Armed with data about the first gravitational waves was last year, and the theoretical analysis, physics has shown that gravity waves can oscillate between two different forms of g – and f-types of gravitational waves. Physicists explain that this phenomenon is similar to how neutrinos oscillate between three different flavours – electron, muon and Tau. The oscillating gravitational waves appear in a modified theory of gravity called bioticheskie gravity, or “bigravity”, and physics show that oscillations can be detected in future experiments.
The work of Kevin max, Moritz Pletcher and Yuri Smirnov was published in a recent issue of Physical Review Letters.
Physics note that this work can help to find the answer to the question, “what is 95%” of the Universe. The fact that the answer may lie in modifications of gravity, and no new particles.
“Only 5% of matter relate to the fact that we think we understand,” said Smirnov at Phys.org. “Trying to answer the question, what is in our universe (dark energy and dark matter), most authors discuss alternative models of particle physics, with new particles. However, experiments such as those conducted at the Large hadron Collider, has not yet found any exotic particles. The question arises: maybe you need to reconsider the gravitational side?”.
“In our work, we wonder what signals we might expect from the modified gravity. It turns out that the bigravity has such a unique signal and therefore can be separated from the background of other theories. The recent discovery of gravitational waves has opened for us a new window into the dark sectors of the Universe. Regardless of whether the nature of the General theory of relativity, the bigravity or any other theory, we are left to study only the specific signals.”
Two of the graviton instead of one
Currently, the best theory of gravity is General relativity of Einstein, which uses a single metric to describe space-time. As a result of gravitational interaction mediated by a hypothetical particle – the graviton – which has no mass and therefore travels at the speed of light.
The main difference between the General theory of relativity and bigravity in the fact that bigravity uses two metrics g and f. While g is the physical metric and associated with matter, f is a sterile metric and matter is not bound. In bigraphical gravitational interaction mediated by the two gravitons, one of which has mass, and the other not. Both graviton consist of different combinations (or superpositions) of the metrics g and f, and therefore contact with surrounding matter in different ways. The existence of two metrics (and two gravitons) within the framework of bigraphical eventually leads to the phenomenon of oscillation.
As explained by physics, the idea that there may be a graviton, with mass, was born almost simultaneously with the General theory of relativity.
“The General theory of relativity predicts a mediator of gravitational interactions (graviton) moving at the speed of light (which is massless),” says Max. “In the 1930s, people tried to find a theory in which the mediator will have and therefore move at speeds less than light. The task was extremely difficult and was completed only in 2010. Bigravity became a variation of this development 2010, only to have contained not one, but two new dynamic metrics. One of them is associated with matter and the other not; their linear combination becomes massive (slower than the speed of light) and the other massless (at the speed of light).
Oscillations
Physicists have shown that in the framework of bigraphical when gravitational waves are produced and propagate through space, they oscillate between g – and f-types – although only the g-type can be detected. Although previous studies have shown that such oscillations can exist, they have led to far from the physics results, for example, violate the law of conservation of energy. A new study has shown that oscillations can theoretically occur in realistic physical scenarios involving massive graviton, which is large enough to be detected in the course of the experiment.
So we can understand these oscillations, scientists and compare them to the neutrino oscillations. Although neutrinos come in three flavors (electron, muon and Tau), the nuclear reactions are usually born of electron neutrinos (or electron antineutrinos), because the others are too heavy to form a stable substance. Similarly, in bigravity only one metric associated with the substance, so gravitational waves are astrophysical events like the merging of black holes, g-type to f-type gravitational waves associated not just with substance.
“The key to understanding the phenomenon of oscillations that the electron neutrinos do not have a definite mass: they represent a superposition of three neutrino mass States,” explains Pletser. “Wave equation that describes their motion through space, zamechal them and will lead to oscillations”.
“The same is true for bigraphical: g is a mixture of massive and massless gravitons and so when a gravitational wave passes through the Universe, it will oscillate between g – and f-types of gravitational waves. However, we can only measure first with the help of detectors (composed of matter), and the second to go unnoticed. And that if bigravity is a valid description of Nature, will leave an important trace on the signal of gravitational waves that we did.”
The similarities between neutrinos and gravitational waves is maintained even despite the fact that neutrino oscillations is a phenomenon of quantum mechanics, described by Schroedinger’s wave equation, and the oscillation of the gravitational wave is not a quantum effect and is described by the classical wave equation.
One of the specific effects that predict physics, is that of oscillations of gravitational waves lead to large modulations than General relativity predicts. These results outline a path for the experimental detection of oscillations of gravitational waves, and search support for bigraphical.
“Bigravity as a very young theory, still have much to do and explore. In this direction has been done some work, but we hope to contribute in the future,” the researchers say.
Gravitational waves can oscillate as neutrinos
Ilya Hel