Tagged Questions
1
vote
1answer
82 views
Could the shadow move with faster-than-light speed? [duplicate]
If I make a huge laser with a figure for shadow in front of the laser, and I shine it on to the moon, will I see the light from the laser AND the shadow moving the same speed? (I read somewhere the ...
3
votes
3answers
100 views
Reaching the speed of light via quantum mechanical uncertainty?
Suppose you accelerate a body to very near the speed of light $c$ where $v = c - \epsilon$. Although this would take an enormous energy, is it possible the last arbitrarily small velocity needed -- ...
0
votes
1answer
44 views
Velocity of measurement
As per to Heisenberg uncertainty we will not be able to calculate the position and momentum at same instant because by the time we calculate the next of the one, it changes (i.e.) the changes are very ...
9
votes
1answer
298 views
How is quantum mechanics compatible with the speed of light limit?
Consider a free electron in space. Let us suppose we measure its position to be at point A with a high degree of accuracy at time 0. If I recall my QM correctly, as time passes the wave function ...
1
vote
0answers
245 views
What happens with photon when it is slowed down substantially?
In a dispersive media light's velocity can change substantially. Imagine we can slow it down to near 0 what the wave would look like?
Frequency of light does not seem to change even at v=0 (at least ...
0
votes
2answers
220 views
speed of light,breaking the barrier
when the sound barrier is broken,a series of concentric waves of sound is produced.Does it mean when the speed of light barrier is broken,a ripple of photons are created in the space-time fabric?
12
votes
3answers
936 views
Is the universe a quantum computer - is light speed barrier a computational constraint
There is currently a debate ongoing on leading maths blog Gödel’s Lost Letter, between Gil Kalai and Aram Harrow, with the former arguing that building a quantum computer may not be possible due to ...
2
votes
3answers
476 views
Can a photon be emitted with a wavelength > 299,792,458 meters, and would this violate c?
Just curious if the possibility exists (not necessarily spontaneously) for a photon with a wavelength greater than the distance component of c to be emitted, and would this inherently violate the ...
2
votes
2answers
503 views
Why don't quantum effects invalidate the speed of light barrier?
While proving that no matter can reach the speed of light (a fact which I call the kinetic energy barrier), Einstein uses the fact that he can calculate the velocity and position of an electron. ...
14
votes
10answers
6k views
Does the Pauli exclusion principle instantaneously affect distant electrons?
According to Brian Cox in his A night with the Stars lecture$^1$, the Pauli exclusion principle means that no electron in the universe can have the same energy state as any other electron in the ...
2
votes
1answer
363 views
Spin up, spin down and superposition
I'm just starting to study quantum mechanics. Please explain the error in this thinking:
You set up decay of two $\pi$ mesons and get $2\mathrm{e}^-$ on Mars and $2\mathrm{e}^+$ on Earth.
On Earth ...
10
votes
3answers
886 views
What really cause light/photons to appear slower in media?
I know that if we solve the maxwell equation, we will end up with the phase velocity of light is related to the permeablity and the permitivity of the material. But this is not what I'm interested in, ...
