All Questions
Tagged with speed-of-light causality
108
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If the speed of causality changes, could you go FTL?
In the middle of some research, I reached a sort of confusion that I’d like to sort out. In flat space FTL is impossible, because in a Minkowski metric,
$$\mathrm{d}s^2=c^2 \mathrm{d}t^2-\mathrm{d}x^2-...
- 689
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Could relativity be consistent if there are multiple light-like fields with different invariant speeds?
My understanding of real physical theory of electromagnetism goes like this:
The Maxwell equations can be used to derive the speed of light;
$$\nabla\cdot\textbf{E}=0$$
$$\nabla\cdot\textbf{B}=0$$
$$\...
- 5,148
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About information transmission speed [duplicate]
Einstein says information cannot be transmitted faster than light.
Say I set an alarm that ring at 9:00 am. I go to school, and wait until 9:00 am. Then I tell my friends that my alarm rang. If the ...
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Do events very far away happen in a different timeline?
I am not sure how to ask this question in a concise manner so I am sure somebody out there explained it but I cannot seem to find it.
So I recently watched some videos explaining that $c$ not only ...
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Is the speed of causality slower in water?
I've recently read that what most people learned to think of as the 'speed of light' is actually the 'speed of causality', and that light just happens to travel at that speed (through free-space.) I'...
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If a photon is absorbed, does the associated wave function disappear instantaneously, or at the speed of light?
I came to this question while thinking about light with extreme wavelengths. Say we had light (em radiation) with a wavelength of 100's of thousands of kilometres and we absorbed a photon of it on ...
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Does electric field have a speed itself?
If we bring a charge into the system, it produces electric field around it. I wonder if the propagation of this electric field has the same speed as light. Note that I don't mean electromagnetic field....
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How to show mathematical equivalence between the idea of relativistic mass and the geometric explanation of why massive objects can't reach $c$?
I've frequently seen two different explanations for why, in SR, it's impossible for an massive object to reach $c$:
As a massive object approaches $c$, its kinetic energy starts being converted to ...
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Mathematical proof of causality in special relativity
I am trying to work through a proof of causality in special relativity using the Lorentz transformations, but there is one assumption that is necessary for the proof that I don't see as correct.
The ...
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Speed of gravity according to Laplace
We find first of all that it requires us to assume that gravitational propagation is not instantaneous, but occurs with the speed of light. One might think that this is reason enough to reject the ...
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Stuck on thought experiment about light [duplicate]
Say we have a very long fluid pipe with the width of a few astronomical units, and that this pipe is perfectly resistant to sustain the stress of a perfectly incompressible fluid going through it ...
- 87
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Question about a paper on "Aberration and the Speed of Gravity"
I found a paper online by S. Carlip (https://arxiv.org/abs/gr-qc/9909087 Aberration and the Speed of Gravity) that looks pretty good, except I can’t get past his metric equation [2.1]! He says it is ...
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How much time does it take for the gravitons generated by a black hole singularity to travel before exerting gravity forces on other celestial bodies?
It is known to all that the travelling speed of gravitons (the propagation speed of gravitational field) is not instant. So for black holes, the gravitons (the gravitational field) generated by the ...
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Could the speed of causality be (significantly) faster than $c$?
The other day my son (13) asked me whether it was possible that light went very slightly slower than our best measured $c$, and at the same time had a very tiny mass, but we aren't able to measure ...
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Self-coupling of gravity and gravitation escaping a black hole - contradiction?
The field equations are non-linear, that can be interpreted as gravity is coupling with itself, see for example here:
Non-linearity and self-coupling of gravity
I'm trying to understand what that ...
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