Peter Higgs of Britain and Francois Englert of Belgium won the Nobel Prize for Physics today for conceiving of the so-called "God particle" which confers mass.
Higgs, 84, and Englert, 80, were honoured for theorising a particle -- discovered last year after an agonising quest -- that explains why the Universe has any substance at all.
"This particle originates from an invisible field that fills up all space. Even when the Universe seems empty this field is there," the jury said in a statement.
"Without it, we would not exist, because it is from contact with the field that particles acquire mass."
Shortly after the announcement, the University of Edinburgh posted a statement from Higgs saying he was "overwhelmed" by the honour.
"I would also like to congratulate all those who have contributed to the discovery of this new particle and to thank my family, friends and colleagues for their support," Higgs said.
"I hope this recognition of fundamental science will help raise awareness of the value of blue-sky research."
Englert told AFP in a brief comment: "I'm very happy to have received the prize."
Known as a boson, the discovery was popularly dubbed the "God Particle" on the grounds that it is everywhere yet baffingly elusive to find.
Without it, say theorists, we and all the other joined-up atoms in the Universe would not exist.
The presumed particle was discovered last year by Europe's mega-scale physics lab at CERN, near Geneva, after a decades-long search.
"As an achievement, it ranks alongside the confirmation that the Earth is round or Man's first steps on the Moon," Canadian particle physicist Pauline Gagnon told AFP.
Higgs and Englert, at the Free University of Brussels, were honoured for "the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles," the jury said in its formal citation.
The duo received the world's most prestigious award for excellence in physics nearly a half century after they and others set down the theoretical groundwork.
The history of the discovery dates back to 1964, when six physicists, working independently in three groups, published a flurry of papers.
In line with tradition, the laureates will receive their prize at a formal ceremony in Stockholm on December 10, the anniversary of prize founder Alfred Nobel's death in 1896.
The pair will share the prize sum of eight million Swedish kronor (USD 1.25 million), reduced because of the economic crisis last year from the 10 million kronor awarded since 2001.
