Improvements in data may help address discrepancy in universe’s expansion rate

New Scientist : A new study reveals a disparity between the two leading methods for calculating the rate of expansion of the universe. Adam Riess of the Space Telescope Science Institute in Baltimore, Maryland, and his colleagues compared the two best techniques—looking at the size of the temperature fluctuations in the cosmic microwave background (CMB) and measuring the rate at which distant galaxies are receding. The receding galaxies method, which Riess pioneered in the 1990s, implies that the universe is expanding 9% faster than theoretical estimates based on CMB data suggest. The researchers say that discrepancies in the CMB data may be to blame. If so, newer equipment and measuring techniques should resolve the problem. If the models prove to be accurate, however, the discrepancy could indicate that changes need to be made to our understanding of the laws of physics; for example, dark energy may be growing denser.