Proton to proton collisions

[Little Bang]

A strange thought occurred to me. The odds of other civilizations existing before us are exceedingly high. There have probably been billions if not trillions before us. Surely they had proton to proton collision devices. If true, how many protons have civilizations destroyed in the past ten billion years.

[Little Bang]

How would this affect charge conservation for the Universe? Wouldn't this add a repulsive force to the Universe?

[CraigD]

A strange thought occurred to me. The odds of other civilizations existing before us are exceedingly high. There have probably been billions if not trillions before us. Surely they had proton to proton collision devices. If true, how many protons have civilizations destroyed in the past ten billion years.

Speculation about the likelihood of past intelligent entities having made particle colliders like our own aside – though I agree it seems likely – p + p and p + n collisions have almost certainly been happening in vastly greater quantities than any artificial sources since there were protons and neutrons. Artificial particle accelerators aren’t needed to collide proton, even for scientific experiments – some of the earliest observations of an exotic particles strange lambda baryons ([imath]\Lambda^0[/imath]), were made in 1947, observing natural p + p collisions due to cosmic rays (source: hyperphysics’s The Lambda Baryon page)

 

I think it’s inaccurate to describe these events as “destroying protons”, however, because as best I’ve been able to gather with my not-a-particle-physicist reading of the literature is that such collisions usually eventually (in less than a second) produce as many or more protons as the 2 involved in the collision, along with other long-lived fermions, mostly positrons and neutrinos.

How would this affect charge conservation for the Universe? Wouldn't this add a repulsive force to the Universe?

No – or at least, not very much.

 

In most cases of p + p, p + n, and n + n collisions, charge is conserved. Although the protons’ + charges may end up in a particle other than protons, such as a positrons ([imath]e^+[/imath]), and the total number of charged particles may decrease, as antiparticles annihilate, producing neutral charge photons, no net increase or decrease in the amount of positive charge in the universe occurs.

 

The exception to this is when certain long-lived exotic particles, such as charged K mesons and B mesons, are produced. These particle oscillate between their antiparticles, but with a slight asymmetry, so that a small statistical violation of conservation of charge can occur. For more information of this complicated (and mostly over my head) subject, see some of the many webpages and articles on the subject of “CP violation”, such as this wikipedia article

[Qfwfq]

If true, how many protons have civilizations destroyed in the past ten billion years.

The most common kind of naturally occuring beta decay is neutron becoming proton, electron and neutrino. In many cases of neuclear fisson a proton becomes neutron, positron and neutrino. In general the number of protons may increase or decrease, with baryon number conserved. The higher the energy of your proton-proton collision, the more stuff it's likely to spew out, shifting the average toward increase of protons.

 

How would this affect charge conservation for the Universe? Wouldn't this add a repulsive force to the Universe?

Guess what. Charge is conserved. Suppose there are no protons in what is spewed out, there will be positively charged particles and subtracting any negative charges you'll get the same +2 total as came in.

[Little Bang]

Can you clarify that a little, like what permanently existing particles with charge remain after the collision?

[Qfwfq]

There are so many possible outcomes. In the end, it'll work out into the surrounding materials being altered. If there are altogether less protons and more neutrons, there will also be less electrons.