What is the shape of the universe?

CrazyNeutrino said:

What is the shape of the universe?

See answer to question 1.

Indeed.

Since we have no ‘outside’ view of the universe that classical notion of shape doesn’t make a lot of sense.

Instead what we can (approximately) measure are intrinsic propeties like curvature and topology. S’far’s we can tell the Universe is flat and simply connected.

> What is the shape of the universe?

Let me answer this in several parts: 1) shape as in curvature, 2) shape as in spin and spin-induced deformations, 3) shape as in topology, 4) shape as in metastability of the false vacuum

First let me say that the visible part of the universe is spherical, everything else in this post relates to the whole universe, not just the visible part.

to be continued.

> What is the shape of the universe?

Let me answer this in several parts: 1) shape as in curvature, 2) shape as in spin and spin-induced deformations, 3) shape as in topology, 4) shape as in metastability of the false vacuum

First let me say that the visible part of the universe is spherical, everything else in this post relates to the whole universe, not just the visible part.

The latest results from the Planck telescope tell us that curvature of the universe is indistinguishable from zero. If the curvature of the universe is actually zero then the shape is indistinguishable from that of an infinite region of 3-D space. If the curvature were to be positive then the universe would fold back on itself in a hypersphere. If the curvature were to be negative then the universe would be hyperbolic in shape.

The latest results tell us that the spin of the universe is indistinguishable from zero. If the spin is actually zero then the universe is isotropic – exactly the same in every direction. If the universe has spin then it would have a preferred direction, parallel to the spin axis.

Results from WMAP, confirmed (I think) by Planck, are that the universe that we see has no strange topology – no cosmic strings, no loop-backs with or without twist. Again, this means that the shape is indistinguishable from that of an infinite region of 3-D space.

The metastability of the false vacuum, as shown by the recent Higgs particle mass, strongly suggests that somewhere out there, beyond the reach of light, the universe has gone unstable, with a wave of instability passing through it like a bubble expanding at the speed of light. If this is correct, then the shape of the universe more closely resembles a Swiss cheese, containing bubbles within which different universes are found.

Good enough?

mollwollfumble said:

The metastability of the false vacuum, as shown by the recent Higgs particle mass, strongly suggests that somewhere out there, beyond the reach of light, the universe has gone unstable, with a wave of instability passing through it like a bubble expanding at the speed of light. If this is correct, then the shape of the universe more closely resembles a Swiss cheese, containing bubbles within which different universes are found.

Good enough?

Wasn’t the analysis that this sort of instability was a possibility rather than being a current reality? Is the instability the cause of the hypothesised bubble universes?