Science in Christian Perspective

Is Steady-State Cosmology Really Dead?*
OWEN GINGERICH
Smithsonian Astrophysical Observatory and Harvard University 
Cambridge, Massachusetts

From: JASA 24 (March 1972): 8-10.

Independence for Cosmologists

Astronomers from all over the world converged on Brighton, England, in August 1970 for the triennial Congress of the International Astronomical Union (IAU). There they shared the latest data on pulsars and quasars, named the formations on the far side of the moon, and resolved to call 1973 the "Copernican Year." Scarcely noticed among the multiplicity of lectures, symposia and overlapping commission meetings was a battle about whether to create still another commission, one on cosmology.

Traditionally, the cosmologists worked within the commission on galaxies. This happened because when the study of cosmology first became popular in the 1930's, the galaxies provided virtually the only information about the large-scale structure of the universe. The hoped-for answers to questions about the curvature of space, the extent or finiteness of the universe, and the time scale since creation, lay with the distant nebulae and the red shifts of their spectra.

But the last decade has brought an abrupt trans formation in the observational base of cosmology. The field, which had been straight-jacketed by ever-ambiguous data, suddenly gained new vigor with the discovery of the quasars and the socalled 3-degree background radiation. For these reasons the cosmologists in the IAU grew restive within the unit on galaxies and sought a commission of their own. Several astronomers fought the new division simply because IAU members can participate officially in only three of the Union's many commissions and yet another group made it more difficult to keep their fingers in a variety of interests. Nevertheless, the ultimate formation of the cosmology commission accurately reflected the new diversification in the data on which cosmological systems rest.

New Data

Dennis Sciama, a one-time steady-state cosmologist, has described his own reaction to the new flow of data:

I have often wondered what it must have been like to be a nuclear physicist in the early 1930's, particularly in 1932-that annus mirabilis which saw the discovery of the neutron and the positron and the first splitting of the nucleus by artificially accelerated particles. Now I think I know. As a cosmologist I have seen in the 19611's a similar stream of discoveries following one another at an almost indecent rate.¹

The first of the unexpected new phenomena were the quasi-stellar radio objects or quasars. Discovered at Palomar in 1960, they posed such an enigma that no formal account appeared in print until 1963. The quasars emitted strong radio radiation, but unlike the majority of radio sources, they appeared star-like on photographic plates. Their spectra exhibited a puzzling pattern of emission lines. These spectral features were at last deciphered as enormously redshifted lines normally found in the far ultraviolet spectra. In a sense this discovery only deepened the mystery. Interpreted as Doppler shifts, the displaced spectral lines indicated velocities approaching the speed of light; assuming they fit the same red-shift-distance relation of the galaxies, then their distances have to be immense. From this it followed that their luminosities must be incredibly large in order to he seen so well at such great distances.

Standing alone, the quasars seemed too contradictory and unsatisfactorily explained to give any direction in cosmology; yet astronomers quickly recognized that if they really were at immense distances (and hence represented the universe as it appeared in a far-gone epoch), the homogeneity in space and time required by one of the two main rival cosmologies, the steadystate theory, was lacking.

Big Bang vs. Steady State

Readers will recall that, in the absence of decisive data, the 195O's had brought acrimonious disputes between the partisans of the "big bang" theory (which pictured a universe expanding from a super dense state at some definite past epoch) and the "steadystate" theory (which postulated a universe uniform and infinite in time as well as space). Perhaps the best known of the steady-statists was Fred Hoyle of Cambridge University, whose widely-read paperbacks publicized his cosmological view that the universe had existed in the same form forever. Hoyle's openly avowed atheism did not endear him to religions-minded astronomers, who, nourished by the writings of Eddingtnn and Mime, intuitively trusted the "big bang" cosmology with its longpast moment of creation.

During the 1960's the radio astronomer, Sir Martin Ryle, Fred Hoyle's archrival at Cambridge, had already claimed other evidence for an absence of the homogeneity in distant space requisite for the steady-state cosmology. Ryle based his view on a statistical analysis of the faint radio sources he was observing. The strong radio sources appeared comparatively more numerous at great distances and hence in earlier epochs galaxies radiated more actively in radio wavelengths. The ensuing controversy, of the sort that English dons seem to wage with more enthusiasm than American professors, led to bitter claims and fierce rebuttals in the English press and to wry remarks about "pouring Hoyle on Ryled waters."

Undoubtedly the increasing strength of Ryle's observations would have ultimately proved persuasive by themselves, but before they did, a second un-an ticipated new phenomenon turned up. At the Bell Telephone Laboratories, and almost simultaneously at Princeton University, weak cosmic radio radiation, corresponding to a blackbody temperature of 3°K, was found coming from all directions. The most elementary interpretation of this 3° background radiation explained it as the far red-shifted remnants of the primeval fireball from which the universe began its (roughly) 15 billion-year expansion.

Faced with these new data Fred Hoyle finally renounced his steady-state cosmology in a nowfamous capitulation published in Nature.² As an alternative, he proposed that the universe might go through an unending series of oscillations, expansion followed by contraction like a perfectly elastic bouncing ball.
But more recently, Hoyle has remarked in a televised interview that the steady-state theory has never been more alive or vital.

Can the steady-state cosmology be revived? In order to gain more insight into this possibility I took advantage of a recent visit to England to ask several investigators for an opinion on the current state of cosmology. Unfortunately Hoyle himself was on sabbatical leave from his Institute of Theoretical Astrophysics (IOTA) in Cambridge, but I soon gathered from his colleagues that no very serious effort to save the steady-state theory was underway there. "Of course Fred has a basic commitment to the theory," I was told. "He has been working with fluctuations in a steady-state model, and he can always make it work if the fluctuation is the size of the observable universe! But so far there has been no acceptable alternative explanation to the 3° radiation."

The Background Radiation

Attempts to explain the background radiation in some other fashion have exploited the fact that it has been observed at comparatively few wavelengths. Thus the detailed shape of the microwave radiation curve is not yet known, and it can only be hypothesized that the radiation follows a smooth black-body relation. Given the proper chemical composition of interstellar grains, they could emit selectively at just the observed wavelengths, producing an apparent but spurious black-body curve. The trouble with this scheme is that whenever observations become available at another wavelength, the proposed composition of the grains must be revised to a still more esoteric form. Not only are the observations available at comparatively few wavelengths, but it is only conjecture that the curve turns downward at the proper longer wavelengths. In fact, some recent measurements made by a group at M.I.T. indicates that the curve does not turn hack down as anticipated for 3°K black-body radiation, but these experiments are disputed by other investigators. Although most astronomers specializing in this area discredit the M.I.T. results, those measurements sustain lingering doubts that all may not be well with the present explanation of the background radiation.

Quasars

The interpretation of the quasars is even more controversial. Some astronomers maintain that the quasars are relatively nearby high-velocity ejecta from the nucleus of our own Milky Way galaxy. This view avoids the difficulty of the fantastic intrinsic luminosity that quasars must have if they are at great distances, but it fails to explain how an explosion in the center of our galaxy could yield so much kinetic energy. Most astronomers consider this a fatal objection to the "local" interpretation of quasars.

The fact that some quasars exhibit simultaneously several patterns of spectral absorption lines, with multiple red shifts, provides a serious challenge to the simple red-shift-distance interpretation. At the very least, some additional physical mechanism must be involved. Equally puzzling is the result of Geoffrey and Margaret Burbinige, still debated, that the quasars exhibit a marked propensity to have a set of absorption lines at a specific red shift of 1957, a phenomenon that would not be expected if the red-shifts indicate distance and if the quasars were somewhat randomly distributed in distance. C. Burbidge and Hoyle have also shown that when the red shift is plotted versus apparent magnitude, there is a great deal of scatter, in contrast to a similar diagram for faint galaxies. In their opinion, this scatter argues against any simple redshift-distance relation³.

In spite of the fact that the puzzling pieces of data about quasars don't all fit into place, most astronomers agree that they are at immense or "cosmological" distances simply because the resulting picture is comparatively tidy. As Palomar's Alan Sandage has pointed out, the quasars seem to fit at the end of a smooth sequence that goes from distant ordinary galaxies through galaxies with peculiarly bright and active nuclei (including the so-caller! Seyfert galaxies) and through a class of radio sources linked with faint galaxies. The fact that lIovIe and Burbidge have found a scatter diagram its the graph of red shifts versus magnitudes for quasars can merely mean that quasars, like stars, have different intrinsic luminosity classes, and the multiple absorption-line red shifts could result from the absorption by material between us and the more distant quasars.

As the astrophysicist Philip Morrison reminds us, it is the duty of scientists to make sense out of the universe and this must he done by searching for unity rather than disparity in the interpretation of phenomena, Certainly at present the most unified vies' of the cosmos places the quasars at immense distances from our own galaxy, and on a sequence with other galaxies and radio sources. But such an interpretation is automatically an evolutionary picture that rules out a steady-state cosmology, for it concentrates the quasars at a remote bygone epoch when the universe was far different than it is now.

Oort's Explanation

An ingenious and coherent explanation for the distant concentration of quasars and radio sources has recently been outlined by the Dutch astronomer Jan Oort.⁴ His argument exploits the fact that within a Big-Bang cosmology, increasing distances reveal the universe at increasingly younger stages in its development. Oort notes that whereas the population density of radio sources was hundreds of times greater when
the universe was only 20% of its present age, the numbers then drop off very rapidly for still greater distances and younger times. In fact, not a single radio source has been found at a distance greater than that corresponding to 13% of the present age of the universe. Only at an age of about 20% had the universe expanded sufficiently for the density to allow the formation of the rotating spiral galaxies, Oort believes, and hence in this period an immense concentration of galaxy births occurred. Associated with the birth trauma of the spirals, he hypothesizes, was an intense, explosive activity in the galactic nuclei that reveals itself as quasars and other radio sources.

It is the duty of scientists to make sense out of the universe and this must he done by searching for unity rather than disparity in the interpretation of phenomena.

Oort also remarks on the most interesting fact that the universe apparently has just enough energy to keep expanding forever, but not much excess. He goes on to say that if it had much less energy than this, it would have quickly collapsed again, thus not giving time for the evolution of intelligent life, whereas if it had had much more energy, the density would have dropped so rapidly that galaxy formation might not have occurred. The single argument of this kind is not by itself so impressive, but I recall another passage of the same genre in the last chapter of Hoyle's hook Nuclei, Galaxies and Quasars. There he remarks that if the nuclear energy levels of oxygen were only slightly different with respect to carbon, the formation of oxygen would have been greatly enhanced at the expense of carbon, so that carbon would have been so rare that life could not have formed. Another considerably more famous phenomenon of the same sort concerns the uniqueness of water, carefully explained in Henderson's hook on The Fitness of the Environment.

Personalities at Cambridge

Soon after I arrived in Cambridge, England, I encountered Martin Rees, one of the IOTA staff members. In a recent Scientific American article he and Joseph Silk had addressed themselves to the formation of galaxies⁵; although their main arguments were embedded within the framework of an evolutionary universe, they included a rather weak claim that the ideas might also work in a steady-state situation. I chided Rees for trying to have it both ways, and he conceded that the steady-state theory looked moribund. He added however, " I try not to have any beliefs on cosmological theories. I want to be open minded and prepared to accept evidence for any of them."

Dennis Sciama, who had joined our discussion, countered Rees' position: "You can try to be neutral, but you have to make a commitment for what you are willing to do. I won't spend any more time working on the steady-state cosmology', and so for me personally steady-state is dead." Others with whom I spoke agreed that few cosmologists were spending time on the steadystate theory these days.

One of the most penetrating thinkers I met was W. H. McCrea, Research Professor at Sussex University, who has not only accepted the big-hang cosmology, but has worked out a philosophy about why it is the sort of universe we view. His "A Philosophy for BigBang Cosmology" printed in 1970 in Nature⁶ presents a stimulating analysis. McCrea points out that in spite of the simplifing assumptions underlying the cosmology of the expanding universe, it is, "self-consistent in so many unexpected ways that it can scarcely be illusory." As McCrea sees it, increasingly sophisticated theorems show that many of the observed properties of the universe (e.g., its particular chemical composition, its expansion, its isotropy) will arrive almost independently of the particular conditions of its origin; conversely, observations on these features will reveal comparatively little about the initial circumstances.

MeCrea's philosophy is in part an answer to the unsparing anti-cosmological criticism unleashed by Gerard de Vancouleurs in 1970 in Science.⁷ The Texas astronomer argued convincingly for a hierarchy of inhomogeneities, which, in his opinion, vitiated the simplified relativistic models of the expanding universe that have now won wide acceptance. McCrea's response is that ultimately the simplifications don't matter; where somehow we can't get enough observations of homogeneous properties, this lack does not destroy our ability to describe the large-scale universe.

Physical theory is not in general designed to make predictions about the universe in the large. If it does, they will be about the smoothed-out universe; for this and other reasons they will not he subject to precise tests. But the fact that the theory does apparently make generally valid predictions of this uucoveoaoted sort gives a new kind of confidence in physical theory.

McCrea's arguments give little encouragement to those who would seek an ever-closer parallel between Genesis 1 and contemporary cosmology. To be sure, the difficult problem of reconciling a steady-state universe that had existed forever with the concept of creation has apparently vanished with the demise of the steady-state cosmology. But the picture of a universe that is less and less "knowable" as we work hack toward the initial singularity gives only the fuzziest view of creation.

That our physical laws are created constructions of the human mind should serve as awaiting to anyone who would prove or disprove Genesis 1 by modern astronomy.

Contrast this with "the first half hour of creation" popularized by George Gamow a decade or two ago. In Gamow's version the highly condensed primeval energy converted itself into matter within a calculable number of minutes, producing the present distribution of chemical elements in that initial nuclear cook-out. A fundamental contribution of Hoyle and his associates, stimulated by the requirements of the steady-state cosmology, is the recognition that the heavy elements (beyond hydrogen and helium) could he synthesized by nuclear reactions in stars. As MeCrea reminds us, we know now that the chemical composition of the universe is only roughly dependent on the initial conditions contrary to Gamaw's hypothesis.

MeCrea raises the issue of the evolution of physical laws themselves. Admittedly the notion of changing laws is not very useful, but, he continues (and I think rightly), "in this fashion we get away from the concept that physical laws are something that the universe must obey. They are something our thinking about the universe must obey." That our physical laws are created constructions of the human mind has been maintained for years by many philosophers of science; McCrea's perceptive remarks emphasize the situation with respect to the origins of the universe. They should serve asawarning to anyone who would "prove" or "disprove" Genesis 1 by modern astronomy.

REFERENCES

Note: References 1, 3 and 5 have been reprinted in Frontiers in Astronomy, a Scientific American reader edited by Owen Giogerich (W. Il. Freeman & Company, 1970).

¹Dennis Sciama, "Cosmology before and after Quasars" (book review), Scientific American, September, 1967.
²Fred Hoyle, "Recent Developments in Cosmology," Nature, October 9, 1965, vol. 208, pp. 111-114.
³Gcoffrcy Burhidge and Feed Hoyle, "The Problem of Quasistellar Objects," Scientific American, December, 1966.
⁴J.H. Oort, "Galaxies and the Universe," Science, 25 December 1970, vol. 170, pp. 13631370.
⁵Martin Bees and Joseph Silk. "The Origin of Galaxies," Scientific American, June 1970.
⁶ William H. McCrea, "A Philosophy far Big-Bang Cosmology," Nature, October 3, 1970, vol. 228, pp. 21-24.
⁷Gerard de Vaueaulcnrs, "The Case for a Hierarchical Cosmology," Science, 27 February 1970, vol. 167, pp. 1203-1213.

* This paper was originally written in the spring of 1971. In the year since it was prepared, the picture in cosmology remains