This is true if the observer begins and ends his/her trip inside our universe. Beyond being philosophical, what would an observer outside our universe observe about our universe? -- assuming some sense can be made of such a question.DaveC426913 said:By extension it applies to the 3-dimensional universe. The universe can be wrapped around upon itself so that, if you travel in one direction long enough, you will (in theory) arrive back at your destination.
It is philosophical. There need be no outside. Any speculation about an outside is just that.Hugh de Launay said:This is true if the observer begins and ends his/her trip inside our universe. Beyond being philosophical, what would an observer outside our universe observe about our universe? -- assuming some sense can be made of such a question.
I disagree that it is philosophical. I think it is nonsensical. "Universe" is, by definition, all there is. It is one thing to say that there might be a part of the universe that has different characteristics than the rest (and there is not at present any inkling that there is such a place) but even if there were, it would STILL be part of the universe, not "outside" it.jbriggs444 said:It is philosophical. There need be no outside. Any speculation about an outside is just that.
Since no edge is required and no evidence for an edge is found, no edge is assumed. Instead, we use Occam's razor and take the simple background assumption that, on the largest scales, the universe is the same everywhere. https://en.wikipedia.org/wiki/Cosmological_principle. A universe with an edge would violate this principle. A universe that is finite but which wraps around on itself would not.Hugh de Launay said:Is such an abstraction applied to the "edge" (if any) of our universe?