Universal Expansion Is Speeding Up and It's Blowing Scientists' Minds
The universe is expanding; we've known this for almost a century. (Edwin Hubble is usually given credit for that.) But let's put aside the question of whatever void it's expanding into for a moment and dive into another mystery: why does it appear to be expanding faster than it was before? If the newest research from the Hubble Space Telescope is correct, then the answer may change everything we know about physics.
Back in 2016, Adam Riess of the Space Telescope Science Institute and Johns Hopkins University announced the results of a study that clocked a new rate for universal expansion with 97.6% certainty: 45.5 miles per second per megaparsec. This number is between 5-9% greater than the rate of expansion measured near the beginning of the Big Bang by NASA's Wilkinson Microwave Anisotropy Probe and the ESA's Planck satellite. This means that the universe's expansion rate has been increasing ever since its inception... We just don't know why.
According to Riess:
"If we know the initial amounts of stuff in the universe, such as dark energy and dark matter, and we have the physics correct, then you can go from a measurement at the time shortly after the big bang and use that understanding to predict how fast the universe should be expanding today. However, if this discrepancy holds up, it appears we may not have the right understanding, and it changes how big the Hubble constant should be today."
Riess' study has recently been published in The Astrophysical Journal, but some questions remain. Three potential causes have been identified for this weird discrepancy: dark energy may be pushing the boundaries of universe faster and faster, sterile neutrinos may be adding something to the equation we didn't count on, or dark matter may have a bigger effect on matter or radiation than we thought.
Either way, errors in measurement probably aren't to blame. The Planck and Hubble research seems solid, according to Riess: "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."