There will be no dark energy in the universe! Here’s why

In 1998, cosmology, the scientific study of the properties of the universe, was influenced by observations of supernovae, catastrophic explosions of stars, and making it possible to measure great distances outside our galaxy. Adam Reiss and Saul Permter, who won the 2011 Nobel Prize in Physics for this discovery, then stunned the world by showing that the expansion of the universe, instead of slowing down, was actually accelerating.

To explain this behavior, physicists were therefore obliged to add a new force to the equation devoted to the behavior of spacetime, a force called “dark energy”. We identified the problem, but we didn’t quite understand it. What was that dark energy!

The expansion of the universe is not the same everywhere, and this changes everything.

The announcement discussed here is just as spectacular, causing a stir in the global scientific community: for researchers in Christchurch, New Zealand, the expansion of the universe will be neither uniform (uniform…) nor isotropic ( … in all directions), which will change everything.

In fact, the “laws” of the universe must be the same everywhere in the cosmos. Thus, we cannot imagine discovering a planet where gravity pulls things upward, because it does not exist. Can, provided its substance is not aggregated. In their article, the New Zealand astronomers explain that the expansion is not uniform at equal distances, perhaps depending on a factor that has hitherto been known to us. has survived, or even that it will just be some kind of illusion that forces us to invent dark energy.

What if the expansion of the universe was just a gravitational illusion?

We often hear that time passes faster in space than on Earth. This is partially true. Although these effects are detectable by modern technology, such as satellites using GPS, they are often extremely small. Basically, the passage of time depends on factors such as an object’s (relative) speed and mass. To summarize, a clock placed in the dense center of a galaxy will “see its time” much slower than another clock running in the empty space between two galaxies.

A clock in the Milky Way runs 35% slower than in the galactic vacuum.

A cosmological model known as the “time landscape” posits that the vast gaps between galaxies seen – compared to ours – have time speeding up due to the absence of matter. Therefore this space vacuum would have allowed the expansion to do more work, not because it would be stronger there, but simply because it would have had more time to do so. Specifically, the model predicts that a clock in the Milky Way runs 35 percent slower than another clock in a larger cosmic space.

If Albert Einstein’s general relativity predicts that matter slows down the speed of time, this time the landscape model is based on a way of averaging to integrate the effects of cosmic space into the behavior of spacetime. depends on Physicists call this effect feedback, and not everyone agrees on its importance. Some say it’s negligible. Others, like New Zealand researchers, think so. On the contrary that at these cosmological scales the effect becomes significant enough to account for the illusion of rapid expansion.

The Euclid space telescopes and soon Nancy Grace will be able to test the Roman “time landscape” model.

Euclid, an ESA space telescope already in orbit and responsible for the stunning images, should help better understand the nature of the universe’s expansion. It would take about 1000 observations of supernovae to distinguish which of the standard cosmology models or “timescapes” is correct. Of course it will also be important to use NASA’s future telescope, the Nancy Grace Roman Telescope, James Webb’s successor, which we’ll tell you about shortly…