Yesterday 04:14 PM
https://bigthink.com/starts-with-a-bang/...spacetime/
KEY POINTS: In all directions, in all locations, there seems only to be more Universe from our perspective, with the only edge to spacetime set by the limits of how far back in time we can see: all the way back to the Big Bang. But what we understand our Universe to be may not be all there is; our Big Bang could just be one location in space and time where cosmic inflation ended, giving rise to a bubble universe within a sea of inflating space. While we see no evidence for such an edge to the part of the Universe we can observe, it’s possible that someone born right up against such a bubble wall would indeed see an edge. Here’s what that would look like.
EXCERPT: Now, it’s true: we’re not close to one of those edges, and such an edge isn’t contained within our observable Universe. But we can imagine — if this picture is indeed correct — what someone would see if they did come into existence close to one of those edges.
The answer, as frustrating as it would be, is just that: an abrupt edge. We would see isotropy and homogeneity everywhere we looked, until we encountered that edge. And then, wherever that edge occurs in space, there would be absolutely nothing.
No stars. No galaxies. No normal matter. No dark matter. No neutrinos. Not even the leftover glow of the Big Bang, since all of the primordial radiation that originated in that direction would have already passed you by.
All that would be there, beyond the “edge” of the region where the hot Big Bang occurred, would be nothing. You’d simply observe an abrupt end that cuts across one hemisphere of the sky, ellipsoidally shaped from your perspective, with an angular size that corresponded to how close you were to that edge and how much time and expansion had elapsed since the hot Big Bang occurred in your region of space... (MORE - missing details)
KEY POINTS: In all directions, in all locations, there seems only to be more Universe from our perspective, with the only edge to spacetime set by the limits of how far back in time we can see: all the way back to the Big Bang. But what we understand our Universe to be may not be all there is; our Big Bang could just be one location in space and time where cosmic inflation ended, giving rise to a bubble universe within a sea of inflating space. While we see no evidence for such an edge to the part of the Universe we can observe, it’s possible that someone born right up against such a bubble wall would indeed see an edge. Here’s what that would look like.
EXCERPT: Now, it’s true: we’re not close to one of those edges, and such an edge isn’t contained within our observable Universe. But we can imagine — if this picture is indeed correct — what someone would see if they did come into existence close to one of those edges.
The answer, as frustrating as it would be, is just that: an abrupt edge. We would see isotropy and homogeneity everywhere we looked, until we encountered that edge. And then, wherever that edge occurs in space, there would be absolutely nothing.
No stars. No galaxies. No normal matter. No dark matter. No neutrinos. Not even the leftover glow of the Big Bang, since all of the primordial radiation that originated in that direction would have already passed you by.
All that would be there, beyond the “edge” of the region where the hot Big Bang occurred, would be nothing. You’d simply observe an abrupt end that cuts across one hemisphere of the sky, ellipsoidally shaped from your perspective, with an angular size that corresponded to how close you were to that edge and how much time and expansion had elapsed since the hot Big Bang occurred in your region of space... (MORE - missing details)