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Ann O'Maly

Gaia clocks speedy cosmic expansion

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Ann O'Maly -
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Artwork Gaia and Milky Way

Artwork: Gaia is making the definitive map of our Milky Way Galaxy

Europe’s Gaia space telescope has been used to clock the expansion rate of the Universe and - once again - it has produced some head-scratching.

The reason? The speed is faster than what one would expect from measurements of the cosmos shortly after the Big Bang.

Some other telescopes have found this same problem, too.

But Gaia’s contribution is particularly significant because the precision of its observations is unprecedented.

“It certainly ups the ante,” says Adam Riess from the Space Telescope Science Institute (STScI) and the Johns Hopkins University, both in Baltimore, Maryland, US.

The inability to lock down a value for the expansion rate has far-reaching consequences - not least in how we gauge the cosmic timescale.

If the Gaia speedometer is correct, it would mean having to reduce the estimated 13.88-billion-year age of the Universe by perhaps a few hundred million years.


Read more: http://www.bbc.co.uk/news/science-environment-37438458


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I imagine the error-rate of these cosmic "speedometers" is yet to be established? I wonder how we know when we are getting "more accurate" measurements? 


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18 hours ago, admin said:

I imagine the error-rate of these cosmic "speedometers" is yet to be established? I wonder how we know when we are getting "more accurate" measurements? 


I guess all astronomers can do is continue observing, collecting data, and refining. If they can improve their knowledge on how 'dark' matter and energy affect the universe's expansion rate, the predictions based on Cosmic Microwave Background will better harmonize with the results yielded from the 'standard candle' method. Prof. Riess explained,

“Ultimately, when Gaia is done, we ought to be able to measure the Hubble Constant to 1% precision. That’s the same precision that is predicted by the Cosmic Microwave Background. That will be really powerful.

"And if there is a discrepancy, if there's something interesting going on in the dark sector of the Universe, it should give us much better evidence of what that is”.


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