Does space really go on forever and ever? Or have we just not discovered where it stops?

Question: Does space really go on forever and ever? Or have we just not discovered where it stops?
- Keywords:
  space
Asked by Timmy to Sha, Olivia, Marco, Amanda, Alex on 13 Mar 2017.
- Alex Evans answered on 13 Mar 2017:
  
  The answer is, we’re not really sure!
  
  We know a bit about the “observable universe”, which is as far as we can be sure the universe goes – but there could be lots more universe out beyond that!
  
  We think the diameter of the observable universe is about 91 billion light-years across, which is about 535,000,000,000,000,000,000,000 miles! :O

Question: Does space really go on forever and ever? Or have we just not discovered where it stops?