The forces that govern matter and light could be united at last

A new grand unified theory seems to unite electromagnetism and the weak and strong nuclear force without resorting to supersymmetry

Immediately after the big bang, there was just one force. As the universe cooled, this force split into two, then three, and then the four forces of today’s universe. Physicists have long been searching for a grand unified theory that combines everything except gravity into one force. Now, a new idea does just that, but without making predictions that had jinxed earlier attempts.

Of the four fundamental forces – gravity, electromagnetism, and the weak and strong nuclear forces – experiments at particle colliders have shown that electromagnetism and the weak nuclear force become one “electroweak” force at energies of about 100 gigaelectronvolts (GeV). This takes us back to about a trillionth of a second after the big bang.

“But the question is what happened after one trillionth of a trillionth of a trillionth of