Questions tagged [spacetime]
Within relativity (both special and general), changes of reference frames can change both the notions of space and of time, with one depending on the other as well. As a consequence, it is necessary to treat both concepts in a unified manner. Hence the term spacetime.
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Can you tell who is moving through time? [closed]
In relativity, there is no way to tell if you are moving through space. So, if you were inside of a box, there would be no way for you to tell if you were moving or not. However, can you know who is ...
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Time function as a function of energy (from velocity and gravity)?
Is there any formula, preferably in terms of energy, for the time dilation an object experiences taking both relativistic velocity and mass into account? I see both formulas frequently, but haven't ...
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What objects are solutions to the Einstein Field Equations?
The usual way the solutions of the Einstien Field Equations are introduced is by saying they are (pseudo-) riemannian metrics that satiafy the diff equations for a given EM Tensor. My question is: ...
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How many dimensions are in string theory? [duplicate]
How many dimensions are in string theroy? I heard that there are 11 but to my understanding, there is an infinite, also can strings be on a 2D plane?
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Understanding Wormholes Geometrically
Is the folding sheet analogy really that good for understanding what a wormhole is? After all, space-time curvature doesn't require any ambient space (it's intrinsic), as such a picture would suggest. ...
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What is $r$ in a metric signature in general relativity? If $v$ and $p$ are the time and spatial coordinates?
The Wikipedia article on metric signatures says that the signature of a metric can be written $(v,p,r)$, where $v$ is the number of positive eigenvalues, $p$ is the number of negative eigenvalues, and ...
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How do black holes move if they are just regions in spacetime?
If black holes are just regions of spacetime, how can black holes even move? When matter moves through spacetime, it bends the spacetime around it, but if black holes are just regions of spacetime, ...
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How can you use gravity while trying to model gravity? [duplicate]
So consider the usual pop-science spacetime model, a bowling ball on a trampoline. Apparently, the ball should sink into the trampoline, causing a dip in the fabric which causes nearby objects to fall ...
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Vacuum solutions in presence of mass?
Here is the page I will be referencing: Vacuum solution (general relativity) - Wikipedia
My point is: if $T_{\mu\nu}=0$ implies that there is no mass, how can Schwarzschild vacuum be a solution, if ...
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Does it make sense to talk about time in absence of matter? [duplicate]
The equations of general relativity should predict (although I might be wrong) that in absence of mass the spacetime is everywhere flat. That is, time is the same everywhere. However, I'm not sure ...
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Seemingly equivalent linear form of the Sagnac effect
This is a derivative of the question regarding the Sagnac effect. Judging from the metric $ds^2=-dt^2+(rd\phi)^2$ for a constant $r$ for this question, it should be no different from that on a line ...
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Does dark matter have mass?
When trying to understand what dark matter is, it is helpful to know that some properties of it can already be derived from various observations, such as, it only interacting via gravity and no other ...
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If we consider the spacetime of the universe to be four-dimensional, does the Big Bang lie in its center?
Apologies for the (hopefully now somewhat less) clickbait-y title. Now, of course, I know that the Big Bang did not happen at any point connected to a single point in our current $3$-dimensional ...
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Does quantum entanglement arise from perpendicular time vectors? [closed]
From what I understand, "quantum entanglement" is a phenomenon where certain information travels instantly between entangled particles, regardless of distance in space.
When thinking of ...
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Does time arising from entropy agree with GR?
There's a theory that the direction of time arises from entropy and the correlations (interactions) between bodies. However, I don't see how this would incorporate the effects of General Relativity, ...
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