Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bigger Rip with No Dark Energy   By studying a modified Friedmann equation which arises in an extension of
general relativity which accommodates a time-dependent fundamental length
$L(t)$, we consider cosmological models where the scale factor diverges with an
essential singularity at a finite future time. Such models have no dark energy
in the conventional sense of energy possessing a truly simple pressure-energy
relationship. Data on supernovae restrict the time from the present until the
Rip to be generically longer than the current age of the Universe.

19
The categories of this paper are: eess
2
The categories of this paper are: math
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
14
The categories of this paper are: math-ph