Last year, an international team of astronomers detected the most powerful gamma-ray explosions ever seen. At the time, three articles were published in the journal Nature attesting that the explosions, called GRB 190114C and GRB 180720B, produced the highest energy photons ever recorded for this type of event.
Now, scientists have used this data for a new experiment: to test, 105 years later, the validity of Albert Einstein’s Theory of General Relativity. The result a study, published in Physical Review Letters, which proves that the speed of light is constant in the vacuum and that the German physicist was covered with reason.
In 1915, Einstein proposed that mass and energy interact with space-time, creating a phenomenon known as gravity. This concept has been tested in various situations and scales, and it has always been proven correct, postulating that the speed of light is constantly 299,792,458 meters per second.
The validity of these tests depends on a fundamental principle of special relativity, the Coventry of Lorentz (proposed by Dutch physicist Hendrik Lorentz), which expresses that, no matter where you are in the universe, the laws of physics – including the speed of light in the vacuum – remain the same.
However, some theories suggest that very high energies could cause a change in the speed of light, due to the effects of quantum gravity. This hypothetical phenomenon is called Lorentz’s Violao da Covarincia, and its effects are believed to be too small to be measured – unless they are accumulated over a very long period. If that were to happen, we would need a new physical theory to explain.
A gamma-ray explosion would be a good source of data to support this hypothesis. Distant and very powerful, they emit highly variable and extremely energetic signals. If the Lorentz Covarincia Violao were correct, the more energetic photons would be more influenced by quantum gravity, and the journey of billions of years to reach Earth would increase the effect.
Explosions are believed to be triggered when giant stars collapse into black holes, causing a supernova. The result is a jet of light that produces gamma rays through complex interactions with magnetic fields and radiation. When it hits Earth, it unleashes a phenomenon known as Cherenkov light, which can be detected by special telescopes.
On January 14, 2019, the Magic (Major Atmospheric Gamma Imaging Cherenkov) telescope detected the explosions we discussed earlier in the story. The photons visible to the naked eye have about 1 electron-volt of energy, but the photons recorded in this explosion carry more than 1 teraeltron-volt, which represents a billion times more energy. By far, the most energetic photons ever seen and a perfect setting for the experiment.
Careful analysis of the data revealed no delay in the arrival of gamma rays from a galaxy 4.5 billion light years away. That is, the amount of energy did not change the speed of light in the vacuum.
The researchers, however, caution that this does not mean that Lorentz’s Covarincia cannot be breached with even higher energies. The study, however, prevents restrictions on both the hypothesis of the violation and the effects of quantum gravity.
Astronomy physics einstein Quantum physics Theory of relativity astrophysics Science & Space