High School Elasticity of Spacetime: Does Spacetime Stiffen?

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SUMMARY

The discussion centers on the concept of spacetime elasticity, specifically questioning whether spacetime can exhibit stiffness or elasticity. Participants clarify that spacetime is not a tangible entity but rather a geometric framework described by pseudo-Riemann Geometry. The conversation highlights that while spacetime appears stiff at first derivatives, it becomes stretchy at second derivatives. Additionally, the speculative model treating spacetime as an elastic medium lacks a formal name and is considered a theoretical exploration rather than a necessity for understanding General Relativity.

PREREQUISITES
  • Understanding of pseudo-Riemann Geometry
  • Familiarity with General Relativity
  • Knowledge of first and second derivatives in calculus
  • Basic concepts of geodesics in differential geometry
NEXT STEPS
  • Research the implications of pseudo-Riemann Geometry in modern physics
  • Study the mathematical foundations of General Relativity
  • Explore the concept of geodesics and their significance in spacetime
  • Investigate speculative models in theoretical physics regarding spacetime properties
USEFUL FOR

Physicists, mathematicians, and students interested in theoretical physics, particularly those exploring the geometric nature of spacetime and its implications in modern cosmology.

sqljunkey
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Does spacetime have elasticity ? I was reading this and they are talking about the stiffness of spacetime.
 
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sqljunkey said:
Does spacetime have elasticity ? I was reading this and they are talking about the stiffness of spacetime.
Spacetime is not a "thing" that can be bent or stretched, or have stiffness or elasticity, it is just geometry. We use the term "bent" regarding the path of objects through space-time but that is only by applying Euclidean Geometry, which actually does not apply. Objects, in the absence of other force, travel in straight lines in space-time, but these "straight lines" are more correctly called "geodesics" and are straight lines in Riemann Geometry (but bent in Euclidean Geometry) which is the correct math to describe space-time.

EDIT: I should also note to be completely correct that I have been told by people who understand this thing way better than I do that it is actually "pseudo" Riemann Geometry that describes space time.
 
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sqljunkey said:
Does spacetime have elasticity ? I was reading this and they are talking about the stiffness of spacetime.
Spacetime is stiff upon first derivatives then gets stretchy at 2nd derivatives.
 
dsaun777 said:
Spacetime is stiff upon first derivatives then gets stretchy at 2nd derivatives.

What do you mean by that?
 
sqljunkey said:
I was reading this and they are talking about the stiffness of spacetime.

What they are talking about is a speculative model in which what we call "spacetime" is treated as if it were an elastic medium in order to investigate the implications of such a model. It is not something that can really be discussed at the "B" level and it is certainly not something that needs to be considered at all in order to understand the standard model of spacetime in General Relativity.
 
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yeah I'm sorry it's confusing to me to figure out which discussion level to use here. Does this speculative model have a name?
 
sqljunkey said:
Does this speculative model have a name?

Not that I know of.
 
I think it's just Kirk playing with numbers.
 
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