Science Common Sense

1488 - Why do free neutrons decay through the weak interaction into protons and other particles?

A free neutron decays because inside the neutron, there are three small particles called quarks: two 'down' quarks and one 'up' quark. The 'down' quarks have a slightly higher mass than the 'up' quarks, which makes the neutron a bit heavier.

In a process called beta decay (or weak interaction), one of the down quarks in the neutron can change into an up quark, making the neutron lighter and turning it into a proton.

This happens because the universe likes balance and equilibrium (or harmony). Since the neutron has a bit too much energy (or mass) compared to a proton, it tries to lose some of that energy by decaying into a proton and releasing a tiny particle called an electron and also an antineutrino (which is like a 'ghost' particle that's almost invisible).

This process helps the universe to become more balanced and stable, which is why free neutrons don't live forever and eventually decay into protons and other particles.