THE MATTERI - KNOT OF INFINITE ?
ATOMIC AND NUCLEAR MODEL
- Hypothesis –
Historic: The atom, in its smallness, must include answers to a lot of questions. After all, what is gravitation? What is the nature, the cause of gravitation? Analyzing the movements of the moon around the Earth, Newton wrote: „Till now, we named the centripetal force, the force with that the heavenly body is maintained on its circle. But, we conclude that it is the same with the gravity (charge) and that´s why, from now on we shall name it GRAVITY".
In fig.1 it is represented the Earth and its natural satellite, the moon. The explanations of the functioning of this system, supplies us with new questions: What is the nature, the cause of the centrifugal force? But the one of the heavenly body? Do these forces have something in common? Are they one and the same phenomenon? We speak here about hierarchical movments. How can we explain the phenomenon „inertia movement"?
Probably these questions challenged also Newton when he said: „Till now we set forth the phenomenon of the skies and our seas, but we gave not the cause of gravitation. This force is born from a certain spirit, that enters to the centre of the sun and the planets… But till now we couldn´t establish the cause of these properties and we couldn’t imagine hypothesis".
And questions follow… What do we know about the nature of the electric field? Fig.2. This phenomenon might be generalized at the level of any material particle? Why? The field lines are continuous or discontinuous? The same questions appear as well for the magnetic phenomenon fig.3. Belong the field lines of a magnet to the magnetic body, that is a kind of in space prolonged „moustache"? Is it difficult to imagine a picture where each material grain disposes of such prolongations to the infinite. If we shall consider a material form in the universe, that might be influenced by the disposing of own causes to the material particles, the electric and magnetic fields, that might get a logic meaning.
We know that in chemistry, the atoms reaction specific, according to their valence and we might foresee the result. Much more, we might foresee also the space form of the resulted molecule fig.4. This means that the valence, the points of connection, do have a specific topography to each element. Thus, the placement of these points on the surface of the atom isn´t fortuitous. How is explained the stability and the specific topography of the points of connection on the surface of atoms to each element?
The Greek philosopher Aristotel (335 b.Chr) considering the order of nature, resumes the system of the four superposed elements – fire, water and earth, for the under-moon sphere, to that it adds a fifth „quintessence", the ether, for superior regions.
Under this influence, probably, the notion of ether served also as intermediary of the gravitational interactions.
In 1801, a hundred years from the dispute of Newton and Huygens regarding the corpuscular nature, respectively the undulatory of light, the English physician Thomas Young and the French physician Augustin Fresnel, see themselves at their studies, to come back to the undulatory theory of light, elaborated by Huygens through the analogy with the theory of the acoustic waves.
As acoustic waves do have as modulated environment (disturbed) the air, of material nature, Huygens supposes that light waves propagate themselves also in vacuum, modulate the cosmic ether, also of material nature, existing everywhere and entering in all bodies.
Fresnel enhances a lot the researches regarding the properties of ether and in this direction he imagined and made experiments that attracted also other physicians to the study of this fluid.
Faraday introduced for the first time in physics, the idea after that the electric field and the magnetic field are material entities and the energy of these field consists of the property to deform of the electromagnetic ether.
Reporting to the magnetic field, the electric field and the ether carrier of light with its contradicted properties – infinite rigidity and infinite elasticity – Maxwell has shown that in fact a unique ether, but still covered in mistery, was enough in all the three cases. Maxwell brought his contribution in this direction, establishing the famous electromagnetical equations, that have shown him at the beginning theoretical, the existance if electromagnetic waves and that the German physician H. Hertz has shown it experimental.
Still by calculus, it is obtained the conclusion that the speed of propagation in vacuum of the electrmagnetic waves is equal to the speed of light. Thus it is realized the synthesis to that made reference Maxwell, of a unique ether, premises of electric, magnetic and light phenomenon. Ether still remains on the scene, but it remains this time in the shadow of the electromagnetism as a catalysing phenomenon.
The attempt to ellaborate a unique model for ether, in order to revelate intuitive the electromagnetic phenomenon, remained without any result, with all tests of Maxwell and of other physicians.
In the year 1880 there existed in Europa, a dispute between two groups of physicians, regarding the training and non-training of ether in the orbital movement of the Earth, with the idea of establishing a fixed point in the universe. For the elucidation of this phenomenon, it was imagined an experiment, by exactly metering the propagation speeds of the light radius released and reflected in two directions, one in the direction of the orbital movement of the earth, the other rectangular to this direction.
The length of the two arms being identical, the conditions of propagation through ether in the two directions follow to show or not a time difference from the return of the two radii.
Although there wasn´t foreseen a possibility of realizing this experiment with the needed precision, it was done in 1881 by the young officer of the American marine, the physician A. Michelson. Michelson being present into a leave in Europe, having the passion and the special ability for metering the light speed, makes the sketches of an interferometer suited for the metering of eventual interferance bands and after realizing and installing the device, there takes place the experiment with a negative result. Between the radii that crossed the two arms of the interferometer, there existed no significant differences.
The hope to give evidence of an environment to which there might be metered the absolute speed of earth swept away.
The physician Hendrik Anton Lorentz, contrary to the negative result of the experiment, remained convinced that ether is perfectly motionless and based on it he works out during five years his famous electronic theory, where there are found again the basic equations of Maxwell as a particular case.
The mathematic demonstration of Lorentz, shows the fact that the experiment of Michelson, however certain they could have been executed, couldn´t register a speed difference between the two beams, even if it existed.
Concerning ether, Lorentz enunciates „Ether is always and everywhere motionless. It isn´t a fluid with material qualities (density, electricity); it is the vacuum space, whose pure electromagnetical properties are described by the equations of Maxwell, admitted as postulates".
Thus, the hypothesis of ether is practically taken out of the preoccupations of the physicians.
Coming back to the „elements" of Aristotel, fig.5, let´s tell them environment and look at two aspects of these environments. First of all the aspect of the stableness or unstableness of these environments.
Earth, soil, has as unstableness the seismic movement that spread themselves in the form of elastic waves, the modulated environment being the earth´s surface. The second environment, water, has as unstableness the movement of the liquid mass, with the aspect characteristic to the surface, the waves, that do have as well undulatory character. The next environment, the atmospheric one, has also a characteristic disturbance, under the form of acoustic waves, the modulated medium being air. At last, we jump over fire and conclude that ether, the cosmic environment, is infinite and we know it less or at all. Although, we must allot to it as instability, the electromagnetic spectrum fig.6.
The other aspect of this environments is the knowledge and the use of their properties, in the field of transports.
As general features there might be observed that each of this environment has been conquered at the beginning with rudimentary means, then, after lots of alternatives, one might reach the performance apparatus.
If on earth and on water, between start and performance there passed thousands of years, to the atmospheric environment it was needed a little under a century.
The earth´s surface, the soil, is the environment for that it was invented the wheel fig.7. After thousands of years, the wheel became motor car, with means of propulsion and handling adequate to this environment „the road". If the motor car could be sent to the times of the inventor of the wheel, it should have appeared as supernatural.
The aquatic environment had probably as primary means of transport the canoe, a hollowed tree trunk where one or more rower set fig.8. The ship, the machine of performance, has as propulsion and handling means, of principle different from the one of the motor car, water being the environment that scientifical imposed these means.
What impression should have made a ship sent over milleniums, under the glances of the rowers in the canoe?
The first means of transport in the atmosphere illustrate the tendency of taking over some elements of propulsion, from the means of the other environments, where they were effective.
Actually, also some types of ships used as means of propulsion the wheel paddles, taken over from the land environments, so that afterwards the balloon shall take over for basket the form of ship and the paddles as means of propulsion fig.9.
If the balloon was the „canoe" of the atmospheric environment, the jet aircraft is the performance machine. Out of this family of apparatus there was spotlighted the rocket, that left the atmospheric environment and entered into ether, in the cosmic space. But, base on the way the other environments have been conquered, it is easily observed that in fact, the rocket is the „canoe" of the cosmic space fig.10.
Then, how could look the performance machine of this environment?
Out of this presentation it is spotlighted the idea that only after the solid knowledge of the cosmic environment, only after the discovery of a phenomenological and technological principle, that should allow us the „lining" on this environment, we might build the performance craft.
The notion of atom – indivisible particle – comes from the antiquity, developed by Democrit of Abdera (420 b.C.). Probably as answer to the idealistic philosophy. The atoms were in the image of Democrit the constituents of the universe fig. 11, that moved in the empty vacuum, another notion for whose control the people shall reach later on to a series of discoveries regarding the laws of gases, the machine with steam, etc. The atoms of Democrit had different geometrical forms, by whose combining there resulted different forms of things, while their movement justifies the idea of transformation. The corpuscular hypothesis, the atomic one, is reactualized by Gasendi (1592 – 1655), priest, astronomer, mathematician and philosopher, who considers the atoms as mass particles, in the inertia state, with possibilities of movement in the vacuum whose existence has been proved by Toricelli.
THE STATIC MODEL OF THE ATOM
To the end of the nineteenth century, the avalanche of discoveries released by theoretical and practical achievements in the field of the electricity, leads to the need to imagine a model of the atoms´structure.
From the study of catodic radii, one might reach to the conclusion that they are negative electric charges and the charge unit was named electron, by Johnston Stoney in 1894. Then, this name goes over to the particle itself.
J.J. Thomson (1856 – 1940) concluding that the electrons are extracted from the most different substances, that they are identical and indivisible particles, consider that they come from the atom, being thus its constituents.
1903 Thomson elaborates the static model of the atom fig. 12, considering the atom, a spherical mass, uniformely charged with positive charge, in its interior being the electrons with negative charge, that might be extracted by irradiation. The negative charges must be equal to the positive charges, so that the atom is neutral from the electrical point of view.
The static model of the atom couldn´t be adopted by the fact that it doesn´t explain some phenomenon such as the coexistence of positive and negative charges, the emission and absorbtion of radiations etc. There have been proposed some dynamic models, but they kept the same defaults as the static model. It is discussed, first of all, the problem of the place occupied by electric charges, if they are distributed in all volume of the atom, or are localized in a restricted area.
THE PLANETARY MODEL OF THE ATOM
In order to give an answer to these questions, it is made a call to the experiment. Ernest Rutherford designs a parallel beam of radiations alpha – helium atoms with two positive charges and the mass of 7000 times the mass of the electron – over a gold film with the thickness of approximately three atomic layers and studies the form of this beam, beyond the film, by using the oscialltions produced on a fluorescent screen, phenomenon named later on „Rutherford scattering" fig.13. As accelerated alpha particle source he used a little oven with radioactive substance. The information supplied by this experiment allowed Rutherford to elaborate an atomic planetary model fig.14, establishing also the main sizes. Under such a model appears for the first time the notion of atomic nuclei, a very restricted area in the centre of the atom, where it is situated almost the entire mass of the atom and the positive charges. Similar to the planetary system of the sun, the negative electric charges, the electrons rotate around the nuclei, under the action of the electrostatic forces of attraction, shown with certainty by the experiment, balanced by the centrifugal forces of the electrons. The functioning of this model explains the magnetical, optical and chemical properties of the atom, as phenomenon established by the properties of the electronic shell.
His publication in 1911 makes him being rapidly known by the physicians and there appeared the first critics. On theoretical plan, the electron with its negative charge, in his orbital movement, according to the electrodynamic laws, should permanently radiate electromagnetic energy and at last, consuming its energy, to fall in the nucleus.
This remark remains in the history of physics under the name of "the atoms’ catastrophe" fig.15.
The way it might be observed in fig.16, the model isn’t an exact copy of the solar system, the atomic planetary model allowing any plan of the electronic orbitals, while the planets rotate in the equatorial plan of the sun, with less exceptions.
Discussions and experiments have shown two possible directions: Either was the model wrong or the laws of the electromagnetism loose the validity at this level.
The Danish physician Niels Bohr (1913) solved this dilema, by using the quantic theory of Planck…
Max Planck, studying the spectral distribution and the laws of the radiation of heated bodies, observed (1900) that the classic image of some oscillators that continuously radiate energy does not suit to the real phenomenon and introduced the idea of the quantification of these oscillators.
Thus, the oscillators that radiate and absorb radiations, might have only special energies, that are multipes of the energy quantum
E = hn.
Bohr, cooperator of the savant Rutherford, by using the most recent results of the research in this field and by applying the theories introduced by the quantic mechanics, where the absorbtion and emission phenomenon of radiation are explained, formulated the following postulates:
According to his postulates, Bohr analysis the condition of stability for the hydrogen atom, having the nucleus formed of a proton with positive charge and an electron that gravitates on a circle orbital under the coulomb attraction between the positive nucleus and the negative electron, balanced by the centrifugal force of the electron.
The results obtained might not be applied to other atoms, imposing the need of the models’ improvement.
THE ATOMIC MODEL BOHR-SOMMERFELD
A. Sommerfeld (1915), based on the quantic mechanics, brings as news the atomic planetary model, the movement of the electron on elyptical orbitals, the nuclei occupying one of the focuses of the elypse. This movement imposes to the electron the permanent variation of the speed and mass, without that the total energy being changed, phenomenon named "degeneration". To this new term, there are added also others as "penetrating orbitals", "fine structure of the spectra of hydrogen", etc.
"The electronic orbitals" of the atomic model of Bohr-Sommerfeld doesn’t form an exact description of reality, but gives the possibility of interpretation for some phenomenon and behaviours of the atom investigated by spectroscopical methods.
STUDIES AND INTERPRETATION
The spectroscopical analysis, by its exact results, shows the necessity of improvement for the atomic model. The experimental study of the light radiation, emphasizes the dual character wave-particle of the photon. Louis de Broglie (1925) issues the hypothesis, later on acknowledged, that the elementary particles demonstrate the wave-particle duality. This duality puts the theoretical physics in front of special difficulties, because by applying the representation that exists in the classical physics, in case of atomic processes, we came to the result that it looses its validity.
L. de Broglie going further on, conceives the material particle as a bundle of waves "de Broglie" that do not spread into space.
The works of Schrödinger (1926) set the fundamentals of an unified theory of substance and radiation, that shall lead then to the theory that is named "the undulatory quantic mechanics". In this period of time there are done lots of experiments for direct metering of some physical sizes characteristic to the electron. Being given the small sizes of the electron, the impossibility of identifying the studied electron among the others that are identical, as well as the absence of some compatible instruments, the tests remained without the expected results.
The uncertainty relations of Heisenberg (1927) show the fact that it is impossible to exactly establish the position and the kinetic moment of an electron at the same time. All this, due to perturbations introduced by the used instruments, in comparison to the sensitivity and smallness of the particle. Moreover, in the interpretation of the quantic mechanics this thing is impossible, because the coordinates and their adequate speeds do not exist simultaneously. Applying the undulatory quantic mechanics to the atomic model, there appear new terms "electronic orbital", "electronic cloud", etc. even in case of an existence of a single electron, understanding by this the most trespassed area by the electron. The uncertainty equations of Heisenberg annul practically the classic intuitive representations of electronic orbitals with radii and periods of revolution, going to genuine mathematic methods of interpretation.
THE VECTORIAL MODEL OF THE ATOM
The vectorial model of the atom transposes the data furnished by the spectroscopy under the form of vectors, allowing an interpretation in this context for complex atoms too, beneath finding the main data, already known. This model doesn’t offer an integral representation of reality, being a needed instrument for the further research of the atomic phenomenon.
THE ATOMIC NUCLEUS
The investigations done by Rutherford for the atom allowed him make estimations of the nucleus, concluding that it occupies a very restricted space, in the centre of the atom, containing almost the whole mass of the atom and it has positive charge.
Making reference to the lightest element, hydrogen, that occupies the first place in the table of elements, Rutherford proposes that its nuclei that has an equal positive charge with the electron, to be considered as unit of electric charge and he names it "proton". Thus, the positive charge of a proton, annuls the negative charge of an electron, becoming neutral from electrical point of view.
There has been infered that the proton has the mass 1836 times bigger than the electron. Thus, one might understand, that the nuclei of the other consecutive, heavier elements shall have an adequate bigger number of protons with positive charges. But it appears immediately the remark that the atom of Helium must have four positive charges fig. 17a, having the mass number 4. It is known, that helium has two positive charges and two electrons. The same situation was also concluded at other elements. It has been supposed that, beneath protons, the nucleus contains also electrons, for annulling a part of the positive charge. This protono-electronical structure fig. 18b has been considered as valid in 1930, because it explains some phenomenon.
The parameters of the electron and at first its sizes, comparable to the one of the nucleus, weakens the validity of this structure.
Thus, it is imposed to find a structure model, that should contain next to the proton another particle having the same characteristics with the proton, but without electrical charge.
This particle has been emphasized in year 1932 and was named "neutron".
The structure of the nucleus containing protons and neutrons fig. 17c is the form considered as being the real one and further research allowed people of science to bring practical and theoretical realizations of great importance in the modern physics. The protons and neutrons being component particles of the nucleus and being very similar, got the general name "nucleon".
In the structure of the nucleus there shall be considered also other particles, for granting to it logics and stability that it characterizes.
Among the questions that were asked, was also the one of how there could coexist the positive charges in the nucleus, knowing that the electric charges of the same sign repell themselves. Moreover, the conclusion that the nucleons not even repell themselves, but they keep bound with very powerful forces, the nuclear forces. These forces got a special nature, a special field, named "mesonic" field. The way the interaction between electric charges seen by the prisma of quantic mechanics is intermediated by the electromagnetic field by a change of photons, the same way the interaction between nucleons is realized through the mesonic field and the change particles named "mesons".
Regarding the atomic mass, it has been shown, that the nucleus contains almost the entire mass of the atom. There existed the proposal that the mass unit should be considered the nucleus of the hydrogen atom, that is the proton. It has been observed that the sum of the masses of the nucleons in a compound nucleus is bigger than the mass of the adequate nucleus. This difference is named mass default and is found in the connection energy between the nucleons. In order to better appreciate the mass of the atom, there has been adopted in an international convention in 1962 the unit of atomic mass "u", expressed by the twelvest part of the mass of carbon 12.
This could be an easy glance over the atom and its nucleus. The things have complicated themselves with the research of the phenomenon of radioactivity, phenomenon that makes reference to the dynamics of changes in time for the structures of the nucleii of some elements.
The research in this field is mainly made by the bombardment of the studied element, with the help of some strong accelerated particles, that might enter in the target nuclei fig.18., realizing interactions at this level. The result of the interactions, the expulzed fragments are analyzed with apparatus of detection that in their greatest part analyze the effects of the fragments. The interpretation of these information lead to the inventory of an amount of elementary particles proceeding from the nucleus, complicating very much their structure.