Origin of 3 spatial dimensions

In summary, a recent post inquired about the necessity of physical space being three-dimensional, but the conversation turned into a heated exchange and was closed. The author expressed sympathy for another poster who was subject to personal insults. The original post also requested references to papers discussing a universe with multiple spatial dimensions and how matter could collapse within them. The responder suggested looking into string gas cosmology, which proposes that all nine spatial dimensions were initially bound up in strings and only the three-dimensional subspace was able to grow to cosmological size.
  • #1
Tom Mcfarland
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A recent post asked "why does physical space need to be 3-dimensional?"

However, the thread became infected with personal insults and was (properly) closed.
I felt sorry that PeterDonis, whose posts I respect, was subjected to this abuse !

I have read several posts which start by assuming that our universe has a certain topology, such as a shell universe.

Could anyone refer me to paper(s) that postulate a universe which starts with particles thinly spread out in multiple spatial dimensions, 10, 11, or perhaps even Hilbert space, none of the dimensions being degenerate. Then, taking advantage of the instability of orbits for spatial dimensions greater than 3, describes the collapse of matter within this hyper-space into either singularities, or into 3-D sub-manifolds with perhaps varying topologies, for each of which orbits become stable.

Note that such a paper need not assume that our universe actually started this way, but would be entirely a mathematical exercise.
 
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  • #2
Tom Mcfarland said:
Could anyone refer me to paper(s) that postulate a universe which starts with particles thinly spread out in multiple spatial dimensions, 10, 11, or perhaps even Hilbert space, none of the dimensions being degenerate. Then, taking advantage of the instability of orbits for spatial dimensions greater than 3, describes the collapse of matter within this hyper-space into either singularities, or into 3-D sub-manifolds with perhaps varying topologies, for each of which orbits become stable.

I haven't seen any model like this. String theory has models with more dimensions, but I'm not sure they can be described as having matter "collapse" the way you describe.
 
  • #3
You might want to look into "string gas cosmology" for an interesting, if speculative, proposal that initially all 9 spatial dimensions were bound up in string. These "winding modes" are able to easily annihilate only in the 3-dimensional subspace, allowing these dimensions to grow to cosmological size while keeping the remaining 6 dimensions compactified.
 

1. What is the origin of the three spatial dimensions?

The origin of the three spatial dimensions is a complex and ongoing area of research in the fields of physics and cosmology. While there is no definitive answer, current theories suggest that the three dimensions (length, width, and height) emerged during the Big Bang, the event that gave rise to the universe. However, the exact mechanisms and processes that led to the emergence of these dimensions are still being explored.

2. How do we know that there are only three spatial dimensions?

The concept of three spatial dimensions is based on our observations and experiments in the physical world. We can perceive and measure objects in three dimensions, and our understanding of physics and mathematics also supports the existence of three dimensions. Additionally, various experiments and observations, such as the behavior of particles in particle accelerators, have consistently shown evidence for only three dimensions.

3. Can there be more than three spatial dimensions?

While it is currently accepted that there are only three dimensions in our observable universe, some theories suggest the possibility of additional dimensions beyond the three that we can perceive. These theories, such as string theory, propose that there may be extra dimensions that are too small for us to detect. However, these theories are still highly speculative and have not been proven.

4. How do the three spatial dimensions interact with each other?

The three spatial dimensions are interconnected and affect each other in various ways. For example, an object's position in all three dimensions determines its location in space. Additionally, the laws of physics, such as gravity and electromagnetism, rely on the three dimensions to function. The exact nature of these interactions is still being studied and is a subject of ongoing research.

5. Could there be universes with different numbers of spatial dimensions?

Some theories, such as the multiverse theory, propose the existence of multiple universes with different physical laws and dimensions. While there is no concrete evidence for these theories, they are a subject of ongoing research and debate in the scientific community. However, as we can only observe our own universe, it is currently impossible to prove or disprove the existence of other universes with different numbers of spatial dimensions.

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