All Questions
Tagged with faster-than-light inertial-frames
65
questions
-4
votes
1
answer
99
views
In SR, why do we claim length contraction rather than faster than $c$ travel in the rocket frame? [closed]
In special relativity, a rocket traveling at .5c will take .86 years (in the astronauts frame) to travel 1 light year (in a stationary observer frame). There are two possible ways to look at this
...
- 4,783
0
votes
3
answers
150
views
Two-way tachyonic anti-telephone
Consider the two-way tachyonic antitelephone where the speed at which message is transmitted is $a$. A person $A$ sends a message to $B$ which is moving away with a speed of $v$ with respect to $A$. ...
- 1,200
-2
votes
1
answer
65
views
Lorentz transform causes Faster than light motion for Spacelike-separated object?
Consider a 5-meter rod which exists on the x-axis of a frame of reference:
Now consider an observer moving at a velocity $0.1c$ relative to this reference frame, from right to left. Their frame of ...
0
votes
0
answers
19
views
If a photon travelled in the opposite direction of another photon [duplicate]
If a photon travels in the opposite direction as another photon, then what is the speed of the second photon relative to the first. Is it 2 times the speed of light? Also what if two photons travelled ...
- 329
4
votes
2
answers
126
views
How to show that a if $v > c$ there is a frame which breaks causality in special relativity?
I'm reading about special relativity and looking at the Lorentz transformations.
I'm reading that:
If $v > c$, we can find a frame in which $t_2' < t_1'$, i.e. a signal arrived before being ...
- 937
2
votes
0
answers
28
views
Special Relativity and Light [duplicate]
I just started learning about relativity in my physics class and would like some help understanding the concepts.
My question is imagine two objects start emitting light and are 1 lightyear away from ...
- 61
-2
votes
1
answer
80
views
Will light be travelling faster than the speed of light? [duplicate]
If a photon is emitted from a light source travelling with some velocity, then surely the photon emitted in the direction of travel would have a velocity equal to the speed of light plus the velocity ...
-7
votes
3
answers
244
views
Can one record a speed faster than $c$?
A ship goes to the moon at 0,5 c, the captain will record on his clock about 2 seconds and a half, right?
Now he increases the speed to 0,999 c (or more), thanks to relativity he should record on his ...
- 691
-5
votes
3
answers
601
views
FTL travel without time travel (again)
In discussions about FTL communication and time travel, there is a simple thought experiment: the relativistic duel which is used to demonstrate that FTL travel implies time travel (I know it has a ...
- 7
-3
votes
5
answers
1k
views
But why can't i travel faster than the speed of light? [duplicate]
I'm laying in my bed right now. Am I traveling 0mph? Am I traveling 850-ish mph (south texas) as the earth rotates? Am I traveling 67,000mph as my planet orbits the sun? Am I traveling 560,000mph as ...
- 23
-5
votes
1
answer
112
views
These guys occur but why? [closed]
We all know that if we consider the assumption of Einstein that is no material object can travel faster than light to be true then two effects that are
Length Contraction And Time Dilation
seem to be ...
5
votes
3
answers
427
views
Velocity addition for tachyons
How does the velocity of a tachyon transform under a Lorentz boost? Suppose we only consider motion along the $x$ direction for simplicity. If the velocity of the tachyon is $u$ in the lab frame, what ...
- 843
6
votes
5
answers
3k
views
If a muon travelling fast can “extend” its lifespan due to relativistic effects, would the muon see itself travelling faster than light?
In other words, if I put a bomb set for 2.2 microseconds and send it out at .99c, would it travel further than (.99c x 2.2 microseconds)? And if it does, like muons do, wouldn’t the bomb be able to ...
- 93
-2
votes
1
answer
122
views
Would it be possible to reach the speed of light using this example? [duplicate]
Let's say I were to have made a train that travels at $60$ $mph$. Let's also say that I have another train inside of the first train that is also moving at $60$ $mph$ in the same direction. So from an ...
- 1
1
vote
6
answers
2k
views
Why does FTL imply that BACKWARDS time travel is possible? - Very Detailed! [closed]
I know this question has been asked before and I have read and understand the answers however imo none of them still imply that backward time travel is possible.
I understand moving forward in time ...
- 127