All Questions
Tagged with speed-of-light faster-than-light
286
questions
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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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1
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108
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Can the velocity of an image produced by a plane mirror be greater than that of light?
We are currently studying ray optics in school and it made me wonder if the velocity of an image produced by a plane mirror can theoretically be greater than that of light.
Using the relation $v_i = 2 ...
5
votes
1
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90
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Would the effective speed of an Alcubierre drive be limited by the propagation speed of gravity?
The idea of a warp drive is to "expand space behind the ship and contract it in front"- in this way reaching a target destination faster than one could conventionally. However, the actual ...
- 87
-4
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2
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Can we use the fabric of spacetime to go faster than the speed of light?
If the fabric of spacetime isn't bound by the limit of the speed of light (the universe is expanding faster than the speed of light), could humans somehow wrap a spaceship in a bubble of the fabric of ...
0
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1
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51
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Speed in a medium
Let's say, that there is medium, where the speed of light is $10^8 \, \rm m/s$. So in that medium if there exists a particle that is moving through without any hindrance what would be the speed limit ...
- 151
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3
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134
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Faster than light is possible? [duplicate]
I know that some particles can go near or more than half the speed of light. So, say we shoot two particles in opposite directions at more than half the speed of light. Say one is moving at 50% the ...
- 11
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68
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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 ...
- 49
3
votes
1
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109
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Spacetime that allows matter to rotate faster-than-light
Is there a solution to Einstein's equations which allows:
the object to be rotating at sub-light speed when viewed from within itself.
for a distant observer the object to rotate at superluminal ...
- 131
1
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1
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53
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Speed of light getting lower in densed medium [duplicate]
In densed medium speed of the light gets lower so in this kind of situation is there anything which can travel quicker than light?
- 21
2
votes
2
answers
96
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Speed of wave more than $c$
We are always told that information cannot travel faster than light (speed $c$). So, my question is, if we talk about a wave lets say a transverse wave. We can define a wave as the systematic ...
-2
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3
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103
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Can gravity make something faster than light? [duplicate]
Scenario,
Let's say we have complete vacuum and nothing in the universe.
If we place 2 bodies at infinite separation and have HUGE masses ($m1, m2 \sim 10^{1000}$ kg or something):
They will attract.
...
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1
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149
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How does a refractive index of less than one not violate relativity?
If I am not mistaken, this video says that X-rays travel faster in glass than in a vacuum. Special Relativity says that information can not travel faster than the speed of light in a vacuum, so what ...
1
vote
1
answer
152
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Different Escape Velocities of Black Holes?
I am no physics major nor math major to this but merely an amateur cosmology enthusiast, so in my previous inquiries I wasn't able to find anything on the premise that if all black holes obviously ...
- 29
3
votes
1
answer
130
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Confusion regarding recessional velocity and Lorentz transformation
Consider that you are receding at a velocity faster than the cosmic speed limit (say, $2c$ with respect to $A$) due to the expansion of our universe. According to me, $A$ is moving at $2c$ and thus ...
user355398
5
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361
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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 ...
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