Today’s about the date that I’d pick for the 30th anniversary of the First Superstring Revolution. Witten’s paper Some Properties of O(32) Superstrings arrived at the journal Physics Letters on September 28,1984, so presumably was finished and sent out around September 25.
The effect of this paper on the field was a bombshell. Witten was at the time far and away the most influential person in the field, regularly producing staggeringly original work that was having a huge impact. The arrival that fall of a preprint from him announcing that he had stopped work on everything else, and now had what looked like a viable, consistent unified theory of everything, one that he claimed was determined by a single parameter and made predictions (“It predicts axions and stable Nielsen-Olesen vortex lines”) was the true First Superstring Revolution.
I wrote about this in some detail ten years ago, for the 20th anniversary, so won’t repeat what is here and here, supplemented by comments from Larry Yaffe. For something more recent along the same lines, see here.
Ten years ago the 20th anniversary of the First Superstring Revolution was celebrated with a symposium at Aspen, but as far as I know, no one has organized a 30th anniversary celebration. There are now many, many known ways of trying to get unification out of strings, with the original 1984 hope that anomaly cancellation gave a more or less unique possibility long gone. As for unification itself, thirty years later Witten remains a true believer in the vision that came to him in September 1984 (see here and here), although he now seems to see little hope for vindication during his lifetime.