I New paper gravitomagnetism explains dark matter effects

kodama
Messages
1,076
Reaction score
144
TL;DR Summary
Models of galactic rotation curves built of a general relativistic framework could use gravitomagnetism to explain the effects of dark matter
I'm not sure if this paper belongs in GR or astrophysics but

This articleG. O. Ludwig (2021), Galactic Rotation Curve and Dark Matter According to Gravitomagnetism, European Physical Journal C 81:186, DOI 10.1140/epjc/s10052-021-08967-3

there's no need for dark matter,as GR's Gravitomagnetism could explain galaxy rotation effects, similar in spirit to MOND, but using just plain GR.

could GR experts weigh in on this
 
  • Like
Likes ohwilleke and Dale
Physics news on Phys.org
The basic idea of gravitomagnetic effects is valid; GR does predict them. The question is whether the paper's estimate of their magnitude for a rotating disk-shaped galaxy is correct. I think it will take some time for other researchers to check the work.
 
  • Like
Likes ohwilleke and vanhees71
PeterDonis said:
The basic idea of gravitomagnetic effects is valid; GR does predict them. The question is whether the paper's estimate of their magnitude for a rotating disk-shaped galaxy is correct. I think it will take some time for other researchers to check the work.

is gravitomagnetic effects always attractive like gravity, and therefore add up?
 
kodama said:
is gravitomagnetic effects always attractive like gravity

No. The effects in general are not as simple as just changing the magnitude of a central force. (That is also true of ordinary magnetism.)
 
I asked a question here, probably over 15 years ago on entanglement and I appreciated the thoughtful answers I received back then. The intervening years haven't made me any more knowledgeable in physics, so forgive my naïveté ! If a have a piece of paper in an area of high gravity, lets say near a black hole, and I draw a triangle on this paper and 'measure' the angles of the triangle, will they add to 180 degrees? How about if I'm looking at this paper outside of the (reasonable)...
From $$0 = \delta(g^{\alpha\mu}g_{\mu\nu}) = g^{\alpha\mu} \delta g_{\mu\nu} + g_{\mu\nu} \delta g^{\alpha\mu}$$ we have $$g^{\alpha\mu} \delta g_{\mu\nu} = -g_{\mu\nu} \delta g^{\alpha\mu} \,\, . $$ Multiply both sides by ##g_{\alpha\beta}## to get $$\delta g_{\beta\nu} = -g_{\alpha\beta} g_{\mu\nu} \delta g^{\alpha\mu} \qquad(*)$$ (This is Dirac's eq. (26.9) in "GTR".) On the other hand, the variation ##\delta g^{\alpha\mu} = \bar{g}^{\alpha\mu} - g^{\alpha\mu}## should be a tensor...
Back
Top