Is astrophysics at the dawn of a revolution? A study carried out by the team responsible for the Dark Energy Spectroscopic Instrument (DESI) project and detailed in Quanta Magazine suggests that the expansion of the universe may be slowing down, contrary to what was previously thought.
Entering its fourth year of activity, DESI is a scientific instrument that can analyze light and map more than 40 million distant galaxies. This should contribute to the study of the nature and evolution of dark energy, which makes up 68% of the universe.
Concept introduced by Einstein in 1917 in order to complete his theory of relativity, it is a repulsive force which would act against the gravitational force. In 1998, two scientists highlighted its role in the expansion of the universe: according to their theory, it would be growing faster and faster. This phenomenon has been schematized by the mathematical model “Lambda CDM”, or concordance model, which should make it possible to predict it.
The universe could contract
The DESI observations were combined with three recent maps of supernovas (the bright explosion marking the death of a star) and the cosmic microwave background (a very homogeneous electromagnetic radiation observed without a specific origin). There, the scientists noticed that the concordance model’s predictions differed very slightly from their data.
If this divergence is confirmed by future observations, dark energy would indeed be weakening over time, slowing the expansion of the universe. Ultimately, the latter would begin to contract under the effect of gravitational force: its disappearance would therefore not be the consequence of a “Big Rip” (“big tearing” in French), but of a “Big Crunch”, that is to say it would collapse on itself).
In…
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