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The 'big bang' is both a point in time, and in space. The boundaries of the universe are the light cone of the big bang. It is conceivable that our 'universe'

by _yb2s 4y ago

The 'big bang' is both a point in time, and in space. The boundaries of the universe are the light cone of the big bang. It is conceivable that our 'universe' is just one regional phenomena within a much larger universe. Multiple such 'universes' in the same physical space could seem to be isolated until they expand to the point of overlap and begin to collide. This image from Max Tegmark illustrates this idea well: https://space.mit.edu/home/tegmark/multiverse.jpg https://space.mit.edu/home/tegmark/multiverse.jpg As shown in that figure, a level 1 multiverse is simply whatever other areas exist beyond our universes light cone. There could very well be 'stuff' out there that we are expanding into!

Nevermark 4y ago
> The boundaries of the universe are the light cone of the big bang. That "boundary" is not a spacial boundary, but simply the farthest distance we can "see". The universe is expanding fast enough that any given space-time point can only "see" a finite region of the greater universe. But it is all connected. We can see objects far away, whose citizens (if they exist) can see beyond our visible boundary, and so on. And our area is not expanding "into" other areas. Think of the expansion as equally inflating every area, including our own. Pushing distant areas to be more distant. All in a smooth way across the region of the universe we can see and beyond.
pan69 4y ago
Interesting. Would that larger universe also be expanding and of so, what would it be expanding into? Maybe the larger universe exists in a larger-larger universe? Maybe the universes that are expanding inside a larger universe would not overlap but repell when they encounter each other, i.e. push each other out of the way instead changing the shape of a universe.
vernon99 4y ago
The article says it’s NOT a point in space btw and that it happened everywhere simultaneously. This is an interesting idea I wasn’t aware if and trying to wrap my head around it now :)

by _yb2s 4y ago

Nevermark 4y ago

> The boundaries of the universe are the light cone of the big bang. That "boundary" is not a spacial boundary, but simply the farthest distance we can "see". The universe is expanding fast enough that any given space-time point can only "see" a finite region of the greater universe. But it is all connected. We can see objects far away, whose citizens (if they exist) can see beyond our visible boundary, and so on. And our area is not expanding "into" other areas. Think of the expansion as equally inflating every area, including our own. Pushing distant areas to be more distant. All in a smooth way across the region of the universe we can see and beyond.

pan69 4y ago

Interesting. Would that larger universe also be expanding and of so, what would it be expanding into? Maybe the larger universe exists in a larger-larger universe? Maybe the universes that are expanding inside a larger universe would not overlap but repell when they encounter each other, i.e. push each other out of the way instead changing the shape of a universe.

vernon99 4y ago

The article says it’s NOT a point in space btw and that it happened everywhere simultaneously. This is an interesting idea I wasn’t aware if and trying to wrap my head around it now :)