Albert Einstein made more contributions to our understanding of the universe as a whole than any other single person, but he wasn’t perfect. Einstein was never a fan of quantum theory, and his calculations often contradict the work of more contemporary physicists. According to a report from Time, it appears as though decades of quantum research have begun to leave much of Einstein’s work behind.

Quantum theory is bizarre. Difficult to grasp for even some of the leading researchers in the field, a single object can exist in more than one state at once. A particle can have two different positions, orientations, and charges at the same time, but will only explicitly reveal one of the states once it has been observed or measured.

Recent research into the theory of quantum entanglement is even stranger. It suggests that two particles, miles, or even light-years apart, can be linked by their quantum state. If a particle on one end of the universe switches its orientation, another particle at the complete opposite side would instantly change as well, and vice-versa.

Perhaps the most important discovery made through quantum research is that the galactic speed limit, the speed of light, may not be so strictly enforced after all. This was one of the main tenets of Einstein’s work, and calls a number of his theories into question once it is no longer a given.

Einstein was never much of a fan of quantum theory, and he particularly disagreed with the idea of quantum entanglement. He believed that it was possible for some sort of field or wave to affect a particle on the opposite side of the universe, but it was regulated by the speed of light. This would suggest that the particle would not change instantly, but after however many light years it took the signal to reach its companion particle. If two particles were a million light years apart, for example, it would take a million years for the change of one particle to affect the other.

Einstein dismissed the idea of quantum entanglement as a kind of “spooky action at a distance,” and largely left it alone in his work. A new experiment from researchers at the Delft University of Technology in Holland suggests that the idea may be more of a reality than we once thought.

Einstein’s silver bullet for dispelling quantum entanglement was his theory of local-realism, which stated that a signal from any sender to any receiver would travel no faster than the speed of light, and that the outcome of the transmission could be determined before it was complete.