I’m not smart enough to prove my hypothesis, nor am I smart enough to understand any proof that I am wrong, but I’m not entirely 100% convinced that dark matter exists as an attractive phenomenon inside galaxies the way it is often described.
The way I see it, it might as well be a repulsive force between galaxies. This way it could also help explain Dark Energy.
The primary thing we have detected is an attractive force within galaxies. Whether that’s otherwise-undetectable particles or a mistake in how we calculate gravity or something else, we definitely know it’s that there is more attractive force holding galaxies together than there should be based on detectable matter and general relativity.
Simply put: galaxies rotate too fast. Much, much too fast. That can’t be caused by repulsion between galaxies. Only by the stars within a galaxy being pulled towards the centre of that galaxy my than we would expect. Similar to how you have to spin faster to hold a big bucket of water horizontal without spilling than to hold a small bucket of water.
While there may be a part of it being “different gravity”, dark matter cannot 100% be explained by modified gravity of any kind.
Why do we know this? Well there are observable galaxies that survived collisions and have been stripped of their dark matter, and the reverse is also true (galaxy-sized dark matter blobs without baryonic matter in it).
We have never detected dark matter. Dunno what you’re talking about. It’s existence was posited because of differences in observed velocities at the edge of galaxies vs what we expected to see.
How do you explain the mounting evidences of double images and observing the same event twice (or more) with exactly the expected delay by grav lensing?
Anyhow, no new physics ever went against the old math, it always just adds corrective terms. Any new mathematics will need to be able to make the same predictions as GR in the limited cases of whatever this new limit will be (small distance or something?)
The old saying that “Einstein proved Newton was wrong” is a gross misunderstanding. A nevessary base principle for GR to be accepter was that it reduces to Newtonian mechanics at low speeds.
I really don’t get the prevalence of the attitude “If we don’t see it with light, it does not exist”.
Is it that improbable that there is some matter which does not interact with light?
imo, similar argument could be made to deny existence of atoms - we cannot see it directly.
A big argument for “not all matter must necessarily interact electromagnetically” is that we know of particles which don’t interact with the strong force - why should that fundamental force be special?
Read your source. There’s lots of criticism in the source itself. If gravitational lensing was proof of dark matter, many someone’s would already have a Nobel prize for it. They don’t.
What we know is that general relativity fails to explain gravitational interactions at very large scales for the matter we can see in telescopes.
The simplest answer for this conundrum is that there is extra matter that we can’t see in telescopes - aka it is ‘dark’ matter. This substance doesn’t appear to interact at all outside of gravity - which is a property we haven’t observed anywhere else. Further, in order to explain the motions we see, it would have to outweigh all the visible matter in the universe by a factor of 5, which seems to strain credibility given that - again - we have never seen anything like it.
Another answer for the observations is we are wrong about gravity, that it behaves differently at very large scales. This doesn’t require a massive amount of invisible magic substance conveniently spread throughout the universe, but to date no theory has been able to explain all the strange observations - and Dark Matter remains the moderate consensus view.
This doesn’t mean dark matter absolutely exists, it is just a hole in our current understanding. We’ve been looking for it for nearly a century and have yet to find direct evidence. In fact, there isn’t even one theory of Dark Matter because it also has difficulty explaining every available observation.
In summary: we have mountains and mountains of evidence that our current theory of gravity fail to explain the big stuff, we have exceedingly little evidence as to what the disconnect with reality is.
The tone of your messages come off as a bit confrontational, that’s probably the reason sorry!
Anyway, like many other situations before, there is probably no single fix to dark matter.
There’s probably a huge swath of cold hydrogen that still goes undetected that would explain part of the small scale stuff (bullet cluster and such), and then some quantum gravity or modified gravity to explain the very low range stuff.
Also, there are papers out there about how large scale simulations assume smooth distribution of matter, but then when computing with the actual distribution of matter, the some dark matter phenomenons tend to disappear.
Anyhow, exiting stuff to get new physics to learn about!
I’m not entirely 100% dark matter exists in galaxies the way often described. … The way I see it, it might as well be a repulsive force between galaxies opposed to the current understanding of it being am attractive force. Plus, if it were a phenomenon that pushed things apart, it could also explain Dark Energy.
And to me, that’s a perfectly valid theory. Like other proposed explanations for dark matter or dark energy or “whatever the hell it is we can detect the effect of but can’t identify”, it’s difficult to test.
That’s why I enjoy science. It’s like a big puzzle, and sometimes you get halfway done and realize you put it together wrong and have to start over.
I would like to emphasize the first part of my previous comment. As I am a hillbilly occasionally cosplaying as a smart and educated person, I am incapable of exploring my statement further than just making the claim. And for that I must insist on referring to it as an hypothesis, unless someone shows me some math that it could actually work. And I hope anyone showing me said math brings the necessary crayons and puppets to explain it in a manner that I can understand.
I am a hillbilly occasionally cosplaying as a smart and educated person
Same. Which explains why I (twice, lol) incorrectly used the terms “theory” and “hypothesis” interchangeably when those are totally different things in sciences.
Unfortunately of course such hypotheses are extraordinarily difficult to actually test. However intuitively I do kind of like where you’re coming from. I’ve always been fascinated by how everything that we conceptually are aware of has a sorta polar opposite that we kind of define it by.
We know that’s not the case because we can see different galaxies with different levels of dark matter.
Dark matter doesn’t interact with anything else except by gravity, we don’t know why, but we can detect that behavior by seeing the way it clumps together.
We can also see that galaxies that collide with each other have different levels of dark matter than galaxies that haven’t recently done so. The dark matter appears to just pass through each other and continue on while the regular matter hits each other and stays generally together in one group.
It’s pretty interesting when you work through the details of what we do and don’t know.
Wouldn’t that mean that that force would be stronger on the edges of the galaxies, instead of the center? I imagine this is something we could figure out
I guess on a similar note, my own wacky theory is that our dimension can be affected at any given time by up to 13 other dimensions, but which 13 can change amongst a potentially infinite number. I imagine certain dimensions would more likely be co-terminus (I term I believe I’m borrowing from a Dungeons and Dragons type source) with ours than others but who knows.
One of the biggest harms sci fi and fantays did to public scientific literacy is the abuse of the word “dimension”
D&D’s astral and ethereral planes are not seperate dimenions so much as they are four-dimensional planes seperated from the really mortals live along a axis of reality.
The “11 dimensional reality” idea is an attempt to explain the asymmetry of the four fundamental forces by postulating that there are additional axis straught line axis that those forces propagate through.
![References: [1] out of his ass](https://mander.xyz/pictrs/image/7d954d56-4739-4230-b641-f7a2ed05fa5c.jpeg){kind=link}
I’m not smart enough to prove my hypothesis, nor am I smart enough to understand any proof that I am wrong, but I’m not entirely 100% convinced that dark matter exists as an attractive phenomenon inside galaxies the way it is often described.
The way I see it, it might as well be a repulsive force between galaxies. This way it could also help explain Dark Energy.
The primary thing we have detected is an attractive force within galaxies. Whether that’s otherwise-undetectable particles or a mistake in how we calculate gravity or something else, we definitely know it’s that there is more attractive force holding galaxies together than there should be based on detectable matter and general relativity.
Simply put: galaxies rotate too fast. Much, much too fast. That can’t be caused by repulsion between galaxies. Only by the stars within a galaxy being pulled towards the centre of that galaxy my than we would expect. Similar to how you have to spin faster to hold a big bucket of water horizontal without spilling than to hold a small bucket of water.
While there may be a part of it being “different gravity”, dark matter cannot 100% be explained by modified gravity of any kind.
Why do we know this? Well there are observable galaxies that survived collisions and have been stripped of their dark matter, and the reverse is also true (galaxy-sized dark matter blobs without baryonic matter in it).
I can refer you to this wonderful PBS Spacetime video about it: https://youtu.be/5t0jaE--l0Y
We have never detected dark matter. Dunno what you’re talking about. It’s existence was posited because of differences in observed velocities at the edge of galaxies vs what we expected to see.
What is your definition of “detected”? If only direct interaction using the EM field is required, then we have never detected anything…
There are lots of gravitational lensing images of dark matter, we can even see some structures in its shape and distribution.
Check this out: https://en.wikipedia.org/wiki/Bullet_Cluster
Gravitational lensing uses the same mathematics that dark matter is needed to correct.
How do you explain the mounting evidences of double images and observing the same event twice (or more) with exactly the expected delay by grav lensing?
Anyhow, no new physics ever went against the old math, it always just adds corrective terms. Any new mathematics will need to be able to make the same predictions as GR in the limited cases of whatever this new limit will be (small distance or something?)
The old saying that “Einstein proved Newton was wrong” is a gross misunderstanding. A nevessary base principle for GR to be accepter was that it reduces to Newtonian mechanics at low speeds.
I really don’t get the prevalence of the attitude “If we don’t see it with light, it does not exist”. Is it that improbable that there is some matter which does not interact with light? imo, similar argument could be made to deny existence of atoms - we cannot see it directly.
A big argument for “not all matter must necessarily interact electromagnetically” is that we know of particles which don’t interact with the strong force - why should that fundamental force be special?
Read your source. There’s lots of criticism in the source itself. If gravitational lensing was proof of dark matter, many someone’s would already have a Nobel prize for it. They don’t.
What are you talking about? We know for a fact dark matter exists. We just have absolutely no idea what it is.
What we know is that general relativity fails to explain gravitational interactions at very large scales for the matter we can see in telescopes.
The simplest answer for this conundrum is that there is extra matter that we can’t see in telescopes - aka it is ‘dark’ matter. This substance doesn’t appear to interact at all outside of gravity - which is a property we haven’t observed anywhere else. Further, in order to explain the motions we see, it would have to outweigh all the visible matter in the universe by a factor of 5, which seems to strain credibility given that - again - we have never seen anything like it.
Another answer for the observations is we are wrong about gravity, that it behaves differently at very large scales. This doesn’t require a massive amount of invisible magic substance conveniently spread throughout the universe, but to date no theory has been able to explain all the strange observations - and Dark Matter remains the moderate consensus view.
This doesn’t mean dark matter absolutely exists, it is just a hole in our current understanding. We’ve been looking for it for nearly a century and have yet to find direct evidence. In fact, there isn’t even one theory of Dark Matter because it also has difficulty explaining every available observation.
In summary: we have mountains and mountains of evidence that our current theory of gravity fail to explain the big stuff, we have exceedingly little evidence as to what the disconnect with reality is.
Yeah, I’m not sure why I’m getting so much flack from people. This is pretty much all I was saying.
The tone of your messages come off as a bit confrontational, that’s probably the reason sorry!
Anyway, like many other situations before, there is probably no single fix to dark matter.
There’s probably a huge swath of cold hydrogen that still goes undetected that would explain part of the small scale stuff (bullet cluster and such), and then some quantum gravity or modified gravity to explain the very low range stuff.
Also, there are papers out there about how large scale simulations assume smooth distribution of matter, but then when computing with the actual distribution of matter, the some dark matter phenomenons tend to disappear.
Anyhow, exiting stuff to get new physics to learn about!
Right, we don’t know what it is, where it is, how it interacts. We only know that our observations don’t match, so it must be there 🙄
If I look at a glass and I see that it is half empty by looking at the empty part, does that mean I didn’t detect anything?
Dark matter can be detected through gravitational lensing. Rotation curves was just the first way we detected it.
That is not detection of dark matter. That is indirect evidence at best. And for all we know it really just tells us our equations are wrong.
Well, that’s how it’s detected.
it’s existence is inferred, but not verified.
just because i heard a noise, doesn’t mean i know wtf caused it.
Fair enough. I believe it’s ducks. Ducks with ambition.
And to me, that’s a perfectly valid theory. Like other proposed explanations for dark matter or dark energy or “whatever the hell it is we can detect the effect of but can’t identify”, it’s difficult to test.
That’s why I enjoy science. It’s like a big puzzle, and sometimes you get halfway done and realize you put it together wrong and have to start over.
I would like to emphasize the first part of my previous comment. As I am a hillbilly occasionally cosplaying as a smart and educated person, I am incapable of exploring my statement further than just making the claim. And for that I must insist on referring to it as an hypothesis, unless someone shows me some math that it could actually work. And I hope anyone showing me said math brings the necessary crayons and puppets to explain it in a manner that I can understand.
Same. Which explains why I (twice, lol) incorrectly used the terms “theory” and “hypothesis” interchangeably when those are totally different things in sciences.
Unfortunately of course such hypotheses are extraordinarily difficult to actually test. However intuitively I do kind of like where you’re coming from. I’ve always been fascinated by how everything that we conceptually are aware of has a sorta polar opposite that we kind of define it by.
We know that’s not the case because we can see different galaxies with different levels of dark matter.
Dark matter doesn’t interact with anything else except by gravity, we don’t know why, but we can detect that behavior by seeing the way it clumps together.
We can also see that galaxies that collide with each other have different levels of dark matter than galaxies that haven’t recently done so. The dark matter appears to just pass through each other and continue on while the regular matter hits each other and stays generally together in one group.
It’s pretty interesting when you work through the details of what we do and don’t know.
non luminous matter is a better term, but it doesn’t sound as cool and mysterious.
No we can’t see that, we can see most galaxies spin faster than our models say they should and some galaxies spin a lot faster.
https://www.universetoday.com/articles/astronomers-find-a-third-galaxy-missing-its-dark-matter-validating-a-violent-cosmic-collision-theory
You don’t appear to be up to date on the latest research.
Evidence against MOND is not evidence for dark matter.
Wouldn’t that mean that that force would be stronger on the edges of the galaxies, instead of the center? I imagine this is something we could figure out
That’s a popular hypothesis, that “dark matter” is actually an envelope surrounding galaxies rather inside of them.
Plausible!
I had a bachelor’s in physics a decade ago.
But here’s how my memory describes how we discovered, or at least how we did it in my computational physics class.
You have stars of known size, and there for light output as its directly proportional to size. You also have a known distance.
You can then calculate how bright the star should be. But its wrong.
Meaning there’s things in the way thats blocking light.
So we call it dark matter because it hasn’t been directly observed and its clearly there. It could be our fundamentals are wrong, but that’s unlikely.
It could very well follow gravitational fields, and then attracted to galaxies with large masses.
But it could also be something in the vacuum. We just have no evidence to suggest either way.
I guess on a similar note, my own wacky theory is that our dimension can be affected at any given time by up to 13 other dimensions, but which 13 can change amongst a potentially infinite number. I imagine certain dimensions would more likely be co-terminus (I term I believe I’m borrowing from a Dungeons and Dragons type source) with ours than others but who knows.
One of the biggest harms sci fi and fantays did to public scientific literacy is the abuse of the word “dimension”
D&D’s astral and ethereral planes are not seperate dimenions so much as they are four-dimensional planes seperated from the really mortals live along a axis of reality.
The “11 dimensional reality” idea is an attempt to explain the asymmetry of the four fundamental forces by postulating that there are additional axis straught line axis that those forces propagate through.
Oh, I hear ya. And although obviously inspired by RPGs, I do conceptualize my wacky theory more in the context of string theory and related ideas.