
The Most Shocking Discovery in Astrophysics Is 25 Years Old
A quarter of a century after detecting dark energy, scientists are still trying to figure out what it is
A quarter of a century after detecting dark energy, scientists are still trying to figure out what it is
After years of delay, the most ambitious observatory ever built has at last left Earth. It now faces a high-stakes series of deployments in deep space
Two divergent measurements of how fast the universe is expanding cannot both be right. Something must give—but what?