Ignoring gravity, experimental bounds seem to suggest that special relativity

Special relativity

Special relativity is the physical theory of measurement in an inertial frame of reference proposed in 1905 by Albert Einstein in the paper "On the Electrodynamics of Moving Bodies".It generalizes Galileo's...

 with its Lorentz symmetry and Poincare symmetry describes spacetime. Surprisingly, Cohen and Glashow have demonstrated that a small subgroup of the Lorentz group

Lorentz group

In physics , the Lorentz group is the group of all Lorentz transformations of Minkowski spacetime, the classical setting for all physical phenomena...

 is sufficient to explain all the current bounds.

The minimal subgroup

Subgroup

In group theory, given a group G under a binary operation *, a subset H of G is called a subgroup of G if H also forms a group under the operation *. More precisely, H is a subgroup of G if the restriction of * to H x H is a group operation on H...

 in question can be described as follows: The stabilizer of a null vector

Null vector

Null vector can refer to:* Null vector * A causal structure in Minkowski space...

 is the special Euclidean group

Euclidean group

In mathematics, the Euclidean group E, sometimes called ISO or similar, is the symmetry group of n-dimensional Euclidean space...

 SE(2), which contains T(2) as the subgroup of parabolic transformations. This T(2), when extended to include either parity

Parity (physics)

In physics, a parity transformation is the flip in the sign of one spatial coordinate. In three dimensions, it is also commonly described by the simultaneous flip in the sign of all three spatial coordinates:...

 or time reversal

Time reversal

Time reversal may refer to:* In physics, T-symmetry - the study of thermodynamics and the symmetry of certain physical laws where the concept of time is reversed — ie...

 (i.e. subgroups of the orthochronous and time-reversal respectively), is sufficient to give us all the standard predictions. Their new symmetry is called Very Special Relativity (VSR).