Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Can Quantum Gravitational Effects Influence the Entire History of the
  Universe?   In this work, a flat Friedmann-Robertson-Walker (FRW) universe with dust and
a cosmological constant is quantized. By means of a canonical transformation,
the classical Hamiltonian is reduced to that of either a harmonic oscillator or
anti-oscillator, depending on whether $\Lambda<0$ or $\Lambda>0$, respectively.
In this way exact solutions to the Wheeler-DeWitt equation can easily be
obtained. It turns out that a positive cosmological constant alone may account
for an early inflationary regime and a later accelerated expansion phase, with
a period of decelerated expansion in between. This suggests that quantum
gravitational effects can influence most of the history or even the entire
history of the Universe.

29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
4
The categories of this paper are: cond-mat
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas