Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Flow of Time   Current theoretical physics suggests the flow of time is an illusion: the
entire universe just is, with no special meaning attached to the present time.
This paper points out that this view, in essence represented by usual
space-time diagrams, is based on time-reversible microphysical laws, which fail
to capture essential features of the time-irreversible nature of decoherence
and the quantum measurement process, as well as macro-physical behaviour and
the development of emergent complex systems, including life, which exist in the
real universe. When these are taken into account, the unchanging block universe
view of spacetime is best replaced by an evolving block universe which extends
as time evolves, with the potential of the future continually becoming the
certainty of the past; spacetime itself evolves, as do the entities within it.
However this time evolution is not related to any preferred surfaces in
spacetime; rather it is associated with the evolution of proper time along
families of world lines. The default state of fundamental physics should not be
taken to be a time irreversible evolution of physical states: it is an ongoing
irreversible development of time itself.

13
The categories of this paper are: quant-ph
4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
24
The categories of this paper are: dg-ga
1
The categories of this paper are: cs
2
The categories of this paper are: math
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
11
The categories of this paper are: hep-lat