Scientists challenge Einstein with the theory of chameleons

Few things are more constant than gravity. Of all the objects of a shelf or an office with large planets like Jupiter and Saturn, everything obeys gravity in the same way. But physicists at the University of Durham in the UK now say that may not be the case.

Scientists are studying an alternative to the standard theories of gravity that they christened the theory of chameleon, which, they say in a press release, "change the behavior according to the environment".

Traditionally, Einstein's theory of general relativity explains the gravity and formation of galaxies. Einstein believed that gravity was a geometric property of space and time, or of space-time. It is intended to explain the functioning of large bodies in the space, such as for example to understand the orbit of Jupiter around the sun and that of Europe to Jupiter. It has been proven that the complex theory worked definitively at the galactic level in 2018, thanks to the observations of ESO's Very Large Telescope.

By conducting simulations with the Durham DiRAC Data Centric system, physicists claim that a galaxy can form in more than one way.

"Chameleon Theory makes it possible to modify the laws of gravity in order to be able to test the effect of gravity changes on the formation of galaxies," said co-lead author Christian Arnold, of the Institute of Computational Cosmology of Durham, in a press release. "Thanks to our simulations, we showed for the first time that even if you changed the gravity, it would not prevent the formation of disk galaxies with spiral arms."

Although the researches of Arnold and his team do not prove that general relativity is false, "this shows that this does not necessarily have to be the only way to explain the role of gravity in the world. evolution of the universe, "he says.

Also known as gravity f (R), the complex theory modifies that of Einstein. The black holes, like those seen in a photo earlier this year, were a crucial part of his theory. The surrounding black holes are huge disks that generate a tremendous amount of heat – so much heat, in fact, that what is sent into the universe can alter gravity in the surrounding areas.

"In general relativity, scientists explain the accelerated expansion of the universe by introducing a mysterious form of matter called dark energy – the simplest form that can be a cosmological constant, whose density is a constant in space and time, "says Baojiu Li., also from the Durham Institute for Computational Cosmology.

"However," he continues, "the alternatives to a cosmological constant that explain the accelerated expansion by modifying the law of gravity, just like the gravity f (R), are also largely taken into account given the limited knowledge we have about black energy. "

Everything is very theoretical at the moment, but Arnold and Li hope that they will continue to study their simulations in 2020. It is at this moment that the Square Kilometer Array (SKA), which will be the largest radio telescope of the world, will open its doors. in South Africa. "Challenge Einstein" tops the list of SKA priorities.