(February 23, 2018 at 9:15 pm)vulcanlogician Wrote:(February 23, 2018 at 9:08 pm)polymath257 Wrote: Once again, you have an image of some boundary expanding outwards. That is NOT what the BB model says. There is no 'beyond the universe' spatially. Instead, wherever you are, the basic 'look and feel' is the same: galaxies in all directions.
The universe isn't 'expanding into' some space beyond the universe (even in models where space is finite). Instead, the distances between galaxies *within* the universe are getting larger over time.
In a technical sense, the universe is literally expanding into the future, not into more space.
I think I get what you mean. The universe expands, but not into something. But I'm curious, according to the big bang model (and assuming the universe is finite), is there a place "on the edge" of the universe where one could stand and see the universe in front of him, but if he turns 180 degrees he will see nothing but an abyss? Or does that question even have an answer?
The answer to that is NO. yes, the question makes sense. NO, there is no such place.
In this case, a finite universe would have the property that no matter which direction you decide to go (up, down, left, right, forward, backward, etc), if you keep on going, you will eventually circle back to your initial position. Think of the surface of the Earth on this. No matter which direction you go, if you keep going that direction, you will eventually go all the way around the Earth. In a universe with a finite amount of space, the same thing happens only in all 3 dimensional directions.
There is no boundary in the BB model.
