Very basic questions about visualizing spacetime

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    Spacetime Visualization
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Discussion Overview

The discussion revolves around the validity and limitations of the rubber sheet analogy for visualizing spacetime, particularly in the context of general relativity. Participants explore whether this analogy can adequately represent the curvature of spacetime around gravitating objects and discuss the implications of using such visualizations in understanding complex concepts in physics.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants question the effectiveness of the rubber sheet analogy, suggesting it is limited and does not accurately depict spacetime as a whole.
  • There are inquiries about the meaning of "true enough" in relation to the analogy, indicating a need for clarity on its applicability.
  • One participant proposes that spacetime might exhibit radial wrinkles around gravitating objects, akin to a flexible material being deformed.
  • Another participant challenges the validity of using random graphics from the internet to visualize general relativity, asserting that they do not provide accurate representations.
  • Some participants suggest that differential geometry is a more appropriate framework for understanding the behavior of spacetime compared to the rubber sheet analogy.
  • Clarifications are made regarding the distinction between the rubber sheet analogy representing space versus spacetime, emphasizing its limitations.

Areas of Agreement / Disagreement

Participants express differing views on the rubber sheet analogy, with some acknowledging its limited usefulness while others argue against its applicability to spacetime. The discussion remains unresolved regarding the adequacy of the analogy and its implications for understanding general relativity.

Contextual Notes

Limitations include the ambiguity of terms like "true enough," the dependence on specific definitions of spacetime and gravity, and the unresolved nature of how well visual analogies can convey complex mathematical constructs.

jaketodd
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I'd like to start with: Does the rubber sheet analogy still hold true enough? Or is there really no visualization (it's all mathematical constructs)?

Does this picture analogy hold at all here?

mass deforming spacetime.jpg


With the curved geodesics influencing the paths of things.

Thanks!
 
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jaketodd said:
Does the rubber sheet analogy still hold true enough?
What does "true enough" mean? The rubber sheet analogy is fine as far as it goes, but it doesn't go very far at all. So you'll need to explain why you are asking and what you actually want to know.
 
Does it hold true enough that there are radial wrinkles in spacetime around a gravitating object, like in this picture of a flexible material being pushed down on at the center?

spacetime wrinkles.png


Thanks
 
jaketodd said:
Does it hold true enough that there are radial wrinkles in spacetime around a gravitating object, like in this picture of a flexible material being pushed down on at the center?
Where are you getting this from? Please give a reference.

If you want an answer to the more general question "does this random graphic I found on the Internet give a true enough visualization of General Relativity", the answer is no.
 
jaketodd said:
I'd like to start with
Where do you want to end up? So far your questions do not seem well designed to get you anywhere useful.
 
I thought if it's like a rubber sheet, it might deform like a rubber sheet. Is differential geometry a good start to understanding how it really behaves? Thanks
 
jaketodd said:
I thought if it's like a rubber sheet, it might deform like a rubber sheet. Is differential geometry a good start to understanding how it really behaves? Thanks
Differential geometry of spacetime?
Yes.

Differential geometry of a rubber sheet?
No.
 
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jaketodd said:
I thought if it's like a rubber sheet, it might deform like a rubber sheet.
What "it" do you mean? If "it" means "spacetime", then no, the rubber sheet does not describe it. The rubber sheet analogy is a (limited) analogy for space around a spherically symmetric gravitating body, not spacetime.

jaketodd said:
Is differential geometry a good start to understanding how it really behaves?
Yes, as presented in any of a number of GR textbooks. When you have taken the time to read some, you can ask further questions if you have them about what you read.

In the meantime, this thread is closed.
 

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