How Does Galaxy Spin Help Us Understand Dark Matter?

[leonstavros]

I was watching a program on dark matter and how galaxy spin was used to deduce the existence of dark matter. The thought occurred to me if the rate of galaxy spin has been measured on many galaxies and how does the spin differ if it does. Another question arose are there any galaxies with identical spin? Also if there are galaxies with identical spin rates are the galaxies connected with an Einstein-Rosen wormhole?

 

[mathman]

It is not so much the galaxy spin as the fact that as you go from the center to the edge of the galaxy, the speed of the stars around the center does not decrease, which it would if all the matter was in the stars. Compare to the solar system where the outer planets are much slower than the inner planets.

 

[Nabeshin]

Another question arose are there any galaxies with identical spin? Also if there are galaxies with identical spin rates are the galaxies connected with an Einstein-Rosen wormhole?

Wait, what? No.

 

[leonstavros]

Wait, what? No.

What I meant was if our galaxy has a black hole in it's center and black holes have been theorized to be worm hole developers then is it possible that two galaxies can be connected via the same wormhole? A clue to whether that is possible may be the spin for both galaxies would be the same.

 

[Tanelorn]

Leon, on a similar vein I have sometimes wondered if all black holes are connected to each other and "meet at infinity" where the singularity breaks through our space time to some where beyond, but I am probably mixing up science with the popular science press, or worse Sci-fi.. :)

 

[leonstavros]

Leon, on a similar vein I have sometimes wondered if all black holes are connected to each other and "meet at infinity" where the singularity breaks through our space time to some where beyond, but I am probably mixing up science with the popular science press, or worse Sci-fi.. :)

You are right, worm holes are speculative at this point of our science but what's science fiction today would be reality in the future. Someone said "what reality is today was magic a few hundred years ago"

 

[Nabeshin]

You must understand that what a physicist (real physicist) thinks of when they hear wormhole is a very particular mathematical subtlety in a solution to Einstein's equations. True, some people have put in some legitimate work to study the properties of similar such bridges connecting two regions of spacetime, but all of these constructions are artificial in the highest degree. That is, although they exist as valid solutions to the Einstein equations (although it is not clear if they are possible/stable when quantum corrections are introduced), it is impossible to find them in nature.

Science-fiction authors then took the idea of wormholes and twisted it around so much that it does not even resemble the original idea.

Furthermore, even if there did exist a traversable wormhole between two galaxies in our own spacetime, that would in no way account for the overall rotations of the galaxies being similar. Which is assuming that there would be galaxies with identical rotations (there are not). The phenomenon are simply completely independent.

It is true that we do not know everything, especially considering the quantum-gravity corrections that will undoubtedly muddle the true nature of black holes, singularities, and worm holes. However, the purpose of this forum is to educate people as to the current state of knowledge, not to engage in wild speculation.

If you're actually interested in wormholes as mathematical objects, I suggest you read:
https://www.amazon.com/dp/1563966530/?tag=pfamazon01-20
After you have had some training in general relativity and quantum field theory.