Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: How to detect an anti-spacetime   Is it possible, in principle, to measure the sign of the Lapse? We show that
fermion dynamics distinguishes spacetimes having the same metric but different
tetrads, for instance a Lapse with opposite sign. This sign might be a physical
quantity not captured by the metric. We discuss its possible role in quantum
gravity.

31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
4
The categories of this paper are: cond-mat