Paladio

Four Force S or elementary interactions are responsible for all the phenomena Physique S observed in the Univers. They are the strong nuclear interaction, the electromagnetic Interaction, the weak nuclear interaction and the Gravitation.

In Physical traditional, the laws of the gravitation and electromagnetism were regarded as axioms. However in Quantum theory of the fields, these forces are described by the exchange of Boson S virtual S: the standard model describes the strong, weak and electromagnetic interactions, but a quantum theory of the fields has not been able yet to be worked out for the gravitation.

The powers of these fundamental forces are normally very different (see low), but if the kinetic energy of the particles increases, the powers approach. It is thought that the four forces had the same power with extremely high energies which were concerned right after the Big Bang.

Strong interaction

The strong nuclear interaction has the following properties:

it is responsible for the cohesion of all the Hadron S (Baryon S and Méson S), i.e. all the particles made up of Quark S; it is responsible, indirectly, of the cohesion of the atomic nuclei;
range operating only 2,5·10⁻¹⁵ m (0,000 000.000.000 0025 m), because the Charge of color does not appear " nue" at larger distances (see Containment);
most powerful of all the known interactions;
transported by the Gluon S.

Electromagnetic interaction

The electromagnetic Interaction has the following characteristics:

responsible for the majority of the daily phenomena: Light, electricity and Magnetism, Chemistry,… For example, it retains decorations on the vertical walls of your refrigerator;
in theory, unlimited operating range. But in practice, the positive and negative loads tend to be neutralized with large scales;
can be gravitational or pushing back according to the sign of the electric charges; that is also worth for the poles says Northern and the poles says Southern of a magnet;
hundred times less strong than the strong interaction;
transported by the Photon.

Weak interaction

The weak nuclear interaction has the following characteristics:

responsible for one of the types of Radioactivity, the radioactivity beta, it plays also a big role in the nuclear Fusion (such as for example in the center of the Sun);
very short range operating, 10⁻¹⁸ m;
10¹³ time less powerful than the strong nuclear force;
transported by the heavy Boson S: Z⁰, W⁺ and W⁻.

Gravitation

The Gravitation has the following properties:

it is the force which retains us on the ground;
it is dominant for the great structures of the Univers because it is always gravitational and cannot be armor-plated like the electric forces;
unlimited range operating;
weakest of all the interactions, 10³⁸-fois weaker than the strong nuclear interaction;
transported by the Graviton, a hypothetical particle still .

Tabular summary

Short history of the unification of the elementary interactions

During the XXe century, the électrofaible Théorie was first of all developed to unify electromagnetism with the weak interaction. Then the strong interaction could be unified with the two first giving the standard model then physics whose predictions were checked with a very high degree of accuracy in the particle accelerator . Nevertheless, even if these interactions are described within a common framework, the intensities of the three forces, also called constant of coupling, are not the same ones. However, it is noted that these constants are constant only in one approximate direction. Their value changes according to the range of energies concerned. The fact that the constant of coupling of the weak interaction varies much more quickly than that of electromagnetism made their unification relatively easy, as well as the experimental checking of this unification. The range of energies to which, they meet is still accessible to the experiments on accélérateurs.
The goal of the theories of Great unification is to provide, on the one hand, a unified description of the three forces in which, they would share the same constant of coupling (description which would be valid on very large scales of energy about 10¹⁵ GeV), and, in addition, a mechanism by which this symmetry between the three forces is broken on energy scales that we currently let us observe.

Lastly, all these descriptions do not mention gravitation whose influence remains negligible as long as concerned energies are weak in front of the scale of Planck, about 10¹⁸ GeV, but whose effective constant of coupling to this energy joined that of the other interactions. As the theory of the Big Bang informs us that the Univers known in its very first moments a very hot phase and very dense, called the era of Planck, it is allowed that a correct description of this paramount universe requires to have at its disposal a quantum theory of the gravitation. Several theories candidates are under development to provide this quantum gravity. It is on the one hand about the Théorie of the cords which is also given for objective to describe the other interactions on these scales, (one speaks about Théorie of the whole), and of the quantum Gravitation to loops which is less ambitious and only aims at describing gravity without including quantiquement the other interactions.

See too

chronological Plank of microscopic physics
Physical of the particles
Theory of gauge

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