View Full Version : Latest Estimate on The Universe's Expansion Shows We Need New Physics to Explain It

07-13-2018, 07:47 AM
Astronomers have come up with the most precise measurement of the Universe's expansion rate so far - and sure enough, it still appears to be accelerating.

The increasing speed shouldn't come as a shock we've suspected it for a while. What this measurement does is reduce the odds that it's a coincidence to 1 in 5,000, meaning we're really going to need some clever new ideas to explain it.

After six years of measurements based on a rather clever use of NASA's Hubble telescope, astronomers have calculated the rate of our Universe's stretch with only 2.3 percent uncertainty.

We know space is expanding. The push behind this swelling of space, whatever it might be, is quantified by a number the Hubble Constant, given in kilometres per second per megaparsec.

As you might expect, the tools we use to arrive at this figure produce slightly different answers. Most tend to say the Universe is expanding a touch over 70 km/s/Mpc (around 44 miles/s/Mpc).

But one tool comes up with a significantly different result. By analysing the cosmic microwave background the echo of light still rippling through space 13.8 billion years ago the Planck Mission has come up with a figure closer to 67.8 km/s/Mpc (about 42 miles/s/Mpc).

That doesn't seem like much of a difference, but it's enough to give astronomers pause.

"The community is really grappling with understanding the meaning of this discrepancy," says this latest study's lead researcher Adam Riess from the Space Telescope Science Institute (STScI) and Johns Hopkins University.

The conclusion by Nobel Laureate Brian Schmidt and Nicholas B. Suntzeff in the 1990s was that the expansion of the Universe isn't winding down, but winding up.

And results like those from Hubble and Planck only confirm the Universe was probably expanding slower in the distant past.

Still, physicists and astronomers don't like to gamble on 'probably'. So they look for even more ways to refine those numbers in the hope they either come together or reveal something we've missed.

Riess's team used Hubble to gather data on objects called Cepheid variable stars.

Latest Estimate on The Universe's Expansion Shows We Need New Physics to Explain It (LINK) (https://www.sciencealert.com/universe-expanding-hubble-constant-record-discrepancy-latest-estimate-cepheid-brightness)

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