The Largest Known Prime by Year: A Brief History
primes.utm.edu
primes.utm.edu
Is there any use beyond crunching giant numbers for theoretical physics and knowing a certain number can't be divided - or is this just the math geek equivalent of knowing the Baltimore Orioles had four 20-game winners in 1971?
See http://primes.utm.edu/notes/faq/why.html, but it boils down to "something really interesting can be found along the way, primes relate to other important topics so learning about them has intrinsic value, there's some money in it (but you have a 99.9% chance of spending more than the prizes in your search... and you still won't win)".
> ...this record, which stood for 75 years, MAY stand
> forever as the largest prime found by hand calculations.
I shudder to imagine the holocaust which would have to happen before this record could be broken. Though I suppose we may find an alien species who might have found a larger prime "by hand."https://en.wikipedia.org/wiki/Double_Mersenne_number might be one place to start.
[1] http://en.wikipedia.org/wiki/Scheme_(mathematics)#Modern_def...
This page claims to have been last updated 21 April 2012, http://primes.utm.edu/largest.html
I'm not sure why we haven't found any more lately though, but the information seems to be correct.
The wikipedia page is interesting. We have discovered new large primes since 2008, they just haven't been bigger.