Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Backflow in relativistic wave equations   We show that, contrary to the statements made by many authors, the backflow
is not a nonclassical effect. The backflow is a characteristic feature of
solutions of the wave equations: quantum and classical. We present simple
solutions of the Dirac equation, Maxwell equations and equations of linearized
gravity where the backflow phenomenon is clearly seen. In this work we describe
backflow in relativistic theories but this phenomenon can occur in the
solutions of all kinds of wave equations: quantum and classical.

1
The categories of this paper are: cs
18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
14
The categories of this paper are: math-ph
4
The categories of this paper are: cond-mat
33
The categories of this paper are: plasm-ph