## 1. Overview: Cosmology, theology and religion



Christianity and other monotheistic religions (Islam and Judaism)
assume a transcendent and sovereign God who created the universe and
continually maintains its existence. The world only exists because of
an ultimate and supernatural cause which is, as Newton said,
"not blind and fortuitous, but very well skilled in Mechanicks
and Geometry" (Cohen 1978, 282). Whether in a general
philosophical sense or in a scientific sense, cosmology has always
been part of theism, but it is only relatively recently that cosmology
based on physics and astronomy has entered the discussion concerning
the existence and role of God. A limited application of physics to the
study of the universe can be found in the second half of the
nineteenth century when the cosmological consequences of the law of
entropy increase were eagerly discussed in relation to the Christian
doctrines of a world with a beginning and end in time. However,
physical cosmology is essentially a twentieth century science which
emerged as a result of the discovery about 1930 that the universe is
in a state of expansion that possibly started a finite time ago.
Cosmology as a subdiscipline of physics differs in some respects from
mathematical, philosophical and classical observational cosmology, but
of course the different approaches are in constant interaction. In a
modern sense, physical cosmology became established after the
discovery of the cosmic microwave background in 1965 which quickly
turned the hot big bang model into the standard model of the universe.
Jim Peebles' *Physical Cosmology* of 1971, possibly the
first book with this title, may be taken as the beginning of modern
physical cosmology.



Although physical cosmology based on general relativity theory and
elementary particle physics is thus a modern science, many of the
theologically relevant questions related to current cosmology are old.
Did the universe come into existence a finite time ago? Will it come
to an end? Why are the cosmic evolution and the laws of nature of just
such a kind that they permit intelligent life to exist? These and
other questions of obvious relevance to theism are currently being
discussed in the light of the most recent cosmological theories and
observations, but the questions themselves (and, indeed, many of the
answers) were familiar to medieval philosophers and theologians. This
is also the case with the question that is sometimes considered the
ultimate one: Why is there a cosmos? There is no reason to expect that
today's advanced physical cosmology, or the even more advanced
of tomorrow, will provide final answers that satisfy theists and
atheists alike.


## 2. Creation and the big bang



Einstein's general theory of relativity shows that the structure
of spacetime is itself a dynamical variable, subject to causal
influence by the material constituents of the universe. Indeed,
Einstein immediately saw the potential to apply general relativity to
large-scale cosmological questions. The first cosmological model of
Einstein (1917) described a static universe, i.e. one whose spatial
geometry is constant over time. However, Einstein's static
universe was empirically inadequate: it could not account for the
redshift data gathered by Edwin Hubble and others in the 1920s. The
redshift data indicated that distant stars are moving away from us,
and moving faster in direct proportion to their distance. Thus, the
data indicated an expanding universe.



In the 1920s and 1930s, a number of cosmological models of general
relativity were proposed that predict the expansion of the universe.
The most accurate account of the data is given by the family of
Friedmann-Robertson-Walker (FRW) models. The key characteristic of
these models is that space is *homogeneous*, and hence
isotropic (i.e. looks the same in all directions). From the
homogeneity assumption, it follows that the entire 4-dimensional
spacetime divides neatly into a stack of 3-dimensional
"spaces" each of which has constant curvature. The three
possibilities for this curvature correspond to the three classical
geometries: Euclidean (flat), spherical (positive), or hyperbolic
(negative). In a given FRW spacetime, the geometry of space at one
time is related to the geometry at any other time by means of a scale
factor *S*(*t*). Indeed, pick a reference time *T*,
such as 2021, pick two reference galaxies, and let *d*(*T*)
be the distance between these galaxies at time *T*. Then the
distance between the two galaxies at any other time *t* is given
by *d*(*t*)=*S*(*t*)*d*(*T*), where we
set *S*(*T*)=1. This number *S*(*t*) is called the
scale factor, and its behavior encodes the dynamics of a FRW
universe.



In those FRW spacetimes that can reasonably be thought to model our
cosmos (e.g., those with massive objects), the time parameter *t*
has an absolute lower bound *t*0. In particular, as
*t* decreases towards *t*0, the scale parameter
*S*(*t*) goes to zero. What happens when *t* reaches
*t*0? In short, these models cannot say what happens,
because there are *no* points of spacetime with time coordinate
*t*0. That is, *t*0 is an ideal point
that is never reached: the universe exists at all times after
*t*0, but not before or at time *t*0.
A spacetime model with this feature is called *singular*, and
the ideal point that is never reached is called a
*singularity*. In other words, the big bang is a singularity in
a FRW spacetime.



The FRW spacetimes are extremely accurate descriptions of the large
scale structure of our universe. Since these models describe a
universe with a *finite lifetime*, it is reasonable to conclude
that the universe has not always existed.



But many physicists and philosophers hesitate to draw this conclusion.
In fact, the standard view in the 1950s and early 1960s was that the
singularities of the FRW models were consequences of false idealizing
assumptions, namely assumptions of perfect isotropy and homogeneity.
But this escape route from singularities was definitely closed when
Robert Geroch, Stephen Hawking, and Roger Penrose proved the
"singularity theorems," according to which *almost
all* spacetimes are singular, and in particular, almost all
cosmological models describe a finitely old universe.



A number of theists take the past-singular nature of cosmological
models as confirmation of the claim that God created the universe
*ex nihilo*. The list of advocates of this "big bang
theology" includes Pope Pius XII, Francis Collins (director, US
National Institutes of Health), and apologists William Lane Craig and
Hugh Ross. And indeed, big bang cosmology does provide *prima
facie* support for theism. After all, big bang cosmology says that
the universe has a finite age, and (traditional) theism says that God
created the universe out of nothing. Does big bang cosmology not
confirm traditional theism? We give several reasons to be cautious
about such claims.



Advocates of big bang theology are most interested in the claim that
the universe is finitely old. Thus, the chain of inferential support
should run as follows:



> 
> Big Bang Model - *supports* - Universe Finitely Old
> - *supports* - Theism
> 



Before discussing the first supposed inferential relation, we note
that not all theists are committed to the claim that the universe is
finitely old. For example, Aquinas claims (in several places,
including the *Summa Theologica*) that Reason cannot
demonstrate the finitude of the universe. But Aquinas also thinks that
Reason can demonstrate the existence of God; therefore Aquinas does
not think that the very concept of God as creator implies that the
universe is finitely old. (Contrary to some contemporary theologians,
Aquinas claims that a Christian theist should *believe* that
the universe is finitely old. For Aquinas, the finite age of the
universe is a revealed doctrine, like the divinity of Christ.)



Contemporary theologians Arthur Peacocke and Ian Barbour also claim
that the doctrine of the "creation" of the universe is
best interpreted as one of the universe's timeless dependence on
God, and that such dependence does not demand a temporal creation
event. This is also the view of William Stoeger (2010), a Jesuit
priest and cosmologist, who argues that scientific cosmology can
purify theology but never be in conflict with what theology
legitimately asserts. For the remainder of this article, we will not
discuss further the question of whether theism requires, or strongly
supports, the claim that the universe is finitely old. (Arguments for
this claim are assessed in (Copan & Craig 2004).) For now we focus
on versions of theism that are committed--in a perhaps naive
way--to creation *ex nihilo*. Even on this understanding
of theism, there are still reasons to exercise caution in seeing the
big bang as confirming the prediction that God created the
universe.


### 2.1 Whose theism is the big bang supposed to confirm?



The big-bang theologian argues that the claim



> 
> "The universe is 13 billion years old"
> 



provides evidential support for theism. But there are many theists for
whom the discovery that the universe is 13 billion years old would
actually serve as a disconfirmation of their theistic belief. For
example, Bishop Ussher of Ireland (1581-1656) claimed to derive
from the Bible that the universe was created in 4004 B.C.; and even in
the twenty-first century, some Christian thinkers claim Biblical
warrant for an age of the universe much less than 13 billion years
(see Kelly 2000 and Byl 2001). For these thinkers, then, the big bang
would disconfirm theism--or at least their version of theism,
which is committed to the literal accuracy of the Biblical account of
creation. More strongly, it seems that Christian theism is committed
to a belief in a finitely old universe primarily on the basis of its
commitment to the accuracy of Biblical accounts of creation. Thus, if
a theist comes to believe the big-bang account of the universe's
origin, and hence to doubt the literal Biblical account, then she will
lose one reason--and possibly her only reason--for believing
that the universe is finitely old.



Of course, there are also theists who interpret Genesis metaphorically
as implying that the universe was created, but not indicating a
specific age for the universe. For these theists, finding that the
universe is finitely old might confirm rather than undermine their
belief.


### 2.2 Should the theist look for confirmation from scientific cosmology?



According to traditional Christian theism, creation *ex nihilo*
is miraculous--something which the laws of nature cannot explain.
But then why should a theist expect to be able to derive creation
*ex nihilo* from the laws of nature? Compare with other
supposed miracles, e.g., within Christianity the claim that Jesus
changed water into wine. Do Christian theists claim that chemistry
should predict that water can transform into wine? Of course not: God
is supposed to be able to transcend the laws of nature, and the laws
of nature are defeasible when it comes to describing what actually did
happen (since God could have intervened). But then couldn't the
best (most explanatory, most elegant) cosmological theory posit an
infinite past, whereas in reality God created it some finite time in
the past?



The puzzle we have just encountered trades on the special status of
cosmology as a historical, yet law-based science, with only one actual
model. While theists would certainly not expect the laws of chemistry
to predict that water can transform into wine, they do believe that an
accurate historical account would include reference to those miracles
that did occur. So, is cosmology more like history, or more like
chemistry? If God did create the universe, should a cosmological
theory report (or predict or entail) such a fact? Or should cosmology
only be required to provide laws for universes, laws which might in
fact have been broken in our universe?


### 2.3 Which cosmological models support a doctrine of creation *ex nihilo*?



Suppose that the theist takes a harder line and says that theism
requires (or favors) cosmological models with a finitely old universe.
In this case, the time parameter in our cosmological models should
never take values lower than some fixed number, which we can
conveniently set to zero.



But the interval (0,*t*) is topologically isomorphic to
([?][?],*t*), suggesting that duration of time (finite
versus infinite) might lack intrinsic physical or theological
significance. Such a point was made already by E.A. Milne in 1935, and
then independently by Charles Misner in 1969. In particular, Misner
replaces the time parameter *t* with the negative of its
logarithm (i.e., [?]log *t*) in order to assuage worries that
a bounded time parameter makes no sense. According to Misner (1969,
1331), even in models that begin with singularities, "the
Universe is meaningfully infinitely old because infinitely many things
have happened since the beginning." Interestingly,
Misner's move can hardly be motivated by a desire to obviate the
need for a creator: Misner is a self-described Catholic Christian.



The possibility that the finite/infinite time distinction is
conventional was noted by the Catholic philosopher of science Ernan
McMullin, who concludes that the theological doctrine of creation ex
nihilo must not be given a metric interpretation (McMullin 1981).
Rather, claims McMullin, the *ex nihilo* doctrine should be
interpreted order-theoretically: the time series has a first point.
But this order-theoretic criterion will not help theism, at least not
in regard to current cosmological models. On the one hand, FRW
cosmological models *fail* the order-theoretic criterion: they
have no first moment of time. On the other hand, an ideal first moment
of time could be adjoined to *any* spacetime, even those that
have a metrically infinite past (see Earman 1995). Thus, a simple
order-theoretic criterion is a bad guide to whether cosmological
models are consistent with the doctrine of creation *ex
nihilo*.



A more adequate criterion of when a cosmological model is consonant
with creation *ex nihilo* would require a detailed analysis of
singular spacetimes (for extensive discussion of the latter topic, see
Earman 1995). The best current account of when a spacetime is truly
singular (as opposed to merely being described with inadequate
coordinates) is when it contains inextendible geodesics of finite
length. Intuitively, a geodesic is the path that would be followed by
a clock in freefall. If a clock were travelling on a past-inextendible
geodesic, then at some finite time in the past, the clock did not
exist; more strongly, spacetime itself did not exist. Thus, the
big-bang theologian would do best to claim that creation *ex
nihilo* is confirmed precisely by those cosmological spacetimes
that have inextendible geodesics. (Indeed, this criterion does hold
for FRW models.) The main problem with such a proposal is that it ties
a robust, intuitive theological doctrine down to an extremely precise
technical feature of Lorentzian manifolds (as described by
differential geometry). The risk then is that by doing so, one would
add extraneous content to the theological doctrine: a future model
might fail the technical criterion while still being consistent with
the theological doctrine. Furthermore, many Christian theists claim
that core theological doctrines are perspicuous--in particularly,
not understood exclusively by an elite class of priests or scholars.
But the notion of a Lorentzian manifold having incomplete geodesics
can hardly be said to be accessible to the average layperson.


### 2.4 Can we trust General Relativity?



Finally, big-bang theology overreaches if it says that general
relativity and the singularity theorems have settled once and for all
that the universe had a beginning in time. In fact, relativistic
cosmology predicts its own invalidity for times close to a dynamic
singularity, such as the big bang. (For a dissenting opinion, see
Misner 1969.) The reason that relativistic cosmology predicts its own
own invalidity is that in the neighborhood of singularities,
gravitational effects are intense, and quantum effects can be expected
to play a predominant role. But general relativity does not
incorporate quantum effects, and indeed it is untested in such regimes
of intense gravitational force. Thus, there is little reason to
believe that the singularity theorems make a valid prediction about
the structure of a future successor theory of general relativity that
includes quantum effects. We discuss this issue further in Section
4.


### 2.5 Does the big bang provide evidence for atheism?



Most philosophers and physicists have thought that big bang cosmology
is either neutral towards, or supportive of, traditional theism. Thus,
atheists have usually taken a defensive stance, trying to defeat the
arguments of the big-bang theologians. But a vocal minority--we
might call them "big-bang atheologians"--have made
the stronger claim that big bang cosmology disconfirms theism. The
most visible proponents of this big-bang atheology are the
philosophers Adolf Grunbaum and Quentin Smith. In the case of
Smith, quantum cosmologies are taken to provide even stronger evidence
against theism.



In putting forward their arguments, big-bang atheologians make a
number of points that seem to have been overlooked by their theistic
counterparts. One such point is that FRW cosmological models have no
first state. Thus, a theist who invokes the big bang cannot say that
there is a state of the universe, say A, such that God created
the universe in state A. He or she will have to invoke a more
sophisticated notion of God creating initial temporal intervals, or
something like that. Are these more sophisticated developments still
consonant with traditional theology?



Big-bang atheologians also argue that it makes no sense to accept both
that there were no times before the big bang (since time itself comes
into existence with the universe) and that the universe was caused. Of
course, many theists claim that God causes the universe timelessly,
and they would attempt to defend the coherence of such a notion in the
face of these criticisms.



The case of quantum cosmology provides further complications for
theology. Without going into excessive detail of specific proposals, a
common theme of many quantum cosmologies is that they postulate a
probability distribution over universes themselves. In other words,
quantum cosmologies provide a measure of likelihood that certain sorts
of universes exist. Some older quantum cosmologies (e.g.,
Hawking's early proposals) still predict that the universe is
finitely old. And yet, one might consider their further explanatory
power--over and above classical general relativity--as
undermining theistic explanations of the universe. In particular,
quantum cosmology predicts with a high probability that a universe
like ours would exist. Seen from this perspective, one might take
quantum cosmologies to offer a competing, non-theistic explanation for
the origin of the universe.



Theists have argued, in response, that quantum cosmologies do not
provide *unconditional* probabilities for the existence of the
universe. For example, Craig (1997), Deltete & Guy (1997), and
Oppy (1997) argue that quantum cosmologies provide only conditional
probabilities for the existence of some universe configurations given
other universe configurations. Smith (1998) responds by defending the
claim that the probabilities in quantum cosmology are unconditional.
But neither side of this debate has attended to the special
complications involved in interpreting *quantum*, rather than
classical, probabilities. For example, Smith treats the universal
wavefunction
Ps(*h**i j*, *f*) as
providing a probability distribution over universe configurations
(*h**i j*, *f*). But we know,
from elementary quantum mechanics, that it is literally inconsistent
(i.e., leads to contradictions) to treat a wavefunction as giving
probabilities in an absolute sense. (This contradiction is derived by
the famous Kochen-Specker theorem.) We conclude that in order for the
metaphysical significance of quantum cosmologies to be assessed, a
more nuanced consideration of the interpretation of quantum mechanics
will be required.


## 3. Steady-state theories



Aristotle's cosmology belonged to the class of steady-state
theories in so far that his universe was changeless and eternal. When
Einstein in 1917 proposed the first relativistic model of the
universe, he unwittingly pictured a universe which had qualitative
features in common with Aristotle's: it was finite in space, but
infinite in time. The discovery of the expansion of the universe
excluded the steady state from relativistic cosmology, but not from
other forms of cosmology. Robert Millikan, Nobel laureate and famous
physicist, was among those who in the 1930s favored an eternally
recurrent universe with a continual creation of matter and energy to
counter the increase of entropy. He thought that such an eternal and
evolving universe revealed the creator's continual activity and
explicitly presented his cosmological view as support for the
doctrines of Christianity in general and for the immanence of God in
particular.



Contrary to the earlier ideas of a steady-state universe, the theory
that Fred Hoyle, Hermann Bondi and Thomas Gold introduced in 1948
accepted that the universe is expanding. Conceptually the theory was
founded on the "perfect cosmological principle," that is,
the postulate that the universe in its large-scale features is not
only spatially but also temporally homogeneous. Although this
classical steady-state theory was abandoned in the 1960s because of
its inability to account for new discoveries (such as the cosmic
microwave background and the redshifts of quasars), it remains an
instructive case in the cosmology-theology discussion. Moreover, the
theory is not quite dead yet, as some of its characteristic features
survive in the quasi-steady-state cosmology (QSSC) still defended by
Jayant Narlikar and a few other cosmologists. This model does not
satisfy the perfect cosmological principle, but it assumes an
indefinite cosmic time scale during which matter is continually
created. In this respect it is an alternative to the big-bang theory
and its supposed association with divine creation. In 1994, at a time
when he was developing the QSSC model, Hoyle referred to big-bang
cosmology as "a form of religious fundamentalism" (Hoyle
1994, 413). According to the classical steady-state theory, the
universe has expanded for an infinity of time and will continue to do
so for ever; yet the average density of matter remains constant
because matter, or rather matter-energy, is continually being created
out of nothing. (In later versions of the theory, matter creation was
not *ex nihilo*.) Both features--the infinite time scale
and the continuous creation of matter--were controversial and
caused concern of a philosophical and also a theological nature.



It was widely assumed in the 1950s that the steady-state universe was
contrary to theism or at least made God superfluous as a creator of
the cosmos. After all, how can God have created a universe which has
existed in an infinity of time? According to the astronomer, science
popularizer and non-believer Carl Sagan, "this is one
conceivable finding of science that could disprove a
Creator--because an infinitely old universe would never have been
created" (1997, 265). However, although the argument may seem to
pose a real problem for theism, the theologians were well
prepared--it had been discussed since the thirteenth century when
Thomas Aquinas suggested that God could indeed have created an
infinitely old universe. Moreover, theological responses to an
infinitely old universe were far from new, for they had already been
developed in relation to eternally cyclic models, either in the more
speculative versions of the nineteenth century or the relativistic
models that were proposed in the 1930s onwards.



According to the Thomistic doctrine of *creatio continuans*,
God causes things to exist in the sense that their existence depends
wholly on his power. If they were left to themselves they would turn
into, or return into, nothingness. From this point of view creation is
basically a metaphysical rather than a physical and temporal concept,
and an eternal yet created universe is perfectly possible.
Interestingly, the leading steady-state physicist William McCrea was
also a devout Christian who argued that cosmology, in whatever form,
must necessarily include the postulation of a divine creator. As
theologians in the 1950s, both Protestants and Catholics, were quick
to point out, Hoyle's eternal universe was not particularly
heretical, for it was still in need of a creator. Not only did they
mobilize the old concept of continual divine creation, emphasizing
that cosmic creation is primarily about the ontological dependence of
the world on God, they also stressed that faith in God has little to
do with physical cosmology in whatever of its versions. Erich Mascall,
a priest and philosopher of religion, saw no reason why the
steady-state model should cause worry among the faithful. As he said
in 1956, "The whole question whether the world had a beginning
or not is, in the last resort, profoundly unimportant for
theology" (Mascall 1956, 155).



Views similar to Mascall's have been held by many later
theologians and Christian philosophers, but not by all. There is
disagreement about how solidly based in the Bible the concept of
atemporal continual creation is, and also about the significance of an
absolute beginning of the world (for opposite views, see Copan and
Craig 2004 and May 1994). The view that cosmology is essentially
irrelevant to Christian belief has not gone uncontested. As Ernan
McMullin has pointed out, Christian doctrines are more than
metaphysics and codes for moral conduct; they are also cosmic claims
that say something about the universe and what it contains of things.
For this reason theologians need to pay attention to cosmology in
particular and to science in general.



Some Christian scientists and philosophers have seen the continual
creation of matter, as posited by the steady-state theory, as a
manifestation of perpetual divine creation. Thus, the Catholic
philosopher Philip Quinn (1993) adopted the old notion of creatio
continuans to the case of steady-state cosmology. The argument is
essentially that since *ex nihilo* creation of matter violates
energy conservation, there must be an external creative cause that
accounts for the violation, and this cause he identifies with
perpetual divine creation. This kind of reasoning has been severely
criticized by Adolf Grunbaum, who flatly dismisses the claim that
underlies the idea of perpetual divine creation, namely that
nothingness is the natural state of the universe. This claim has also
been argued in detail by Richard Swinburne (1996), who finds it
extraordinary that there exists anything at all and from the fact that
something exists infers the existence of God. But according to
Grunbaum there is no room for divine creation in either big-bang
or steady-state cosmology. "Steady-state cosmology," he
concludes, "is indeed *logically incompatible* with [the]
claim that divine creative intervention is causally necessary for the
nonconservative popping into existence of new matter in the
steady-state universe" (Grunbaum 1996, 529).



Whereas steady-state cosmology is at least problematical from the
point of view of traditional theology, it goes well together with the
ideas of process theology or philosophy, where God is seen as
interacting creatively and incessantly with natural processes. In a
general sense, Whitehead's philosophy is more in harmony with
the steady state than the big bang universe. The prominent British
astronomer Bernard Lovell (1959), a devoted Christian inspired by
process thinking, was in sympathy with the steady-state theory and saw
no reason why it should be a threat to belief in a divine being. To
him, the creation of matter was a sure sign of God's
activity.


## 4. Quantum and string cosmologies



As we mentioned previously, there are reasons to suspect the
invalidity of classical general relativity in regions near a
singularity--most importantly, for times very close to the big
bang. In particular, when lengths are very small, and curvature and
temperatures are very high, then--if the gravitational force
behaves like all other known forces of nature--quantum effects
will take over, and we should accordingly expect different outcomes.
This observation is itself sufficient to destroy the aspirations of
big-bang theology--unless there are good reasons to think that
the finite-age prediction of relativistic cosmology will be preserved
in a quantum gravity or in string theory. In this section, we briefly
review the known data about singularities in theories that attempt to
unify gravity and quantum mechanics. Our review supports two
conclusions: (1) We do not know yet if the best model will predict a
finitely old universe, but (2) there are good reasons to think that
the big bang is not necessarily an absolute beginning.



There have been a number of proposed theories of quantum cosmology.
Perhaps best known of these is the proposal of Stephen Hawking, which
results in a universe with no boundary--motivating the famous
question, "what place, then, for a creator?" The bearing
of Hawking's cosmology on theism has already been discussed
extensively by Craig & Smith (1995), Deltete & Guy (1997),
Craig (1997), and Smith (1998). But it would be ill advised to take
Hawking's theory as giving the final version of quantum
cosmology. As noted by Drees (1990), Hawking's approach is just
one among several competing attempts to incorporate quantum effects
into relativistic cosmology, and we are not compelled to accept its
idiosyncratic metaphysical picture. More to the point, Hawking's
cosmological model is *ad hoc* in the sense that it does not
flow from a more comprehensive unification of general relativity
quantum theory. In this section we turn to two cosmological theories
that do result from systematic and comprehensive unifications of
general relativity and quantum theory: loop quantum cosmology and
string cosmology.



Loop quantum cosmology (LQC) is an approach to cosmology within the
framework of the loop quantum gravity (LQG) program (Rovelli 2004),
which itself starts with the idea that unifying quantum theory and
general relativity will require "quantizing" the
gravitational field--and hence the structures of spacetime
itself. Roughly speaking, to quantize a theory means that the
quantities (e.g., position, momentum, scalar curvature, etc.) are
replaced by "matrices," or more generally with
"operators on a Hilbert space." This replacement can have
profound physical consequences, most particularly the spectrum of a
quantity (i.e., the numerical values it can possess) can become
discretized where it was previously continuous, or bounded where it
was previously unbounded, and quantities can be forced to obey a
Heisenberg uncertainty principle.



For our purposes, the important question is what happens to those
quantities (e.g., spatial curvature) that grow unboundedly large in
classical FRW spacetimes as the time parameter *t* approaches the
initial boundary time *t*0? To answer this question
requires going through intricate technicalities involving domains of
definition of operators, etc.. To summarize, however, the most
prominent proposal (championed primarily by Martin Bojowald and
collaborators; see Bojowald 2009) results in a scale parameter
*S*(*t*) that is bounded away from zero, entailing that
curvature is bounded from above. More is true: the dynamical equations
of LQC extend through the big bang, i.e., the universe existed
*before* the big bang.



It would be premature to take loop quantum cosmology as having
decisively overturned the big-bang, finite-age cosmological model.
Nonetheless, there is a non-negligible probability that it will do so
in the near future; and hence there is a non-negligible probability
that the big bang is not the beginning of the universe, and a
fortiori, not the creation event (even if there was one).



However, loop quantum gravity is not the most popular--in terms
of sheer number of researchers--approach to unifying quantum
theory and gravity. The title of most popular belongs to string
theory, and so string theory's perspective on the big bang event
is of crucial interest for those wishing to assess the bearing of
physical cosmology on traditional theological doctrines.



All indications from string cosmology point to the fact that the
universe existed before the big bang. In particular, string theory
claims that if we apply fundamental symmetry transformations to
cosmological models of the recent universe, then we get a copy of the
universe (with important quantities inverted) that might be called the
"pre-big-bang universe." In this scenario, the absolute
big bang disappears and is replaced by a saddle point in the dynamical
evolution of spacetime curvature: before this point, curvature is
increasing, and after this point, it is decreasing.



According to Gasperini (2008), string cosmology's prediction of
a pre-big-bang universe results from a principled application of
symmetry principles. Furthermore, string theory has a built in
mechanism (namely a minimum string length) that seems to rule out
singularities of infinite curvature or spatial length shrinking to
zero. As was the case in LQC, the values of physical quantities in
string theory are constrained by quantum mechanical laws; and so some
quantities that grew beyond bounds in classical theory are
well-behaved in quantized versions of that theory.



We currently lack the empirical data that would distinguish between
competing models of quantum cosmology. But these models make different
empirical predictions from each other, and they also make different
predictions from classical relativistic cosmology. Hence, it is an
empirical, rather than a metaphysical, question whether the big bang
was the beginning of the universe.



However, just as the big-bang is not unambiguously friendly to theism,
so quantum cosmology is not unambiguously hostile to theism. Indeed,
Chris Isham (1993, 405) has suggested that quantum cosmology's
description of a boundary-free universe accords quite well with
theism's insistence that God sustains the universe at all times.
(See also the discussion in Drees 1988, 1990, 1991.) Clearly, theism
has shown some flexibility in integrating its doctrines with
prevailing scientific worldviews--as evidenced, e.g., in the
integration of Aristotelian cosmology, and in the exploitation of
big-bang cosmology. Should we expect the situation to be any different
with quantum cosmology?


## 5. Other non-standard cosmologies



Apart from the quantum-based cosmologies mentioned above, there are
several other theories of the universe that differ from the generally
accepted big bang theory and are, in this sense,
"non-standard." A few of these models have been discussed
within a religious context. We shall limit ourselves to two groups of
theories, cyclic cosmologies and multiverse theories.


### 5.1 Cyclic cosmologies



Origen, a third-century Christian philosopher, speculated that God,
before he created our universe, had busied himself with the creation
of an endless series of earlier worlds. His idea of an eternal cyclic
universe was however condemned by the church and has since then
generally been regarded as associated with atheism and materialism.
Indeed, from about 1850 to 1920 the classical cyclic or recurrent
universe was popular among many atheistic thinkers who found it to be
incompatible with Christian doctrines. Nonetheless, some theists have
endorsed such a universe, e.g., Joseph Smith's claim that
"as one earth shall pass away, and the heavens thereof even so
shall another come" (Mormon Book of Moses 1:38).



Although Einstein's cosmological field equations do not justify
a series of pulsating universes, many cosmologists have suggested ways
in which a collapsing universe can reappear from a nonsingular state
and thus give birth to a new universe, perhaps ad infinitum. It should
be pointed out that Lemaitre, the cosmologist-priest, did
*not* suggest such a "Phoenix universe," in spite
of numerous claims to the opposite. In some cases atheism has been
part of the motivation for proposing singularity-free models with an
unlimited past and future. For example, the British physicist William
Bonnor considered the new big bang theory "the opportunity
Christian theology has been waiting for ever since science began to
depose religion from the minds of rational men" (Bonnor 1964,
117). His own favored candidate, a universe oscillating smoothly and
eternally between two states of finitely high density, avoided a
divine miracle and theistic exploitation of cosmology, in which
respect it was similar to the steady-state theory. Steven Weinberg
noticed the similarity: "Some cosmologists are philosophically
attracted to the oscillating model, especially because, like the
steady-state model, it nicely avoids the problem of Genesis"
(Weinberg 1977, 154).



Classical-relativistic cyclic models presupposed a closed universe
disagreeing with current observations, for which reason they are no
longer considered viable alternatives. But the twenty-first century
has witnessed several new proposals, of which we shall mention only
two: the "conformal cyclic cosmology" developed by Roger
Penrose, and the "new cyclic cosmology" developed by Paul
Steinhardt and Neil Turok.



In his theory of conformal cyclic cosmology, Penrose claims that as
the big bang is approached, massive objects play a negligible role, so
that the physics is governed by degrees of freedom that are invariant
under rescaling of lengths and times. Such degrees of freedom are
called "conformal invariants." Thus, Penrose claims, we
make a mistake to model the early universe by a Lorentzian manifold
with a metric (as is done in classical general relativity). Rather,
spacetime should be described by a *conformal manifold*, which
is essentially a conformal equivalence class of general relativistic
spacetimes. The "cyclic" part of Penrose's cosmology
comes from noticing that the future of one ever-expanding universe can
be smoothly bridged to the past of another big-bang universe by means
of such a conformal manifold. In this case, the big bang is not a true
beginning, but only a sort of phase change from one
"epoch" to another (Penrose 2010).



The new cyclic cosmology of Steinhardt and Turok develops ideas from
string theory to describe a universe without inflation going through
an endless sequence of cycles--in which case, the big bang is not
the beginning of time (Steinhardt and Turok 2007). In this respect the
model is similar to the steady-state model, and Steinhardt and Turok
have indeed described it as a "remarkable reincarnation"
of Hoyle's old theory. Although the new cyclic model has
attracted a fair amount of attention, it is not widely accepted. Nor
is this the case with the pre-big-bang bouncing cosmology advanced by
Gabriele Veneziano and Maurizio Gasperini on the basis of string
theory. According to the pre-big-bang model the universe is not only
eternal into the future, it is also eternal into the past, the two
cosmic phases (contracting and expanding) being separated by a
non-singular big bang.



Eternal bouncing models qualitatively similar to the pre-big-bang
scenario have been proposed earlier, either on the basis of the
relativistic field equations or on the idea of a plasma universe.
According to the Swedish physicist Hannes Alfven, a Nobel
laureate of 1970 who developed the latter idea, the plasma universe
was an alternative to the theistic big bang theory. Since none of the
models considered in this section operate with an absolute beginning,
they may seem to be problematic from a theistic point of view.
However, the theist can always appeal to perpetual divine creation,
just as in the case of the steady-state universe.


### 5.2 The multiverse



The modern idea of the multiverse is theologically more controversial.
In its so-called landscape version, which since 2002 has been promoted
and developed by Leonard Susskind and many other physicists, it is
based on the apparent non-uniqueness of the equations of string
theory. The solutions of the equations describe, in a sense, possible
worlds with different physical parameters, interactions, types of
particles, and even dimensionality; the multitude of solutions are
then identified with really existing worlds which generally are
causally separate from ours. As a mechanism for generating the huge
number of universes, multiverse physicists make use of the eternal
inflation scenario. Moreover, the multiverse is closely associated
with anthropic reasoning: we find ourselves in our universe, with its
particular physical laws and content of particles, not because other
universes are impossible or improbable, but because our kind of life
cannot exist in other universes. The theory of the multiverse has
seductively great explanatory power (while it has almost no predictive
power), which is a major reason why many physicists and cosmologists
find it attractive. On the other hand, other physicists dismiss it as
pseudoscience because it is practically untestable.



It is common among supporters of the multiverse to conceive it as an
alternative to a divinely created world and ideas of natural theology.
Because it represents our universe as a chance universe, special only
by the fact that we live in it, the multiverse has been likened to
another and more famous anti-design theory, neo-Darwinianism. Weinberg
puts it as follows: "Just as Darwin and Wallace explained how
the wonderful adaption of living forms could arise without
supernatural intervention, so the string landscape may explain how the
constants of nature that we observe can take values suitable for life
without being fine-tuned by a benevolent creator" (Weinberg
2007, 39). At least to some theists, the multiverse stands in sharp
contrast to Christian belief. As Richard Swinburne sees it, "To
postulate a trillion trillion other universes, rather than one God in
order to explain the orderliness of our universe, seems the height of
irrationality" (Swinburne 1996, 68).



Swinburne joins several other philosophers and physicists in seeing
physical cosmology as providing key data for a new design argument.
The strength of such
 fine-tuning
 arguments continues to be a hotly contested issue among philosophers
(see Collins 2009, Colyvan et al. 2005, McGrew et al. 2001, White
2000).



On the other hand, there is no one-to-one correspondence between the
multiverse and belief in a divine creator. Several philosophers have
argued that if theism is true, we should expect the actual world to be
a multiverse: being a perfect being, God would create a multiverse
rather than just a single universe (Kraay 2010). It is possible to
answer affirmatively to the question, "does God love the
multiverse?", such as the physicist Don Page did at a symposium
in 2008 (see Page 2008). Even if there are 10500
universes (but not, perhaps, if
there are an infinite number of them), they could have been
providentially created by the almighty God with a purpose we cannot
fathom. Why not? It has even been suggested (by Paul Davies) that
multiverse explanations are reminiscent of divine explanations and
unintentionally reintroduce a transcendent creator.



Mormon theology differs in several respects drastically from the
theology of traditional Christianity. Not only is God personal and
held to have been created by a prior god (who was again created by a
prior god, etc.), according to the central doctrine of "eternal
progression" human beings will ultimately become like God
himself. There is an infinite number of beings and it takes an
eternity for them to become gods. Standard big bang cosmology, based
as it is on a universe of finite age, is incompatible with Mormonism,
where existence has neither beginning nor end. Whereas traditional
theologians have no problem with a universe created *ex
nihilo*, and many subscribe to this doctrine, Mormons flatly
reject it. In order to overcome the conflict with physical cosmology,
some Mormon thinkers have turned to the multiverse. Realizing that the
attempt to harmonize the Mormon dogma of eternal progression with
modern cosmology is problematic, Kirk Hagen says: "For
Mormonism, a compelling reason to consider a multiverse cosmology is
to attempt a reconciliation of modern cosmological ideas and the
central tenet of Mormon doctrine" (Hagen 2006, 28).



The anthropic principle, an integral part of multiverse cosmology, has
similarly been discussed in theological contexts and, again similarly,
without any consensus emerging from the many discussions. In its most
common version, called the weak anthropic principle, it states that
what we observe is selected by our existence in a universe with just
such properties that allow us to exist. Swinburne and some other
theists in favor of design arguments find the anthropic principle to
be, at best, unnecessary and obfuscating. To them, the values of the
cosmic parameters and constants of nature appear to be fine-tuned
because they are fine-tuned, the designer being God. The atheist
Richard Dawkins goes further, arguing that the anthropic principle is
an alternative to the design hypothesis and provides strong evidence
for a world without God. However, theists do not generally see
anthropically based arguments as a problem for a divinely created
world. William Lane Craig and John Polkinghorne are among those who
hold that the anthropic principle is compatible with divine design and
can even be seen as indirect support for theism. According to the
South-African cosmologist (and Quaker) George Ellis, anthropic
fine-tuning is the result of a purposeful design of the universe. He
has suggested a "Christian anthropic principle" as the
basis for an ultimate understanding of the universe that combines
scientific and religious perspectives (Ellis 1993).



In relation to the design argument, as reinvigorated by the
discussions of the anthropic principle, some physicists and
philosophers have returned to an old objection to it, namely that it
is not an argument for the *Christian* God; it is at best an
argument for a cosmic architect in a deistic sense, or for that matter
several such architects. On the other hand, theists have replied that
even if this objection be true it does not constitute a proof that the
God of theism does not exist. Although design arguments frequently
occur in connection with the anthropic principle, it needs to be said
that they were not part of the original anthropic program initiated by
Brandon Carter in 1974.


## 6. Infinity and the universe



Cosmological theory has gone through many phases and proposals over
the past 100 years. Some have included universes with infinite pasts
and these were mentioned previously. However, for the past forty years
there has been a strong consensus on the modern big bang theory which
has a finite past. But even if the universe is temporally finite in
the past, it may well be spatially and materially infinite. If space
is infinite and the cosmological principle is assumed to be valid, the
universe will contain an infinite number of galaxies, stars, atoms and
everything else. Such actual infinities not only cause philosophical
and logical problems, they may also cause problems of a theological
nature. In his thought experiment known as "Hilbert's
hotel" the famous mathematician David Hilbert argued that
(countable) actual infinities are so bizarre that they cannot have
anything to do with the real world we live in. In this thought
experiment, Hilbert imagines that he arrives at a hotel with an
infinite number of rooms, all of which are occupied. The desk clerk
claims nonetheless that there is a vacancy. He then proceeds to ask
each guest to move to the room with the next highest number in the
sequence (see Oppy 2006, 8; Kragh 2014, Other Internet Resources).



Hilbert himself was uninterested in religion, but later philosophers
and theologians have occasionally used his peculiar hotel
apologetically, as an argument for the existence of God and also for
the finitude of the universe.



The theological problems related to an infinitely large universe are
not specifically related to modern physical cosmology but have been
discussed since the early days of Christianity. On the other hand,
they may be seen as even more relevant today, when the favored
cosmological model has zero curvature, meaning that space is flat.
Although a flat cosmic space does not necessarily imply an infinite
universe, many cosmologists assume that the universe is indeed
spatially infinite.



The theological implications of an infinite universe were discussed by
the church fathers and, in greater detail, by Johannes Philoponus in
the sixth century. Many of the arguments were of the same kind as
those used in the attempts to prove the impossibility of a temporal
infinity. At the time of the scientific revolution it was commonly
assumed that physical space cannot be truly infinite, only
indefinitely large. Infinity was seen as a divine attribute not to be
found elsewhere; to claim that nature is infinite would be to endow it
with divinity, a heretical view characteristic of pantheism. While the
generally accepted view among theists was, and to some extent still
is, that an infinite universe is philosophically absurd and
theologically heretical, there was no consensus on the issue. In fact,
several Christian thinkers, from Descartes in the seventeenth century
through Kant in the eighteenth to Edward Milne in the twentieth, have
argued that an infinite universe is in better agreement with
God's will and omnipotence than a finite one. According to
Milne, "It requires a more powerful God to create an infinite
universe than a finite universe; it requires a greater God to leave
room for an infinity of opportunities for the play of evolution than
to wind up a mechanism, once and for all" (Milne 1948, 233). The
correlation between finitism and theism, and infinitism and atheism,
should be seen as historically contingent rather than justified by
either scientific or theological reasons.



During the early period of modern cosmology, relativistic models with
zero or negative curvature were sometimes associated with materialism
and atheism because they implied a universe of infinite size.
Conversely, Einstein's closed and finite universe was welcomed
by theists. According to Ernest W. Barnes, the mathematically trained
bishop of Birmingham, infinite space was "a scandal to human
thought," (Barnes 1931, 598). His argument was epistemic as well
as theological: only if God's universe is finite can we hope to
understand the full range of his activity. Lemaitre thought
likewise that the universe had to be finite in order to be
comprehensible. In agreement with his later warning against the
"nightmare of infinite space" (Kragh 2004, 139), both of
his two innovative cosmological models, the expanding model of 1927
and the big-bang model of 1931, were spatially closed. The
steady-state model of the 1950s was not only unpopular among
Christians because of its lack of a cosmic creation, but also because
it implied a homogeneous universe of infinite extent. According to
Stanley Jaki, a Benedictine priest and historian of science, the
infinite universe is a scientific cover-up for atheism. Mormons do not
agree, though, for they need a universe which is infinite in both time
and space.



The present consensus model of a geometrically flat accelerating
universe is usually taken to imply an infinite cosmos. The general
attitude of cosmologists is to ignore the troublesome philosophical
problems and speak of the infinite universe as just an indefinitely
large one. They rarely reflect on the weird epistemic consequences of
an actual infinity and even more rarely on the theological
consequences. Ellis is an exception to the rule. He and his
collaborators have argued forcefully against an infinite universe,
suggesting that the flat space of the consensus model is probably an
abstraction that does not hold physically (Ellis, Kirchner and Stoeger
2004). If the universe is really infinite and uniform it can be (and
has been) argued that there will be an infinity of identical copies of
all human beings and indeed of everything. Such a consequence, as
discussed by Ellis, Max Tegmark, Alan Guth and others, clearly is
theologically disturbing.



Even more disturbing, says Ellis, is that God may then not be able to
keep track of and give attention to the infinite number of beings in
the universe. Moreover, if there is a multitude of cosmic regions,
each of which is inhabited with intelligent beings, one may need to
contemplate a multitude of Christ-figures, incarnations and
crucifixions. Ellis was not only willing to consider such a scenario,
he also thought that it strengthened the case for a finite universe,
for then "we would have to countenance only a finite number of
civilizations needing redemption. Surely an infinite number of
Christ-figures must be too much, no matter how one envisages
God" (Ellis 1993, 394).


## 7. Physical eschatology



The cosmological field equations are time-symmetric and the
fundamental laws of physics are assumedly valid at any time. Thus,
modern cosmology is not only about the past of the universe, it also
offers scenarios about its far future, including speculations about
the fate of intelligent life. Given that the apocalyptic passages in
the Bible speak of an end of the world and a possible new creation
(e.g., 2 Peter 3:10-13), the cosmic future may seem to offer
another point of contact between cosmology and theistic religion. But
can there be a secular or scientific eschatology?



Scientifically based speculations about the state of the cosmos in the
far future and the possibility of endless life were first discussed in
the late nineteenth century in connection with the controversy over
the heat death predicted by the second law of thermodynamics. Some of
the German scientists involved in the controversy argued that life
might persist even in the very high-entropic environment of the far
future, and they explicitly referred to the eschatological aspects of
cosmology. Characteristically, while the heat death scenario was
welcomed by Christian authors, it was vehemently opposed by
materialists and atheists who argued for an eternal universe with
eternal life. As Eddington, a Quaker and an advocate of the inevitable
heat death, later asked: "Since when has the teaching that
' heaven and earth shall pass away' become
ecclesiastically un-orthodox?" (Eddington 1935, 59).



Since the 1970s "physical eschatology" has emerged as a
new subfield of astrophysics and cosmology, pioneered by Freeman
Dyson, Jamal Islam and others (see the survey in Kragh 2011,
325-353). The field deals primarily with the state of the
universe in the remote future as based on extrapolations of
cosmological models and the assumption that the presently known laws
of physics will remain indefinitely valid. The favored scenario is the
open ever-expanding universe where extrapolations typically result in
an ultimate future (at about 10100
years from now!) in which the universe consists of nothing but an
exceedingly thin electron-positron plasma immersed in a cold radiation
of neutrinos and photons. Other studies presume a closed universe
collapsing in a big crunch and others again investigate the nearer
future of humankind, say a few million years from now. While many of
these studies are not concerned with the final state of life, some
are, and it is this latter group that constitutes physical eschatology
proper. According to John Barrow and Frank Tipler, the research field
is, "the study of the survival and the behavior of life in the
far future" (Barrow & Tipler 1986, 658).



Physical eschatologists usually ignore the religious associations of
their studies or deny that they exist. Tipler is a controversial
exception, however. Not only does he argue that some kind of life can
continue forever in a closed universe, he also claims that it is the
very collapse of the universe that permits eternal life. When the
final eternity has been reached at what he calls the "omega
point," life becomes omniscient and the temporal becomes
atemporal. According to Tipler, the final singularity is God and
"theology is nothing but physical cosmology based on the
assumption that life as a whole is immortal" (Tipler 1995, 17).
In his book *The Physics of Christianity* (Tipler 2007), he
continues his idiosyncratic exploration of modern cosmotheology
according to which theology is merely a branch of physics.
Tipler's views are undoubtedly extreme, but (and perhaps for
this reason) they have caused much discussion among theologians.



The term physical eschatology indicates a connection to biblical
eschatology, but it is far from clear that the two are related in any
meaningful sense. The message of the Bible is not so much the end of
the physical universe as it is about the imminent return of Christ,
the transformation of humans from flesh to spirit, and the final
kingdom of God. It is about the ultimate destiny and goal of humans,
not of self-reproducing robots. As Jefferson Davis (1999) notes, the
ultimate *hope* which is crucial in theology cannot be supplied
by the laws of physics. The scenario of a closed universe, such as
argued by Tipler, may appear to be more compatible with the biblical
view than the case of the ever-expanding universe, but even in the
former case it is hard to establish a meaningful connection. While the
end of the world does not conflict with the Bible, the claims of
immortality of intelligent life forms (not necessarily humans) do. The
Bible says that God alone is immortal and that all his created beings
are doomed to extinction unless God decides otherwise.



Several theologians have expressed concern about the
cosmologists' scenarios of the end of the universe and stressed
that there is a world of difference between these scenarios and proper
eschatology. According to Wolfhart Pannenberg the Christian
affirmation of an imminent end of the world is scarcely reconcilable
with the cosmological extrapolations of the state of the universe
zillions of years ahead. Karl Peters probably speaks for the majority
of theologians when he writes: "If the expanding universe is
indeed open, expanding forever, then how can one speak of God
recreating the universe? If the universe is closed, then it is likely
to end in a 'big crunch' of mammoth black-hole
proportions. Again, it is difficult to see how a new creation can take
place" (Schwarz 2000, 180). According to Peters, the physical
end of the universe would in effect imply the non-existence of God as
understood in the Christian tradition. Whereas Pannenberg, Peters,
Arthur Peacocke and others tend to think that physical and Christian
eschatology are either contradictory or incommensurable, Craig has
taken a more reconcilable view. According to him, the
cosmologists' versions of secular eschatology furnish grounds
for taking seriously the hypothesis of a transcendent creative and
omnipotent agent. This agent may not be the classical God, but more
likely God in a panentheistic version.



Finally, Robert Russell (2008) argues that the potential conflict
might be resolved by appealing to God's omnipotence and freedom
to perform miracles: the future of the universe *would* have
been what science predicts had God not decided to act at Easter and
bring about, and will continue to bring about, the new creation. This
view is allegedly not in conflict with science, but only with the
philosophical assumption that the events predicted by science must
happen, and this assumption Russell sees no reason to accept.


## 8. Conclusions: Cosmology and God



The question, "why does the universe exist?" admits of
answers from traditional religions as well as from contemporary
cosmological theories. However, according to Bede Rundle (2004),
neither of these answers are needed, for philosophical analysis is
sufficient to prove the existence of a physical universe. While some
claim that the scientific answer has superseded all theological
answers, others claim that the scientific answer reinforces the claim
that God created the universe. Indeed, the story of the interaction
between scientific cosmology and theology is by no means a simple tale
of a better theory replacing an inferior; nor a simple tale of the
convergence of diverse sources of knowledge. A naive or ideological
reading of twentieth century cosmology might count big bang cosmology
as providing new support for theism, and alternatives such as
steady-state cosmology as atheistic backlashes. (And of course, the
work of apologists such as W.L. Craig lends credence to this sort of
picture.) But such a view misses many nuances, both in the historical
record, as well as in the logical structure of these issues. From a
historical point of view, there has been little correlation between
religious views of scientific cosmologists and their proposed
cosmological models. From an epistemological point of view, there are
numerous obstacles to claiming that the big bang confirms the
hypothesis that God exists. And from a metaphysical point of view,
God's hand is not manifest even in big bang models: these models
have no first state for God to create, and these models have no time
for God to exist in before the big bang.



By pointing out some of the subtleties in the relationship between
scientific cosmology and theology, we do not intend to claim that the
two are nonoverlapping magisteria (to borrow a phrase from Stephen Jay
Gould). To the contrary, contemporary cosmology is fascinating
precisely because it has such intricate logical relations with
traditional metaphysical and theological issues.