The weak force is one of the four fundamental forces that govern all matter in the universe. The other three are gravity, electromagnetism, and the strong force. While other forces hold things together, a weak force plays a big role in breaking them down.
The weak force is stronger than gravity, but it is effective only at very small distances. The Force operates at the subatomic level and plays a critical role in providing energy to the stars and creating the elements. It is also responsible for most of the natural radiation in the universe.
Fermi Theory
Italian physicist Enrico Fermi developed a theory in 1933 to explain beta decay, the process of converting a neutron into a proton and expelling an electron, often referred to in this context as a beta particle. He identified a new type of force, the so-called weak force, which was responsible for decay, the fundamental process of the transformation of a neutron into a proton, a neutrino and an electron, which was later identified as an antineutrino.
Fermi originallyassumed that there was zero distance and adhesion. The two particles had to be in contact for the force to work. It has since been revealed that the weak force is actually an attractive force that manifests itself over an extremely short distance, equal to 0.1% of the diameter of a proton.
Electroweak force
In radioactive decays, the weak force is approximately 100,000 times smaller than the electromagnetic force. However, it is now known to be intrinsically equal to the electromagnetic one, and these two apparently distinct phenomena are thought to be manifestations of a single electroweak force. This is confirmed by the fact that they combine at energies greater than 100 GeV.
Sometimes they say that the weak interaction is manifested in the decay of molecules. However, intermolecular forces are of an electrostatic nature. They were discovered by van der Waals and bear his name.
Standard Model
Weak interaction in physics is part of the standard model - the theory of elementary particles, which describes the fundamental structure of matter using a set of elegant equations. According to this model, elementary particles, that is, that which cannot be divided into smaller parts, are the building blocks of the universe.
One of these particles is the quark. Scientists do not assume the existence of anything less, but they are still looking. There are 6 types or varieties of quarks. Let's put them in ordermass increase:
- top;
- lower;
- weird;
- enchanted;
- adorable;
- true.
In various combinations, they form many different kinds of subatomic particles. For example, protons and neutrons - large particles of the atomic nucleus - each consist of three quarks. The top two and the bottom make up a proton. The top one and two bottom ones form a neutron. Changing the kind of quark can change a proton into a neutron, thereby turning one element into another.
Another type of elementary particles is a boson. These particles are interaction carriers, which consist of energy beams. Photons are one type of boson, gluons are another. Each of these four forces is the result of an exchange of interaction carriers. The strong interaction is carried out by the gluon, and the electromagnetic interaction by the photon. The graviton is theoretically the carrier of gravity, but it has not been found.
W- and Z-bosons
Weak interaction is carried by W- and Z-bosons. These particles were predicted by Nobel laureates Steven Weinberg, Sheldon Salam and Abdus Gleshow in the 1960s and discovered in 1983 at the European Organization for Nuclear Research CERN.
W-bosons are electrically charged and are denoted by the symbols W+ (positively charged) and W- (negatively charged). W-boson changes the composition of particles. By emitting an electrically charged W boson, the weak force changes the sort of quark, making a protoninto a neutron or vice versa. This is what causes nuclear fusion and causes stars to burn.
This reaction creates heavier elements that are eventually thrown into space by supernova explosions to become the building blocks of planets, plants, people and everything else on Earth.
Neutral current
Z-boson is neutral and carries a weak neutral current. Its interaction with particles is difficult to detect. Experimental searches for W- and Z-bosons in the 1960s led scientists to a theory that combines the electromagnetic and weak forces into a single "electroweak". However, the theory required the carrier particles to be weightless, and the scientists knew that theoretically the W boson would have to be heavy to explain its short range. Theorists have attributed the W mass to an invisible mechanism called the Higgs mechanism, which provides for the existence of the Higgs boson.
In 2012, CERN reported that scientists using the world's largest accelerator, the Large Hadron Collider, had observed a new particle "corresponding to the Higgs boson."
Beta Decay
Weak interaction is manifested in β-decay - the process in which a proton turns into a neutron and vice versa. It occurs when, in a nucleus with too many neutrons or protons, one of them is converted into another.
Beta decay can occur in one of two ways:
- In minus-beta decay, sometimes written asβ− -decay, the neutron splits into a proton, an antineutrino and an electron.
- Weak interaction is manifested in the decay of atomic nuclei, sometimes written as β+-decay, when a proton splits into a neutron, neutrino and positron.
One of the elements can turn into another when one of its neutrons spontaneously turns into a proton through minus-beta decay, or when one of its protons spontaneously turns into a neutron through β+ -decay.
Double beta decay occurs when 2 protons in the nucleus are simultaneously transformed into 2 neutrons or vice versa, resulting in the emission of 2 electron-antineutrinos and 2 beta particles. In a hypothetical neutrinoless double beta decay, neutrinos are not produced.
Electronic capture
A proton can turn into a neutron through a process called electron capture or K-capture. When the nucleus has an excess number of protons relative to the number of neutrons, the electron, as a rule, from the inner electron shell seems to fall into the nucleus. The electron of the orbital is captured by the parent nucleus, the products of which are the daughter nucleus and the neutrino. The atomic number of the resulting daughter nucleus decreases by 1, but the total number of protons and neutrons remains the same.
Fusion reaction
The weak force is involved in nuclear fusion, the reaction that powers the sun and fusion (hydrogen) bombs.
The first step in hydrogen fusion is the collision of twoprotons with sufficient force to overcome the mutual repulsion they experience due to their electromagnetic interaction.
If both particles are placed close to each other, strong interaction can bind them. This creates an unstable form of helium (2He), which has a nucleus with two protons, as opposed to the stable form (4He), which has two neutrons and two protons.
The next step is the weak interaction. Due to an excess of protons, one of them undergoes beta decay. After that, other reactions, including intermediate formation and fusion 3He, eventually form a stable 4He.
