Scientists are dumbfounded with the latest observations by Hubble that revealed that the Universe is expanding faster than believed.
Hubble’s observations have enabled astronomers to make the most precise measurements of the expansion rate of the universe since it was first calculated nearly a century ago. While the measurement has got scientists excited, they are really grappling with understanding why the universe to be expanding faster now than was expected from its trajectory seen shortly after the big bang.
Over the course of last six years a team of astronomers has been using Hubble to observe distant galaxies and refine the measurements of distances to those galaxies using their stars as milepost markers. These distance measurements have enabled them to calculate how fast the universe expands with time, a value known as the Hubble constant. The team’s new study extends the number of stars analyzed to distances of to 10 times farther into space than previous Hubble results.
Based on previous measurements of European Space Agency’s Planck satellite the Hubble constant value should now be 67 kilometers per second per megaparsec (3.3 million light-years), and could be no higher than 69 kilometers per second per megaparsec. However, the latest study measured a value of 73 kilometers per second per megaparsec, indicating galaxies are moving at a faster rate than implied by observations of the early universe.
The Hubble data are so precise that astronomers cannot dismiss the gap between the two results as errors in any single measurement or method. “Both results have been tested multiple ways, so barring a series of unrelated mistakes,” one of the authors explained, “it is increasingly likely that this is not a bug but a feature of the universe.”
One of the possibilities being thought about is that dark energy could be pushing galaxies away from each other with even greater — or growing — strength.
Another idea is that the universe contains a new subatomic particle that travels close to the speed of light. Such speedy particles are collectively called “dark radiation” and include previously known particles like neutrinos, which are created in nuclear reactions and radioactive decays. Unlike a normal neutrino, which interacts by a subatomic force, this new particle would be affected only by gravity and is dubbed a “sterile neutrino.”
Yet another attractive possibility is that dark matter (an invisible form of matter not made up of protons, neutrons, and electrons) interacts more strongly with normal matter or radiation than previously assumed.