# TIme Dilation & Quantum Entanglement Question

1. Aug 5, 2010

### alphauser51

Yesterday, my 12 year old nephew asked me a physics question after we watched
a documentary about Einstein and relativity on the science channel. I know just enough
about physics to be dangerous, and I can usually answer his questions but this time he had me stumped, and I couldn't find anything on the net. Here goes.

Twin brothers Harry and Joe bid each other farewell. Joe gets on a spaceship and takes
off on a long voyage at a significant fraction of the speed of light. Harry and Joe also
built an audio/video communications device that utilizes quantum entanglement
and "spooky action at a distance" to allow instantaneous 2 way communication at any distance with no delay. Would they be able to hold a real time conversation with one another. Additionally, if each had a web cams setup and pointed at a clock with a second hand, would the brother on earth see the second hand moving slower than his own?
Any help or feedback would be appreciated..

2. Aug 5, 2010

### unusualname

You can't use quantum entanglement for instantaneous communication even one-way, never mind two-way.

3. Aug 5, 2010

### JesseM

As it turns out, it can be proven that according to QM it is impossible to use quantum entanglement for transmitting information FTL, the proof is known as Eberhard's theorem. I posted some other papers discussing Eberhard's theorem in post #22 of this thread. The inference of "spooky action at a distance" has to do with correlations that are seen when you compare measurements on a group of entangled pairs, but if you look at data from a series of particles which each constituted one half of an entangled pair, without seeing the data from measurement of their "twins", it will just look random regardless of what was done to the "twins" far away.

4. Apr 24, 2011

### San K

they cannot use quantum entanglement, however lets say they are separated by 1 light hour.

thus they can wait an hour to get the other person's signal/video....the video would play...with a lag of 1 hour....

thus they could see the other aging faster/slower.....via a video that plays with a lag of 1 hour...