# entanglement

adding page after watching einstein quantum riddle (doc).. so first part esp .. really about quantum entanglement i guess..

https://en.wikipedia.org/wiki/Quantum_entanglement

**Quantum entanglement** is a physical phenomenon that occurs when pairs or groups of particles are generated, interact, or share spatial proximity in ways such that the **quantum** state of each particle cannot be described independently of the state of the others, even when the particles are separated by a large distance.

*Measurements of physical properties such as position, momentum, spin, and polarization, performed on entangled particles are found to be perfectly correlated*.

*Einstein and others considered such behavior to be impossible, as it violated the local realism view of causality (Einstein referring to it as “spooky action at a distance”) ^{} and argued that the accepted formulation of quantum mechanics must therefore be incomplete.*

*The utilization of entanglement in communication and computation is a very active area of research.*

*An entangled system is defined to be one whose quantum state cannot be factored as a product of states of its local constituents; that is to say, they are not individual particles but are an inseparable whole. In entanglement, one constituent cannot be fully described without considering the other(s). *

*In this section, the entropy of a mixed state is discussed as well as how it can be viewed as a measure of quantum entanglement… Most (but not all) of these entanglement measures reduce for pure states to entanglement entropy, and are difficult (NP-hard) to compute*

from film:

## 51 min – (sean carroll @seanmcarroll):

truly understanding quantum mechanics will only happen when we put ourselves on the entanglement side.. and stop privileging the world that we see and start thinking about the world as it actually is

see page on doc for more

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