Actually, it's a rather short play (only 85 small pages in my Dutch translation) and I've read it in fall/winter 1963/64 when I was just 18 yo and still at school.
So I really had to find some recent info as I didn't remember much about it. I also skimmed through it just now, to refresh my memory even more.
Dűrrenmatt is a Swiss writer who wrote this play in 1961. It was staged in 1962 in Zűrich and published afterwards in the same year. It's widely considered one of his best stageworks if not THE best.
For more info (good synopsis) see here: http://en.wikipedia.org/wiki/The_Physicists
This work is very typifying for the world view of the writer as well as for the epoch in which it was written, i.e. in the heights of the Cold War situation. Much recommended for those who have a knack for absurdities with very hefty ethical undercurrents and for sudden twists and turns in a plot.
Related info here:
http://www.complete-review.com/reviews/suisse/durrmf.htm
http://www.coursesindrama.com/modules/smartsection/item.php?itemid=145
http://www.amazon.com/The-Physicists-Friedrich-Durrenmatt/dp/0802150888
In the same vein but unrelated: http://cassiopaea.org/forum/index.php/topic,27609.0.html
Hope this helps a bit.