New York – Ancient, distant galaxies are giving scientists more clues that a mysterious force called dark energy might not be what they thought.
Astronomers know that the universe is expanding at an accelerating rate and have been puzzled for decades about what could be speeding it all up. They theorize that a powerful and constant force is at play, one that fits well with the main mathematical model that describes how the universe behaves. But they can’t see it and don’t know where it comes from, so they call it dark energy.
It is so vast that it is believed to make up almost 70% of the universe, while ordinary matter like all stars, planets and people make up only 5%.
However, findings published a few months ago as part of an international research collaboration of more than 900 scientists from around the world threw up a big surprise. By analyzing how galaxies move, they found that the force that pushes or pulls them did not appear to be constant. And the same group this week published a new, broader set of analyzes that yielded a similar answer.
“I didn’t think such a result would happen in my lifetime,” said Mustapha Ishak-Boushaki, a cosmologist at the University of Texas at Dallas who is part of the collaboration.
What is DESI collaboration?
The Dark Energy Spectroscopic Instrument (DESI) uses a telescope southwest of Tucson, Arizona, to create a three-dimensional map of the universe over 11 billion years to see how galaxies have clustered over time. of time and in space. That gives scientists information about how the universe evolved and where it might be heading.
The map they are building would make no sense if dark energy were a constant force, as theorized. Instead, the energy appears to be changing or weakening over time. If that is indeed the case, this could upset astronomers’ standard cosmological model. It could mean that dark energy is very different than scientists thought, or that something completely different is happening.
“It is a moment of great emotion, and also of some confusion and reflection,” said Bhuvnesh Jain, a cosmologist at the University of Pennsylvania who is not involved in the research.
The collaboration’s latest finding points to a possible explanation for an older theory: that over billions of years of cosmic history, the universe expanded and galaxies clustered together as predicted by the theory of general relativity. Einstein.
Is dark energy dead?
The new findings are not definitive. Astronomers say they need more data to replace a theory that seemed to fit very well. They hope that observations from other telescopes and new analyzes of the new data in the coming years will determine whether the current view of dark energy stands or falls.
“The importance of this result for now is tempting”said Robert Caldwell, a physicist at Dartmouth College who is not involved in the research, “but it is not like a gold-plated measurement.”
Why does dark energy matter?
There is a lot riding on the answer. Because dark energy is the largest component of the universe, its behavior determines the fate of the universe, explained David Spergel, astrophysicist and president of the Simons Foundation. If dark energy is constant, the universe will continue to expand, becoming colder and emptier. If it is growing in strength, the universe will expand so rapidly that it will destroy itself in what astronomers call the Great Rip.
“There is no need to panic. “If this is what is happening, it will happen billions of years from now,” said. “But we would like to know.”