Is There Time in the Bulk? Understanding Brane Cosmology

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In summary, the bulk constantly produces 'hubble spaces'. The new bubbles can appear in any direction, but if there is time, it goes in the same direction as the Hubble spaces. The Standard model is different in different bubbles, and perhaps there are more than 1 time dimension.
  • #1
Dmitry67
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My question is naive and may be incorrectly formulated

So, the bulk: http://en.wikipedia.org/wiki/Brane_cosmology
which is constantly producing 'hubble spaces'.

I wounder if there is 'Time' in the Bulk. If there is time, does in point to the same direction as in the Hubble spaces. If not, how the new bubbles can appear.

Also, what exactly makes the parameters of the Standard model different in different bubbles. Can the number of dimensions be different? Can there be more then 1 time dimension?

Thank you
 
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  • #2
Well I'm not really knowledgeable about Brane Theories. I know a lot about string theory, but not so much about branes. However, it seems that your question is really dealing with the time dimension. Its interesting to think of multi-time dimensions, however, you cannot think of time in the same way as spatial dimensions. Time does go forward and in theory, backward, but that is simply one dimension. I really don't think there are other ways for time to move, such as with space which could go up and down side to side, etc. And a lot of the mathematics show that the multi-dimensions are spatial dimensions, most likely Calabi-Yau Manifolds, which are shown here

http://universe-review.ca/I15-15-CalabiYauSpace.jpg

But its very interesting to think about, and would certainly be cool. I once had an idea that what if time where two dimensional, would that be able to partially explain why a particle can appear in two places at the same time on a very short scale, wave-particle duality pretty much? It's just a thought though.
 
  • #3
I do not understand string theory well, but I've seen models where "time" in our universe is described as just a property of the brane our universe is stuck to-- such that the brane happens to curve in such a way that our spacetime has a "signature" of three spacelike and one timelike dimensions. But other branes within the bulk might have no timelike dimensions, or more than one timelike dimension, depending on what their signature is.

The existence of models where the "timelikeness" of dimensions is determined by the properties of the brane seems to me to imply that braneworld models do not have a preferred "time" dimension or direction.
 
  • #4
Thank you
So time belongs to a brane?
Hence, there is no time in the bulk?
If so, I see the problem with the initial conditions because the configuration of the bulk (including the positions of all branes) must be predefined.
 

1. What is brane cosmology?

Brane cosmology is a theoretical framework that suggests our universe is a three-dimensional membrane (brane) embedded in a higher-dimensional space known as the bulk. This theory attempts to explain the origin and evolution of the universe, including the presence of dark energy and the accelerating expansion of the universe.

2. How does brane cosmology relate to time?

In brane cosmology, time is a dimension that exists within the membrane (brane) while the bulk is considered to be timeless. This means that time only exists within our universe and is not a fundamental aspect of the higher-dimensional space.

3. Is there a way to test the existence of time in the bulk?

Currently, there is no direct way to test the existence of time in the bulk. However, some researchers suggest that gravitational wave detection and studying the cosmic microwave background radiation may provide evidence for the presence of extra dimensions and the concept of time in the bulk.

4. What implications does the concept of time in the bulk have for the Big Bang theory?

Brane cosmology challenges the traditional Big Bang theory by proposing that the universe did not originate from a singularity, but rather from the collision of two branes in the bulk. This collision would have resulted in the creation of our three-dimensional universe and could explain the expansion of the universe without the need for dark energy.

5. Are there any competing theories to brane cosmology for understanding the concept of time in the bulk?

Yes, there are other theories such as string theory and M-theory that also propose the existence of extra dimensions and a higher-dimensional space. However, brane cosmology offers a more testable and simplified framework for understanding the concept of time in the bulk.

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