Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Is dark energy meaningless?   We show that there are isometrically nonequivalent Robertson-Walker metrics
which have the same set of geodesics. While one of these metrics satisfies the
Einstein equations of pure dust without a cosmological constant, all the other
describe pure dust with additional energy momentum tensor of cosmological
constant type. Since each of these metrics have the same geodesics it is not
clear how to distinguish experimentally between the Universes whose energy
momentum tensor includes or not the cosmological constant type term.

6
The categories of this paper are: astro-ph
9
The categories of this paper are: nlin
28
The categories of this paper are: alg-geom
13
The categories of this paper are: quant-ph
14
The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex