It’s hard for me to comprehend the idea that space never ends. Is there really no boundary to space? How do scientists know this?
In: Planetary Science
people are talking about a hard edge and how it wouldn’t make sense for there to be a hard stop to the universe, but i want to specifically address “how do scientists know this?”
if it makes no sense to assume a hard edge to the universe, there is still a way for there to be a finite universe. the 2D equivalent is a globe. there’s no hard edge on that globe, but there is still only a finite universe.
similarly, even if we don’t directly see a hard edge to our universe and also it doesn’t make sense to assume such, we can still have a “spherical” universe; it’s hard to visualize but what it essentially means is that if were in such a curved universe, and you are immortal and go on a spaceship away from earth in a straight line, you would eventually after many eons “loop around” and come back to earth.
so scientists spend a lot of time trying to measure the curvature of spacetime in much the same way some clever ants could figure out that they’re on a globe and not a flat sheet of paper if they did some very sophisticated measurements; yeah it’s very very hard to visualize, we’re talking about 4d spacetime bending. scientists have been able to measure the curvature of spacetime with increasing levels of accuracy through some pretty clever experiments and analysis. So far, our estimates on the curvature of spacetime is extremely consistent with the most likely explanation of spacetime being flat, which would imply an infinite universe. While scientists have not computed an exact curvature (and probably never will be able to), if there is a positive curvature to spacetime, the “spherical”-ness of spacetime would have to be very very incredibly vast, even when talking on a cosmic scale
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