New data from the Hubble Space Telescope suggests that the universe appears to be growing faster than expected, possibly requiring the rules of physics to be rewritten to explain the phenomenon.
As detailed in a news release on the NASA website, a team of researchers led by Nobel Laureate Adam Riess discovered a “nagging discrepancy” based on the latest findings from Hubble, one that shows the universe expanding at a faster rate than what was previously inferred from its post-Big Bang trajectory. With this inconsistency raising more questions than providing answers, the researchers believe that the findings might only be justified if new physics laws are created.
“The community is really grappling with understanding the meaning of this discrepancy,” observed Riess, who is affiliated with Johns Hopkins University and the Space Telescope Science Institute.
Since 2012, Riess and his colleagues have been using the Hubble Space Telescope to come up with more accurate figures for the distances separating galaxies, with their stars serving as mileposts. The figures obtained are then used to measure the so-called Hubble constant, which is a value that refers to the speed in which the universe is expanding.
According to Newsweek, the researchers’ methodologies featured a blend of classical and modern techniques, as they first sought to measure the distances of eight newly studied pulsating stars known as Cepheid variables, by determining their parallax. These Cepheids are located about 6,000 to 12,000 light-years from Earth, making them approximately 10-times farther away from our planet than any previously analyzed star of their kind.
As explained by NASA’s website, parallax is a value invented by the ancient Greeks that determines how much an object’s apparent position has shifted as a result of an observer’s own point of view changing. Due to the new Cepheids’ distance from Earth, measuring this value with Hubble would have been tricky, but Riess’ team devised a new technique that allowed the telescope to periodically measure the positions of stars at a rate of 1,000 times per minute.
After calibrating the data, the researchers compared their values against those returned by the European Space Agency’s Planck satellite, which mapped the leftover electromagnetic radiation from the universe’s formation in a four-year mission that lasted from 2009 to 2013. Based on preliminary results, the Planck mission revealed a Hubble constant between 41.6 and 42.9 miles per second per megaparsec, which is about nine percent lower than the value of 45.4 miles per second per megaparsec suggested by the new Hubble Space Telescope data. Interestingly, the researchers noted that the odds of the discrepancy being a coincidence are very slim, at only 1 in 5,000.
“Both results have been tested multiple ways, so barring a series of unrelated mistakes, it is increasingly likely that this is not a bug but a feature of the universe,” Riess commented.
At the moment, there are a few possible reasons why there is a disconnect between the Planck and Hubble data. According to Riess, there’s a chance that dark energy is pulling galaxies farther apart with greater intensity. The invisible and mysterious substance known as dark matter might also be having more intense interactions with visible matter or radiation than once thought. Finally, dark radiation could be a third explanation that might justify the discrepancy – Newsweek explained that this radiation is formed by super-fast particles called sterile neutrinos, which get their name because they are only affected by gravity.
Going forward, Riess’ team hopes to answer at least some of the questions posed by their recent findings, come up with more accurate results, and consequently determine the how and the why behind the discrepancy. To this end, they plan to gather data from the Hubble Space Telescope and the ESA’s Gaia space observatory, which, as NASA noted, “will measure the positions and distances of stars with unprecedented precision.”