Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Combinatorial Dark Energy   In this paper, we give a conceptual explanation of dark energy as a small
negative residual scalar curvature present even in empty spacetime. This
curvature ultimately results from postulating a discrete spacetime geometry,
very closely related to that used in the dynamical triangulations approach to
quantum gravity. In this model, there are no states which have total scalar
curvature exactly zero. Moreover, numerical evidence in dimension three
suggests that, at a fixed volume, the number of discrete-spacetime microstates
strongly increases with decreasing curvature. Because of the resulting entropic
force, any dynamics which push empty spacetime strongly toward zero scalar
curvature would instead produce typically observed states with a small negative
curvature. This provides a natural explanation for the empirically observed
small positive value for the cosmological constant (Lambda is about 10^(-121)
in Planck units.) In fact, we derive the very rough estimate Lambda=10^(-187)
from a simple model containing only the two (highly-degenerate) quantum states
with total scalar-curvature closest to zero.

23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
6
The categories of this paper are: astro-ph
0
The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph