Re:A Physicist Who Denies That Dark Matter Exists
by Avshalom on Monday February 27, 2017 @05:21PM
(#13748945)
Geometrically if a force radiates uniformly it either
A)has infinite density
B)drops off as 1/r^2
We know that gravity drops off as 1/r^2 for all cases except galaxy rotation curves so for it become 1/r for just this specific scale requires that from gravity's perspective the surface area of a sphere usually but doesn't always increase as r^2. Which in turn means it doesn't move through the 3 spacial dimensions that everything else does.
Re:A Physicist Who Denies That Dark Matter Exists
by jcranmer on Monday February 27, 2017 @07:59PM
(#13750210)
The electromagnetic force (specifically, the Coulomb interaction) is 1/r^2. The strong force is actually effectively constant at long ranges, since it becomes energetically favorable to create an antiquark/quark pair. The residual strong force is exp(-r)/r. The weak nuclear force is exp(-r)/r^2 (or exp(-r)/r? I can't really tell with the links on hand--I just know for sure there's an exp(-r) term in it). Gravity being 1/r wouldn't be a surprise given the other known forces.
Re:A Physicist Who Denies That Dark Matter Exists
by effie on Wednesday March 01, 2017 @03:17PM
(#13767871)
> it either
A)has infinite density
B)drops off as 1/r^2
How did you arrive at this? Which force has infinite density and where? k/r is finite except at the point where the source is, the formula is invalid there.
Why? I think I can use simple force formula such as F=k/r without any idea of extra dimensions or topology.