So, we know that the state of quantum vacuum does carry energy, as it was measured in the Casimir effect. This energy comes from particles almost instantaneous creation and annihilation. Even if they only exist for a short time, those particle are, for instance, in two possible states, e.g. if $e^-$ and $e^+$ are created, then they can be either in $$ |e^-, \uparrow; e^+, \downarrow \rangle $$ or $$ |e^-, \downarrow; e^+, \uparrow \rangle $$ Or in general a superposition of the two. Then, for a very brief moment, the system has a finite entropy(something like $\ln(2) $).
What you guys think about this?
[UPDATE] It is probably right to state that empty space carry no entropy, since it is a pure quantum state, $S = \text{Tr} (\rho \ln \rho) $. However, to add a bit to the question, i did some research, and found this paper on Casimir entropy, where they calculate the entropy of the Casimir effect. Their calculation proves that the force between the plates is of entropic nature, simply because the particles created inside the plates are constrained on the wavelength.
In this paper, they calculate the entropy of a black hole, and it turns out that most of this entropy comes from 'vacuum'.
No comments:
Post a Comment