fifth force

English

Noun

fifth force (plural fifth forces)

1. (physics) A hypothetical fundamental force, distinct from gravity, electromagnetism, and the strong force and weak force, proposed to explain various anomalous observations that do not fit existing theories.
   • 2023 August 11, Nicola Davis, “Scientists may be on brink of discovering fifth force of nature”, in The Guardian‎^[1]:

     The tantalising theory that a fifth force of nature could exist has been given a boost thanks to unexpected wobbling by a subatomic particle, physicists have revealed. […] Dr Mitesh Patel, from Imperial College London, said: “We’re talking about a fifth force because we can’t necessarily explain the behaviour [in these experiments] with the four we know about.”