The Planck mission’s data put a kink in precision cosmology
Milky Way: Serge Brunier/ESO; Gaia: D. Ducros /ESA
For as long as humans have wondered about it, the universe has concealed its vital statistics — its age, its weight, its size, its composition. By the opening of the 21st century, though, experts began trumpeting a new era of precision cosmology. No longer do cosmologists argue about whether the universe is 10 billion or 20 billion years old — it was born 13.8 billion years ago. Pie charts now depict a precise recipe for the different relative amounts of matter and energy in the cosmos. And astronomers recently reached agreement over just how fast the universe is growing, settling a controversy born back in 1929 when Edwin Hubble discovered that expansion.
Except now the smooth path to a precisely described cosmos has hit a bit of a snag. A new measurement of the speed of the universe’s expansion from the European Space Agency’s Planck satellite doesn’t match the best data from previous methods (