Not able to understand a word in Zhang's paper, but i found this quite good
for layman like me.
********************
Zhang proved that a set of 3.5 million numbers with a certain mathematical
property produces an infinite number of similar sets and that these contain
at least two primes. He then showed for a particular series of sets that
these primes are at most 70 million apart. But with a fairly quick
calculation it is possible to choose other sets with a smaller gap.
********************* http://www.newscientist.com/article/dn23644#.Ud1BRPmqDQk
