Time travel when velocity> light speed

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Discussion Overview

The discussion revolves around the concept of time travel and perception when traveling faster than the speed of light. Participants explore theoretical implications, particularly in relation to quantum mechanics and the behavior of light and particles at such velocities.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions what a traveler would see when moving faster than light, drawing a parallel to the experience of a jet pilot exceeding the speed of sound.
  • Another participant asserts that since no massive body can travel faster than light, the question lacks meaning within the framework of current physics.
  • A different viewpoint introduces tachyons, hypothetical particles that can exceed light speed, suggesting that they would be perceived as traveling backward in time, yet they do not violate causality.
  • Another participant discusses the effects of extreme velocities on light perception, noting that an observer traveling at speeds close to light would still measure light at speed c, but would experience shifts in wavelength, affecting visibility.

Areas of Agreement / Disagreement

Participants express differing views on the meaningfulness of the question regarding faster-than-light travel, with some asserting it is not meaningful while others explore hypothetical scenarios. The discussion remains unresolved regarding the implications of tachyons and the perception of light at extreme speeds.

Contextual Notes

Limitations include the dependence on theoretical constructs such as tachyons and the unresolved nature of how light behaves at velocities exceeding c, along with the implications of causality in such scenarios.

shredder666
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Not sure if this will have anything to do with quantum mechanics.. but...
Ok so if you're traveling faster than light speed, then what do you see?

I'm not talking about the whole doctor who scenario, its like traveling faster than sound, if the jet pilot is traveling faster than the sound it makes, then he/she wouldn't hear that sound. Would this be of a similar case with your eyes?
 
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shredder666 said:
Ok so if you're traveling faster than light speed, then what do you see?
No massive body can travel faster than light, so the question isn't meaningful in light of current physics.
 
shredder666 said:
Not sure if this will have anything to do with quantum mechanics.. but...
Ok so if you're traveling faster than light speed, then what do you see?
There are hypothetical subatomic particles which travel faster than c. As a group they are called tachyons. Just like our sublight particles cannot ever reach or exceed c, tachyons can never slow down to or slower than c. This means they are forever cut off from our universe.

That being said, a tachyon is equivalent to a regular subatomic particle traveling backward through time.

It won't do you much good though, since they still do not violate causality. Wiki has a note on http://en.wikipedia.org/wiki/Tachyon#Causality".
 
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Remember also that at speed .99999999999999999999999999999999999C an observer STILL measures light at speed c, and color from a light source in his reference frame is normal (ok for reading a book).

But at such incredibly high speed, light coming toward you from opposite the direction of your velocity appears shorter in wavelength and light coming from the rear direction is looooooooooooonger in wavelength...relative to a "stationary" source...both out of the range of visible light. You can check out such effects by looking at references for red shift and blue shift...
 
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