Scientists are expected to announce tomorrow that they have found the first strong signs of the Higgs Boson - a particle vital to support Albert Einstein's ideas on the working of the universe.
While warning there will be no announcement of a full scientific discovery, scientists said even confirmation that something like the long-sought Higgs boson has been spotted would point the way to major advances in knowledge of the cosmos.
"I am feeling quite a level of excitement," said Oliver Buchmueller, a senior member of one of the two teams seeking the particle amid vast volumes of data gathered in CERN's Large Hadron Collider.
There are reports that CERN research groups - known as ATLAS and CMS - have found signals that look very much like the Higgs.
"The anticipation among physics enthusiasts is almost palpable," said theoretician Sascha Vongehr.
The observation of a "light Higgs" is expected to be announced at a seminar tomorrow.
CERN's director general, revealing the seminar would be given updates on the Higgs search by the heads of the ATLAS and the CMS groups - who work independently of each other - said there would be no "discovery" announcement.
For that, there would have to be a high degree of certainty - measured at 5 sygma - by both groups. Informed bloggers are saying it is hovering at about 2.5 sygma for CMS and 3.5 for ATLAS - enough to qualify the sightings as "an observation".
But Mr Buchmueller - without confirming that reading for his own team - said that if the ATLAS group had found signals similar to those seen in CMS, "then we're moving very close to a conclusion in the first few months of next year".
The boson was posited in 1964 by British physicist Peter Higgs as the agent that gave mass to matter in the wake of the Big Bang 13.7 billion years ago, making possible the formation of stars and planets, and eventually the appearance of life.
But efforts since the mid-1980s to find the particle in the US Tevatron collider and the LHC's predecessor at CERN - the LEP - have so far failed.
The colliders search for the boson by smashing particles together at high speeds and creating mini Big Bangs.
The boson has been called the "capstone" of Albert Einstein's universe of elementary particles and three fundamental forces that control the cosmos under the "Standard Model" finalised by physicists in the 1970s.
The Higgs particle was the missing linking brick in this architecture.
Its discovery, if eventually confirmed - and especially if it is at the low mass levels where bloggers are saying ATLAS and CMS have found it - would open the way to what CERN calls the "New Physics" of super-symmetry and dark matter.
Some top scientists, such as Stephen Hawking, have long voiced doubt that the boson exists and should be replaced in the Standard Model by something else.
But in an interview in the December edition of the British monthly Prospect, 82-year-old Peter Higgs - who has been tipped for a Nobel prize - said that "if you tried to modify the theory to take it out, the whole thing becomes nonsense".
