Time's Arrow. For whatever reasons, perhaps for
“magical” ones, an asymmetry, when pronounced, can
be perturbing, both to our reason and to our psyche;
and nothing can be more, or more universally perturb-
ing than the asymmetry of time, which cosmology and
evolution like to call the arrow of time, and physics
its irreversibility.
When Saint Augustine asked, as others had already
asked before him, what God had been doing before
creating the world, his query was a challenge to creed
and theology. But when Schoolmen, believers in Crea-
tion, asked the parallel question how and why God
had chosen to create the world at the instant of time
at which he had done so, then this question was not
addressed to theology only, but, in a sense, to scientific
reasoning too. In the twentieth century updated ver-
sions of this question arise in any evolutionary theory
of cosmology as well, especially when there is seem-
ingly conflicting evidence that the evolutionary process
might have started ten, or thirteen, or fifteen billion
years ago. Most importantly, however, while in our
stream of consciousness and variety of experience,
especially experience of and in the mind, there is a
qualitative difference between “past” and “future,”
“before” and “after,” yet there is also great need—in
any kind of organized knowledge, scientific or his-
torical, legal or medical, ethical or religious—for the
representation of time on a geometrically interpreted
time axis, on which the present is a point, and past
and future are half lines that are bilaterally symmetric
with regard to this point. And bilateral symmetry, in
its mathematical conception, does not provide for a
distinction of the two halves that are symmetrically
opposed to each other or paired with each other.
The philosopher Henri Bergson was very insistent
that, because of this trait and of related ones, geo-
metrically controlled time be banished from the pre-
cincts of his élan vital and évolution créatrice and
the related vitalistic manifestations. Bergson never
seriously proposed to show how to keep this geometri-
cally controlled time from intruding into the precincts
of his vital processes. But even if he had done so
successfully, the problem of the symmetry and
asymmetry of time within the general intellectual cli-
mate of our time would not have been thereby resolved
by half, because the problem is fully encountered in
exact science, even in the case of physics itself. In fact,
nineteenth-century physics arrived at conclusions
which as a package were ill-assorted, and physicists
around 1900 were discomfited by them. The following
were several of the items of the odd assortment.
(1) Some physical processes are reversible, meaning
that it is theoretically possible—though perhaps none
too probable—that they be run totally in reverse, as
when a movie is shown backwards. Of such kind are
all purely mechanical processes that, schematically, do
not involve the macroscopic production and propaga-
tion of heat.
(2) However, the creation and propagation of heat
is irreversible, meaning that a physical process in a
closed system involving them cannot be totally re-
versed so as to restore the initial situation in its
entirety. Rudolf J. E. Clausius also introduced (1850)
a quantitative measure of irreversibility which he
termed entropy, and he posited the so-called second
law of thermodynamics by which for a closed physical
system the total entropy of the system cannot decrease
in time but only increase or at most remain constant.
(3) And yet, the nineteenth century also erected the
“kinetic theory of matter” which, qualitatively and
quantitatively, interpreted thermal energy in terms of
mechanical motions and collision of molecules. Now,
mechanical processes of this kind are totally reversible,
and
It was recognized as paradoxical that the completely re-
versible gas model of the kinetic theory was apparently able
to explain irreversible processes, i.e., phenomena whose
development shows a definite direction in time
(Ehrenfest,
p. 13).
This paradox was somehow overcome (Ehrenfest, p.
3) by an argument from probability. There is in the
argument a step that is intuitive, but, in full, the argu-
ment is “technical,” and a faint residue of discomfort
seems to linger on. Also, a parallel difficulty, if not
a paradox, from the organic world picture remains, and
it is the following.
(4) If the second law of thermodynamics is presumed
to apply to the entire universe as one physical system,
as physics around 1900 was bound to presume, then
the total entropy of the system must be constantly on
the increase. However, “entropy also measures the
randomness or lack of orderliness of the system, the
greater the randomness the greater the entropy” (Blum,
p. 15). On the other hand,
Living organisms represent systems that are highly
“organized”, that is, they display less randomness than the
materials from which they are “built”; and it is therefore
justifiable to say that a decrease in entropy is involved in
their building
(Blum, p. 99).
Thus, whenever a form or unit of life comes into being
on any spot of the universe then any such occurrence,
taken by itself, runs counter to the general trend to-
wards an increase of the entropy, and, in fact,
... the small local decrease in entropy represented in the
building of the organism is coupled with a much larger
increase in the entropy of the universe
(ibid.).
In sum, since any organization of parts and phenomena
of the universe represents, in some appropriate sense,
the creation of design and symmetry in the order of
the universe, and randomness represents the opposite
of design and symmetry, therefore, by the second law
of thermodynamics, that is, by the arrow of time, the
order of the universe cannot but gradually disintegrate
and dissolve. It is true that in the immediate vicinity
of a rise of life there is a preservation and even a small
strengthening of the symmetry. But these features are
confined by location, and fleeting by duration, and they
are compensated for by an acceleration of the process
of decline in the remainder of the universe.
In the twentieth century it has been difficult to
reconcile this bleak vista with the outlook of most
cosmological theories emerging, even when no tech-
nical inconsistencies could be argued. An even greater
difficulty, from entropy, is posed by any theory of a
cosmogonic creation of the universe, assuming as most
theories do, that there really was a Creation. In theories
of today—as in fact, much more naively, in the theories
of the pre-Socratics—almost any cosmogonic theory
of creation starts out with a physical state in which
there is some kind of turbulence, or less systematically,
turbulent disorder, or at least formlessness. Out of this
initial state develops some kind of gaseous or galactic
organization on a comprehensive universal scale, and
together with this various standard physical processes
begin to take place, some reversible and some
irreversible. How all this could accord with the second
law of thermodynamics nobody dares to suggest, but
there seems to be an understanding among cosmologists
in the second half of the twentieth century not to allow
this difficulty to prevent speculation.
