TEK IMAGE/SCIENCE PHOTO LIBRARY
The quantum world keeps getting bigger. An experiment on crystals made from 10 billion atoms proves that even relatively large objects follow the weird rules of quantum mechanics.
One such rule is entanglement: the properties of two particles can be linked together so that changing one affects the other in what Einstein called “spooky action at a distance”.
A standard test for entanglement is Bell’s inequality, which sets a limit on how often two particles can end up in the same state by chance, with no …