Three of the forces in the universe get reunited

摘要

JUST after the big bang, there was one force. As the universe cooled, it split into the four forces of today's universe: gravity, the weak and strong nuclear forces and electromagnetism. To explain that, 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 predictions that had jinxed earlier attempts.