Matter and Anti-Matter

Matter, Antimatter and Dark matter.

Astronomy and Astrophysics.

The atomic nucleus is something very compact. Rather massive in comparison with atoms as a whole subject having a typical size of about ten to the minus fifteenth power of a meter. 

It's really a very, very small object. But this object proofs to be quite a complicated object – it’s a structure. And we had found out that in this structure there are certain particles in a list of two sorts. One sort of particle are so-called a proton.

They are electrically charged, positively charged and carry an elementary positive electric charge, each of them.

Another sort of particle constituting the atomic nucleus is neutron. Those neutrons are very similar to protons. They have practically the same size, the same mass. But they have no electric charge. 

They are necessary because otherwise positively electrically charged protons would simply repulse from each other and the nucleus would simply disperse. 

There would be no nuclei, there would be no atoms, there would be no us, there would be no other matter.  And neutrons are keeping all the structure together, with the help of some new forces which are called strong forces. 

And thus we have a stable nucleus, we have a stable atom, we have chemistry, we have biology, we have ourselves here on our Earth.

Those protons and neutrons, which were first theoretically predicted as certain particles constituting a nucleus, are soon, in the very beginning.

 First protons were discovered. And the first experiments, where protons were observed, were performed by the same great physicist– Sir Ernest Rutherford.

Neutrons were discovered a little bit later, in the thirties, by another English physicist – James Chadwick. And a neutron proved to be quite a curious particle.

In comparison with a proton it has two major differences. First of all it has no… it carries no electric charge. But the second difference is that a neutron, if you throw it out of a nucleus, is not stable, it doesn't live long. It lives approximately 15 minutes, about 1,000 seconds. 15 minutes and then it decays. 15 minutes plus-minus of course, because the process is quite a random process. 

It’s statistically the average lifetime of a neutron is about 1,000 seconds. And then it decays, decays producing several particles. It produces a positively charged proton, a negatively charged electron plus something else. Why do I say “plus something else''? Because when the neutron was initially discovered by Chadwick immediately initially it was discovered that it is not stable, and that it decays by producing protons and electrons. 

And the first studies of this process of decay of the neutron brought quite unpleasant, I would say so, unpleasant for the majority of physicists results. 

Why unpleasant? It was very easily shown that the energy of the produced particles – a proton plus an electron together – is sufficiently  less  than the energy of the initial particle. And then there are two possible explanations of this situation. First explanation, that energy is not conserved in this process.

Up to that moment the energy conservation law was considered to be the primary, the very first, the most important law of nature. And based on this law all the laws of mechanics, all the laws of electrodynamics were formulated. And it was proved experimentally in thousands and thousands of different experiments. 

And in this particular process for some strange reason energy is not the same after the decay than it was before the decay. 

Another possibility is that simply we do not notice some third participant of this decay.

 Probably not only a proton and an electron appear after the decay of a neutron, but something else. And then the energy conservation law is saved! 

But we should answer another question: “Why don’t we see this third mysterious particle?” The answer was proposed by the Austrian theoretician – Wolfgang Pauli – also in his mid-thirties. And his proposal was the following.

He mentioned that most probably the third particle that is produced during the decay of the neutron is first of all very small, and it doesn't interact with other particles. 

And it interacts probably with matter only with some very, very weak forces, which have completely another nature. The first idea about the nature of this new interaction, new fundamental interaction that exists in nature, was formulated by the Italian physicist Enrico Fermi also in his thirties. 

Everything was happening  simultaneously… And as this interaction was supposedly really very weak, much weaker than for example electromagnetic one, it received the name – “weak interaction”. 

Everything is quite reasonable.  So from this moment physics has to consider four different types of interactions:

Gravitation, electromagnetic, and two new – strong interactions, which helps the nucleus to be stable, which keeps neutrons and protons together. 

It is not necessary for the existence of atoms, but for some strange… initially it seems to be a strange reason. This interaction also exists in nature. 

In the 1970s when the kohoutek comet was observed, Rojanski (physicist) recommended the hypothesis of antimatter comets; he also added that gamma ray can be made of the comet to test hypotheses.