Physicists at CERN are increasingly confident that they have discovered the elusive Higgs boson – the so-called 'God particle' that is thought to be a key component of our understanding of the cosmos. Why does the Higgs boson matter?
It has been called "the brick that built the universe", "the angel of creation" and "the god particle".
It is thought to have emerged from the Big Bang 13.7 billion years ago and have brought much of the rest of the flying debris together to form galaxies, stars and planets.
It is a key component of the "Standard Model" - the all-encompassing theory developed by physicists of how the cosmos as we know it works at its basic level of particles and forces.
But until now, in the four decades since it was first posited, no one has convincingly claimed to have glimpsed the Higgs Boson, let alone proved that it actually exists.
At an eagerly awaited briefing on Tuesday at the CERN research centre near Geneva, two independent teams of "Higgs Hunters" - a term they themselves hate - were widely expected to suggest they were fairly confident they had spotted it.
But not confident enough, in the physics world of ultra-precision where certainty has to be measured at nothing less than 100 percent, to announce "a discovery".
In the jargon, this level is described as 5 sigma, which would exclude the possibility that the results recorded by the ATLAS and CMS teams at CERN - the 21-nation European Organisation for Nuclear Research - are a fluke.
As one scientist explained, that level of accuracy would equate to the 17th-century discoverer of gravity, Isaac Newton, sitting under his apple tree and a million apples one after another falling on his head without one missing.
Some leading scientists, including Briton Stephen Hawking, doubt that the tiny piece of matter that would be visible only as a trace on a computer screen is out there at all.