# Origin of Dimensions: Evidence of Order or Big Bang Simultaneity?

• DiracPool
In summary, the Hartle-Hawking state suggests that spatial dimensions preceded time in the very early universe. It is motivated by the Wheeler-Dewitt equation and has a Hamiltonian Constraint equal to zero. All we know is that the whole thing got kicked at 10^-43 seconds, the so-called, "Planck time."
DiracPool
I've been reviewing the timeline of the big bang...

http://en.wikipedia.org/wiki/Chronology_of_the_universe
http://en.wikipedia.org/wiki/Graphical_timeline_of_the_Big_Bang

...and wasn't able to find an answer to a question I have.

That question is, is there any evidence that the spatial and time dimensions unfolded in any certain order, or, as the saying goes, "did all 4 dimensions just spring forth simultaneously and fully formed from the head of Zeus?"

For example, I typically think of "time" as the 4th dimension, which implies a sense of seriation. I think of it as coming last. I think of the first dimension as coming first, the second second, the third third, and the fourth time. I think of these dimensions as "evolving" out of one another. Maybe I think that way because that is really how we learn these things. We typically model systems when we learn them in one dimension, using ODE's, and then only invoke the Laplacian, reluctantly, when we need to or want to step up our game, so to speak.

But the origin of the universe? I was looking into the Hartle-Hawking state: http://en.wikipedia.org/wiki/Hartle–Hawking_state

The Hartle–Hawking state is the wave function of the Universe–a notion meant to figure out how the Universe started–that is calculated from Feynman's path integral.

More precisely, it is a hypothetical vector in the Hilbert space of a theory of quantum gravity that describes this wave function.

It is a functional of the metric tensor defined at a (D − 1)-dimensional compact surface, the Universe, where D is the spacetime dimension. The precise form of the Hartle–Hawking state is the path integral over all D-dimensional geometries that have the required induced metric on their boundary. According to the theory time diverged from three state dimension – as we know the time now – after the universe was at the age of the Planck time.

What does that mean? "Time diverged from the three state dimension?" From what I understand, all we know is that the whole thing got kicked at 10^-43 seconds, the so-called, "Planck time." So it seems to me that the "Time" dimension had to have come first, OR, all 4 dimensions must have come into existence simultaneously. Does anyone have some insight on this?

The Hartle-Hawking state suggests spatial dimensions preceded time in the very early universe. In that sense, the universe had no 'beginning'. Under Hartle-Hawking, all three spatial dimensions emerged simultaneously followed by the emergence of time. It is motivated by, and believed to be a solution to the Wheeler-Dewitt equation.

Chronos said:
The Hartle-Hawking state suggests spatial dimensions preceded time in the very early universe. In that sense, the universe had no 'beginning'. Under Hartle-Hawking, all three spatial dimensions emerged simultaneously followed by the emergence of time. It is motivated by, and believed to be a solution to the Wheeler-Dewitt equation.

This is all I know of the Wheeler-Dewitt equation...

H(x)|psi> = 0
"The functional over all possible universe phase states, given as a wave function, has a Hamiltonian Constraint equal to zero."

That doesn't seem to give any indication of why a time dimension suddenly appeared or evolved. What caused that?

And what about the spatial dimensions pre-time? Were there just 3 dimensions sitting there? For how long? (I guess that question isn't relevant) And why 3 dimensions? Doesn't it make sense that we had to start with one? Then two, then three?

## 1. What is the origin of dimensions?

The origin of dimensions is a complex and ongoing question in the field of physics. One theory is that dimensions emerged at the same time as the Big Bang, while others suggest that they existed before the Big Bang or are a product of quantum fluctuations.

## 2. Is there evidence of order in the origin of dimensions?

There is evidence of order in the origin of dimensions, as the laws of physics that govern our universe seem to be finely tuned to allow for the existence of dimensions. However, the exact mechanism for this order is still a subject of debate and research.

## 3. What is the role of the Big Bang in the origin of dimensions?

The Big Bang theory is currently the most widely accepted explanation for the origin of our universe, and by extension, the origin of dimensions. It suggests that all matter and energy in the universe were compressed into a singularity before rapidly expanding and creating the dimensions we know today.

## 4. Can the concept of simultaneity be applied to the origin of dimensions?

The concept of simultaneity, or events occurring at the same time, is difficult to apply to the origin of dimensions. This is because our understanding of time and space breaks down at the very beginning of the universe, making it challenging to determine what happened simultaneously.

## 5. How do scientists study the origin of dimensions?

Scientists study the origin of dimensions through various methods, including theoretical models, mathematical equations, and experiments. They also use data from observations and measurements of the universe to refine and test their theories about the origin of dimensions.

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