Researchers working at the Large Hadron Collider have said they expect to discover the Higgs boson particle by the end of 2012.
If the LHC does not turn up evidence of the Higgs during this run, physicists say they may have to significantly alter their views of physical laws.
The Higgs boson particle explains why other particles have mass, but it has not yet been observed by physicists.
The LHC is housed in a 27km-long tunnel under the French-Swiss border.
It smashes together proton particles travelling at close to the speed of light in a bid to uncover secrets of the Universe.
According to Professor Tom LeCompte of the Argonne National Laboratory, US, who works at the LHC: "The most likely place for the Higgs to be is in a very good place for us to discover it in the next two years."
The LHC has now restarted after its winter shut down - and is about to embark on a run of work that could make or break the current view of how the Universe was formed.
The most widely accepted theory of particle physics requires the existence of the Higgs - and the detection of this particle is one of the LHC's main objectives.
If the collider does not detect the Higgs within two years, researchers say they will know that it does not exist - at least in the form required by the Standard Model, the framework which was devised to explain the behaviour of fundamental particles.
"The Higgs is one model of many," according to Professor LeCompte.
"It's a model that we like. It's simple, its elegant, but it's entirely possible that there is something else beyond the Higgs that does its job instead, and what we may discover is instead of the Higgs itself we may discover something much more interesting.
"There could be multiple Higgses or there could be something completely different doing the same job as the Higgs in a completely different way."
But he adds that not finding the Higgs may be more exciting than finding it - because researchers may have to modify their current view of sub-atomic physics.
"If we don't see it after this two-year run it means that something is perhaps not the way that we think it is, either the Higgs search itself had to be amended in some way or some of its indirect evidence may be pointing us in the wrong direction," said Professor LeCompte.