Before we get into whether the Universe is curved and in what way it might be curved, let's figure out what number the OP is talking about:
I know a googol is more than 10 billion. I meant that the article I read stated you could fill the universe with 10 billion less than a googol particles of sand. Sorry if that was unclear.
Oh, I wondered if that dash meant subtraction, but that interpretation still doesn't look right. A
googol is 1 followed by 100 zeros, or this 101 digit number:
10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000.
Ten billion (
at least in the USA) is this 11-digit number:
10000000000.
The difference is this 100 digit number:
9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999990000000000.
This is mathematically different from a googol, but it's so much the same as a googol (it's the same to 1 part in 10^90) that there's no way the difference could be measured.
Perhaps the article meant something like one ten-billionth of a googol. I recall a figure from decades ago (perhaps a George Gamow book) that the known universe has something like 10^88 particles (grains of sand? atoms? subatomic particles? I forget) in it. That would be roughly the same size number (off by only a couple of orders of magnitude).
Or maybe it was that it would take "only" 10^88 particles (again, I don't recall of what particle) to fill the known universe. It's obviously been a while since I read it.