How the standard spacetime model relates to reality

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Discussion Overview

The discussion revolves around the relationship between the standard spacetime model and the concept of personal experience of time. Participants explore how individual experiences of time correlate with the geometric representation of spacetime, addressing theoretical aspects of time travel, causality, and the nature of simultaneity within different spacetime frameworks.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants describe the standard spacetime model as a 4-dimensional geometric object, where personal history is represented as a curve within this model.
  • Others propose that the "present" is a subjective experience that does not have a clear representation in the spacetime model, as different observers may perceive different "presents" based on their relative motion.
  • A participant suggests that the entity experiencing time can be modeled as a 'test particle', and the curvature of spacetime is influenced by the Stress-energy tensor.
  • There is a discussion about the distinction between Minkowski spacetime and Riemannian manifold, with some participants favoring Minkowski for simplicity in the context of their questions.
  • Some participants argue that while a worldline represents a path through spacetime, the individual exists only at a single point along that path at any given moment, raising questions about the nature of existence in spacetime.
  • One participant mentions that the "now" is not experienced but is calculated based on events in the past light cone, while the future remains uncertain.
  • Another participant emphasizes that the spacetime diagram does not distinguish "present" from other times, but rather categorizes events into future light cone, past light cone, and regions outside both light cones.

Areas of Agreement / Disagreement

Participants express differing views on the nature of the "present" in the spacetime model, with some asserting that it is a subjective experience while others argue it lacks a clear definition in the model. The discussion remains unresolved regarding how personal experience correlates with the geometric representation of spacetime.

Contextual Notes

Participants highlight the complexity of defining simultaneity and the implications of different observers' perspectives in the spacetime model. There are unresolved questions about the nature of existence along a worldline and the implications of causality in relation to personal experience.

  • #31
name123 said:
Are you suggesting that in the block universe interpretation of the mathematics, that there is a distinction between what I was experiencing while you were experiencing what you were experiencing and simultaneity? Such that event A being simultaneous to event B does not imply that a witness of event A, located at the location of event A, would have of experienced event A while a witness of event B, located at the location of event B would have of experienced event B.

I don't know any way of answering that question until you can provide a definition of that word "while" that I've bolded above.
 
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  • #32
Nugatory said:
name123 said:
Are you suggesting that in the block universe interpretation of the mathematics, that there is a distinction between what I was experiencing while you were experiencing what you were experiencing and simultaneity? Such that event A being simultaneous to event B does not imply that a witness of event A, located at the location of event A, would have of experienced event A while a witness of event B, located at the location of event B would have of experienced event B.

I don't know any way of answering that question until you can provide a definition of that word "while" that I've bolded above.

If you are asking for a definition of how you could tell experimentally what I was experiencing while you are experiencing then the answer is I'm not sure that one exists. But in both cases I used it, I was assuming that the experience of each person was changing, and was considering what the one person's experience was as the other was at a certain point of their changing experience, or during a certain period of their changing experience. They don't have to be experiencing clocks or if they were what they experienced the clocks doing doesn't come into it. It is related to the idea that other people are experiencing change in parallel to your experiencing change, that corresponding to your experience of change, other people are experiencing change and so on. I presume these aren't exactly alien concepts to you, so if you aren't able to understand, perhaps you could highlight what is causing you confusion? If you think you can understand, then you should be ok to answer.
 
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  • #33
name123 said:
If you are asking for a definition of how you could tell experimentally what I was experiencing while you are experiencing then the answer is I'm not sure that one exists.

Such a definition does not exist; there is no such experimental method because, as I said, "simultaneity" is not a physical thing; it's a convention.

name123 said:
The discussion is about the interpretation, not the maths.

Then it's off topic here. We discuss physics here, not "interpretations" that make no difference to experimental predictions.

name123 said:
I don't see how having different "static perceptions" at different points along your worldline is having a changing experience

It is because the model says it is; that is how "changing experience" is modeled in SR.
 
  • #34
Since discussion of interpretations is off topic here, this thread is closed.
 

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