Dark Matter vs GR


#1

I know I can look this up online but I’m hoping to engage in a conversation about this.

Why is dark matter the leading theory for the matter that’s not directly visible but detectable?

The proposed matter doesn’t interact electromagnetically but interacts gravitationally. Why isn’t this further proof of relativity? Why are scientists trying to invent a new mechanism for this when one already exists?

Matter inside a black hole would create the gravitation without being visible or interactive from our frame of reference. Isn’t this a win for GR? Why is dark matter required to reconcile this disparity? Why can’t the matter be locked up in black holes?


#2

The short version is galaxies are too large to hold together and stars along the edge spin too fast to match the predictions of Einstein’s equations. The theory is there is a vast invisible bubble which contains more than 80 percent of a galaxies gravitational mass that surrounds it. This holds it together and pulls the stars along the edge to move faster.

The tension, in fact the singular reason for dark matter, comes from whether gravity is a force between objects or the result of relativistic curvature to spacetime because neither is completely proven or ruled out. If you only use relativistic reasoning you need dark matter or something like it, if you use point force reasoning you need to modulate gravity similar to the way the electromagnetic field modulates between the near and far field to make a galaxy.

A main reason I have been skeptical of cold dark matter theory is it rests on a single fundamental assumption, that gravity results only from relativistic curvature. If a theory only needs one assumption to be challenged to fall apart completely the theory itself is incomplete.


#3

As for sequestration any black hole has a finite and measurable gravitational footprint. The density is infinite so you only need a circumference to determine total mass so it isn’t hiding in black holes.

I did talk to a scientist recently promoting an idea called RAMEN which is a theory about the Shapiro time delay around large gravitational objects acting like a trap for passing gravity waves causing them to collect, self amplify and effectively work as additional mass. In order to work the effect would have to be cumulative and ultimately non local, but I like the thinking there…


#4

Thank you for the time and response. So matter in black holes can not produce the same gravitational effects as a dark matter halo around a galaxy?

I understand the rotational discrepancy but I still do not understand why these effects give different results. I was reading some on the bullet cluster. A topic I first encountered on Brian’s blog on FB lol! I guess black holes can’t account for that observation either. I’d imagine black holes would not create a smooth total curvature around the galaxy either unless they were evenly sized and distributed.

We have a mechanism that prevents matter from interacting electromagneticly but still allows for it to contribute gravitationally but cannot account for the matter we see that only interacts gravitationally. I guess that would be too easy.

Any articles you think might be relavent please share!

Again, thank you!


#5

Black holes could produce the same gravitational effects to explain the discrepancy in galactic rotation. But I believe what Ishkoday was saying is that, for most black holes, this matter wouldn’t be hidden and is therefore not ‘dark’. If dark matter were stellar-mass black holes, we would be able to observe many of them via their interaction with nearby stars, gravitational lensing etc. And if we could observe them, we can measure the amount of mass inside the black hole.

There is however a theory that primordial black holes could be a solution for dark matter. Brian has written an article on this: https://briankoberlein.com/2017/04/01/black-holes-dark-matter/
This idea however appears to have a lot holes in it (sorry) and isn’t a top contender for dark matter candidates.


#6

We can use car engine analogy. There is financing(gas), combustion over compression and exit gas as byproduct. Again, if BH act as engine and being financed by matter and has some byproduct(dark matter maybe) then we need to find the way or name/concept for conveying all the energy remains into BH body(whatever it’s made of) plus there are some bad distortions(common sense) so we may expect that mainly distorted part is “pure” spatial one. I think that it may look much like a tree roots, so, that may be how galaxy spin in whole the same way. Those vains may be condensed and finite state of dark matter, as most pure state of that specific spatial dimensional area.
There may be also other free forms of DM/strings that forms from echoed dark matter(which also must be energy/financial part) sub-strings(like blueprints) for our dimensional matter(measurable).