# Galactic rotation curves question

I think I need to ask this question now, because it's in my mind for several years and I just can't find an answer to it. After observations of those galaxtic rotation curves, it's pretty clear, that there must be some additional thing, responsible for the additional gravity that is needed to hold those galaxies together.

Dark matter is what would be a easy explaination -> just more matter, not visible to us, and it will be there for sure.

But wouldn't the most simple explaination just be, that the spacetime around the galaxy is warped? Doesn't it make sense for such big things to have a "torsional force" to spacetime itself? Or Maybe our frame of reference is warped as well, so if a star in a far away galaxy goes around in a circle, it's just our observation from our point of view. Here is a quick sketch of what I mean: It's not perfect, but with the explaination I think it makes a lot of sense. If our frame of reference or the spacetime is torn like this, we could actually observe stars moving in a circle while in reality they are not moving in a circle around the galaxy but in a more straight line away from it, if that makes sense. So it depends on the frame of reference ;)

I am not sure if it's the same thing described here, because I am not a physicist :(

But to me this makes the most sense and is in my opinion the most easy explaination for this observation. You should never trust your eyes only if relativity is involved so I want to know if a real scientist had the same idea once and did some calculations ^^ This question has been in my head for years and finally it's out now, please don't roast me >_<

• From the article on frame-dragging you linked: The Lense–Thirring effect is very small – about one part in a few trillion. To detect it, it is necessary to examine a very massive object, or build an instrument that is very sensitive. That is undoubtedly too small to explain the rotation curves, if there is even an effect. Jun 18, 2021 at 10:35
• Bear in mind as well that the evidence for dark matter comes from multiple angles. Galaxy rotation curves is the easiest one to explain without dark matter, but the other observations (especially the CMB data) are much, much harder. Jun 18, 2021 at 10:36
• Ah, thank you very much. But isn't it weird that spacetime behaves this way? like.. something that can be bended but not rotated or only ever so slightly... <_< It's very hard to imagine. Jun 18, 2021 at 10:43