Space-Time Puzzle: Why Objects Can't Be in Two Places at Once

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Discussion Overview

The discussion revolves around the question of why objects can occupy the same location at different times but cannot be found in different locations at the same time. It explores concepts related to worldlines in the context of relativity, particularly focusing on timelike and spacelike intervals.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant questions the possibility of an object being in two places at once, suggesting that an object's worldline is always timelike.
  • Another participant introduces the idea of a hypothetical faster-than-light particle with a spacelike worldline, indicating that such a particle could be in different places at the same time according to certain inertial frames in relativity.
  • A subsequent reply reiterates the concept of a faster-than-light particle and discusses the relativity of existence, positing that being in different places at the same time could imply the existence of another particle.
  • Further contributions suggest that classically, identifying a timelike particle at different times is straightforward, and propose that a similar approach could apply to spacelike particles if their worldline remains continuous.
  • One participant expresses agreement with a previous point and hints at considering the implications of a zero gravitational field in this context.

Areas of Agreement / Disagreement

Participants express various viewpoints regarding the nature of worldlines and the implications of faster-than-light particles, with no clear consensus reached on the interpretations or implications of these concepts.

Contextual Notes

The discussion does not resolve the assumptions regarding the nature of faster-than-light particles or the implications of spacelike worldlines, leaving these points open for further exploration.

Mueiz
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Why is it possible that an object can be found in the same place in different times but can not be found at the same time in different places?
 
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Because an object's worldline is always timelike.
 
Yes, if you could have a faster-than-light particle with a spacelike worldline, then according to the definition of "same time" used by inertial frames in relativity, there would be at least some frames where the particle would be at different places at the same time.
 
JesseM said:
Yes, if you could have a faster-than-light particle with a spacelike worldline, then according to the definition of "same time" used by inertial frames in relativity, there would be at least some frames where the particle would be at different places at the same time.

This means that if you could have a faster-than-light particle then even the existence of a particle is relative because diffirent place at the same time means another particle
 
Mueiz said:
This means that if you could have a faster-than-light particle then even the existence of a particle is relative because diffirent place at the same time means another particle
Classically we have no difficulty in identifying a given timelike particle now and earlier as the same particle provided the worldline is continuous. I would think that we would similarly have no conceptual difficulty in identifying a given spacelike particle here and there as the same particle provided the worldline is continuous.
 
DaleSpam said:
Classically we have no difficulty in identifying a given timelike particle now and earlier as the same particle provided the worldline is continuous. I would think that we would similarly have no conceptual difficulty in identifying a given spacelike particle here and there as the same particle provided the worldline is continuous.

Yes, good answer
(now i am thinking to involve the case of zero gravitational field here :-p)
 

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