The largest map of the cosmos hints that dark energy is changing. It could prove Einstein wrong and upend a pillar of modern physics.

• For decades, astronomers have puzzled over dark energy and why it's pushing our universe apart.
• New data from the largest 3-D map of our universe suggests we may be wrong about dark energy.
• Dark energy was thought to be an unchanging force, but it may not be so constant, after all.

Scientists have constructed the largest 3-D map of our universe to date, and it's come with a couple of interesting surprises.