meta user
network profile
| bio | website | |
|---|---|---|
| location | ||
| age | ||
| visits | member for | 3 months |
| seen | 35 mins ago | |
| stats | profile views | 51 |
|
May 20 |
awarded | Fanatic |
|
May 11 |
awarded | Citizen Patrol |
|
May 5 |
comment |
QED photon propagator to one-loop order gets different answers Well that's not really what you asked for. How about this: 152.78.192.50/hepwww/staff/D.Ross/qft/aqft3.pdf ? |
|
May 5 |
answered | QED photon propagator to one-loop order gets different answers |
|
Apr 20 |
comment |
Connection and Christoffel symbols What have you tried? |
|
Apr 20 |
comment |
Transforming an equation to the co-vector version You're right. I've changed my answer to reflect this. |
|
Apr 20 |
revised |
Transforming an equation to the co-vector version deleted 51 characters in body |
|
Apr 20 |
comment |
Transforming an equation to the co-vector version It's true as long as $\frac{d}{d \lambda} g_{\mu \nu} = 0$, which is true for most choices of $\lambda$ when considering a timelike geodesic (which is usually what one's interested in) when there's a timeline Killing vector. In physical scenarios where there's no t-symmetry, i.e. the FLRW metric, one's generally not interested in test particles anyway. |
|
Apr 20 |
answered | Transforming an equation to the co-vector version |
|
Apr 19 |
answered | proper variation of action term |
|
Apr 19 |
comment |
How do forces work Necessary classic: youtube.com/watch?v=wMFPe-DwULM |
|
Apr 16 |
answered | Interval and proper time |
|
Apr 11 |
comment |
Einstein's theory tells us that gravity is a curve in space and time but how does that causes attraction in mass? youtube.com/watch?v=DdC0QN6f3G4 |
|
Apr 4 |
comment |
Why does the index of refraction change the direction of light The easiest way to answer this is, of course, with Fermat's Principle. But that may not be what you're looking for. |
|
Mar 23 |
comment |
Universe Expansion and two tennis balls Well, since we have no idea what "dark energy" actually is, that's a tough question to answer. |
|
Mar 23 |
comment |
Universe Expansion and two tennis balls You're not reading it wrong, but you're missing Jerry's point. The reason the universe is expanding is because it is filled with dark energy, i.e. there is a nonzero cosmological constant. By "clear the universe of all matter" it was assumed that dark energy should also be removed. Remove the DE and space doesn't expand. Leave it in and it will, albeit at a different rate than we observe because the normal matter in the universe helps to "counteract" the effect of DE. |
|
Mar 22 |
comment |
Future light cones inside black hole To add to this, you can't avoid falling toward the singularity any more than you can avoid growing older. |
|
Mar 20 |
comment |
Einstein gravity versus Newton's gravity youtube.com/watch?v=DdC0QN6f3G4 |
|
Mar 19 |
comment |
Generating artificial gravity by using rotation This is a rather subtle issue. In General Relativity, observables (like time, distance, etc.) are dependent on the metric tensor field. The value of metric is determined by the energy/momentum distribution in spacetime. It is assumed in your problem that the objects involved have little effect on the metric. The metric of a rotating coordinate system (i.e. the rotating clock) yields the above result. If the ring, etc., were sufficiently massive then they too would have an effect on the metric. |
|
Mar 19 |
answered | Generating artificial gravity by using rotation |
