If protons decay. There isn't really any reason to believe they're not stable.

And recent DESI data suggests that dark energy is not constant and the universe will experience a big crunch in a little more than double its current age, for a total lifespan of 33 billion years, no need to get wild with the orders of magnitude on years into the future. The infinite expansion to heat death over 10^100 years is looking less likely, 10^11 years should be plenty.

https://www.sciencedaily.com/releases/2026/02/260215225537.h...

Protons can decay because the distinction between matter and energy isn't permanent.

Two quarks inside the proton interact via a massive messenger particle. This exchange flips their identity, turning the proton into a positron and a neutral pion. The pion then immediately converts into gamma rays.

Proton decayed!