> He entered Oxford University at 17 without A-levels and left around a year later without graduating. He was bored and he had been invited to cross the pond by the prestigious California Institute of Technology (Caltech) to do a PhD. "I had written a bunch of papers and so was pretty well known by that time," he explains.
Is it still possible today? Yes. Alessio Figalli is another example, from 2006-2007, and Glen Weyl in 2007-2008.
It's very rare.
Interestingly this article says that "he was never able to do arithmetic". https://www.nytimes.com/1981/05/24/us/physicist-awarded-geni...
Bear in mind this part:
"Now, are mathematicians actually that bad at arithmetic? Compared to engineers and accountants, perhaps. Compared to the average person on the street, of course not. The “bad at arithmetic” thing is probably overplayed."
This article says that he graduated from Oxford but the gaurdian article says he left oxford without graduating?.