From Brian Wood
Jason Palmer reports that weakly interacting massive particles (WIMPs) may in fact interact, annihilating one another and releasing gamma radiation (15 March, p 10). If so, this would presumably cause the universe’s mass to slowly decrease, so reducing the gravitational drag on its expansion.
What’s more, the masses of the postulated WIMPs are supposed to be much larger than a proton’s, so WIMPs being destroyed would release a strong pulse of radiation. Radiation can exert a pressure, so this would also tend to accelerate expansion. This seems to me to be a plausible picture of how disintegrating WIMPs could offer an alternative explanation to dark energy for the universe’s accelerating expansion. But then I am only a microbiologist, so what do I know of such things?
Lenzie, East Dunbartonshire, UK
