A new experiment suggests that reality can split into multiple intertwined timelines, a phenomenon termed “entangled histories”. Choose Your Own Adventure books are fun, but they let readers choose only one version of events at a time. Quantum mechanics, a new experiment suggests, requires that multiple adventures occur simultaneously to create a consistent account of history. Nobel laureate Frank Wilczek at MIT and colleague Jordan Cotler, now at Stanford University, provide evidence for what they call entangled histories in a paper posted online January 12 at arXiv.org. The researchers proposed and collaborated on an experiment that started and ended by measuring a particular property of a photon; in between, the experimenters subtly probed the photon without disturbing its delicate quantum state. The head-scratching result was that there was no way to create a single chronology that could describe how the photon changed. Instead, there must be multiple chronologies that are entangled, sharing a quantum connection usually reserved for groups of particles rather than chunks of time. “There really is something very deep going on here about the nature of quantum mechanics and time”, Cotler says. “Our best description of the past is not a fixed chronology but multiple chronologies that are intertwined with each other”.
In other words a single chronology is insufficient to explain the observed changes in the properties of a particle. Just as the understanding of an entangled particle is impossible without considering its partner, the history of a particle could be incomplete without the existence of multiple entangled timelines. 
Many worlds? Or many histories?
Many particles? Or one particle?
One possibility? Or a magnitude of probabilities?
Parmenides just saw One.
We broke that One into pieces.
And now we understand that we cannot describe the world unless we bring the pieces together…