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How do you know for sure that space never ends?
Question Date: 2013-02-14
Answer 1:

We don't know for sure that space never ends. It seems most likely that either space goes on forever or that it wraps back around on itself like a circle. Everything we know about the universe tells us that space is pretty flat, but that just means that if space is like a circle it must be a really huge circle, so huge that the part of it we can see is just a tiny piece.

You might also wonder if space could just end with some sort of wall. Well, Einstein's theory of relativity tells us that it's impossible for anything to travel faster than the speed of light and recent observations tell us that the universe is expanding so there are parts of the universe we can never see. The region of the universe we can see is called the "observable universe" and the boundary of this region is called our "cosmological horizon." So in a way the cosmological horizon is like the edge of the (observable) universe.

Answer 2:

Actually we do not know. But looking as far as we can into space, there is no apparent limit to the shape of space.

Answer 3:

That is a fantastic question! I’m not sure that the smartest person on Earth can answer this difficult question, but I will try to answer based on how I understand it. Most scientists think that our universe is infinite– that space goes on forever and never ends. The problem is that our universe has a finite age (the big bang probably happened 13.7 billion years age). This means that there is space that is too far away to observe or measure. We can measure light that reaches Earth today that has traveled for 13.7 billion years. This light came from 13.7 billion light years away in our universe. There is probably light that comes from further in the universe, for example from 100 billion light years away, but it would take 100 billion years to reach us, so it hasn’t arrived yet. For this reason, we can’t measure how big our universe actually is.

Some people think that space is actually shaped like a ball or a sphere. This means that space would have to be infinite or never ending. If you walk all the way around a sphere, you get back to where you started. This means that you could walk around and around space without it ever ending. The NASA website has some good information on this topic


I know that this probably sounds really confusing– that is because it is very complicated! I have gone to school for over 20 years and I don’t know the answer! Great scientists are great because they ask themselves tough questions like the one you asked!

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