All Questions
24
questions
-1
votes
1
answer
71
views
What happens if we differentiate spacetime with respect to time? [closed]
Essentially, what would differentiating space-time with respect to time provide us with? What are the constraints associated with such operations? Is it possible to obtain a useful physical quantity ...
3
votes
1
answer
124
views
What is the problem with two time dimensions? [duplicate]
I am reading a book "General relativity: The theoretical minimum" by Leonard Suskind.
In page 168-169, the author explains the reason why we don't consider the case with two time dimensions ...
- 311
1
vote
0
answers
74
views
Why can't the metric have more than one timelike coordinate? [duplicate]
In one of his lectures, L Susskind stated that he cannot make sense of a metric with more than one timelike dimension. I also have trouble imagining it, but is there a good mathematical or physical ...
- 795
1
vote
1
answer
147
views
In relativity, is the fourth spacetime dimension spatial or nonspatial?
In "An Introduction to Modern Astrophysics" Carroll and Ostlie describe the curvature of space by mass as:
curving in a fourth spatial dimension perpendicular to the usual three of "...
- 13
0
votes
1
answer
121
views
Dimensionality problem in special relativity
Suppose $A$ is a null $4$-vector in Minkowski space-time, $M$. Then the vector space spanned by $A$: $\operatorname{span}(A)$ is unidimensional. The orthogonal complement of this vector space $\...
- 61
4
votes
0
answers
99
views
Electromagnetism in spacetime with 2-times split-signature $(+,+,-,-)$ metric
Maxwell's equations can easily be generalized to any $(m,n)$-spacetime. Is there any material analyzing what such a theory will look like?
Note that a particle still moves in spacetime forming a line. ...
- 487
11
votes
2
answers
1k
views
Features of General Relativity applicable only to 3+1 dimensions?
While studying general relativity, I noticed that much of the theory could easily be generalized from a $(3,1)$-dimensional spacetime to an $(n,1)$-dimensional spacetime without any changes. So, is ...
- 1,588
0
votes
1
answer
95
views
Is it possible to treat the time dimension as the rate of change of an extra spatial dimension? [closed]
In Minkowski Spacetime metric the time dimension is multiplied with $c$. This would allow us to swap it against a fourth space dimension: $cdt=dx_4$. One interpretation would be that the rate of ...
- 61
1
vote
1
answer
1k
views
Meaning of 1+1 dimensions
I came across the notion of 1+1 dimensions in a condensed matter context and, in particular, while studying bosonization, which relates to 1D quantum systems. Indeed, the Wikipedia article about it ...
- 1,396
0
votes
1
answer
130
views
Why did Kaluza-Klein need an additional dimension? [closed]
Why did Kaluza-Klein need an additional dimension and not just treat the fourth dimension as a description of both time and space?
Assume that you can exchange the time dimension to a space dimension ...
- 61
34
votes
11
answers
11k
views
Is the "spacetime" the same thing as the mathematical 4th dimension?
Is the "spacetime" the same thing as the mathematical 4th dimension?
We often say that time is the fourth dimension, but I am wondering if it's means that time is like the fourth geometrical axis, or ...
- 1
5
votes
3
answers
1k
views
When exactly is a dimension spatial?
I every so often hear claims like:
M-Theory predicts that there are 10 spatial dimensions!
Now I'm not really sure what these claims mean. There are three spatial dimensions that I normally observe ...
4
votes
2
answers
362
views
Spatial and temporal dimensions orthogonality
It seems that the spatial dimensions are orthogonal: a particle can move along one axis without changing its position in relation to other two axes.
It seems that the temporal dimension is somewhat ...
-2
votes
1
answer
68
views
Time difference between all particles and waves [closed]
Since all elementary particles and waves were created simultaneously in the big-bang (t0) would there be any time difference between any interacting elementary particles and/or waves after t0? I'm ...
- 11
-1
votes
3
answers
534
views
Kaluza-Klein theory metric
What are the physical dimensions of the $5\times 5$ Kaluza-Klein metric? (the metric should be dimensionless but doesn't look so with the inclusion of the four potential and the scalar field)
