Charge invariance
Encyclopedia
Charge invariance refers to the fixed electrostatic potential
of a particle, regardless of speed. For example, an electron
has a specific rest charge. Accelerate that electron, and the charge remains the same (as opposed to the relativistic mass and energy increasing). The key word here is relativistic. Some particle characteristics are relativistically invariant (charge
, spin
, and magnetic moment
). Others are relativistic (mass
, energy
, and de Broglie wavelength). The key factor is
where
is speed
, and
is the speed of light
. Typically, we write:
,
,
, and
where the first equation describes relativistic energy, the second – relativistic mass, the third – charge invariance, and fourth – spin invariance. Notice that
does not appear in the third or fourth equations. 
is a function of speed (relative to some rest frame where 
and 
refer to rest energy and mass). So, to say "rest charge" or "rest spin" is redundant. Notice also that as 
(speed) increases, 
increases, and so 
(and 
) increases too. The origin of charge invariance (indeed, all relativistic invariants) is under speculation presently. There may be some hints proposed by string
/M-theory
. It is possible the concept of charge invariance may provide a key to unlocking the mystery of unification
in physics (the theoretical unification of gravity, electromagnetism
, the strong, and weak nuclear forces).
The property of charge invariance follows from the vanishing divergence of the charge-current four-vector
,
with
.
Potential
*In linguistics, the potential mood*The mathematical study of potentials is known as potential theory; it is the study of harmonic functions on manifolds...
of a particle, regardless of speed. For example, an electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
has a specific rest charge. Accelerate that electron, and the charge remains the same (as opposed to the relativistic mass and energy increasing). The key word here is relativistic. Some particle characteristics are relativistically invariant (charge
Electric charge
Electric charge is a physical property of matter that causes it to experience a force when near other electrically charged matter. Electric charge comes in two types, called positive and negative. Two positively charged substances, or objects, experience a mutual repulsive force, as do two...
, spin
Spin (physics)
In quantum mechanics and particle physics, spin is a fundamental characteristic property of elementary particles, composite particles , and atomic nuclei.It is worth noting that the intrinsic property of subatomic particles called spin and discussed in this article, is related in some small ways,...
, and magnetic moment
Magnetic moment
The magnetic moment of a magnet is a quantity that determines the force that the magnet can exert on electric currents and the torque that a magnetic field will exert on it...
). Others are relativistic (mass
Mass
Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...
, energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
, and de Broglie wavelength). The key factor is
where
is speedVelocity
In physics, velocity is speed in a given direction. Speed describes only how fast an object is moving, whereas velocity gives both the speed and direction of the object's motion. To have a constant velocity, an object must have a constant speed and motion in a constant direction. Constant ...
, and
is the speed of lightSpeed of light
The speed of light in vacuum, usually denoted by c, is a physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time...
. Typically, we write:
,,, andwhere the first equation describes relativistic energy, the second – relativistic mass, the third – charge invariance, and fourth – spin invariance. Notice that
does not appear in the third or fourth equations. is a function of speed (relative to some rest frame where and refer to rest energy and mass). So, to say "rest charge" or "rest spin" is redundant. Notice also that as (speed) increases, increases, and so (and ) increases too. The origin of charge invariance (indeed, all relativistic invariants) is under speculation presently. There may be some hints proposed by stringString theory
String theory is an active research framework in particle physics that attempts to reconcile quantum mechanics and general relativity. It is a contender for a theory of everything , a manner of describing the known fundamental forces and matter in a mathematically complete system...
/M-theory
M-theory
In theoretical physics, M-theory is an extension of string theory in which 11 dimensions are identified. Because the dimensionality exceeds that of superstring theories in 10 dimensions, proponents believe that the 11-dimensional theory unites all five string theories...
. It is possible the concept of charge invariance may provide a key to unlocking the mystery of unification
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....
in physics (the theoretical unification of gravity, electromagnetism
Electromagnetism
Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...
, the strong, and weak nuclear forces).
The property of charge invariance follows from the vanishing divergence of the charge-current four-vector
Four-vector
In the theory of relativity, a four-vector is a vector in a four-dimensional real vector space, called Minkowski space. It differs from a vector in that it can be transformed by Lorentz transformations. The usage of the four-vector name tacitly assumes that its components refer to a standard basis...
,with
.