Question

Assuming that the whole universe doesn't collapse upon itself, would matter eventually lose cohesion at an atomic level and cease to exist?

Answer 1

The ultimate fate of matters depends on whether protons decay.

Explanation:

Some theories of unification requires that protons decay. The decay mechanism is:
`p^+ rarrpi^0+e^-`
`pi^0 rarr 2 gamma`
Proton decay has not yet been observed and the lower limit for its half life is `10^32` years.

Neutrons, which are heavier than protons, have a half life in their free state of about 10 minutes. Neutrons decay into a proton and an electron. Bound neutrons have a half life in the order of that of protons.

So, if protons decay then ultimately all matter will decay.