For the last few years, cosmologists have been dealing with an unexpected finding that threatens to undermine the standard model of cosmology. Measurements of the expansion rate of the Universe get different values depending on if you measure the very first light in the universe or “closer” objects.
According to the standard model, the discrepancy shouldn’t be there but more refined estimations continue to show it. A new measurement, from the H0LiCOW (H0 Lenses in COSMOGRAIL's Wellspring) project, estimates an expansion rate of 73 kilometers per second per megaparsec, with a 2.4 percent uncertainty.
This means that a point locater 3.3 million light-years away (one megaparsec) appears to be moving away from us at 73 kilometers per second due to the expansion of the universe. The value obtained from the cosmic microwave background, the first free-moving light in the cosmos, is instead 67 kilometers per second per megaparsec. The difference between the two is significant enough to put a big question mark on what we know.
"If these results do not agree, it may be a hint that we do not yet fully understand how matter and energy evolved over time, particularly at early times," H0LiCOW team leader Sherry Suyu of the Max Planck Institute for Astrophysics in Germany, the Technical University of Munich, and the Academia Sinica Institute of Astronomy and Astrophysics in Taipei, Taiwan, said in a statement.
The measurement was achieved by studying gravitationally lensed quasars, which have already been employed in another successful discovery this week. A galaxy is a quasar when its core is so bright it outshines all the stars within itself. It is the light from these that encounter the space-time distortion created by massive foreground galaxies.