The gory details are apparently in these two papers. I'm not a physicist so they're pretty opaque to me.

http://arxiv.org/abs/1003.5914

http://arxiv.org/abs/1102.3434

If so then Flatland was a story not so much of mathematics, but of evolution.

This hypothesis makes me wonder about the following:

1. What sort of threshold would cause the universe to develop another dimension? Could this have something to do with the concept of emergence, and discrete levels of organization? Perhaps when a given dimension (or set of dimensions) contain enough 'complexity' to start exhibiting emergent behavior, information about that emergent layer can effectively be encoded in a 'new' dimension.

2. When such a threshold is crossed the amount of information required to describe the universe jumps dramatically. Isn't this inconsistent with what we believe to be true of the level of the velocity of entropy in complex systems?

If I recall correctly, the dimensions of the early universe in these kinds of models depends on counting the degrees of freedom of the universe. At high energies, everything becomes an internal degree of freedom, hence the universe behaves two dimensional (space + time). At lower energies, more dof shift from internal to external and the universes behaves multidimensional.

It's a similar pov to 11D supergravity for example. Since 7dimensions are so small, the look like internal dof. The huge added advantage is that gravity simplifies below 4 dimensions and the incompatibilities between GR and quantummechanics disappear.

I'll try to use this bad analogy. Suppose you see a high speed train passing (high E), the people in train would seem to move at high speed aswell from left to right. If a slow train passes, you'll see they'll also move from the far side of the aisle to your side and perhaps from the upper level to the lower level. So you 1D high E train becomes 3D low E.

Can you rephrase #1 without using the words "emergence", "emergent", or "complexity"? I'm having a hard time following what you're talking about.

Complexity - The Emerging Science at the Edge of Order and Chaos by M. Mitchell Waldrop

Amazon reviews don't give me good feelings about that book. Got any others?

I haven't, sorry. I'm almost through Complexity and I can only say it works for me. It's non technical but I agree with the statement In general, he makes the emerging nature of complexity theory accessible to the general reader from the Editorial Reviews. It has given me a good overview and a conceptual framework for digging deeper.

If it could have been one dimensional, could it have been zero dimensional?

That's exactly what we think the case was before the Big Bang, I think, since points are zero-dimensional.

It's truly weird to imagine the Universe exploding from a point into a line, then into a planar region, and then into a three-dimensional domain.

All while not exploding and expanding out into anything else.

Or does it? How can you find evidence for a fourth spacial dimension? We could be living on a "bubble" of three-dimensional space as a fourth is filling in undetectable from us.

Is it possible to conceive of something of anything less than one dimension? If so, how? I'm thinking about the way that Carl Sagan used the tesseract to represent four dimensions.

I just imagine a pinprick of light emanating from a point. The place where light is only exiting, not entering, is a point with no dimensions.

You could have half a dimension, where things can only go one way. Like time.

But then it would have contained no information right?

If it was pure energy and of no mass for a moment, I could imagine that there would be no gravity and therefore a possible lack of dimension?

Then hydrogen atoms form and you've got mass and then gravity.

"Gravitational waves can't exist in one- or two-dimensional space. So Stojkovic and Mureika have reasoned that the Laser Interferometer Space Antenna (LISA), a planned international gravitational observatory, should not detect any gravitational waves emanating from the lower-dimensional epochs of the early universe."

So if it doesn't their theory is proven correct?

Only if there are no alternative explanations for the data. If this turned out to be the only viable explanation, then this theory will stand, at least pending more data that might strengthen it or show it to be in error.