Ok, I have a question regarding 'nothing'. I watched Lawrence Krauss' lecture on youtube where he talks about a universe from nothing. He explains 'nothing' as empty space, and then says this empty space actually weighs something. He argues that the universe did have a begining (I assume the big bang). He also says that the universe is expanding (both claims are consistent with other scientists in this field). My questions are as follows.
1 Was there empty space around before the big bang, or did the universe start from a different type of nothing?
2 what is the universe expanding in to? is it expanding into empty space, or is it expanding into a different type of nothing which is presumably infinite nothingness.
Any answer given, I would appreciate it very much if they could be given in laymans terms please. You can see my knowledge on this subject is pretty poor, but I am genuinely interested whether the answer to the question is something that I can understand or not