Zombie physics: 6 baffling results that just won't die

To celebrate Halloween, Nature brings you the undead results that physicists can neither prove — nor lay to rest.

When a scientific result seems to show something genuinely new, subsequent experiments are supposed to either confirm it — triggering a textbook rewrite — or show it to be a measurement anomaly or experimental blunder. But some findings seem to remain forever stuck in the middle ground between light and shadow. Even efforts to replicate these results — normally science’s equivalent of Valyrian steel — have little effect. Welcome to the realm of undead physics.

Ahead of Halloween, Nature guides you through some findings in physics, astronomy and cosmology that researchers have repeatedly left for dead — only to find that they keep coming back.