# The Naked Scientists Forum

### Author Topic: If neutrinos move faster than light, is time travel possible  (Read 3657 times)

#### thedoc

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##### If neutrinos move faster than light, is time travel possible
« on: 23/11/2011 12:59:33 »

Hi Chris,

The question I'd really like to ask is... Following the reconfirmed results that a neutrino can travel faster than light, why is it then assumed that travelling through time is possible?

A neutrino  coming from the sun would still take several minutes to reach Earth, say, even if it does get here faster then a ray of light that left at the same time. In the media I haven't found the answer to this question, I just come across the assumption!

Cheers,

Shane Record

Visit the webpage for the podcast in which this question is answered.

« Last Edit: 23/11/2011 12:59:33 by _system »

#### Phractality

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##### If neutrinos move faster than light, is time travel possible?
« Reply #1 on: 21/11/2011 04:00:43 »
If there is a speed faster than light, then there can only be one preferred reference frame in which that speed is the same in all directions. In a reference frame moving relative to the preferred reference frame, the thing which is faster than light may arrive before it left when moving in one direction, but it will be delayed by the same amount when moving in the opposite direction. Therefore, there is no violation of causality.

Even if you could send a message instantaneously in the preferred reference frame, you could not send the message to your own future. A 2-way communication, which is instantaneous in the preferred reference frame, could arrive before it is sent, but the reply could not be received before the original message was sent.

That is true because, in special relativity, with motion in the x direction, time depends on the x coordinate. Clocks farther ahead in location show later times.

Time travel is not possible.

#### Soul Surfer

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##### If neutrinos move faster than light, is time travel possible?
« Reply #2 on: 21/11/2011 09:04:02 »
Almost certainly not.  causality may change a bit at tiny scales but not at ours.

#### CZARCAR

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##### If neutrinos move faster than light, is time travel possible?
« Reply #3 on: 21/11/2011 14:51:59 »
IF a neutrino travels faster than C & time reverses, this would provide explanation of how the universe recycles? As is, universe is expanding & accelerating?

#### Silver

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##### If neutrinos move faster than light, is time travel possible?
« Reply #4 on: 22/11/2011 17:05:17 »
Neutrinos travelling through space are slower than c (supernova 1987A) so maybe it is only when they travel through matter they cam be faster? It has been suggested that they take a short cut of some kind.

Time travel is impossible for so many reasons....

#### yor_on

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##### If neutrinos move faster than light, is time travel possible
« Reply #5 on: 01/12/2011 19:05:44 »
"the reconfirmed results that a neutrino can travel faster than light?"

Now, whenever did that happen?
Maybe you mean this?

"The new version of the Opera experiment changes the time structure of the particle beam that travels between Cern and Italy’s Gran Sasso laboratory. Instead of 10-microsecond pulses, the beam will now send much shorter 1-2 nanosecond pulses, with a 500-nanosecond gap in between.

This should allow the researchers to correlate the deparature and arrival times of every batch of neutrinos.

“For every neutrino event at Gran Sasso, you can connect it unambiguously with the batch of protons at Cern,” said Cern research director Dr. Sergio Bertolucci.

The new experiment will run until November, when Cern will stop accelerating protons and start accelerating lead ions. Researchers hope the results will shore up their yet-to-be-published paper about the faster-than-light phenomenon.

Two other teams currently working on experiments at Gran Sasso are scheduled to cross-check Opera’s data next year."

It's the first of December as I write this.

#### The Naked Scientists Forum

##### If neutrinos move faster than light, is time travel possible
« Reply #5 on: 01/12/2011 19:05:44 »