Re: What are the odds we'll find a collision by the time the last bitcoin gets mined?
Not that I don't have faith in either of your calculations but can someone else help settle this?
No, he is right. As I wrote above, I have made a terrible mistake and I'll return my diploma the first chance I get. 
That's a hell of difference in math.
Not that I don't have faith in either of your calculations but can someone else help settle this?
It's just common sense, really. A Bitcoin address is just a 160-bit number. If you want to randomly generate an address and have it exactly match some other address, you need every bit to match. Every bit is like a coin toss, so it's like 160 tosses. The probability for that is 0.5^160 = 6.84E-49. I didn't examine the calculations for the larger 9.7E-29 figure (equal to 93 tosses) but it's probably the chance to succeed in one of a large number of attempts.Not that I don't have faith in either of your calculations but can someone else help settle this?