From the event website:

Dan Goldston

Sums and Differences of Pairs of Primes

"Is every even number greater than 2 the sum of two prime numbers? Is 2 the difference of two prime numbers for infinitely many primes? These are two famous unsolved problems that concern sums or differences of pairs of prime numbers. We will look at a number of such problems, some of which are solved, some of which we think we know the answer but cannot prove it, and some which we don't know the answer for and can't compute or prove anything."

For more information, see the event poster.