Will Neutron Stars Last Forever Without Proton Decay?

[Dremmer]

If proton decay does not occur, will neutron stars just last for eternity unless something collides with them?

 

[phinds]

If the Big Rip holds then no macro objects will persist forever. If there is no Big Rip, then I don't know

 

[Chronos]

They are not much different from a white dwarf. They will eventually shed their heat and become a cold, dead cinder [black dwarf]. They will, however, retain their incredible density so don't try to land on one.

 

[DrStupid]

If the Big Rip holds then no macro objects will persist forever.

Has the neutron star no influence on the expansion of space?

 

[phinds]

Has the neutron star no influence on the expansion of space?

Only locally, and under the Big Rip scenario, even that will be overcome by expansion.

 

[iced199]

Actually, neutron stars have a thin layer of a superhard crust of normal nuclei. This crust keeps the main neutron star material underneath stable. But it does experience proton decay. So slowly the crust will decay and the layer below of neutrons then decays into more protons that then decay again, producing a suicidal cycle that eventually destroys the neutron star. But because only the crust ever decays instead of the whole star, like in a white dwarf, its decay is far slower than a piece of normal matter.

 

[Chronos]

Proton decay is a hypothetical possibility under certain grand unified theories. It has never been experimentally confirmed. Experimental results suggest the half life of protons [if they have one] is at least 10^34 years.

 

[ImaLooser]

If proton decay does not occur, will neutron stars just last for eternity unless something collides with them?

I would think so. I once read that it would take 10^108 years for the magnetic field to decay.

It might gain enough mass to collapse into a black hole, but short of a collision no one knows whether that actually happens.

 

[Naty1]

Kip Thorne describes white dwarfs and neutron stars as 'graveyards'.

That sounds like 'eternal rest' to me.

 

[lpetrich]

Proton-decay mechanisms also make neutrons decay at roughly the same rate.

So a proton-decay mechanism will cause the decay of every nucleon in a neutron star, protons, neutrons, whatever other ones might get formed. If the core of a neutron star becomes quark matter, then the decay mechanism will operate on those quarks.

Proton decay and related sorts of decay work like this:
quark + quark -> antiquark + (anti)lepton

(B - L conserved)
u + u -> d* + e+
u + d -> u* + e+ or d* + nu*
d + d -> u* + nu*
(B - L violated)
u + d -> d* + nu
d + d -> u* + nu or d* + e-

Hadron states:
baryon -> meson + (anti)lepton