I'm not knowledgeable in maths, but this interested me. It's the largest number that was ever used in a serious scientific proof. "Indeed, it is not possible, given the limitations of our universe, to denote Graham's number, or any reasonable approximation of it, in a conventional system of numeration." So, does this mean that it is so large that it can't even be compared to other numbers? I can't find any comparison to anything on it's wiki page. We don't even know how large it is? I'm confused about how it can even be defined at all. A Googolplex may be unwritable, but can at least be said to be 10 to the power of a Googol. It still has meaning. I get the impression that this is as indefinable as infinity though. Is that correct? "Even the mere number of towers in this formula for g1 is far greater than the number of Planck volumes into which one can imagine subdividing the observable universe." How was it even used to prove anything in that case?