10.1-10.-2

I thought it was crazy the history lesson at the start of this chapter and it said Galileo was in jain the last nine years of his life! So many people didn't get the credit they deserved until after they had died.  numerically equivalent is pretty strait forward and I don't think I'll have  a problem with that, I do however have don't understand how a set can be countably infinite, you can't count to infinity. and denumerable is confusing too, I hope it is a little more clear after lecture tomorrow!