A map of the CMB published by ACT researchers. Research by the Atacama Cosmology Telescope collaboration has led to the clearest and most precise images yet of the universe’s infancy, the cosmic microwave background radiation that was visible only 380,000 years after the Big Bang. Image credits: ACT Collaboration; ESA/Planck Collaboration.

Cosmic microwave background data support cosmology’s standard model but retain a mystery about the universe’s expansion rate.