Physics Stack Exchange
Physics Stack Exchange

Questions tagged [faster-than-light]

"Faster-than-light", also known as superluminal velocities, refers to any sort of travel at a speed greater than the speed of light. Prohibited in mainstream physics due to the Special theory of relativity.

"", also known as superluminal velocities, refers to any sort of travel at a speed greater than the . Prohibited in mainstream physics due to . Would be possible for "", particles with imaginary mass, but tachyons indicate an unstable , due to .

Such a phenomenon is generally taken to be false, as it violates .

939 questions
3
votes
2 answers

Is Light our limit?

Suppose something existed faster than light will we be able to perceive it? And even if we encounter it wouldn't seem to travel with speed of light?
Ha'Penny
  • 77
  • 15
2
votes
2 answers

If light is a constant and can be slowed down, can it be sped up?

Can light be sped up, say for instance, when it enters into a black hole?
user42744
1
vote
0 answers

Relativity and the addition of speed

Two rockets, that can each travel slightly faster than half of the speed of light, are launched from opposite sides of the planet. Why isn't rocket A traveling faster than the speed of light relative to rocket B?
Macro
  • 11
1
vote
1 answer

Speed of Light & Distance

If I have a transmitter that signals a relay which turns off a light off which is 300 000 km away – it has travelled at the speed of light. If I connected a rope (which does not stretch) which is connected to this same light bulb and we ignore the…
towtruckdriver
  • 11
0
votes
2 answers

Information can't travel faster than $c$

When we say that information cant travel faster than light, we mean that phase velocity can go beyond $c$ but the group velocity can't. Hence, we say that a plane wave carries no information. What I don't understand is what we mean by information…
Sara Johanson
  • 1
0
votes
0 answers

How does a shadow appear to break the speed of light?

Take the image below for example: For the shadow to travel from point A to B would be extremly fast on the surface on the moon but probably not breaking the speed of light. But if the moon were 20 times larger then it would appear that the shadow…
AnonDCX
  • 101
0
votes
1 answer

Send a signal from Earth to a planet billion light years away instantly

If light was infinitely fast, we could just send a light signal from Earth to the planet. But I was wondering, if we made a perfectly non-elastic rope as long as the distance between earth and the far-away planet. Could somebody pulling the rope…
Michael
  • 119
-1
votes
2 answers

Thought experiment: wired pull long distance communication

Let's imagine that doing research for the space elevator someone manages to build a very strong wire. But instead of using it for the space elevator a wire several millions of kilometers long is attached to 2 satellites and put in orbit around the…
FluidCode
  • 167
-5
votes
2 answers

How Energy can be real if C² isn't real? (E=MC²)

So, Nothing can go faster than speed of light. How come the Energy be real if C² isn't real? Is it even allowed to square C? How can we use C² as a constant as it has not representations in nature?
lopata
  • 139