- Who
- Neutrino
- What
- .00000000000000000000000000000000000015 kilogram(s)
- Where
- Unknown ()
- When
The lightest known particles in the universe are neutrinos which have a maximum mass of 0.0000000000000000000000000000000000018 kg. Neutrinos are come in three varieties - electron, muon and tau neutrinos. The mass is an average of the three types.
Neutrinos are created by radioactive decay and nuclear fusion (the process that powers the sun). The mass of the particles was successfully calculated by scientists at Cambridge University and announced at the Royal Astronomical Society's annual conference in Bristol on 10 April 2002.
These particles interact only very weakly with normal matter - every second trillions of them are passing through your body. They are one of the least understood particles in nature.
