Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Possibility of Building a Black Hole for Electrons in the
  Laboratory   We point out in this work that if our recently proposed unified description
of gravitation and electromagnetism through a symmetric metric tensor is true,
then building in the laboratory black holes for electrons with radii r_E\ge
0.5m in air and with much smaller radii in a vacuum should be possible.

21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
17
The categories of this paper are: q-fin