FTL Paradox: Grandfather Paradox Explained

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SUMMARY

The discussion centers on the Grandfather Paradox in the context of faster-than-light (FTL) travel, specifically involving a superluminal object moving at 10c. Two observer scenarios are presented: one where the observer is positioned between points A and B, and another where the observer is beyond point B. The conclusion drawn is that while the second observer may perceive a violation of causality, no actual causality is broken; rather, the limitations of photon detection obscure the true order of events. The discussion emphasizes that reasoning based on the premise of FTL travel leads to inconsistencies, as the laws of physics do not apply in such scenarios.

PREREQUISITES
  • Understanding of superluminal travel concepts
  • Familiarity with photon behavior and light propagation
  • Knowledge of causality in physics
  • Basic grasp of logical reasoning in theoretical physics
NEXT STEPS
  • Research the implications of tachyonic antitelephones in FTL discussions
  • Explore the principles of causality in relativistic physics
  • Study the behavior of light in non-standard frames of reference
  • Investigate the philosophical implications of time travel theories
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The discussion is beneficial for physicists, theoretical scientists, and anyone interested in the complexities of time travel and causality in the context of advanced physics concepts.

MysticWizard
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So here it goes:

2 points in space A & B.
1 superluminal object (fixed at 10c, no acceleration) that periodically transmits photons as soon as it starts moving.
1 observer with a very high accuracy photon counter removed a sufficiently large distance from the 2 points for light to take a small while to arrive but the distance between A & B is 10 times as large.

Now things are going to be set in motion: The superluminal object moves from A to B. In my view the observer detects the following depending on where he is:

1) If the observer (indicated by X) is positioned as follows:

X----A--------------------------------B

he will detect photons from A, then a trail of photons between A and B and finally detect photons from B

2) If the observer (indicated by X) is positioned as follows:

A--------------------------------B----X


he will detect photons from B, then a trail of photons from B to A and finally photons from A.

Now in situation 2 one could state causality is broken to the observer, but in reality no causality has been broken, we just don't have the means to detect the proper order of events using fotons. I'd also like to state that any human being would just see 1 small flash of light since the timescale is so small that we can't distinguish anything more, nothing close to seeing my grandfather, unless perhaps he lived in a different galaxy but then he'd be dead already.

Now what am I missing in this famous grandfather paradox. Thanks for your time :D
 
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You aren't missing anything, but as you started with a false premise (that there is faster than light travel) the conclusions drawn from that premise need not be either correct or consistent. When you're reasoning about the behavior of light emitted by an object moving faster than light, you're basically saying: "let's apply the laws of physics to a situation in which they do not apply"

For an example of a more striking logical inconsistency that results from assuming faster-than-light travel, google for "tachyonic antitelephone".

This thread is closed, as the issue has been discussed in many previous threads.
 

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