In
theoretical physics and quantum physics, a graviphoton or gravivector is a hypothetical particle which emerges as an excitation of the
metric tensor
In the mathematical field of differential geometry, a metric tensor (or simply metric) is an additional structure on a manifold (such as a surface) that allows defining distances and angles, just as the inner product on a Euclidean space allows ...
(i.e. gravitational field) in spacetime dimensions higher than four, as described in
Kaluza–Klein theory
In physics, Kaluza–Klein theory (KK theory) is a classical unified field theory of gravitation and electromagnetism built around the idea of a fifth dimension beyond the common 4D of space and time and considered an important precursor to ...
.
However, its crucial physical properties are analogous to a (massive)
photon
A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless particles that can ...
: it induces a "vector force", sometimes dubbed a "
fifth force
In physics, a fifth force refers to a hypothetical fundamental interaction (also known as fundamental force) beyond the four known interactions in nature: gravitational, electromagnetic, strong nuclear, and weak nuclear forces.
Some speculativ ...
". The
electromagnetic potential emerges from an extra component of the metric tensor
, where the figure 5 labels an additional,
fifth dimension.
In gravity theories with
extended supersymmetry
In theoretical physics, extended supersymmetry is supersymmetry whose infinitesimal generators Q_i^\alpha carry not only a spinor index \alpha, but also an additional index i=1,2 \dots \mathcal where \mathcal is integer (such as 2 or 4).
Extended ...
(
extended supergravities), a graviphoton is normally a
superpartner
In particle physics, a superpartner (also sparticle) is a class of hypothetical elementary particles predicted by supersymmetry, which, among other applications, is one of the well-studied ways to extend the Standard Model of high-energy physics.
...
of the
graviton
In theories of quantum gravity, the graviton is the hypothetical elementary particle that mediates the force of gravitational interaction. There is no complete quantum field theory of gravitons due to an outstanding mathematical problem with re ...
that behaves like a photon, and is prone to couple with gravitational strength, as was appreciated in the late 1970s.
Unlike the graviton, it may provide a ''repulsive'' (as well as an attractive) force, and thus, in some technical sense, a type of
anti-gravity
Anti-gravity (also known as non-gravitational field) is the phenomenon of creating a place or object that is free from the force of gravity. It does not refer to either the lack of weight under gravity experienced in free fall or orbit, or to ba ...
. Under special circumstances, in several natural models, often descending from five-dimensional theories mentioned, it may actually cancel the gravitational attraction in the static limit.
investigated semirealistic aspects of this phenomenon,
stimulating searches
for physical manifestations of this mechanism.
See also
*
Graviscalar (a.k.a. radion)
*
Supergravity
In theoretical physics, supergravity (supergravity theory; SUGRA for short) is a modern field theory that combines the principles of supersymmetry and general relativity; this is in contrast to non-gravitational supersymmetric theories such as ...
*
List of hypothetical particles
This is a list of hypothetical subatomic particles in physics.
Elementary particles
Some theories predict the existence of additional elementary bosons and fermions that are not found in the Standard Model.
Particles predicted by supersy ...
References
{{particles
Supersymmetry
Bosons
Photons
Hypothetical elementary particles
Force carriers
Subatomic particles with spin 1