Scientists from Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI) in Potsdam have found credible theoretical evidence that hidden dimensions – as predicted by string theory – could influence gravitational waves. In a recently published study, they delve into the possible consequences of extra dimensions on the ripples in space-time, and assess whether or not these effects could be detected.

orbiting supermassive blackholes
Courtesy: Phys.org

Gravitation waves were first detected in September 2015 from a black hole binary system. The discovery had a tremendous impact on our knowledge of the cosmos. In fact, it opened a new window for scientists to observe and learn previously unknown aspects of the Universe.

“Compared to the other fundamental forces like, e.g. electromagnetism, gravity is extremely weak,” says Dr. David Andriot, one of the co-authors of the study. The researchers further predict that the underlying reason for this apparent weakness could stem from gravity’s ability to interact with more dimensions in addition to the four dimensions we interact with in our everyday life.

Extra dimensions are hidden from our “reality” primarily because they are very tiny. At the same time, these dimensions also happen to be an indispensable component of string theory, which is one of the major candidates for a long-awaited theory of quantum gravity.

For the uninitiated, theoretical physicists expect the yet-to-be-figured theory of quantum gravity to unify general relativity and quantum mechanics and put an end to one of the most baffling challenges we have faced since Einstein.

“Physicists have been looking for extra dimensions at the Large Hadron Collider at CERN but up to now this search has yielded no results,” says Dr. Gustavo Lucena Gómez, co-author of the paper. “But gravitational wave detectors might be able to provide experimental evidence.”

According to the researchers, the hidden extra dimensions should have at least two distinct effects on gravitational waves. First, they are expected to cause a certain modification in the “standard” gravitational waves, as well as help form additional waves at frequencies higher than 1000 Hz.

Unfortunately, though, the latter phenomenon is extremely unlikely to be detected by the instruments astrophysicists have at their disposal today (the instruments based on contemporary technologies are not sensitive enough to yield results at higher frequencies).

On the brighter side, the impact of these hidden extra dimensions on “standard” gravitational waves could cause stretch and shrink the fabric of space-time. Scientists are optimistic that any such changes in space-time could be detected by state-of-the-art LIGO detectors.