Long, long ago... a cosmic heatwave

摘要

Climate change doesn't just happen on Earth. Billions of years ago, a heatwave struck the universe, leaving its imprint in the light from distant galaxies. George Becker of the University of Cambridge and colleagues studied the light coming from galaxies at different times in the universe's history. Dark lines in the spectra mark where certain wavelengths have been absorbed by clouds of gas as the light travels to Earth. The hotter the gas, the more blurred these lines become.