A changing understanding of dark energy

Scientists are homing in on the nature of dark energy. The big question is whether it's a constant force, which scientists have long thought, or whether the force is weakening.

Scientists are homing in on the nature of a mysterious force called dark energy, and nothing short of the fate of the universe hangs in the balance.

The force is enormous — it makes up nearly 70% of the universe. And it is powerful — it is pushing all the stars and galaxies away from each other at an ever faster rate.

And now scientists are getting a little closer to understanding how it behaves. The big question is whether this dark energy is a constant force, which scientists have long thought, or whether the force is weakening, a surprising wrinkle tentatively proposed last year.

Results presented at a meeting of the American Physical Society Wednesday bolster the case that the force is weakening, though scientists are not yet certain and they still haven’t worked out what this means for the rest of their understanding of the universe.

The updated findings come from an international research collaboration that is creating a three-dimensional map to see how galaxies have spread and clustered over 11 billion years of the universe’s history. Carefully tracking how galaxies move helps scientists learn about the forces that are moving them around.

https://www.nbcnews.com/science/science-news/dark-energy-changing-understanding-rcna197386

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