Scientists devised a new way to test Euler's and Einstein's theories together

Now, the UNIGE team has shown that we cannot really know if the phenomena of dark matter and cosmic expansion obey the equations of Einstein and Euler.

"The problem is that current cosmological data do not allow us to differentiate between a theory that breaks Einstein’s equations and one that breaks Euler’s equation," Camille Bonvin, associate professor in the Department of Theoretical Physics in the UNIGE Faculty of Science and first author of the study explained in a press statement. "This is what we demonstrate in our study. We also present a mathematical method for solving this problem. This is the culmination of ten years of research."

The main reason researchers were unable to differentiate between the validity of the two separate equations is that they were missing an "ingredient": the measurement of time distortion.

"Until then, we only knew how to measure the speed of celestial objects and the sum of the distortion of time and space. We have developed a method for accessing this additional measurement, and it’s a first," Bonvin explained.

If time distortion is not equal to the sum of time and space, then Einstein's model does not work. If time distortion does not correspond to the speed of the galaxies calculated in Euler's equation, then the latter does not work either.

"This will allow us to discover whether new forces or matter, which violate these two theories, exist in the Universe," Levon Pogosian, professor in the Department of Physics at Simon Fraser University in Canada, and co-author of the study, explained.

Testing a new method

The research team has successfully tested its model on synthetic catalogs of galaxies. Next, it will test it on data from the Dark Energy Spectroscopic Instrument (DESI) in Arizona.

The results of the new study will also make a vital contribution to a number of important missions, including the European Space Agency's Euclid spacecraft, which aims to shed new light on dark matter and cosmic expansion.

"Our method will be integrated into these different missions. This is already the case for DESI, whom we have become external collaborators thanks to this research," Bonvin said.