The idea stems from a subtle effect of quantum physics demonstrated by the Einstein-Podolsky-Rosen (EPR) experiment. One of the basic properties of quantum objects is that their behavior isn't predetermined. The statistical behavior of a quantum system is governed by the laws of quantum theory, but the specific outcome of a particular measurement is indefinite until it's actually performed. This behavior manifests itself in things such as particle-wave duality, where photons and electrons can sometimes behave like particles and sometimes like waves.
One of the more subtle effects related to this property is known as entanglement, when two quantum objects have some kind of connection that allows you to gain information about object A by only interacting with object B. As a basic example, suppose I took a pair of shoes and sent one shoe to my brother in Cleveland, and the other to my sister in Albuquerque. Knowing what a prankster I am, when my sister opens the package and finds a left shoe, she immediately knows her brother was sent the right one. The fact that shoes come in pairs means they are an "entangled" system.
The difference between shoes and quantum entanglement is that the shoes already had a destined outcome. When I mailed the shoes days earlier, the die was already cast. Even if I didn't know which shoe I sent to my brother and sister, I definitely sent one or the other, and there was always a particular shoe in each box. My sister couldn't have opened the box to find a slipper.
But with quantum entanglement, slippers are possible. In the quantum world, it would be like mailing the boxes where all I know is that they form a pair. It could be shoes, gloves or socks, and neither I nor my siblings would know what the boxes contain until one of them opens a box. But the moment my brother opens the box and finds a left-handed glove, he immediately knows our dear sister will be receiving its right-handed mate. TO READ MORE, CLICK HERE...
