Scientists have discovered a new sub-atomic particle which was first theorised by Newcastle born physicist Professor Peter Higgs nearly 50 years ago.
Experiments in the Large Hadron Collider (LHC) in Switzerland show it's highly likely to be the Higgs boson, a tiny particle which is considered to be the missing link in our knowledge of how the universe works.
It's named after Professor Higgs but also is known as the 'God particle' because it's thought to give matter mass and hold the fabric of the universe together.
The discovery was announced at the head quarters of the European Organization for Nuclear Research (CERN) in Geneva this morning.
It is considered to be one of the most important scientific breakthroughs, with scientists hailing the discovery as "momentous".
Prof Higgs said: "I'm rather surprised that it happened in my lifetime - I certainly had no idea it would happen in my lifetime at the beginning, more than 40 years ago, because at the beginning people had no idea about where to look for it, so it's really amazing for me to find out that it's really enough... for a discovery claim.
"I think it shows amazing dedication by the young people involved with these colossal collaborations to persist in this way, on what is a really a very difficult task. I congratulate them."
Professor Valentin Khoze, director of Durham University's Institute for Particle Physics Phenomenology (IPPP), said: "The mounting evidence that Higgs bosons have been produced and detected at the Large Hadron Collider experiment at Cern is a triumph for particle physics.
"Without the Higgs particle, other particles, such as electrons and quarks, would be massless and the Universe would not be what it is.
"Now, with the amazing results from the LHC, we are finally finding growing experimental evidence that the Higgs really exists.
"The second part of the story about the Higgs particle is even more exciting as it provides us with a window to new physics - a tool for the exploration of the truly unknown."
No-one can yet say whether the discovery will ever have any direct practical application. But scientists believe the enormous multibillion-pound cost of searching for the Higgs can already be justified by spin-offs in areas as diverse as medicine, computing, electronics and manufacturing.
One of the most significant was the internet's World Wide Web, which was invented at Cern to aid communication between particle physicists across the globe.