QUITE accurate measurements of the sun's size were made in ancient times. They show us that the sun has not changed its size appreciably over two thousand years. Other evidence indicates that the sun has not appreciably changed its light output during the millenniums since the earliest fossils were buried. If the sun were made entirely of combustible material such as coal, and if an unlimited supply of oxygen were available, it does not appear possible to explain the observed light output without the sun's having used up so much material that the radius would have changed noticeably. This sort of consideration, combined with spectrographic analysis of the sun's radiation, has caused astronomers to adopt the far more effective nuclear reactions (fusion) as the energy source for starlight.
To the question "Is it not possible that God simply 'makes' stars shine without using any natural means such as nuclear energy?" one must answer Yes. Hebrews 1:3 and similar texts have been interpreted to mean that the stars are miraculously caused to shine at a constant rate in violation of the conservation of energy or other natural laws; but the suggestion that God keeps the stars shining at a strictly constant rate does not fit with self-evident observations. Some stars exhibit a regular pulsation in brightness, with periods measured in units of days. Others vary their brightness in a much less regular way and over a time span of decades. Many-fold and catastrophic hundred-million-fold increases of brightness have been observed novae and supernovae, respectively. Some stars are surrounded by expanding shells or streamers of gas that can be identified to have originated at the time of a nova event. There are nebulae of staggering proportions that seem to be associated with past supernovae explosions.
Stars are observed to have various colors and various absolute brightnesses, just as people differ in height and weight. A visitor to earth who had only five minutes to observe people might be led to guess that all people were alike except for age, that is, that all the major differences he observed were related to age. So the cosmologist, having seen the presently observable differences among stars, guesses that the different kinds of stars are at various stages in a life pattern that is fol lowed by each and every star. Furthermore, if nuclear reactions are the cause of the shining of the stars, it becomes seemingly inevitable that any star will undergo change and eventually cease to shine.
How Long May Stars Be Expected to Shine?
Cosmologists have attempted to reach conclusions concerning the length of time a star may be expected to shine. Without the aid of modern high-speed computers these conclusions could not be reached without laborious calculation requiring hundreds of years. As an example of the initial stage of this sort of calculation, consider the computer input for understanding how the sun shines in its present, quite stable condition. One must enter equations which state that the pressure at any point in the star is just adequate to hold up the weight of the material above that point, and which state that energy released throughout the star must equal the total brightness of the star. The various possible nuclear reactions must also be programmed into the computer.
The computations predict that the sun will, during the next 4.7 billion years, continue pretty much as it is now except for gradual increase in brightness and radius. It will then begin an expansion- and-cooling stage that will, at the end of some 6.1 billion years from the present, make it into what is known as a red giant star. Somewhere near 6.4 billion years from now, after a few cyclic changes, stars like our sun may be expected to finally leave the red giant stage with an explosion that produces a helium core surrounded by an expanding spherical shell of hydrogen gas. Eventually what is left of the core collapses into an extremely compact dwarf star. After a time the dwarf core has radiated all of the energy that it can release and the star "dies" into an inert dark ball of matter.
The computations that have been made reveal that the mass of a star is a crucially important variable. Very massive stars burn up their hydrogen at a furious rate, so fast that even though they have more fuel they do not last as long as smaller stars. The explosion that follows their red giant stage is far more catastrophic. The embers remaining are expected to have fascinating properties neutron stars, pulsars, black holes.
The equations for later stages in the life of a star, such as that in which the accumulation of helium in the center of the star collapses, or that in which the hydrogen envelope blows off, are very much more complicated than those that are required to describe the earlier portions of a star's history. There are stages in the computations which, instead of producing within minutes specifications for hundreds of millenniums of star life, require hours of computer time to trace out events taking moments in the experience of a star.
Some modern Christian writers have attempted to connect these predictions of the future of the sun with the writings of John in the Revelation. 1 There are indeed similarities between the computer predictions and the statements in Revelation 16, but these similarities do not bear up under closer scrutiny. For instance, the first approach of the sun to its red giant stage would completely vaporize the earth. Furthermore, the urgency with which the book of Revelation presses its warnings does not seem consistent with a 6-billion-year time span!
Does Modern Cosmology Say Anything About the Past History of the Universe?
In an endeavor to account as far as possible for the past history of the universe on a naturalistic basis, modern cosmologists presume that stars originate from tenuous clouds of interstellar matter drifting in space. It is expected that at certain times and places there may be slightly more dense accumulations of this matter atoms, molecules, dust, and small crystals, but mostly hydrogen gas. Such an accumulation could begin to collect itself by gravitation into a smaller and denser cloud, be coming hotter in the process. Eventually a temperature might be reached at which nuclear fusion would commence and a star would be "born." It follows that some existing stars may have condensed from the explosion remains of previous, now "dead," stars.
Some individuals who are concerned with respect to Cod's role in the creation and maintenance of the universe have wondered if the computer calculations could be correct as far as the future is concerned, but inapplicable to the past. Might the stars come into existence as luminous objects by divine creation and follow a predictable process of decay there after? To this question an answer of Yes must be given, an answer which is consistent with current observations.
On the other hand, evidence that stars condense from matter spread out in space, according to computer calculations, would be hard to find. The postulated col lapse from dimensions of a light-year to dimensions of the earth's orbit is expected to take place over a short period of time measured in months, and soon after its first appearance a new star should be indistinguishable from young stars already in existence. A few blobs of dark gas that can be seen with large telescopes have been pointed out as possible sites for the appearance of new stars. There has been one reported appearance of a previously unobserved, small, bright nebulosity during seven years between photographs,2 but this isolated event does not provide conclusive proof that the postulated process of star formation is actually going on.
Are Changes Taking Place Among the Galaxies?
The several hundred million known galaxies have, as do the observed stars, a variety of properties. As is the case with stars, we are tempted to sort the different kinds of galaxies into a sequence and interpret this sequence as samplings of a historical process.
Some computer studies have been done to see if reasonable assumptions could result in the reproduction, on the computer output screen, of a sequence of dot patterns like the observed galactic shapes. It is very difficult to define the "reasonable assumptions" in a sufficiently simple way, and the results of the work are very impressive but not conclusive. Different sets of "reasonable assumptions" predict that spiral galaxies wind up, or do not wind up, as time goes by. There is, of course, no observed change in the shape of galaxies. Even if change is occurring we would not have had time to become aware of it. The galaxies are so huge, they are so far away, and their rotations take place on so vast a scale that our observations over a century are as the blink of an eye!
Within the galaxies there is evidence of change. The explosive nature of many nebulae has been described earlier in the discussion of changes in stars. The possible contraction of some drifting matter has been mentioned.
The only relevant measurement related to a change in the shape of galaxies that is within our means is a rather arduous one. We are not able to actually see the motion of stars in galaxies, but we can observe small shifts in the spectral colors of various stars inside the nearer galaxies. We interpret these small shifts as due to the motion of these stars within their own galaxy. It is possible to determine whether or not this motion would result in a stable orbit around the center of their galaxy. The results obtained seem to indicate, with wide uncertainty, that galaxies are not expanding or contracting.
It is important to distinguish be tween motions within galaxies and motions among or between galaxies. The totality of galaxies appears to be expanding, that is, galaxies appear to be separating from each other. We arrive at this conclusion from the red shift of the spectral colors of whole galaxies. Although other explanations have been proposed, the most acceptable explanation of this red shift on the basis of present knowledge is in terms of separation between the galaxies. This separation resembles the expansion of debris from an explosion, that is, the most distant galaxies have the greatest speed.
On the basis of the data and inferences concerning separation of galaxies most cosmologists consider that the universe began its present existence with a stupendous explosion. This viewpoint is known as the "big bang" theory.
Is "Big Bang" Creation Scriptural?
Some Christian writers identify the Genesis account of creation with the "big bang" of cosmologists. This identification requires an extremely flexible interpretation of Scripture, particularly as far as chronology is concerned. The most recent suggestions by cosmologists place the "big bang" at a point 20 billion years in the past, give or take several billion. The number proposed in the professional literature on this topic has been increasing steadily as new discoveries and interpretations are made.
Does Cosmology Relate to Planet Earth?
In recent decades astronomers and cosmologists have shown a renewed interest in the past history of the solar system and its individual planets. This interest has been related to the deluge of new observations made by radio astronomy and by the various spacecraft that have been flown to the moon and nearby planets. It is strongly motivated by a desire to explain materialistically how life began on earth, and a related desire to determine whether or not life exists, or has existed, on other planets in the universe.
An interesting aspect of this recent interest is the rapidity with which theories are hatched and discarded for instance, theories about the history of the moon. This hatching and hatcheting of theories is one of the most exciting activities of the scientist the constant search for the simplest theory that explains the largest body of facts, and at the same time successfully predicts new observations. The history of scientific enterprise indicates that theories that are most favored at the present may eventually be dis carded in favor of others that deal more successfully with new data as well as the facts that are now available.
Can a Biblical Cosmology Be Scientific?
Some observations made by cosmologists are obvious and self-evident for instance, the very significant observation that the sky is dark at night. Other observations while straightforward are dependent on sophisticated technology the motion of planets around the sun, and the existence of craters on Mars, for example. Many observations are subtle, indirect, and of uncertain interpretation for example, the evidence for a "big bang" and "black holes." The clear messages from nature should be taken into account in efforts to understand Scripture under the guidance of the Holy Spirit. This precaution will help us to avoid errors similar to those in positions on cosmology that have been taken by theologians in the past (e.g., the Ptolemaic- Copernican controversy).
The theories accepted by the majority of scientists and writers active in cosmology today are materialistic or deistic, not only with respect to what is seen in the universe but also concerning what Bible statements mean. But cosmological studies that take the Bible literally can be scientific, since numerous cosmologies exist that are in accord with the available data and also with a literal interpretation of Genesis. These studies can be expected to improve in quantity and quality in the immediate future as more and more scientists with conservative Christian background enter the field.
1. James Reid, God, the Atom and the Universe (Grand Rapids, Michigan: Zondervan, 1968).
2. Robert Jastrow and Malcolm Thompson, Astronomy: Fundamentals and Frontiers (New York: Wiley, 1972), pp. 147-151.