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if you want to show or prove that pair production cannot occur in empty space, why do you have to use the relativity equation?
It is easiest and most basic to use E^2=p^2+m^2, but you can also prove it by writing the equations for energy and momentum conservation separately.asdf1 said:if you want to show or prove that pair production cannot occur in empty space, why do you have to use the relativity equation?
Yes, that's true.mathman said:It is possible to have pair production in the absence of a nucleus. To do this you need two photons colliding.
What do you mean by this? Aren't you confusing this with matter-antimatter asymmetry?This was the situation immediately after the big bang. That's how matter was produced. It is still not completely settled as to why there was some matter left over.
mathman said:All descriptions of the big bang that I have seen indicate that it started with pure energy. The problem of the excess of matter is an important open question.
What is then pure energy? I think Ben Lillie summarized the topic well.mathman said:All descriptions of the big bang that I have seen indicate that it started with pure energy.
Totally agree.The problem of the excess of matter is an important open question.
If there were not leptons or quarks, does this imply no charged particles? Then there would be not EM field. What then would create photons in the absence of an electric (or electromagnetic) field?mathman said:What I intended to mean by "pure energy" is that at the big bang creation there were no leptons or quarks, but only photons.
mathman said:To clarify: What I intended to mean by "pure energy" is that at the big bang creation there were no leptons or quarks, but only photons.
mathman said:It is now a question of exact time. We really don't know what was the state at time t=0. The equilibrium you are talking about is immediately afterwards, maybe t=10-43 sec. In any case, the point I was trying to make is that there is nothing in any theory I have seen which indicates an excess of matter over antimatter at the beginning. CP violation is supposed to account for the current existence of matter, but a quantitative description has yet to be made.
It is possible to have pair production in the absence of a nucleus. To do this you need two photons colliding. This was the situation immediately after the big bang. That's how matter was produced. It is still not completely settled as to why there was some matter left over.
It was your statement that the matter was produced through photon-photon collisions I didn't like:
I don't know if we are just talking beside each other, but I get the impression you are saying this:mathman said:Why don't you like it?
andThis was the situation immediately after the big bang. That's how matter was produced. It is still not completely settled as to why there was some matter left over
What I intended to mean by "pure energy" is that at the big bang creation there were no leptons or quarks, but only photons.
mathman said:The question of matter excess is what I was mainly concerned about.
The theory of relativity, specifically the special theory of relativity, explains that energy can be converted into matter and vice versa. This means that in a high-energy environment, such as empty space, particles can spontaneously appear and disappear, creating a pair of particles (one matter and one antimatter). This process is known as pair production.
Yes, there is strong evidence for pair production in empty space using the relativity equation. This phenomenon has been observed in high-energy particle collisions, such as those in particle accelerators, and in the cosmic rays that constantly bombard Earth's atmosphere.
Yes, pair production can occur in empty space without any external energy or particles present. This is because of the inherent energy fluctuations in empty space, which can be amplified in high-energy environments to create particle-antiparticle pairs.
The energy-mass equation, E=mc², is a fundamental principle of the theory of relativity. It states that energy and mass are interchangeable, and this is exactly what happens in pair production. The energy from the fluctuation in empty space is converted into the mass of the particle-antiparticle pair.
While pair production in empty space has not yet been harnessed for practical applications, it is an important phenomenon for our understanding of the universe. However, some scientists are exploring the potential of using particle-antiparticle pairs created through pair production in high-energy collisions to generate energy or propulsion in space travel.