or weak nuclear force
Fundamental interaction that underlies some forms of radioactivity and certain interactions between subatomic particles .
It acts on all elementary particles that have a spin of 1 2 . The particles interact weakly by exchanging particles that have integer spins. These particles have masses about 100 times that of a proton , and it is this relative massiveness that makes the weak force appear weak at low energies. For example, in radioactive decay, the weak force has a strength about 1/100,000 that of the electromagnetic force . However, it is now known that the weak force has intrinsically the same strength as the electromagnetic force, and the two are believed to be only different manifestations of a single electroweak force (see electroweak theory ).