The universe is looking younger every day, it seems. New calculations suggest the universe could be a couple of billion years younger than scientists now estimate, and even younger than suggested by two other calculations published this year that trimmed hundreds of millions of years from the age of the cosmos. The huge swings in scientists' estimates—even this new calculation could be off by billions of years—reflect different approaches to the tricky problem of figuring out the universe's real age, per the AP. Scientists estimate the age of the universe by using the movement of stars to measure how fast it's expanding. If the universe is expanding faster, that means it got to its current size more quickly, and therefore must be relatively younger. The expansion rate, called the Hubble constant, is one of the most important numbers in cosmology.
The generally accepted age of the universe is 13.7 billion years, based on a Hubble constant of 70. Inh Jee of Germany's Max Planck Institute for Astrophysics, lead author of the study in the journal Science, and her team came up with a Hubble constant of 82.4, which would put the age of the universe at around 11.4 billion years. Jee used a concept called gravitational lensing, in which gravity warps light and makes faraway objects look closer. Jee and outside experts have big caveats for her number, though: She used only two gravitational lenses (the only ones available), and so her margin of error is so large it's possible the universe could be older than calculated, not much younger. Jee's approach is also only one of a few new ones that have led to different numbers in recent years. "We have large uncertainty for how the stars are moving in the galaxy," she says.
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