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3

The proposed experiment is something like this: Alice and Bob prepare a system in the Bell state: $$|\psi\rangle = \frac{1}{\sqrt{2}}(|01\rangle + |10\rangle)$$ Alice then goes somewhere and wants to communicate say the value "1" to Bob faster than light. To do this, she acts with the operator $U \otimes \mathbf{1}$ on the state (this is a local ...


0

You should be aware of the derivation of these equations and what the different terms mean. The first fraction in your last equation is the classical Doppler effect. The square root expression stems from the relativistic time dilation. This time dilation is between the reference frames of the source and the receiver. If their relative velocity is small ...


0

The light travels at 670,616,629 mph according to an observer on the train and also at 670,616,629 mph according to an observer on the ground. The speed of light is the same for all inertial observers, despite their relative motion. Velocities don’t actually “add” the way you would think they should based on our everyday experience at low velocities. The ...


5

In special relativity, velocities do not simply add up just as in galilean physics. Because special relativity is constructed on the principle of invariant speed of light $c$, and that speeds strictly smaller than $c$ in one reference frame will be smaller than $c$ in any reference frame, it makes sense that composing velocities is not as simple as just ...


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So lets say you start from earth with c/2 in one direction and somebody else (B) with c/2 in the opposite direction. From earth the relative velocity is c. If on earth an observer waits 1 second, you and B are 1 lightsecond apart. This even works if you start with c and B also start with c. Then from earth the relative velocity is 2c, and if an observer on ...


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