The Penrose-Hawking singularity theorems go back 55 years to work starting in 1965. No joke. This has be to near a record in time lag between the work the Nobel committee recognized and when that work was first published. Better late than never I guess (but too late for Hawking, as has been mentioned elsewhere..) EDIT - a detailed analysis: https://physicstoday.scitation.org/do/10.1063/PT.5.2012/full...

I've always thought Nobel prizes are awarded based on the winners' works in that particular year so this came as huge surprise.

Too late for Hawking indeed, he could've very well been one of the winners today.

There's a huge backlog of people who deserve Nobel prizes. The committee is also conservative, and doesn't want to give out a prize for something that turns out to be wrong. Both factors mean that it takes years from discovery to the awarding of a Nobel prize.

It's one thing to allow enough time to pass before a given theory/experiment can be considered as "accepted" by science, and therefore eligible to the award.

However, the Nobel committee's rules can be considered archaic to a fault: 3 winners at most, all winners must be living at the time of the award.

If you want an egregious example of exclusion, look at the 2013 Nobel prize for the discovery of the Higgs boson. The prize was given to Higgs and Englert [0], but by any measure it should have been awarded to the five living scientists who made the discovery [1].

Was there really any reason to exclude Guralnik, Hagen and Kibble, who were all alive at the time of the award, other than a strict adherence to the "rule of three"?

[0]: https://web.archive.org/web/20131008193310/http://www.nobelp...

[1]: https://en.wikipedia.org/wiki/1964_PRL_symmetry_breaking_pap...

Even increasing it to 5 people wouldn't solve the problem. The Nobel prize could be awarded at the institution level rather than invidually but I'm sure there'll be objections to that as well.

The opposite, really. Nobel prizes are given out for major works which are now well-accepted. This can take decades, so typically the Nobel is given to now-old scientists as recognition for work done when they were young.