The particle called graviton mediates gravity, one of the fundamental forces.
A graviton is a hypothetical particle that is postulated in quantum field theory to mediate the fundamental force of gravity, similar to how the photon measured the electromagnetic force. In the framework of quantum theory, the graviton would be a massless spin 2 particle. However, to date, its existence has not been experimentally detected. Graviton theory is proposed in an attempt to unify Einstein's theory of general relativity, which describes gravity at a macroscopic level, with quantum mechanics, which describes the other fundamental forces at a microscopic level.
Origin of the concept
The graviton concept has its origins in efforts to unify Einstein's theory of general relativity , which describes gravity at the macroscopic level, with quantum mechanics , which describes the other fundamental forces at the microscopic level. The idea of the graviton arises as part of quantum field theory, where forces are mediated by particles . In this context, it would be the hypothetical particle that would mediate the gravitational interaction.
The graviton concept was proposed to provide a quantum description of gravity . In 1930, Soviet physicist Matvei Bronstein suggested that gravity might have a quantum nature. In the 1960s, with the development of quantum field theory and the success of the quantum theory of other fundamental forces, physicists began to seriously consider the possibility of a graviton as a mediator of gravity.
The standard model
The standard model of particle physics is the theory that describes three of the four fundamental forces of nature (strong interaction, weak interaction, and electromagnetic interaction) and the elementary particles that evidence them. However, it does not consider gravitation . The inclusion of the graviton in the Standard Model is problematic due to the nature of gravity and the lack of a complete quantum theory to explain it.
The graviton is postulated as a massless spin 2 particle, implying that, like the photon , it should mediate the gravitational force. Unlike the other standard model mediator particles, the graviton has not yet been observed experimentally . Searching for evidence and unifying gravity with the other fundamental forces is an active area of research, including theories such as string theory and loop quantum gravity.
Quantum field theory proposes that forces are mediated by particles.
Related theories
Grand Unification Theory
It seeks to unify the three fundamental forces of nature into one. The graviton is not one of its main components; complete unification would require incorporating gravity, possibly through a broader theory.
Kaluza-Klein theory
An extension of general relativity that attempts to unify gravity and electromagnetism. It proposes that our universe has more than the usual four dimensions (three spatial and one temporal), and that the additional dimensions are compactified or rolled up into a very small space. In this theory, the graviton is described along with other particles that appear due to extra dimensions , providing a framework in which gravity and electromagnetism can be treated similarly.
theory of everything
A hypothetical theory that seeks to unify all the fundamental forces of nature, including gravity, into a single coherent theory. The graviton is an essential part, mediating the gravitational interaction and allowing its unification with the other fundamental forces.
M-theory
An advanced theory that unifies the five different versions of open and closed string theory. It proposes that all fundamental particles and forces result from vibrations of membranes (or branes ) in 11-dimensional space. In this framework, the graviton is an excited particle in closed strings, explaining how gravity emerges in this unified theory.
Gravity quantum loop theory
A theory that attempts to quantize gravity without resorting to additional dimensions or string theories. It proposes that spacetime is composed of small discrete loops . In this context, the graviton would be a quantum excitation of discretized space-time, providing a quantum description of gravity.
Conformal field theory
It studies quantum field theories that are invariant under conformal transformations (they preserve angles, but not necessarily distances). Although not a theory of gravity in itself, it is an important tool in string theory and in the AdS/CFT (anti-de Sitter space/conformal field theory) correspondence , a relationship between certain gravitational theories in spaces of anti-de Sitter type and conformal field theories in one less dimension. In this context, the graviton can appear as an excitation on the gravitational side of the correspondence.
According to quantum loop theory, spacetime is composed of small discrete loops.
Related principles
Heisenberg uncertainty principle
It states that it is impossible to simultaneously measure with arbitrary precision certain pairs of physical properties, such as the position and momentum of a particle. In the context of the graviton, this implies that, due to its quantum nature, not all of its properties can be determined with infinite precision at the same time, which affects predictions about gravity at very small scales.
Anthropic principle
It suggests that the laws and constants of the universe must allow for the existence of conscious observers. In the context of the graviton, this principle can be used to argue that its existence and gravitational force must be such as to allow the formation of complex structures such as galaxies, stars and planets, which in turn allow life.
Equivalence principle
A pillar of general relativity and establishes that the effects of a gravitational field are indistinguishable from the effects of an acceleration in a reference frame. In the context of the graviton, any quantum theory of gravity that includes it must respect this principle, ensuring that the quantum effects of the graviton correspond to the classical experience of gravity.
Holographic principle
It proposes that all the information contained in a volume of space can be represented by a theory that lives at the limit of that space. In the context of the graviton, this principle suggests that gravitational phenomena within a volume can be described by a theory without gravity in one less dimension, which has profound implications for the quantum theory of gravity and the nature of the graviton.
Superposition principle
In quantum mechanics it states that a system can be in a combination of multiple states simultaneously. In the context of the graviton, this means that gravitons can exist in superposition states, which could allow for a variety of quantum configurations of gravitational fields.
Correspondence principle
He maintains that the predictions of a quantum theory must coincide with those of the classical theory in the limit of large quantum numbers. In the context of the graviton, any quantum theory that includes gravitons must agree with Einstein's classical general relativity in situations where quantum effects are small.
Locality principle
It states that objects are only affected by their immediate surroundings and not by events that occur instantaneously at a distance. In the graviton context, this implies that graviton-mediated gravitational interactions must respect locality, that is, the effects of gravity are transmitted through gravitons locally and not instantaneously over finite distances.