Researchers at the Pennsylvania State University have discovered a method to use radio signals from space to test a principle of Albert Einstein's theory of General Relativity several times more efficiently compared to earlier processes that use gamma-ray bursts.
In a study featured in the journal Physical Review Letters, physics Professor Peter Mészáros and his colleagues at Penn State have developed a new way to harness blasts of radio signals known as Fast Radio Bursts to test the Equivalence Principle, which is considered to be an integral part of the General Relativity theory.
According to Einstein's theory, the Equivalence Principle pertains to idea that the geometry of spacetime takes on a curved form as a result of the mass density of different planets, stars, galaxies and other celestial objects.
The Fast Radio Bursts presented in the study are energy blasts that only lasted for a few milliseconds. These signal bursts from space are known to be very rare as there have only been about a dozen of them detected on Earth.
Scientists believe Fast Radio Bursts are caused by unidentified occurrences beyond the Milky Way, and potentially even beyond the group of galaxies the Milky Way belongs to.
The new method developed by the Penn State researchers is viewed as an important step to understanding the Fast Radio Burst observations expected to be made by the future radio-signal observatories.
"With abundant observational information in the future, we can gain a better understanding of the physical nature of Fast Radio Bursts," Mészáros said.
Fast Radio Bursts
Similar to other electromagnetic radiations, Fast Radio Bursts are believed to travel across in the form of photon particle waves, and has a frequency comparable to that of radio signals.
Mészáros explained that once they receive additional observations from more-advanced detectors, they will be able to utilize Fast Radio Bursts to learn more about the origins of the signals. The researchers also hope to use the radio signals to gather more information on the space between different galaxies and the universe's cosmic-web structure, as well as to test aspects of fundamental physics.
As more and more observations of the Fast Radio Bursts are made, Mészáros and his colleagues believed the impact of their new method will also increase. It could allow them to establish the origin of the Fast Radio Bursts more firmly as well.
Mészáros pointed out that if the Fast Radio Bursts do originate from beyond the Milky Way, and if the distances between them can be accurately determined, then these radio signals can be used to develop a more powerful tool to test the Equivalence Principle. They can also be used to extend the range of tested energy to frequencies of radio bands.
Einstein's Principle Of Equivalence
The Equivalence Principle suggests that any two photons of varying frequencies, released by the same source at the same time and passing through the same set of gravitational fields, should reach Earth at exactly the same time.
Mészáros said that if the principle is indeed true, then any delay that could occur between the two photons should not be caused by the gravitational fields they will pass through during their transit. Rather, they should be caused by other physical factors.
Scientists can then determine how closely the two photons follow the Equivalence Principle based on how close in time they are able arrive at the same destination.
Mészáros added that the test they have created involved analyzing the amount of space curvature the two photons were able to experience as a consequence of the massive objects near or along their route through space.
He said that their method consists of measuring how much a certain parameter, such as the gamma parameter, varies for photons with different frequencies.
The analysis of latest observed Fast Radio Bursts superseded the findings of previous Equivalence Principle tests by as much as one to two orders of magnitude. These earlier attempts to determine the accuracy of Einstein's principle were made through the use of gamma rays and other forms of energy from a supernova explosion known as supernova 1987A that occurred in 1987.
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