# is the Universe infinite or not based on today’s science.

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It has been explained to me that “Space” is finite essentially because we can measure things, distance, size, speed of light, ect. Therefore, if “Space” is finite then everything else is finite.

I understand that if you have an infinite number of stars in a finite space then there would be light everywhere for example. I don’t understand why the same would be true if the universe were also infinite. Would that not sort of cancel out the infinite nature of any one object as it would have infinite space to be in.

In: 1 > It has been explained to me that “Space” is finite essentially because we can measure things, distance, size, speed of light, ect.

This sentence isn’t really clear enough to tell you whether you’re wrong or not, but it’s *so* unclear that I suspect you don’t have a clear idea of what you’re trying to say.

> I understand that if you have an infinite number of stars in a finite space then there would be light everywhere for example.

Yes, if the Universe is infinite (which is likely but not certain) then the number of stars in it probably is as well, and vice-versa. There’s a large, but finite number of stars that we can see. The problem is that we can’t see past a certain distance, it’s literally a horizon called the “[observable universe](https://en.wikipedia.org/wiki/Observable_universe)” and we can’t see past it.

Otherwise, the laws of physics don’t indicate or even hint at some sort of “edge” or “end” of the universe, and what we can see is “the same” in all directions, so logically the universe should be infinite.

Or it could be finite, if there’s only a certain amount of matter that makes it up.

> Would that not sort of cancel out the infinite nature of any one object as it would have infinite space to be in.

Trouble with infinities is, [some are bigger, some are smaller](https://en.wikipedia.org/wiki/Aleph_number), they basically have cardinalities and you can’t fit the bigger ones into the smaller ones. They don’t always “cancel each other out” as in a 1:1 match. The book was exploring our current understanding of the univers shape and size and what could / could not be possible.

To briefly summarize, first we don’t know whether or not the univers is finite or infinite.

If the univers were to be finite, it should have a 4 spacial dimensional shape so that one could more forward and come back to its original position (ignoring any speed limit) like you would on the earth. The surface of the earth had no limit, you can move forward indefinitely but the surface is finite.
This reasoning should hold true for a 4D universe whose surface is in 3D (our universe).

The book talks a lot about the different 4D shapes and what it would implies but that’s beyond the point.

Now what is important, if the universe is indeed finite, it has to be of at least a certain size otherwise, beside a few case explained in the book, we would have noticed. The idea would be that if the universe would only hold 100 galaxies (soma very “small” one) when looking further we would just see the same object whose light just did a turn of the universe. It would be basically looking at your own back.
We know the universe has to be at least of a certain size for us to not notice it (i forgot the values, but it was quite decent of a distance)
Above that value more research is required.

There could be a case of the universe being finite but bigger than the visible universe. In that case we wouldn’t know and it would be impossible to differentiate it from a infinite universe

So the current take on the matter (from what I know ) is that we don’t know and unless some break through new technologies or science, we will probably never know unless the univers is small enough for us to notice it.
If the universe is infinite or finite but so big that it is akin to infinity (like bigger than the visible universe) there is no known way to know it beside the curvature of space but it has the same issue, I’d we find a positive/negative/no curvature, is it local? Is it global? Etc etc

A finite universe does sound more logical
Like, it would make sense that the universe contains a fixed amount of things, but at the same time one could argue that “it doesn’t have to” and in the end… The core of the issue hold, how can you know the size of something bigger than the distance you can see? I believe the universe is finite. I believe if you picked a “direction” and kept following that direction forever then eventually you would end up where you started.

As far as science goes, I don’t believe we have any experiment that proves or disproves the infinite. The answer is, we just don’t know. When we look out in space, we are also looking back in time. This limits our ability to see if there is more than what we can see, as we can only see back 13.7 billion years. That’s how long light has had to reach us. Anything farther away than 13.7 billion years, we can’t see because it’s light has not had time to reach us. We can make assumptions and predictions, but no one knows the answer. Space is still expanding faster than light so yes, it is infinite. The strange part of it is is you were to try and get to a planet that is 100 light years away, because of the expansion, if you travel at the speed of light, you would never reach it. You would actually have to travel at light speed plus the additional speed the space between here and there is expanding at.