Our Universe is expanding at an accelerating rate. Scientists do not know what is causing it to speed up. Albert Einstein himself predicted that it is dark energy that is driving the expansion, but there are other theories. Now scientists are preparing experiments to solve this old puzzle.
Einstein argued that gravity is nothing else, but distortions of time and space. He introduced a Cosmological Constant, which was meant to explain the constant size of our Universe. However, later he discarded this theory as it was discovered that Universe is actually expanding. Then, twenty years ago, scientists made another interesting discovery. They found that the expansion of the Universe is actually accelerating, meaning that now it is expanding quicker than it was in Einstein times. This phenomenon is hard to wrap your head around, because it seems to contradict laws of physics. Scientists do not know for sure what is driving the expansion of the Universe and why it is speeding up. However, in a weird way they think that the Cosmological Constant may be important for the answer.
There are some theories dominating discussions about the reason why our Universe is expanding at an increasing rate. Dar energy is one of them and scientists from University of Edinburg will try testing it. However, if gravitational waves that have been discovered not so long ago are proven to be moving at the speed of light, dark energy is not needed for the explanation anymore. In fact, in that case Einstein’s Cosmological Constant may be brought back into equation. In any other case, it has to be revised. And so, scientists will try measuring the speed of gravity in cosmos.
The experiment should be carried out by the Laser Interferometer Gravitational-Wave Observatory. It is a facility that helped detecting gravitational waves back in 2015. Scientists hope that the same equipment can help measuring the speed of gravitational waves, which would eventually help explaining why our Universe is expanding at an increasing rate. Although there are no real deadlines, scientists secretly hope to finish this project in time for the 100th anniversary of Einstein’s Constant.
Physics are constantly changing. New theories are proving old one wrong. But we are living in exciting times when old theories can be tested with actual experiments. Theoretical physics are finally becoming very much real and practical.