Could you say that GR is a theory of four or five dimensions?

In summary, the conversation discusses the number of dimensions involved in general relativity (GR) and whether an additional dimension is needed to describe the curvature of space. It is concluded that GR involves four dimensions (x, y, z, and t) and that the energy-momentum tensor plays a role in curving space, but it is not considered an additional dimension. The energy component (E) is also discussed and it is noted that it can affect our perception of distance, but it is not considered a dimension in GR.
  • #1
zheng89120
149
0
I don't really know much about GR, but I was just wondering about this theoretical question. I am asking this, because I think Special Relativity is a theory of four dimensions, and wasn't sure how many dimensions GR involved.
 
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  • #2
Four. Why would it be 5?
 
  • #3
Because, since space is "curved" in GR, I thought may be an addition dimension could be introduced to describe the curvature of space, but perhaps that is not counted as another dimension.
 
  • #4
Four: x, y, z, and t. What's the 5th dimension?
 
  • #5
zheng89120 said:
Because, since space is "curved" in GR, I thought may be an addition dimension could be introduced to describe the curvature of space, but perhaps that is not counted as another dimension.

Essentially it's all integrals with 4 elements, what makes it GRey is that the volume element changes with position in space-time
 
  • #6
elfmotat said:
Four: x, y, z, and t. What's the 5th dimension?

E?
 
  • #7
zheng89120 said:
Because, since space is "curved" in GR, I thought may be an addition dimension could be introduced to describe the curvature of space, but perhaps that is not counted as another dimension.

The 4 dimensions do describe the curvature of the space-time. For example, let's say you have a can of soda or a ball or something in the 3-dimensional world we're accustomed to. You can fully describe the curvature of those objects by using those 3 dimensions. A 4th dimension need not be introduced in this example.

Same idea with GR, except you now are dealing with a 3+1 dimensional spacetime instead of the 3 dimensional Euclidean space of the soda can/ball example.

TimeContinuum said:
E?

If E = energy, why would E be a dimension? It doesn't measure space-time displacements.
 
  • #8
Pengwuino said:
If E = energy, why would E be a dimension? It doesn't measure space-time displacements.

Sure it does. E alters our perception of distance.
 
  • #9
TimeContinuum said:
Sure it does. E alters our perception of distance.

The energy-momentum tensor in GR tells gravity, as many put it, how to curve, but that certainly does not mean it is qualified to be a dimension. A dimension has very specific meaning.
 
  • #10
TimeContinuum said:
Pengwuino said:
If E = energy, why would E be a dimension? It doesn't measure space-time displacements.
Sure it does.
OK, given an inertially moving rocket in flat spacetime where, from the rocket's perspective, would the 1 J hyperplane be located?
 

What is the "GR" in the phrase "Could you say that GR is a theory of four or five dimensions?"

"GR" stands for General Relativity, which is a theory proposed by Albert Einstein to explain the force of gravity in terms of the curvature of space and time.

Why is GR considered a theory of four or five dimensions?

GR is considered a theory of four dimensions (three spatial dimensions and one time dimension) because it describes the universe using four variables: time and three spatial coordinates. However, some theories based on GR, such as superstring theory, require the existence of additional dimensions (up to eleven in some versions) to be mathematically consistent.

How does the concept of dimensions relate to GR?

Dimensions are used to describe the different aspects of the universe. In GR, the four dimensions are used to describe the curvature of space and time caused by the presence of mass and energy. The more dimensions a theory requires, the more complex and detailed it becomes in describing the universe.

What is the evidence for GR being a theory of four or five dimensions?

The evidence for GR being a theory of four dimensions comes from its successful predictions, such as the bending of light around massive objects and the gravitational time dilation. As for the possibility of additional dimensions, there is currently no direct evidence, but superstring theory and other theories based on GR provide mathematical explanations for phenomena that cannot be explained by four dimensions alone.

Is the concept of dimensions in GR accepted by the scientific community?

Yes, the concept of four dimensions in GR is widely accepted and has been extensively tested and confirmed through various experiments and observations. However, the existence of additional dimensions is still a subject of ongoing research and debate within the scientific community.

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