Standard vs Steady State vs Oscillating Universe

The term “Big Bang,” originally a derisive expression coined by Fred Hoyle to
characterize the beginning of the universe predicted by the Friedman-Lemaître
model, is thus potentially misleading, since the expansion cannot be visualized
from the outside (there being no “outside,” just as there is no “before” with respect
to the Big Bang).60
The standard Big Bang model, as the Friedman-Lemaître model came to be
called, thus describes a universe which is not eternal in the past, but which came
into being a finite time ago. Moreover—and this deserves underscoring—the
origin it posits is an absolute origin out of nothing. For not only all matter and
energy, but space and time themselves come into being at the initial cosmological
singularity. As physicists John Barrow and Frank Tipler emphasize, “At this
singularity, space and time came into existence; literally nothing existed before
the singularity, so, if the Universe originated at such a singularity, we would truly
have a creation ex nihilo.”61 Thus, we may graphically represent spacetime as a
cone (Fig. 3.2).
Time
Space
Initial
cosmological
singularity
Fig. 3.2: Conical representation of Standard Model spacetime. Space and time begin at the initial
cosmological singularity, before which literally nothing exists.
60. As Gott, Gunn, Schramm, and Tinsley write: “The universe began from a state of infinite density
about one Hubble time ago. Space and time were created in that event and so was all the matter in the
universe. It is not meaningful to ask what happened before the big bang; it is somewhat like asking what
is north of the North Pole. Similarly, it is not sensible to ask where the big bang took place. The pointuniverse
was not an object isolated in space; it was the entire universe, and so the only answer can be that
the big bang happened everywhere.” J. Richard Gott III, James E. Gunn, David N. Schramm, and Beatrice
M. Tinsley, “Will the Universe Expand Forever?” Scientific American, March 1976, 65.
The Hubble time is the time since the singularity if the rate of expansion has been constant. The singularity
is a point only in the sense that the distance between any two points in the singularity is zero. Anyone
who thinks that there must be a place in the universe where the Big Bang occurred still has not grasped
that it is space itself which is expanding; it is the two-dimensional surface of an inflating balloon which is
analogous to three-dimensional space. The spherical surface has no center and so no location where the
expansion begins. The analogy of the North Pole with the beginning of time should not be pressed, since
the North Pole is not an edge to the surface of the globe; the beginning of time is more like the apex of a
cone. But the idea is that just as one cannot go further north than the North Pole, so one cannot go earlier
than the initial singularity.
61. John Barrow and Frank Tipler, The Anthropic Cosmological Principle (Oxford: Clarendon, 1986),
442.
128 De Deo
On such a model the universe originates ex nihilo in the sense that at the initial
singularity it is true that there is no earlier spacetime point or it is false that something
existed prior to the singularity.
Now such a conclusion is profoundly disturbing for anyone who ponders it.
For the question cannot be suppressed: why did the universe come into being? Sir
Arthur Eddington, contemplating the beginning of the universe, opined that the
expansion of the universe was so preposterous and incredible that “I feel almost
an indignation that anyone should believe in it—except myself.”62 He finally felt
forced to conclude, “The beginning seems to present insuperable difficulties unless
we agree to look on it as frankly supernatural.”63 The problem of the origin
of the universe, in the words of one astrophysical team, thus “involves a certain
metaphysical aspect which may be either appealing or revolting.”64
The Steady State Model
Revolted by the stark metaphysical alternatives presented by an absolute beginning
of the universe, certain theorists have been understandably eager to subvert the
Standard Model and restore an eternal universe. The first such attempt came in
1948 with the first competitor to the Standard Model, namely, the Steady State
Model of the universe. According to this theory, the universe is in a state of cosmic
expansion, but as the galaxies recede, new matter is drawn into being ex nihilo in
the voids created by the galactic recession (Fig. 3.3).
Fig. 3.3: Steady State Model. As the galaxies mutually recede, new matter comes into existence to
replace them. The universe thus constantly renews itself and so never began to exist.
62. Arthur Eddington, The Expanding Universe (New York: Macmillan, 1933), 124.
63. Ibid., 178.
64. Hubert Reeves, Jean Audouze, William A. Fowler, and David N. Schramm, “On the Origin of
Light Elements,” Astrophysical Journal 179 (1973): 912.
The Existence of God (1) 129
If one extrapolates the expansion of the universe back in time, the density of
the universe never increases because the matter and energy simply vanish as the
galaxies mutually approach!
The Steady State theory never secured a single piece of experimental verification;
its appeal was purely metaphysical. Instead, observational astronomy made it
increasingly evident that the universe had an evolutionary history. But the decisive
refutation of the Steady State Model came with two discoveries which constituted,
in addition to the galactic red-shift, the most significant evidence for the Big Bang
theory: the primordial nucleosynthesis of the light elements and the microwave
background radiation. Although the heavy elements were synthesized in the stars,
stellar nucleosynthesis could not manufacture the abundant light elements such as
helium and deuterium. These could only have been created in the extreme conditions
present in the first moment of the Big Bang. In 1965 a serendipitous discovery
revealed the existence of a cosmic background radiation predicted in the 1940s by
George Gamow on the basis of the Standard Model. This radiation, now shifted
into the microwave region of the spectrum, consists of photons emitted during a
very hot and dense phase of the universe. In the minds of most cosmologists, the
cosmic background radiation decisively discredited the Steady State Model.
Oscillating Models
The Standard Model was based on the assumption that the universe is largely the
same in every direction. In the 1960s and 1970s some cosmologists suggested
that by denying that assumption, one might be able to craft an Oscillating Model
of the universe and thus avert the absolute beginning predicted by the Standard
Model. If the internal gravitational pull of the mass of the universe were able to
overcome the force of its expansion, then the expansion could be reversed into a
cosmic contraction, a Big Crunch. If the matter of the universe were not evenly
distributed, then the collapsing universe might not coalesce at a point, but quantities
of matter might pass by one another, so that the universe would appear to
bounce back from the contraction into a new expansion phase. If this process
could be repeated indefinitely, then an absolute beginning of the universe might
be avoided (Fig. 3.4).
Radius of the universe
Time
Fig. 3.4: Oscillating Model. Each expansion phase is preceded and succeeded by a contraction phase,
so that the universe in concertina-like fashion exists beginninglessly and endlessly.
Such a theory is extraordinarily speculative, but again there were metaphysical
motivations for adopting this model. The prospects of the Oscillating Model were
130 De Deo
severely dimmed in 1970, however, by Roger Penrose and Stephen Hawking’s
formulation of the Singularity Theorems which bear their names. The theorems
disclosed that under very generalized conditions an initial cosmological singularity
is inevitable, even for inhomogeneous universes. Reflecting on the impact of this
discovery, Hawking notes that the Hawking-Penrose Singularity Theorems “led
to the abandonment of attempts (mainly by the Russians) to argue that there was
a previous contracting phase and a non-singular bounce into expansion. Instead
almost everyone now believes that the universe, and time itself, had a beginning
at the big bang.”65
Despite the fact that no spacetime trajectory can be extended through a singularity,
the Oscillating Model exhibited a stubborn persistence. Two further strikes
were lodged against it. First, there are no known physics which would cause a collapsing
universe to bounce back to a new expansion. If, in defiance of the Hawking-
Penrose Singularity Theorems, the universe rebounds, this is predicated upon
a physics which is as yet unknown. Second, attempts by observational astronomers
to discover the mass density sufficient to generate the gravitational attraction required
to halt and reverse the expansion continually came up short. In January of
1998 astronomical teams from Princeton, Yale, the Lawrence Berkeley National
Laboratory, and the Harvard-Smithsonian Astrophysics Institute reported at the
American Astronomical Society meeting that their various tests all showed that
“the universe will expand forever.”66 A spokesman for the Harvard-Smithsonian
team stated that they were now at least 95 percent certain that “the density of
matter is insufficient to halt the expansion of the universe.”67
At the same time, observations of the red-shifts of supernovae yielded unexpected
results that have thrown the discussion of the universe’s fate into a wholly
new arena and served to render questions of its density irrelevant. The red-shift
data gathered from the distant supernovae indicate that, far from decelerating,
the cosmic expansion is actually accelerating! There is some sort of mysterious
“dark energy” in the form of either a variable energy field (called “quintessence”)
or, more probably, a positive cosmological constant or vacuum energy which at a
certain point in the evolution of the cosmos kicks the expansion into a higher gear,
causing the expansion to proceed more rapidly. Consequently, even high density
universes may expand forever; a potentially infinite future is no longer the privileged
prerogative of low density universes. Highly accurate recent measurements
of the cosmic microwave background radiation by the Wilkinson Microwave Anisotropy
Probe (WMAP) indicate, “For the theory that fits our data, the Universe
will expand forever.”68
65. Stephen Hawking and Roger Penrose, The Nature of Space and Time, The Isaac Newton Institute
Series of Lectures (Princeton, N. J.: Princeton University Press, 1996), 20.
66. Associated Press News Release, January 9, 1998.
67. Ibid.
68. See http://map.gsfc.nasa.gov/m_mm/mr_limits.html.