Here are just a few of Hawking's theories, some disproved, others still potentially correct (given its divergence from experimental physics, many elements of theoretical physics remain purely… theoretical).
The second law of black hole dynamics
Hawking suggested that the event horizon (the point where nothing can escape the pull of a black hole) can never shrink. It was Hawking himself who was irritated to discover this was untrue, when he theorised the existence of the next point…
Hawking suggested that empty space was, in fact, full of matter and anti-matter particles constantly popping into existence and promptly cancelling each other out. However, he thought that these pairs could be split up by the pull of a black hole. When a black hole sucks in the antimatter, it shrinks (disproving the second law of black hole dynamics), and the now-isolated matter particle is released as ‘Hawking’ radiation.
Not so much a theory as a scientific wager with fellow cosmologist Kip Thorne, Hawking bet that the galactic X-ray source Cygnus X-1 wasn’t a black hole. Hawking lost, but as he rationalised it, it was a security policy; if black holes had turned out to not exist, most of his research would’ve been incorrect, but at least he would’ve won the bet.
The Higgs Boson
Hawking was a longstanding and fervent sceptic when it came to the formerly hypothetical Higgs boson, the existence of which would prove the ‘Standard Model’ of physics to be correct. In 2012, when CERN declared the existence of the Higgs boson to be all but proven, Hawking conceded defeat and lost his US$100 bet with theoretical physicist Gordon Kane that the Higgs particle would never be found. He went on to recommend that Peter Higgs (originator of the theory) be awarded a Nobel Prize.
Black hole information loss
After Cygnus X-1, Thorne and Hawking joined forces and wagered against John Preskill that information that fell into a black hole would be irretrievably lost. Most physicists disagreed with this since it meant that all of quantum mechanics was wrong. Hawking went on to concede.
In 1992, Hawking conjectured that time travel was impossible, so in 2009, he hosted a party, replete with hors d’oeuvres and champagne. However, he didn’t tell anyone about the party until afterwards, inviting time travellers to (have) attend(ed). Seeing as no-one had turned up, Hawking took it as a tentative victory.
Read article: Stephen Hawkin's Legacy