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Jan
19
comment Critics of Mannheim's Conformal Gravity Theory?
see arxiv.org/abs/1310.0819 for holography in conformal gravity
Jan
19
comment Can there exist a Wave which changes the quantum states of particles?
@JohnRennie: done
Jan
19
answered Can there exist a Wave which changes the quantum states of particles?
Jan
16
comment Does the covariant derivative of a derivative of the metric vanish?
which of these indices are space-time indices? assuming $M,N,P$ (which you would normally denote by greek letters), I don't see why that equation should hold (but I'm far from an expert)
Jan
15
comment Can matter leave the cosmic horizon?
@Anixx: the big bang has infinite redshift due to the scale factor going to zero, but we can't see beyond recombination at $z\approx1100$ anyway; the graphic is correct, but misleading insofar as the redshift/particle horizon overlay is indepent of the lightcone space-time diagram: if you want to relate the overlay to actual events, you need to project the value at a specific time down onto the lightray hitting $d=0$ at that time
Jan
15
comment Can space expand with unlimited speed?
personally, I'd prefer if the curves of constant $z$ would be projected onto the corresponding past light rays so we can map redshifts to events more easily
Jan
14
revised Are conformal, Killing and homothetic vector fields the same in pseudo-riemannian manifolds?
clarified
Jan
14
answered Are conformal, Killing and homothetic vector fields the same in pseudo-riemannian manifolds?
Jan
14
revised Where does a spinning figure skater's energy go when she slows down?
clarified
Jan
14
comment Where does a spinning figure skater's energy go when she slows down?
I hope the edit (last 2 paragraphs) clears up the remaining issues
Jan
14
revised Where does a spinning figure skater's energy go when she slows down?
clarified
Jan
13
answered Where does a spinning figure skater's energy go when she slows down?
Jan
11
comment Nothing can travel faster than the speed of light. In what frame of reference?
@WillO: modulo acceleration/gravity (but instantaneous proper speed will of course remain $c$)
Jan
10
comment Why do we order the variables in certain physics questions the way we do?
I'd go with the terms constant, parameter, variable instead
Jan
6
comment How can the Lorentz transformation cause two objects' masses to both increase?
the concept of relativistic mass aside, there's not really anything particularly special going on in the relativistic case - in a non-relativistic world, the same 'astonishing' thing happens for any other velocity-dependent quantity, eg kinetic energy
Jan
5
revised Why does the moon not revolve around the sun directly?
fix typo
Jan
5
revised Why does the moon not revolve around the sun directly?
add intermediate step
Jan
5
answered Why does the moon not revolve around the sun directly?
Jan
5
comment Why does the moon not revolve around the sun directly?
see also math.nus.edu.sg/aslaksen/teaching/convex.html
Jan
5
revised Can a macroscopic body have wavelength as that of electron?
added 107 characters in body