New Study Tests Einstein's Equivalence Principle in Quantum Physics

The contributions of some scientists have been so significant and set such bold precedents that they have shaped the way we see our world. These principles never go out of fashion, despite the relative rise, or fall, of the popularity. Most would agree that Albert Einstein is one of those luminaries that has contributed such ever-lasting, ever-applicable principles.

Interest renewed

Now, there has been some recently renewed interest in one of the most important principles of the theoretical physicist thanks to a team of researchers from the the University of Queensland Australia (UQ) and the University of Vienna.

These contemporary physicists set out to test how clearly Einstein's equivalence principle (EEP)--the cornerstone of his theory of gravity--applies to the general realm of quantum physics. Specifically, the pair were curious to see whether curved space-time is the only means of achieving an interaction between gravity and quantum objects.

They did this by designing a quantum mechanics-based study which examined the correlation between a system's mass-energy, as well as the effect of this mass-energy on its inertia and weight. Dr. Magdalena Zych, UQ physicist and paper co-author, elaborated on the heart of the research's objectives:

“Einstein’s equivalence principle contends that the total inertial and gravitational mass of any objects are equivalent, meaning all bodies fall in the same way when subject to gravity,” she said, adding, “Physicists have been debating whether the principle applies to quantum particles, so to translate it to the quantum world we needed to find out how quantum particles interact with gravity. We realised that to do this we had to look at the mass.”

Several rounds of testing undertaken

Though the research carried out by the physicists did not produce any definitive answers, they are hopeful that their work will serve as the beginning of other scientific research endeavors that offer a more comprehensive, testable framework for EEP.

Earlier this year a team of astronomers in the University of Amsterdam's Anton Pannekoek Institute of Astronomy tested the possibility of alternative gravity theory principles: EEP was evaluated in the system known as PSR J0337+1715, which is located 4,200 light-years from Earth. Because the bodies are incredibly dense, they offer the perfect conditions for testing the theory. The team detected no orbital distortions, which would suggest some flaw in the principle.

Nina V. Gusinskaia, Ph.D. student at the University, who was also part of the research team, spelled out clearly the results: "Now, anyone with an alternative theory of gravity has an even narrower range of possibilities that their theory has to fit into in order to match what we have seen."

Regardless of the aims or design of the various studies that have come forward over the years, one thing remains clear: the iron-clad principle is solid and irrefutable, and in a way as timeless as the man himself. The goal, then, for the scientific community is to explain the various ways in which it applies.

Details about the study appeared in a paper which was published in the Nature Physics journal last week.

Watch the video: General Relativity: 2a - Equivalence Principle (December 2021).