The Higgs Boson - the particle which gives other particles mass - was discovered at Cern last week… wasn't it?
Well, at least one group of scientists isn't so sure.
Certainly the discovery at Cern's Large Hadron Collider was reported around the world as a massive breakthrough.
Both the Atlas and CMS experiments said that it was 99.9999% (five sigma) certain their results showed a particle like the Higgs.
But the Cern scientists were also careful to say that the particle was only "consistent with the long-sough Higgs boson", and that it could in fact be something else.
Now a group of scientists at the Argonne National Laboratory in the US say the data is also consistent with at least two other particles which are not the Higgs boson.
Researcher Ian Low said that the 'signature' particles produced by the Higgs are not unique, and that Cern has not collected enough data to be sure about what they've found.
Low said in a 20-page paper, published this week, that while one possibility is that the particle is the Higgs, another - equally likely - result is several different particles each of which has elements of the Higgs.
The results could even show as "mixture" of the Higgs and another particle.
"This is only the beginning of a challenging program of “Higgs Identiﬁcation," the report said.
For their part, the Cern researchers have always said that more research is needed, and that the data presented was not the final answer.
So that's good news for Stephen Hawking, then - he may get his $100 back after all.