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Author Topic: Can you send messages into the past?  (Read 2057 times)

Offline thedoc

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Can you send messages into the past?
« on: 25/06/2015 17:50:01 »
Nick asked the Naked Scientists:
   
if two electromagnetic waves are entangled and one is absorbed at some point while the other one continues living and, moreover, it rotates its axis because is passing inside a hollow cylindrical magnet, can the change be paradoxically detected on the already died wave? Basically, can you send messages into the past using this mechanism?

What do you think?
« Last Edit: 25/06/2015 17:50:01 by _system »


 

Offline UltimateTheory

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Re: Can you send messages into the past?
« Reply #1 on: 26/06/2015 19:55:21 »
Quote
Basically, can you send messages into the past using this mechanism?

If you could send photon to the past, Universe in the past would receive energy, and total energy would have to be increased.
We could imagine situation where somebody sends photon to past, then use that energy to send even more photons in the past, and repeat it over and over.
As a result total energy in the past version of Universe would be growing to infinity..
Violating several quantum physics conservations..

Similar situation is with sending somebody, or something, to the past,
Baryon number conservation would be violated.
We would have to have same proton, same electron, same neutron, in multiple places at the same time.
Suppose so you're send to the past,
Protons(Hydrogen) that are in your body, yesterday were in water in some river, or in air as clouds, and you drunk it and they became part of your body.
So, if you would travel in time one day back from now, we could find these molecules either inside of you and in clouds/river/water.... Two places at the same time..
Repeat time travel to the past, and amount of matter would be growing to infinity.

There used to be theory that there exist just one electron in the entire Universe, and it's just traveling back and forth in time.
 

Offline PmbPhy

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Re: Can you send messages into the past?
« Reply #2 on: 27/06/2015 00:45:46 »
Quote from: UltimateTheory
If you could send photon to the past, Universe in the past would receive energy, and total energy would have to be increased.
There's no reason to assume that one has to use photons to send messages into the past since communication is not dependent on the use of photons. E.g. if it was possible to send information from one point to another in space using quantum entanglement (which it isn't) then that form of communication wouldn't depend on photons or energy of any kind.

However, if it was possible to control the photons that existed in the past then we could send messages into the past.
 

Offline jeffreyH

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Re: Can you send messages into the past?
« Reply #3 on: 27/06/2015 00:59:27 »
If wormholes exist, big if, and they send information into the future via a shortcut you could indeed do this. By opening and closing a wormhole in a set pattern you could send signals into the past. The photons that disappear into the wormhole are dashes and the ones that carry on are dots. There it is, wormhole Morse code.
 

Offline jccc

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Re: Can you send messages into the past?
« Reply #4 on: 27/06/2015 01:03:22 »
send photon to the past?

is it even possible to send anything to the past?

past is only in our minds.

i'm not kidding, stuff like this is like witchcraft, not science.

point a laser beam to ANY direction, where is past? everywhere it can go is NOT past.

« Last Edit: 27/06/2015 09:27:13 by jccc »
 

Offline PmbPhy

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Re: Can you send messages into the past?
« Reply #5 on: 27/06/2015 08:37:28 »
If wormholes exist, big if, and they send information into the future via a shortcut you could indeed do this. By opening and closing a wormhole in a set pattern you could send signals into the past. The photons that disappear into the wormhole are dashes and the ones that carry on are dots. There it is, wormhole Morse code.

See: https://en.wikipedia.org/wiki/Wormhole
Quote
An object traveling through a wormhole could carry energy or charge from one time to another, but this would not violate conservation of energy or charge in each time, because the energy/charge of the wormhole mouth itself would change to compensate for the object that fell into it or emerged from it.

However that statement references this article: see http://arxiv.org/abs/gr-qc/0503097
Quote
Wormholes have been advanced as both a method for circumventing the limitations of the speed of light as well as a means for building a time machine (to travel to the past). Thus it is argued that General Relativity may allow both of these possibilities. In this note I argue that traversable wormholes connecting otherwise causally disconnected regions, violate two of the most fundamental principles physics, namely local energy conservation and the energy-time uncertainty principle.
which contradicts what Wikipedia says. Confusing!
 

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Re: Can you send messages into the past?
« Reply #5 on: 27/06/2015 08:37:28 »

 

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