Eggheads confirm it's not a bug – the universe really is expanding 9% faster than expected

Scientists get ready to rewrite the cosmological rulebook

Hubble boffins have confirmed that the universe is expanding about 9 per cent faster than expected thanks to new measurements taken by the venerable space telescope.

Readers might remember the team from Johns Hopkins University and the Space Telescope Science Institute, led by Nobel Laureate Adam Riess, came up with the difference last year as the gang worked to refine the Hubble Constant (how fast the universe expands with time) following results from the European Space Agency's (ESA) Planck observatory.

Back then, scientists were worried that the discrepancy could be down to measurement techniques or instrumentation. However, with the latest research, the chances of this being a fluke has been lowered to 1 in 100,000.

Riess said: "This disparity could not plausibly occur just by chance."

Planck's observations are based on the cosmic microwave background, a relic afterglow from 380,000 years after the Big Bang. The new data is a measurement of how fast things are expanding today (in cosmological terms). The fact the two values differ indicates that something is missing in the current model.

It's good news for scientists since it means that boffins will now have to come up with new theories to explain what is going on. The current thinking is that the cosmic bogeyman, dark energy, may be playing a part.

The new study used the Hubble Space Telescope (HST) to observe 70 pulsating stars called Cepheid variables in the Large Magellanic Cloud. Using the Cepheid variables is nothing new, but harvesting the data has been time consuming. By using the Hubble in a manner delightfully described as "like a point and shoot" camera, the team can snap quick images of the stars.

Scientists combined the Hubble data with distance measurements to the Large Magellanic Cloud made by the Araucaria Project, giving a new estimate of the Hubble constant as 74km (46 miles) per second per megaparsec with the uncertainty now 1.9 per cent (down from 2.2 per cent).

The goal is to get this uncertainty down to 1 per cent.

The study – whose results will be published in The Astrophysical Journal – comes on the 29th anniversary of the launch of the Hubble Space Telescope and, thanks to the efforts of astronauts on servicing missions and engineers on the ground, the machine continues to perform useful science while its successor, the James Webb Space Telescope, struggles to get off the ground.

Failures notwithstanding, the Hubble team expects its ageing spacecraft to continue operating well into the 2020s. ®

Harvard boffins have a fun timeline of the evolution of human knowledge about the Hubble Constant here.

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