in the universe. I'm still not convinced we just don't understand the motion of the universe outside our envelope of observation and it's explainable with conventional matter and energy. Im trying to learn a lot tho. I'm gonna watch that video someone posted to you.