Hubble Space Telescope astronomers have discovered that the universe is expanding 5-9% percent faster than expected. They made the discovery by refining the universe’s current expansion rate to unprecedented accuracy, reducing the uncertainty to only 2.4%. The team made the refinements by developing innovative techniques that improved the precision of distance measurements to faraway galaxies. These measurements are fundamental to making more precise calculations of how fast the universe expands with time, a value called the Hubble constant.
There are a few possible explanations for the universe’s excessive speed. One possibility is that dark energy, already known to be accelerating the universe, may be shoving galaxies away from each other with even greater — or growing — strength.
Another idea is that the cosmos contained a new subatomic particle in its early history that traveled close to the speed of light. Such speedy particles are collectively referred to as “dark radiation” and include previously known particles like neutrinos. More energy from additional dark radiation could be throwing off the best efforts to predict today’s expansion rate from its post-big bang trajectory.
The boost in acceleration could also mean that dark matter possesses some weird, unexpected characteristics. Dark matter is the backbone of the universe upon which galaxies built themselves up into the large-scale structures seen today.
And finally, the speedier universe may be telling astronomers that Einstein’s theory of gravity is incomplete. “We know so little about the dark parts of the universe, it’s important to measure how they push and pull on space over cosmic history,” said Lucas Macri of Texas A&M University in College Station, a key collaborator on the study. More.
Sleep on it.
See also: First dark matter, now dark life
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