Information: - In particle physics , a fermion ( a name coined by Paul Dirac from the surname of Enrico Fermi ) is any particle characterized by Fermi -- Dirac statistics . These particles obey the Pauli exclusion principle . Fermions include all quarks and leptons , as well as any composite particle made of an odd number of these , such as all baryons and many atoms and nuclei . Fermions differ from bosons , which obey Bose -- Einstein statistics . A fermion can be an elementary particle , such as the electron , or it can be a composite particle , such as the proton . According to the spin - statistics theorem in any reasonable relativistic quantum field theory , particles with integer spin are bosons , while particles with half - integer spin are fermions . Besides this spin characteristic , fermions have another specific property : they possess conserved baryon or lepton quantum numbers . Therefore what is usually referred as the spin statistics relation is in fact a spin statistics - quantum number relation . As a consequence of the Pauli exclusion principle , only one fermion can occupy a particular quantum state at any given time . If multiple fermions have the same spatial probability distribution , then at least one property of each fermion , such as its spin , must be different . Fermions are usually associated with matter , whereas bosons are generally force carrier particles , although in the current state of particle physics the distinction between the two concepts is unclear . Weakly interacting fermions can also display bosonic behavior under extreme conditions . At low temperature fermions show superfluidity for uncharged particles and superconductivity for charged particles . Composite fermions , such as protons and neutrons , are the key building blocks of everyday matter . - Gravity, or gravitation, is a natural phenomenon by which all things with mass are brought toward (or "gravitate" toward) one another, including planets, stars and galaxies. Since energy and mass are equivalent, all forms of energy, including light, also cause gravitation and are under the influence of it. On Earth, gravity gives weight to physical objects and causes the ocean tides. The gravitational attraction of the original gaseous matter present in the Universe caused it to begin coalescing, forming stars and the stars to group together into galaxies so gravity is responsible for many of the large scale structures in the Universe. Gravity has an infinite range, although its effects become increasingly weaker on farther objects. - A neutrino (or ) (denoted by the Greek letter ) is a fermion (an elementary particle with half-integer spin) that interacts only via the weak subatomic force and gravity. The mass of the neutrino is much smaller than that of the other known elementary particles. - A baryon is a composite subatomic particle made up of three quarks (a triquark, as distinct from mesons, which are composed of one quark and one antiquark). Baryons and mesons belong to the hadron family of particles, which are the quark-based particles. The name "baryon" comes from the Greek word for "heavy" (, "barys"), because, at the time of their naming, most known elementary particles had lower masses than the baryons. - In particle physics, a hadron ("hadros", "stout, thick") is a composite particle made of quarks held together by the strong force in a similar way as molecules are held together by the electromagnetic force. - A lepton is an elementary, half-integer spin (spin ) particle that does not undergo strong interactions. Two main classes of leptons exist: charged leptons (also known as the "electron-like" leptons), and neutral leptons (better known as neutrinos). Charged leptons can combine with other particles to form various composite particles such as atoms and positronium, while neutrinos rarely interact with anything, and are consequently rarely observed. The best known of all leptons is the electron. - In particle physics, the strong interaction is the mechanism responsible for the strong nuclear force (also called the strong force or nuclear strong force), and is one of the four known fundamental interactions, with the others being electromagnetism, the weak interaction and gravitation. At the range of 10 m (femtometer), the strong force is approximately 137 times stronger than electromagnetism, a million times stronger than the weak interaction and 10 times stronger than gravitation. The strong nuclear force holds most ordinary matter together because it confines quarks into hadron particles such as proton and neutron. In addition, the strong force binds neutrons and protons to create atomic nuclei. Most of the mass of a common proton or neutron is the result of the strong force field energy; the individual quarks provide only about 1% of the mass of a proton. - In quantum mechanics, a boson is a particle that follows BoseEinstein statistics. Bosons make up one of the two classes of particles, the other being fermions. The name boson was coined by Paul Dirac to commemorate the contribution of the Indian physicist Satyendra Nath Bose in developing, with Einstein, BoseEinstein statisticswhich theorizes the characteristics of elementary particles. Examples of bosons include fundamental particles such as photons, gluons, and W and Z bosons (the four force-carrying gauge bosons of the Standard Model), the recently discovered Higgs boson, and the hypothetical graviton of quantum gravity; composite particles (e.g. mesons and stable nuclei of even mass number such as deuterium (with one proton and one neutron, mass number = 2), helium-4, or lead-208); and some quasiparticles (e.g. Cooper pairs, plasmons, and phonons). - In particle physics, mesons (or ) are hadronic subatomic particles composed of one quark and one antiquark, bound together by the strong interaction. Because mesons are composed of quark sub-particles, they have a physical size, with a diameter of roughly one fermi, which is about the size of a proton or neutron. All mesons are unstable, with the longest-lived lasting for only a few hundredths of a microsecond. Charged mesons decay (sometimes through mediating particles) to form electrons and neutrinos. Uncharged mesons may decay to photons. Both of these decays imply that color is no longer a property of the byproducts. - Particle physics (also high energy physics) is the branch of physics that studies the nature of the particles that constitute "matter" (particles with mass) and "radiation" (massless particles). Although the word "particle" can refer to various types of very small objects (e.g. protons, gas particles, or even household dust), "particle physics" usually investigates the irreducibly smallest detectable particles and the irreducibly fundamental force fields necessary to explain them. By our current understanding, these elementary particles are excitations of the quantum fields that also govern their interactions. The currently dominant theory explaining these fundamental particles and fields, along with their dynamics, is called the Standard Model. Thus, modern particle physics generally investigates the Standard Model and its various possible extensions, e.g. to the newest "known" particle, the Higgs boson, or even to the oldest known force field, gravity. - Enrico Fermi (29 September 1901 28 November 1954) was an Italian physicist, who created the world's first nuclear reactor, the Chicago Pile-1. He has been called the "architect of the nuclear age" and the "architect of the atomic bomb". He was one of the few physicists to excel both theoretically and experimentally. Fermi held several patents related to the use of nuclear power, and was awarded the 1938 Nobel Prize in Physics for his work on induced radioactivity by neutron bombardment and the discovery of transuranic elements. He made significant contributions to the development of quantum theory, nuclear and particle physics, and statistical mechanics. What is the relationship between 'fermion' and 'gravity'?
interaction