According to GUT (The Grand Unified Theory), the half life of protons is 1.67×10^34 years if the standard model is incorrect and the time black holes take to evaporate due to hawking radiation is more than Googol years (for stellar mass black holes it is more than 10^67 years to evaporate, this figures refers to higher mass black holes like supermassive and ultramassive), so shouldn't the protons fade first? and if so would the protons in the singularity, decay leaving only other subatomic particles in the singularity like quarks or it would not effect the singularity at all because the laws of physics and CPT symettry does not apply inside the event horizon?

I mean that if the proton decay is faster than the singularity decay, proton decay would already occur, so what would happen to the singularity?

I know that only quantum gravity can give us the ultimate answer, but still are there any estimates by other theories.

(Sorry, This was a Astrophysics question so I did not know to put it into Astronomy SE or Physics SE)



1 Answer 1


It's likely that the "existence of a proton" has no meaning inside the event horizon. But if it does somehow, and the protons eventually decay, that would be invisible outside the black-hole. In proton decay, charge, spin and mass-energy are conserved, so no externally visible properties of the black-hole would be affected at all.

  • $\begingroup$ Thank you for your answer. So if an internal observer somehow observe the singularity, will the laws of physics apply and proton decay is observed $\endgroup$
    – Arjun
    Aug 24, 2023 at 10:14
  • 3
    $\begingroup$ @Arjun You can't observe the singularity, even if you're inside the event horizon. Light rays go towards the singularity, not away from it. That is, the singularity is never in the past light-cone of any observer. So it can never be the cause of any events outside itself. See astronomy.stackexchange.com/q/44316/16685 $\endgroup$
    – PM 2Ring
    Aug 24, 2023 at 12:27

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .