How do we know that space has no end if we can not travel infinite distances? Thank you

Question: How do we know that space has no end if we can not travel infinite distances? Thank you
- Keywords:
  space
Asked by anon-181145 to Claudia on 4 Jun 2018.
- Claudia Bonfio answered on 4 Jun 2018:
  
  That’s a really great question… and I don’t have an answer… yet!
  Whether the Universe is finite or infinite is a really important question. So far, astronomers have no idea what the answer is, but they’re working towards it and maybe someday they’ll be able to tell us.
  At least, I hope so!

Question: How do we know that space has no end if we can not travel infinite distances? Thank you