Summary: The study of astronomy is an old one, but as headlines show, it is a constantly changing field. As our instruments change, we discover that the numbers we thought we knew need some readjustment. In this case, the Gaia space craft from the esa is forcing astronomers to look about the expansion rate of the universe. Again.
This is not the first time there have been some discrepancies in the estimate for the age of the universe. But Gaia is one of the most precise telescopes we have at the moment. Just recently it published precise coordinated for one billion stars. This is leaps ahead of the last survey of this type.
Gaia's estimate of the age of the universe is based upon Cepheid variable stars. These stars pulse with a very specific brightness and rate of pulsation. This makes it easier to tell how far away they are from us and to determine the age of the stars nearby. Gaia has precisely found 212 of these Cepheid stars and with these data, Professor Reiss's team calculates a Hubble constant of 73km/Mpc. This is about the same as they calculated with Hubble data. But it is not the same number found in most textbooks as the accepted value. And it is not due to outdated textbooks. It is because of the methods used to solve for the Hubble constant. The Planck mission gives a much lower value of 66.9km/Mpc.
Why is there such a discrepancy? We aren't entirely sure, but we can probably place a lot of the blame on dark matter. Hopefully as Gaia continues forward on it's mission, we will be able to narrow down the range of possible Hubble constants, and thus the age of the universe and no longer have a few hundred million year gap. Maybe we will even be able to place stricter bounds on what dark matter actually is and what effect it has on our universe.
Source
Also, the Ig Nobel prizes were awarded this week and they are, as always, amazing.
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