# B The age of the Universe

1. Apr 11, 2017

### mcronald

With the life of a proton exceeding 10 to the 34 years and the electron even greater why can't we assume the universe is eternal and the big bang a fluctuation in that duration? Its no more difficult to consider an eternal universe as it is a finite one with nothing coming before as it seems that it will never end.

2. Apr 11, 2017

### .Scott

I guess it depends on how infinite your infinity has to be.
The largest black holes will take 10 ^ 100 to evaporate.
See https://en.wikipedia.org/wiki/Heat_death_of_the_universe#Time_frame_for_heat_death

3. Apr 11, 2017

### Orodruin

Staff Emeritus
I do not quite see how you make this inference. That the proton has a lifetime larger than $10^{34}$ years by no means implies that the universe must be eternal.

Edit: Nobody has observed a proton for $10^{34}$ years. The proton mean-life (or bounds on it) are inferred from observing a large number of protons. Particle decays work according to an exponential distribution and if the mean-life would be $10^{x}$ years and you observed $10^{x}$ particles for one year, you would expect one of those particles to decay.

4. Apr 11, 2017

### Chalnoth

This is a good read on the subject:
https://en.wikipedia.org/wiki/Future_of_an_expanding_universe

The short version of the above, in relation to your question, is that proton decay doesn't change the overall picture: it's more a detail than a big change to the overall picture.