1983 paper on entanglement entropy: "On the Entropy of the Vacuum outside a Horizon"

Abstract

I introduce the concept of *entanglement entropy* (as it's now called) and point out that it follows an *area law* which renders it a suitable source of black hole entropy. I also suggest to conceive the latter as residing on the horizon at approximately one bit per "Planckian plaquette".

This is a verbatim copy of a paper published originally in 1983, before the existence of "arXiv". Also available at http://www.pitp.ca/personal/rsorkin/some.papers/31.padova.entropy.pdf