Humans tend to think they have a pretty good handle on how the physical world operates, but things get unspeakably weird at the small scale. Particles aren’t always particles, and sometimes those particles (or waves) behave in bizarre, counterintuitive ways. One of the strangest features of physics is quantum entanglement, and scientists from the University of Glasgow have just captured the first photo demonstrating the effect.
When two particles or molecules become entangled on a quantum level, they share one or more properties such as spin, polarization, or momentum. This effect persists even if you move one of the entangled objects far away from the other. Einstein famously called entanglement “spooky action at a distance.” Einstein felt the existence of entanglement meant there were gaping holes in quantum mechanical theory.
Scientists have successfully demonstrated quantum entanglement with photos, electrons, molecules of various sizes, and even very small diamonds. The University of Glasgow study is the first ever to capture visual evidence of entanglement, though. The experiment used photons in entangled pairs and measured the phase of the particles — this is known as a Bell entanglement.