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comment Why do we use functional integration in QFT?
@AlexNelson But the path integral doesn't say that "$x^0$ is the $t$-coordinate." You integrate over four-volume $\sqrt{-g} d^4 x$, which is a coordinate-invariant object.
Nov
25
comment Green function integration problem
Do the integral in spherical coordinates then do a coordinate transformation to Cartesian coordinates.
Nov
25
answered A true singularity at $t=0$, coordinate independent Big Bang
Nov
25
comment On which basis we think there is something more than just super dense matter in black holes?
Peter should also be aware the Schwarzschild coordinate $r$ does not actually correspond to "distance from the center." The distance between two values of $r$ is determined by an integral over the line element.
Nov
25
comment Gravity at event horizon
Except the quantity you've defined as "g" is not particularly meaningful. It does not correspond to any type of measurable acceleration. The proper acceleration required to hover near the event horizon asymptotically approaches infinity as $r \to 2GM/c^2$.
Nov
24
comment Time derivative of Magnetic Field as Source for Electric Field
It's not exactly clear what you're trying to do. Could you elaborate on the actual problem you're trying to solve?
Nov
24
revised Gravitational Time Dilation Formula?
Clarified the post.
Nov
24
comment Gravitational Time Dilation Formula?
@Hypnosifl Indeed. I'll edit my post accordingly.
Nov
24
answered Gravitational Time Dilation Formula?
Nov
24
answered What Maxwell done on the Faraday's law and Amper's law and Gauss's law which famous by Maxwell's equations?
Nov
24
comment What does this depiction of a black hole in the movie Interstellar mean?
I remember reading somewhere that Chris Nolan decided to cut out Doppler effects, and he also had them drop the angular momentum well below what would be required for the extreme time dilation the crew experiences. He apparently thought that these would confuse the audience too much.
Nov
24
comment Movie Interstellar - Question about Escape Velocity
@ChristianRau I replied to the post :).
Nov
23
comment Deriving a Useful Solution of the Schrödinger Equation
@Ruslan "Schrodinger" is a common spelling, whether originally correct or not, and is listed as one of the spellings on Erwin's wiki page.
Nov
23
comment Can we explain Newton's first law mathematically?
You might be interested in the answers here: physics.stackexchange.com/q/66057
Nov
22
answered What is the most agreed upon quantum mechanical equation of motion?
Nov
22
comment Is there an equivalent force to magnetism for gravity?
Yes. The effect is called "frame dragging." It is an effect that appears in general relativity. Note that Brandon's link is the weak field limit of GR, where the gravitational field is weak and everything is moving slowly compared to light.
Nov
22
comment Confused about equations for the Big Bang in general relativity ad loop quantum gravity?
@21joanna12 $H^2 \to \infty$ means that space is either expanding or contracting at an infinite rate.
Nov
22
answered Confused about equations for the Big Bang in general relativity ad loop quantum gravity?
Nov
21
comment Derivation of the Riemann tensor confusion
Indeed. As ACuriousMind mentioned, this is the whole point of defining the covariant derivative: so that things remain covariant. I.e. tensors go to tensors under the operation.
Nov
21
comment Derivation of the Riemann tensor confusion
$\lambda_{a;b}$ is a rank-2 tensor. If you take its covariant derivative you'll get two connection terms by definition of the covariant derivative.