Mysterious radio signals from space to efficiently test Einstein's theory

In a tribute to famed theoretical physicist Albert Einstein, scientists have developed a novel way to test one of the basic principles underlying Einstein's theory of General Relativity.

The team from Pennsylvania State University used Fast Radio Bursts (brief blasts of rare radio signals from space) which are 10-100 times better than previous testing methods that used gamma-ray bursts.

The new method is considered to be a significant tribute to Einstein on the 100th anniversary of his first formulation of the Equivalence Principle which is a key component of Einstein's theory of General Relativity.

"With abundant observational information in the future, we can gain a better understanding of the physical nature of Fast Radio Bursts," said Peter Meszaros, professor of physics at Penn State.

More broadly, the new method is a key component of the concept that the geometry of spacetime is curved by the mass density of individual galaxies, stars, planets and other objects.

Fast Radio Bursts are super-brief blasts of energy -- lasting just a few milliseconds.

Until now, only about a dozen Fast Radio Bursts have been detected on Earth.

They appear to be caused by mysterious events beyond our Milky Way Galaxy and possibly even beyond the galaxies that includes the Milky Way.

The new technique will be important for analysing the abundance of observations of Fast Radio Bursts that advanced radio-signal observatories, now being planned, are expected to detect.

Like all other forms of electromagnetic radiation including visible light, Fast Radio Bursts travel through space as waves of photon particles.

With the new method, "we will also be able to use Fast Radio Bursts as a probe of their host galaxies, of the space between galaxies, of the cosmic-web structure of the universe, and as a test of fundamental physics", Meszaros explained.

Einstein's Equivalence Principle requires that any two photons of different frequencies, emitted at the same time from the same source and traveling through the same gravitational fields, should arrive at Earth at exactly the same time.

If Einstein's Equivalence Principle is correct, any time delay that might occur between these two photons should not be due to the gravitational fields they experienced during their travels, but should be due only to other physical effects.

"By measuring how closely in time the two different-frequency photons arrive, we can test how closely they obey Einstein's Equivalence Principle," the authors noted.

The paper was published in the journal Physical Review Letters.