ANNIHILATION OF MATTER AND ANTI-MATTER
" While Men argue, Nature acts."
- Voltaire -
Another complicated issue that arises in cosmology is an old problem of Physics so fascinating and mysterious as the dual wave–particle duality.
The evocation is as follows: We now know that the Universe is composed almost entirely of matter, but it is concluded that it has not always been that way. In its remote past, the Universe contained almost as much matter as antimatter. The antimatter has got symmetric properties of matter; if by any chance two such particles meet each other they will be instantaneously annihilated. And as a result of their collision and annihilation we will assist the emergence of an enormous amount of energy.
The anti-matter was postulated by Paul Dirac, as a result of an equation which he formulated: the Dirac’s equation. This equation intended to unify the Schrödinger equation with the restricted relativity, describing and joining both properties of particles: the quantum properties and also their relativistic properties. The Dirac’s equation, in fact, solved the problem, or almost, but gave us something new.
Unexpectedly, from the solutions of this equation arise some new particles, different from the other known old particles. But curiously, these new particles were not so different after all, their properties seem to be exactly symmetrical. This means that, for each type of particle that we know in Nature, there is an anti-particle of equal mass but with opposite sign of charge. It follows that, for example, the electron has got an anti-particle called ‘positron’, of equal mass but positively loaded!
Antimatter was first time revealed by the Dirac’s equation:
[Ƴμ ( i _d_ – eАμ ) - me ] Ψ ( xν) = 0
The existence of antimatter has been experimentally verified in particles accelerators. Our antiparticles really do exist, but it is good to know that they are not out there on the loose!
The theory of quantum field explores the symmetry of particles. It considers that in the beginning of the Universe, and considering the Dirac’s equation, there should be the same number of particles as anti-particles. Deducing that antimatter has evolved together with matter. However, somehow, matter has prevailed over the anti-matter.
If matter and antimatter existed in an early stage of the universe, the situation would be truly catastrophic. All the matter and antimatter would interact each other and disappear, being mutual annihilated, leaving behind a trail of energy and radiation … and nothing about matter!
So why are there particles of matter instead of nothing?
Placing the question this way it becomes very hard to give an answer … it really seems very difficult to find a solution ... very difficult in deed.
No one has yet imagined a process that may have separated matter of antimatter; or a process that may have offset the increase of matter rather than antimatter.
Physicist talk about minor fluctuations, dissymmetry, minimum excess, lowest probabilities, processes involving different speeds of reaction of matter in respect of antimatter; or that the Universe still has got this antimatter hidden somewhere in the confines of space, so that the quantity of matter and antimatter is still evenly balanced until now, with equal quantities of mater and anti-matter! ... It really seems a highly complex problem.
Matter dominates antimatter but why is that so?
Researches exhaustively work, in order to find the solutions and explanations of why don’t we currently detect the existence of all this antimatter!
This problem takes to the beginning of the Cosmos; to a specific period of the life-time of Universe called as the Hadrons Age or Hadronic Era.
It appears that our Universe, with only 10-7 seconds old, was composed of a set of heavy particles designated as hadrons. Given the extremely high temperatures deemed to be at that time, these hadrons would disintegrate into their fundamental constituent particles, the quarks. So that, the Universe would be filled by a primary plasma of quarks, gluons and high energy photons. The passages of this high energetic photons lead to the creation of antimatter.
Currently you can assist the creation of antimatter in Cosmic Rays, produced in nuclear reactions of stars, like our Sun for example. The cosmic rays represent high energy radiation, gamma radiation; and antimatter can be created by the passage of this radiation in space. The passage of this energy in the vacuum space does arise, spontaneously, a pair of matter-antimatter: the electron-positron pair. Happening that this matter and its homonymous antimatter have an ephemeral lifetime. The antimatter does not 'float' freely in space, it disintegrates in a fraction of a second.
Particles Accelerators can reproduce these events through frontal collisions with fundamental particles, which are quickly annihilated and turned into pure energy. Consecutively, this highly energetically radiation produces matter and antimatter
The theory of the Creation of the Universe, the Big Bang, believes that this process of creation and annihilation of particles actually occurred. However, it does not explain how come particles of matter managed to escape at this early period of annihilation. Considering that, in its remote past, very energetic and very hot, our Universe would not have a chance to escape to such a devastating annihilation!
Sometimes, when we cannot solve a problem we still do have a last resort ... we can try to change the equation!
If you still remember of the model that I have presented you about the prime time of evolution of the Universe, we have seen that the formation of quarks took some time to be develop; the gradual evolution of matter also needed some while to emerge; and certainly the appearance of photons associated with the formation of the electromagnetic force, happened in a much more later period. And the formation of the first atoms occurred in a period which the conditions of temperature, energy and radiation of the Universe were much lower, balanced and stable. In these conditions, with thermical balance and lower temperatures, the passage of photons and the high energy collisions between particles does not happen so often, nor have enough energy to produce antimatter.
At the beginning of the Universe we can not consider the existence of cosmic rays; we can not consider the existence of gamma radiation; not even electromagnetic radiation; much less the photons and convenient hadrons ...
One of the major arguments for the existence of this annihilation process arises from the background radiation which has detected an excess number of photons in terms of baryons or common matter. And it is believed that the reason for this imbalance, between photons and matter, are traces of a process of matter and antimatter annihilation which occur in the past, leaving behind a deficit of matter and a sea of photons.
But even when it is considered that the ratio between the number of baryons and the number of photons in the primordial Universe is quite unbalanced and that the density of photons exceeded the density of neutrons and protons, we can not assume that the explanation for this excess of photons had origin in the matter-antimatter annihilation process, because this excess is insufficient and minimum.
This excess of photons arises from a later period of the story of the Cosmos, and comes from the first form of production of light radiation in a Universe still quite young and absorbed by high energies. In this Universe, we must consider and remember that the intensity of the forces of Nature is variable and, particularly, the intensity of the electromagnetic radiation is much higher at that time, as such, the production of photons is indeed quite higher at this period.
This excess of photons, probably had its origin, not in a process of annihilation, but rather in a process of creation, produced by objects capable of delivering large amounts of light ... the Quasars!
Thus, what we have here is not exactly a problem, but rather a problem in the formulation of the problem, because:
The creation of electron-positron pairs never occurred!
The annihilation of matter and antimatter never took place!
The Hadrons Era never existed!
… There never was a Hadronic Age!
The Primordial radiation, associated with the moment of creation, is not, in any way, related to the electromagnetic radiation.
This early radiation is not, by any chance, connected with some kind of combination of all forces of Nature or with a Unifying Force.
This single radiation, early present in the life time of the Cosmos, is associated with another Exotic Force ... soon we will see what are the origins and characteristics of this Fifth Essence.