NASA Hubble Space Telescope hits new milestone in mystery of universe’s expansion rate

NASA announced Thursday that its Hubble Space Telescope (HST) has calibrated more than 40 «milepost markers» of space and time.

The mile markers help scientists measure the expansion rate of the universe and astronomers have found – using data from the HST and other telescopes – a discrepancy between the expansion rate as measured in the local universe compared to independent observations following the big bang.

The cause of the discrepancy remains unknown, but NASA said HST data supports new physics.

The expansion rate of the universe is called the «Hubble constant,» after Edwin Hubble.

He was the first to calculate the constant from his measurements of stars in 1929, and it can be used to predict how fast an astronomical object at a known distance is moving away from Earth.

However, the true value of the Hubble constant remains up for debate, according to the University of Chicago, Hubble’s alma mater.

Cepheids, or stars that periodically brighten and dim, have long been the gold standard of cosmic mile markers. For greater distances, astronomers use exploding stars called Type Ia supernovae.

In a new paper, a nationwide scientific collaboration called SH0ES (Supernova, H0, for the Equation of State of Dark Energy) measured 42 of the supernova milepost markers with Hubble.

«The SH0ES project was designed to bracket the universe by matching the precision of the Hubble constant inferred from studying the cosmic microwave background radiation leftover from the dawn of the universe,» NASA wrote in a release.

The results of the project are more than double the prior sample of cosmic distance markers.

The agency also explained that the expansion rate of the universe was predicted to be slower than what Hubble actually sees, with a lower value for the Hubble constant calculated using the Standard Cosmological Model of the Universe and measurements by the European Space Agency’s Planck mission than the SH0ES team’s estimate.Nobel Laureate Adam Riess of the Space Telescope Science Institute (STScI) and the Johns Hopkins University, who leads SH0ES, said that – given the large Hubble sample size of mile markers – there is only a one-in-a-million chance astronomers are wrong.


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