A spooky review

For Halloween here is a brief review of the various spooky entities that exist in theoretical physics!

The Ghosts

Ghosts are sort of a catch-all term for unphysical objects in various theories. In particular, the Faddev-Popov ghosts.

In BRST quantization, Fadeev-Popov ghosts

Phantom fields

Phantom fields are a variety of fields for which the kinetic energy is negative

The Demons

Demons refer to a variety of physically-violating entities mostly used in thought experiments. The two most famous ones being Laplace's demon and Maxwell's demon.

Laplace's demon is an entity which

Yet another type of demon in physics appears in the context of the Cauchy problem.

The djinns