To our knowledge, every matter particle has its own pair of antimatter. When a particle collides with its pair, they both get destroyed and change into photon, a neutral particle without mass.
What is the explanation for there being much more matter than antimatter in the universe known by us, which may or may not be the only universe existing? Why did more matter than antimatter come into being? Is there a process that is able to change antimatter into matter?
In a piece on baryons (http://www.pbs.org/wnet/hawking/mysteries/html/gleiser-1.html), Marcelo Gleiser writes about a process of condensation triggered off by the placing of a pot full of water vapor in a pot full of water as a model making the process taking place when the universe was cooling down understandable.
Here is an example of mine to illustrate the collision of matter and antimatter:
1. Let us say we have a completely heat-insulated pot with 1 kg of water vapor of one-atmosphere pressure and a temperature of 1,000 degrees Celsius in it. Let us evenly add 1 kcal of heat per second to the vapor.
In the first stage of the experiment, there is no water of liquid form, and the temperature of the water in the pot slowly increases from the starting temperature of 1,000 degrees.
Now, let us say we have, in a pot completely isolated from the other one, 10 kg of ice of freezing-point temperature.
Let us put the ice in the other pot. Let us suppose that the putting of the ice in the pot, the mixing and the energy equalization between the particles take place immediately, without any delay.
The amount of the vapor and the ice will suddenly be reduced to zero. Water of liquid form will appear, its amount being 11 kg, and the temperature will drop to 20 degrees Celsius.
Following this, the temperature will slowly rise again for a longer period of time. Vapor will appear again, its amount increasing along with the decrease of the amount of liquid water. After a while the liquid water will disappear with vapor left only.
2. Let us repeat the experiment, but with the difference that we do not add all the ice at the same time but in twenty portions of the same amount each, with a 10-minute interval between the first and second portions and an increasingly longer one after each portion afterwards.
This time there will be no liquid water, only the amount of vapor will increase by 0.5 kg after each addition, with the temeprature going down first to 250 degrees Celsius and then to an increasingly higher level. After each portion added, the initial state is restored after a time, with the difference that the amount of vapor increases and so. It takes longer each time to get back to the initial state.
Is it possible that the asymmetric feature of the amount of matter – antimatter was also created by a process in which the small amount of antimatter was „devored” by matter, present in relatively large amounts, and then the decrease in energy that took place in the course of this was through a process made up for in every matter particle? The question is, what the energy resource needed for this is? Or by a process which changed, through another process, photon that came into being on impact into matter? This is, like in the thought experiment above, an energy resource that is of relatively small value but is present constantly or at least for a long period of time, and that is not able to produce a considerable effect within a short span of time but is able to do so in a long enough time span.
Is it possible that photon falls apart (perhaps with another particle acting as an agent) into matter and antimatter? And is it possible that there exists a universe in which the collision process had a reverse result, that is, matter disappeared and only antimatter was left?
In the first experiment both the vapor and the ice got beyond the boundary of their domain of stability and therefore disappeared, but the mixture got into the domain of stability of the liquid water, therefore that is what came into being.Then it slowly got out of it and back into the domain of stability of the vapor.
In the second experiment however they never exceeded the value allowed by their stability reserve and therefore never got beyond their domain of stability.