Have all hydrogen atoms in the universe been created during the Big Bang?

…in the first three minutes after the Big Bang? Thats what I have read? Are there any other subsequent process which have created new hydogen atoms? Perhaps some fission reactions?

Or is every hydrogen atom in the universe dating from the very early aftermatch of the Big Bang?

If you ionise hydrogen (strip off the electron) you get a free proton (i.e not hydrogen). If that proton recombines with an electron to become a neutral hydrogen atom again, is it a new hydrogen atom?

Solar flares throw out ionised hydrogen (basically, free protons and electrons)- these eventually slow down and recombine to form hydrogen. The question is, is it new hydrogen, or recycled hydrogen?

Any process that actually generates free protons may well end up generating new hydrogen - if the protons slow down without combining with a nucleus. This is most likely to occur if the protons are low energy.
High energy protons can collide with a nucleus and be absorbed
(eg Hydrogen + proton -> Deuterium + emitted positron)

There’s also the process of proton emission where highly excited (say, after beta decay) or very proton rich nuclei spontaneously emit protons, which would become hydrogen atoms after electron capture.

Nuclear fission reactions often produce free neutrons. If those neutrons aren’t absorbed by any other nucleus, they’ll decay into protons (and electrons, and anti-neutrinos), and probably those protons with capture electrons eventually to make hydrogen atoms.

That said, however, all of the processes that make new protons are extraordinarily rare, compared to the vast amounts of primordial hydrogen.

I was astounded to discover that thunderstorms can create photons of enough energy to liberate measurable neutrons. Still, over the history of the planet a rough guesstimation would suggest it would yield about enough hydrogen to allow you make a cup of coffee.

Not just solar flares. Solar wind is mostly protons and electrons, and flows all the time.

But I don’t think this counts as new hydrogen; “free protons” are hydrogen ions. It’s only a “new atom” if it’s a new nucleus (proton previously part of a larger nucleus, or generated by decay, etc.)

It makes no difference - a free proton that was once part of a hydrogen atom is indistinguishable from one produced by proton emission, and it will behave identically. Both are likely to slow down, find an electron and pair up into elemental hydrogen.

The question of whether the reformed hydrogen atom is the same hydrogen atom or a different hydrogen atom is one for a philosopher, not a physicist.

I was thinking the same thing. But then I remembered that such processes have been going on for billions (and billions heh) of years.

I’m doubt it totally compensates, but I suspect it does take the edge off a bit for the “rareness” of it.

At this point, once some things get somewhate defined, somebody is going to have to do some math. Don’t look at me!

It my reckoning, it really doesn’t. To a first approximation, the universe is 3/4 Hydrogen and 1/4 Helium, and has been since the universe got cool enough for nuclei to form. The processes that make new free protons (or neutrons, or deuterons) all involve heavier, usually much heavier nuclei. If you took all of the uranium in the universe and broke up every nucleus completely into protons and neutrons, and then let the neutrons decay into protons, you still wouldn’t budge the hydrogen abundance by any noticeable amount.

Of course that takes “hydrogen atom” to mean “hydrogen nucleus”. You take it to mean actual atom such that if a hydrogen atom loses its electron, and then regains another one it is counted as a different atom, I doubt there is very much primordial hydrogen in the universe at all.

Think of it this way: Every proton that wasn’t around and free since the Big Bang has instead come out of some heavier nucleus or another. And each of those heavier nuclei was in turn produced from, ultimately, hydrogen. The vast majority of nuclei don’t emit protons or neutrons at all, and the vast majority of primordial hydrogen has never been fused into anything larger. So the “new protons” must be far, far rarer than the primordial.

By coincidence, NASA’s astronomy picture of the day for the 25th http://apod.nasa.gov/apod/ap160125.html (permalink) is on point. Some of the links in that article are useful as well.