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Jun
19
revised Is the edge of our Hubble Sphere within our Cosmic Event Horizon and why?
clarification
Jun
19
answered Is the edge of our Hubble Sphere within our Cosmic Event Horizon and why?
Jun
18
answered Higher order derivatives - Equation of motion
Jun
15
comment A Subtle Connection Between Time Dilation in SR and GR - Why is this so?
that would be my understanding as well
Jun
15
comment A Subtle Connection Between Time Dilation in SR and GR - Why is this so?
related: arxiv.org/abs/gr-qc/0411060
Jun
14
comment If we say the universe is expanding, shouldn't it be expanding relative to something?
note that instead of expanding space, there's a perfectly valid dual description that shrinks atoms - including rulers; you'll also have to do stuff like speed up clocks, make things more massive and weaken gravity to make it work, but on the plus side, you can get rid of the big bang singularity this way...
Jun
13
revised Conservative Forces & Conservation of Energy?
added 1 character in body
Jun
13
answered Conservative Forces & Conservation of Energy?
Jun
11
comment Euler Lagrange equation in different frames
@user139981: it's independent of parametrization, but not independent of geometry: the derivation of the EL equations assumes coordinates that respect the bundle structure, and if you do a transformation that doesn't, you'll get nonsense
Jun
7
comment Didn't anybody see an apple falling before Isaac Newton?
Newton himself apparently claimed to be inspired by falling apples (see eg newscientist.com/blogs/culturelab/2010/01/…); also note that Ibn al-Haytham might have figured out a lot of the story centuries before Newton
Jun
5
comment Can the Berry Connection be derived from a metric?
Also, I think for every connection, there exists a metric for which the connection is a Levi-Civita connection. This is not the case; see eg mathoverflow.net/questions/54434/…
Jun
5
revised Minkowski metric and definition of coordinate differentials?
added 48 characters in body
Jun
5
answered Minkowski metric and definition of coordinate differentials?
May
25
answered How do I find the generalized coordinates in a certain system?
May
25
answered Tensor algebra doubt
May
24
comment Linear independence of the Covariant Derivative
@V.Moretti: mixed-rank tensors are perfectly fine elements of the tensor algebra - it's just that they are rarely used (and are of course not relevant to the question at hand)...
May
23
comment Is the universe expanding faster than we could catch up with it?
also note that light we emit right now will eventually reach galaxies that currently recede with $v_{\mathrm{rec}}=c$; while there are regions of space that we no langer can "catch up" to, these aren't simply the ones with recession velocities above $c$!
May
15
comment Which is the most fundamental constant between the Planck constant $h$ and the reduced Planck constant $\hbar$?
just to be clear: $\hbar$ converts between energy and angular frequency - for regular frequence, you need regular $h$
May
14
comment Choices within the many-worlds interpretation
universes split on quantum 'measurement', supposedly a decoherence effect that occurs when a sufficiently isolated quantum system interacts (and becomes entangled with) the messy (and thus essentially classical) environment; if quantum effects are relevant for decision-making processes in the brain, 'conscious' choice (which would actually be random) is correlated with splittings; if the process is largely classical, choice would only be affected through macroscopic effects (eg different memories), and these would probably go with further differences between the universes
May
14
answered What is the relation between General Relativity and Newtonian Mechanics?