As we all know, the universe has been expanding since the Big Bang. It is also proven that there is no specific point from which this expansion takes place and all celestial bodies are moving away one from another in the same way. But was this expansion always happening at the same rate? According to a recent research, the speed at which the universe expands may vary depending on how far you look in the past.
Hubble’s Law and Hubble’s Constant
The law that astronomers use to describe the expansion of the universe is Hubble’s Law, which states that the more distant galaxies are moving away much faster than the closer ones. In order to measure the connection between the distance of a galaxy and its speed of expansion, we can use Hubble’s Constant (about 70 km per second per Mega Parsec).
The universe, in which dark energy and dark matter play a big role, can be explained with Hubble’s Law. Additionally, thanks to attempts to make Hubble’s Constant more precise, dark energy was discovered.
Two measurements that can change what we know about the universe
This widely accepted depiction of the expansion of universe is threatened by two recent measurements that seem to disagree one with another.
The first set of measurements was taken by the Planck mission, which was supposed to calculate Hubble’s Constant of the Cosmic Microwave Background. The precise result amounts to about 46,200 miles per hour per million light years (67.4 km/s/Mpc). The other measurements focused on pulsating stars in local galaxies, giving us Hubble’s Constant of 50,400 miles per hour per million light years (73.4 km/s/Mpc). These objects are closer to us when it comes to time. Since a possible mistake in these measurements is only 300 miles per hour per million light years, the difference in movement is really significant.
Why are these two measurements different?
Judging by the gathered data, the nearby part of the universe might expand much faster than the scientists expected. How could we explain this? There are some proposed solutions, such as a new theory of gravity or a new theory of dark energy or dark matter. However, they do not fit with other observations, therefore some consider new physics. Others argue that the difference might be a result of a tiny effect that influenced the measurements or simply a statistical mistake. At the moment, it looks like we will need to gather more data that could explain this mystery once and for all.
As our second lead editor, Anna C. Mackinno provides guidance on the stories Great Lakes Ledger reporters cover. She has been instrumental in making sure the content on the site is clear and accurate for our readers. If you see a particularly clever title, you can likely thank Anna. Anna received a BA and and MA from Fordham University.