Chapter V

 

WHAT IS THE DARK MATTER

 

"Discovery consists of seeing what everybody has seen

and thinking what nobody has ever thought. "

- A. Von Szent-Györgyi -

 

      Is it possible that we can find out what is this exotic matter?!

     Scientists estimate that only in the next ten years we will build appropriate equipment and instruments capable of isolating the dark matter and reveal this great mystery of our Universe.

     Looking for our planetary system we can deduce the speed of the planets around the Sun, considering only the mass and gravitational influence of the star king, the Sun. According to the laws of Kepler, so the planets can maintain its stable orbit, they must acquire a certain speed, and this period of translation has different values depending if the planet is closer or more distant from the Sun. So, Mercury has a very rapid movement of translation, while Pluto, a more distant planet, has a rather slow movement of translation. This means, in practice, that we can deduce which is the peripheral speed of a system due to the gravitational influence of the central star.

     And this was exactly what Fritz Zwicky tried to calculate. When measuring the peripheral velocities and distances from the galaxies  center  of hundreds of thousands of galaxies like the Milky Way, he found out surprising results: he has discover that the mass of the system was 100 times higher than the one estimated based only on light emission from galaxy!

     If you counted the amount of visible matter in a galaxy based only on the emission of light sources, the calculations showed a much lower value than that obtained experimentally and confirmed when measuring the peripheral speed of the galactic system. This is definitely a very surprising result!

     It appears to be that there is a mysterious kind of matter, which we can’t see, surrounding the galaxies and creating a lot of Gravity.

     This strange matter, Dark Matter, which does not emit light, but more surprising is that it does not emit any kind of radiation! Neither Infrared nor Ultraviolet, even X-ray or Gamma radiation ... or anything! Any atom known today processes some kind of radiation!

     And now we ask, how can we look at something that we can’t even see? … The answer to that is very simple ... by the gravitational effect that produces, which affects directly any massive system.

     This strange form of matter seems to have the capability to produce, indeed, immense Gravity. Currently, all astronomers agree and concluded that 90%, or even more, of all mass of the Universe which is capable to exert gravitational forces does not emit any trace of light. Ninety percent of matter in the Universe consists of this very mysterious Dark Matter! It is a lot of matter...

     The Universe is dominated by a totally unknown and mysterious kind of matter, the acclaimed Dark Matter. Nobody knows what this substance is. Where does this matter come from? And more strangely is that it does not emit any electromagnetic radiation!?

     Scientists dismiss the hypothesis of this strange substance to be some kind of atom or chemical element and they concentrate on particles. They already have designated enough names for this dark substance, since particles called WIMP (Weakly Interacting Massive Particles), and other candidates such as Neutralinos and Axions.

     No one is quite sure whether this problem belongs to the field of Particle Physics or Cosmology. I would say that the solution to this mystery relies in the hands of Chemistry!

     In order to reveal this mystery, it would be enough and sufficient if we concentrate on its most peculiar characteristic: the absence of radiation. … I will leave you to reflect about this for a moment …

      Before we continue, it is necessary for us to bring in mind the following table:

 

- Periodic Table of chemical elements -    

    

     Here it is! The Periodic Table of Mendeleev!  A true masterpiece of its author!

     When Mendeleev discovered that all the elements of Nature follow a pattern, he must have been ecstatic and delighted! And all of this with a simple pack of cards …

     As you can see Nature is organized. The chemical elements are all divided according to their atomic number. This number represents the number of protons in an atom, and this is a quality which characterizes and distinguishes all elements of Nature.

     So that, if a particle is composed of eight protons, eight neutrons and eight electrons, we know that we are talking about the Oxygen, whose atomic number is 8.

     Similarly, if we have just a single proton, one neutron and one electron, we know that we are talking about Hydrogen, whose atomic number is 1. This is the simplest element of Nature. Correct?!

     When we refer to chemical elements we can also include another feature that is common to all of them: the number of neutrons.

     A stable atom has, always, the same number of protons, neutrons and electrons. Except in individual cases in which there is an unbalanced number of neutrons, and then we designate these atoms of isotopes, or when there is an unbalanced of electrons, and there for these atoms are called ions.

     The secret balance remains in this perfect triangle:

 

number neutrons = number protons = number electrons

 

     Right?

     Let us remember a little better the composition of our Periodic Table. Indeed, there is one chemical element that avoids this pattern!!

     Most curiously the Hydrogen does not share this sacred triangle! … I wonder why that is! …

     Why is that? The most common and simplest element of the Periodic Table, Hydrogen, it is, strangely that it might seem, an Isotope!? This means that the Hydrogen that we usually find in Nature has lost a neutron!? What happened to this neutron? This is a fact that has been ignored … is this an accidental coincidence of Nature? Nature does not have many coincidences without a reason ….

     Track number 1: What is that Dark Matter and Hydrogen Isotopes do have in common?

     I’ll leave you to a moment of reflection …

     And the answer is … nothing at all! And that is exactly it!! The Dark matter could not proceed in the development of a natural path of evolution. This means that these primitive neutrons were never able to process protons; did not share the capability of a neutron/proton mutation process. Therefore, The Dark Matter has got an atomic number zero because these primitive neutrons never managed to create protons. The particles of Dark Matter will be our 'Chimpanzees' and the Chemical Elements will be our 'Humans '.

     The concept of Darwin’s evolution does not only apply to biological organisms. The process of mutation allowed the neutron-proton evolution.

     Let us now have a more abstract moment ... traveling through time ...  a travel in time to try to look and see what is happening in this period of our Universe.

     We enter in a dark Universe, very dark ... and virtually immobile, static and homogenous ... but full of energy and with a lot of potential!

     There is a mysterious force that is already present in this almost ghostly Universe, and that it is taking shape, this is: the Weak Force, the subtle Force of Instability and simultaneously the Force of Balance … the force responsible for changing neutron in to a proton.

     As we know, one of the forces present in Nature is the Weak Force. We know very little information about this force. But with what we know, we deduce that this is the force responsible for the disintegration of radioactive elements.

     We know that some chemical elements are radioactive because they are unstable, or rather, the instability produces radiation!

     The Dark Matter has not been able to develop the Weak Force, as such, failed to obtain the neutron-proton mutation. That is why this black substance does not produce any kind of radiation at all!!

     The radioactive disintegration process results in an almost magical transformation. For example, if an atomic nucleus has got 6 protons and 8 neutrons, the Weak Force will detect this imbalance and will be responsible for restoring order by turning a neutron into proton. Thus, the atomic nucleus will have 7 protons and 7 neutrons, becoming a more balanced and stable core.

     If we look closely to the values of the masses of neutron and proton, we can see that these values are not exactly equal. The mass of the neutron is slightly higher than the mass of the proton:

 

mn = 1,674 928 6 x 10-27 kg          mp = 1,672 623 1 x 10-27 kg,

 

      This means that there is a tiny amount of mass missing …

     With the changing of the neutron there is the birth of a new particle, almost identical: the proton, but with a particularity that makes all the difference. The neutron is neutral but the proton has got a positive charge.

     However, the mutation of the neutron does not end with the birth of this new particle, the proton, in this process there is also a new particle that arrives. The final mutation comes with another particle of small mass and negative charge: the electron.

     When the neutron is transformed, not only the mass is broken into two parts, but also it divides the charge into two parts.

     Nature only has to satisfy a law of equality and equity of the properties of origin, reflecting the Law of Conservation given by the following equation:

 

neutron mass =proton mass + electron mass

 

neutron charge = proton charge + electron charge

   

     Moreover, this type of disintegration is a bit more complex, and what experiences have shown is that the mutation of the neutron ends with the creation of another new particle almost undetectable. The complete process of mutation is the following:

 

Neutron = Proton + Electron + Neutrino

 

     This new and tiny particle, the neutrino, is a small scale version of the neutron, perhaps in an attempt to keep a line of generation … a descendent. Its mass is still unknown, but is so small that it can be considered as having no mass at all, this value is practically zero. And just like his mother, the neutrino has no charge.

     There will be so many Primordial Neutrinos in the Universe as protons and electrons.  Rather interesting! So many neutrinos ... why?

     All of the primitive neutrons in the Universe, which have triplets of quarks in its constitution, were gradually turning into protons, electrons and neutrinos by a process called Beta Disintegration, and only near that period in time happened the consolidation of the first atoms, the simplest element of the Periodic Table: 1H, Hydrogen isotopes!

     And it is because of this choice of Nature, the sacrifice of the neutron, that the most common element of the periodic table is an isotope of Hydrogen, consisting only of a proton and an electron, which is called more frequently by Protio.

     Accomplishing this process of mutation gave the possibility to consolidate these new particles and with it a more complex structure of Nature: the Atom. With the conquest of this step in evolution came another natural phenomenon even more magic ... With the arrival of this new variable, the Universe is no longer what it was. From that moment in time the Universe is capable of generating Electromagnetic Radiation, and with it billions of photons are born!

     The photons were not always present in the life-time of the Universe. On the contrary of what we usually find in the manuals of Physics, also these particles had to be created  ...

     Very interesting! The photons were not present at the beginning of the Universe ...

     However, this primordial Universe was still very hot, filled with high energy, which did not allow the consolidation of these atoms for a long time. Since we were dealing with a relatively dense and opaque Universe, so when the electrons produced photons, these photons would interact strongly with other charged particles, immediately colliding with other electrons and protons. Before they can travel freely in a straight line through space, these photons were immediately absorbed. The atoms were constantly ionized and broken and the beams of photons, the flashes of light, were constantly being emitted and absorbed as a result of the higher average densities of particles surrounding.

     As such, by this time, the light intensity was still very poor which reflected in a discrete Universe ... brightly light … as if it was being illuminated by a simple candle!

     In order to form stable atoms of Hydrogen, the Universe had to wait until the temperature dropped enough with expansion to allow the stability energy of the atom, what just happened when the Universe has reached 300 000 years old.

     It was in this moment of time that a truly amazing and wonderful phenomenon happened in our Universe ... the creation of light!

     The Universe became transparent to electromagnetic radiation in several ways, and the most beautiful of all ... the Visible Light Radiation!

     Data acquired from the Deep Field Radiation of the Universe, a kind of radio image of the primordial age of our Universe, confirmed that the cosmic background radiation was released when the Universe was approximately 300 000 years old.

     This background radiation is a true register in time, and this comes through space from all directions and arrives at the earth with the same intensity.

     One of the most intriguing questions that astronomers make about the Universe is: Based on data issued by the radiation, astronomers virtually can 'see' the Universe, and what they see is a primitive Universe too much uniform and homogeneous.

     This situation leads us to a problem that no physicist or cosmological astronomer has found a solution to resolve it. It is acclaimed as the Problem of Uniformity or the Problem of Homogeneity.