Looking for an explanation/definition of a "causal diamond"

[Jimster41]

hopefully something a little better than the wiki etc. What does a "deformed" one look like, or one drawn in the case of EPR, entanglement etc.

 

[atyy]

Scott Aaronson has an explanation http://www.scottaaronson.com/democritus/lec20.html with a picture of the causal diamond.

"Bousso formalizes this notion with what he calls a "causal diamond," but I'd just call it a computation with an input and an output. The idea is you have some starting point P and some endpoint Q, and then you look at the intersection of the forward light-cone of P and the past light-cone of Q. That's a causal diamond. The idea is that for any experiment we could actually perform—any computation we could actually do—we're going to have to have some starting point of the experiment, and some end point where you collect the data (read the output). What's relevant isn't the total amount of entropy in the universe, but just the total amount of entropy that can be contained in one of these causal diamonds."

 

[naima]

If P and Q are the birth and the death of the observer, the diamond's surface is an horizon for him. He will follow a line which cannot skip behind this horizon.
Even if there is no acceleration,Roveli writes that a temperature has to be associated to this non eternal observer.
If you see no thermal bath it is because you are eternal!