Grand unification energy
Encyclopedia
The grand unification energy 
, or the GUT scale, is the energy level above which, it is believed, the electromagnetic force, weak force, and strong force become equal in strength and unify to one force governed by a simple Lie group. Specific Grand unified theories (GUTs) can predict the grand unification energy but, usually, with large uncertainties due to model dependent details such as the choice of the gauge group, the Higgs
sector, the matter content or further free parameters. Furthermore, at the moment it seems fair to state that there is no agreed minimal GUT.
The unification of the electroweak forces and the strong force with the gravitational force in a so-called "Theory of Everything"
requires an even higher energy level which is generally assumed to be close to the Planck Scale
. In theory, at such short distances, gravity becomes comparable in strength to the other three forces of nature known to date. This statement is modified if there exist additional dimensions of space at intermediate scales. In this case, the strength of gravitational interactions increases faster at smaller distances, and the energy scale at which all known forces of nature unify, can be considerably lower. This effect is exploited in models of large extra dimensions.
The exact value of the grand unification energy (if grand unification is indeed realized in nature) depends on the precise physics present at shorter distance scales not yet explored by experiments. If one assumes the Desert
and supersymmetry
, it is at around 1016 GeV.
The most powerful collider
to date, the LHC
, is designed to reach a center of mass energy of 1.4 104 GeV in proton-proton collisions. The scale 1016 GeV is only a few orders of magnitude below the Planck scale
, and thus not within reach of man-made earth bound colliders.
, or the GUT scale, is the energy level above which, it is believed, the electromagnetic force, weak force, and strong force become equal in strength and unify to one force governed by a simple Lie group. Specific Grand unified theories (GUTs) can predict the grand unification energy but, usually, with large uncertainties due to model dependent details such as the choice of the gauge group, the HiggsHiggs
The term Higgs appears in:* Alan Higgs, English businessman and philanthropist* Sir Derek Higgs, an English business leader and merchant banker* Eric Sidney Higgs, English archaeologist*Griffin Higgs...
sector, the matter content or further free parameters. Furthermore, at the moment it seems fair to state that there is no agreed minimal GUT.
The unification of the electroweak forces and the strong force with the gravitational force in a so-called "Theory of Everything"
Theory of everything
A theory of everything is a putative theory of theoretical physics that fully explains and links together all known physical phenomena, and predicts the outcome of any experiment that could be carried out in principle....
requires an even higher energy level which is generally assumed to be close to the Planck Scale
Planck scale
In particle physics and physical cosmology, the Planck scale is an energy scale around 1.22 × 1019 GeV at which quantum effects of gravity become strong...
. In theory, at such short distances, gravity becomes comparable in strength to the other three forces of nature known to date. This statement is modified if there exist additional dimensions of space at intermediate scales. In this case, the strength of gravitational interactions increases faster at smaller distances, and the energy scale at which all known forces of nature unify, can be considerably lower. This effect is exploited in models of large extra dimensions.
The exact value of the grand unification energy (if grand unification is indeed realized in nature) depends on the precise physics present at shorter distance scales not yet explored by experiments. If one assumes the Desert
Desert (particle physics)
In particle physics, the desert refers to a theorized gap in energy scales between the TeV scale and the GUT scale in which no new physics appears. The idea of the desert was motivated by the observation of approximate, order of magnitude, gauge coupling unification at the GUT scale...
and supersymmetry
Supersymmetry
In particle physics, supersymmetry is a symmetry that relates elementary particles of one spin to other particles that differ by half a unit of spin and are known as superpartners...
, it is at around 1016 GeV.
The most powerful collider
Particle accelerator
A particle accelerator is a device that uses electromagnetic fields to propel charged particles to high speeds and to contain them in well-defined beams. An ordinary CRT television set is a simple form of accelerator. There are two basic types: electrostatic and oscillating field accelerators.In...
to date, the LHC
LHC
LHC may refer to:* Large Hadron Collider, a particle accelerator and collider located on the Franco-Swiss border near Geneva, SwitzerlandLHC also may refer to:* La hora Chanante, a Spanish comedy television show...
, is designed to reach a center of mass energy of 1.4 104 GeV in proton-proton collisions. The scale 1016 GeV is only a few orders of magnitude below the Planck scale
Planck scale
In particle physics and physical cosmology, the Planck scale is an energy scale around 1.22 × 1019 GeV at which quantum effects of gravity become strong...
, and thus not within reach of man-made earth bound colliders.