Scientists have carried out the most accurate experiments to date to test one of the foundations of the theory of relativity - the idea of Lorentz invariance. This principle consists in the independence of the experimental results from the orientation and speed of motion of the laboratory frame of reference. Two studies on this topic have been published in Physical Review Letters.
Lorentz invariance (also called Lorentz covariance) is a mathematical property of equations describing physical processes, according to which they retain their form under Lorentz transformations. Lorentz transformations are linear transformations of pseudo-Euclidean space that are often used in special relativity. The actual Lorentz transformations allow calculating the new coordinates of a point in four-dimensional space-time during the transition from one inertial frame of reference to another.
Lorentz invariance is the basis of the theory of relativity and the Standard Model, but some new theoretical ideas, in particular some models of quantum gravity, suggest that this principle is violated. To test, scientists use an approach that takes this symmetry into account for all particles and fields. If zero coefficients follow from the experiment, then the symmetry is preserved.
In the first work, scientists used data from superconducting gravimeters - devices that determine local gravitational acceleration. In this subtype of devices, the measurement is carried out over a superconducting sphere levitating in a magnetic field. Data were used for several years, from which zero coefficients follow, and the accuracy of determining some is ten times higher than that of the previous limits.
In the second work, the check was done on the basis of the data of the lunar laser location, that is, the measurement of the time of movement of the laser beam from the Earth to the reflector on the lunar surface and back. Taking the results of experiments that have been going on for more than 48 years, the authors also did not find significant deviations in the values of the coefficients from zero. For some, the accuracy has been improved by hundreds of times compared to previous works.