Several years ago, my family and I drove from Tucson to Los Angeles on a clear and moonless summer night. There were few cars on the road that night, few headlights to ruin my night vision. Some hours into the ride, I noticed a diffuse band of light in the sky. Eager to get a better look at it, I stopped the car and turned off the headlights. Now I could see the luminous patchwork far more clearly, stretching across the sky from one point on the horizon to its opposite.
I immediately recognized what I was looking at, but it was no less wondrous just because I could name it. I had seen the Milky Way often, of course, but never under such ideal viewing conditions as on this dark night in the desert, far from the light pollution of any city. From this viewing site, the glow from the countless stars and nebulae of our home galaxy was not merely something that one could see, with a bit of effort. No, it was the first thing one noticed when looking up—the most prominent attraction in the star-studded sky.
Astronomers have learned a great deal about our Milky Way Galaxy, especially during the last century. Hundreds of billions of stars, sprinkled with thousands of star clusters and glowing gaseous clouds, are arrayed in pinwheel fashion throughout a more or less flat disk. Its dimensions are difficult for our minds to grasp. The diameter of the galactic disk is 100,000 light-years. That is, it would take light—travelling at its characteristic speed of 186,000 miles per second—100,000 years to travel from one edge of the disk to the opposite edge. Our solar system (the sun and its entourage of planets and lesser objects in orbit around it) is located about 30,000 light-years from the center, in the suburbs of the Milky Way. The band of light that I viewed from the darkened desert is what the Galaxy looks like from the inside.
But the Milky Way is merely one of many such astronomical giants. Only a handful of the others are within range of unaided human vision. Most galaxies can be seen only with the additional light-gathering power of a telescope. The central and brightest region of the galaxy M-31—one of our nearest neighbors, "only" 2 million light-years distant—can sometimes be seen without the aid of a telescope as a fuzzy patch of light in the region of sky occupied by the stellar constellation Andromeda.
With the largest of telescopes, astronomers can see hundreds of billions of galaxies, out to distances up to 15 billion light-years. They are distributed in a rather irregular, almost spongelike fashion, with some regions (corresponding to the hollow portions of the sponge) nearly devoid of galactic occupants. And this distribution is itself actively changing, the major alteration being a steady growth in the mean distance between neighboring galaxies or clusters of galaxies.
To our amazement, this growth is not the consequence of galaxies moving through space to new locations. No, the increase in distance is caused by the expansion of space itself. Space, we have learned, is not merely a nothing into which things can be placed. Contrary to our common conception of it, space is a nonmaterial something that can act and be acted on. Its action of expanding is one of the fundamental story lines in the formational history of the universe. From its big-bang beginning—about 15 billion years ago—the size of the universe has been growing. This spatial expansion is what leads the distance between galaxies to increase. Space itself is expanding, and galaxies are going along for the ride.
At the same time, however, the character of space is intimately related to the distribution of galaxies. The properties of the universe's space and the distribution of the universe's matter are embraced in mutual interaction. The qualities of each are influenced by the other. Neither one could be precisely what it is without the other. Matter, we say, tells space-time (made up of the three spatial dimensions plus a fourth dimension representing time) how to curve, and curved space-time tells matter how to move. Locally we experience this interaction of matter and space as gravity. In the cosmic realm of vast distances, the mass of galaxies (plus whatever else might be out there) influences both the geometry of space and the manner in which it develops in time. If we want space to have the properties that make life on planet Earth possible, we need the whole universe of galaxies arrayed pretty much as they are. Galaxies are not merely pretty things to look at through a telescope. These celestial beauties are also essential players in an action-packed universal drama.
This intimate relationship of galaxies and space illustrates what I believe is one of the most fundamental features of the universe that the sciences have affirmed in the 20th century: the universe is truly a cosmos. The universe is not merely a collection of individual objects, each "doing its own thing" here and there, now and then. No, the universe is an elegantly and harmoniously integrated system of interacting members and correlated actions. The word cosmos conveys precisely this concept—the wedding of beautiful form and harmonious action. We live in a cosmos gifted with what I often call functional integrity, gifted with all of the resources and capabilities that are needed to make it a functionally complete and wholly integrated system of interacting constituents.
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Why Do Galaxies Have Stars?
Galaxies, we've just noted, have work to do. One of their jobs is to ensure that we have the particular kind of space we need, both here and throughout the cosmos. But it turns out that this space-crafting task could be accomplished even if galaxies were nothing more than nondescript lumps of matter in the same quantities. Galaxies don't need to be made up of stars in order to work their beneficial effect on the nature of space. So, why do galaxies have stars? Or, to put the question more carefully, why do we need stars? Are they anything more than cosmetic (or cosmic) jewelry for the adornment of our nighttime sky?
One obvious response to this question is to note that we certainly do need one star in particular for our well-being. The Sun is a star and it is, of course, essential to us as the provider of the heat and light we need in order to live comfortably here on Earth. But what about the billions of other stars found in a typical galaxy? Do we need them also?
We certainly do. Why? Because we are made of stardust. Stars are factories that use hydrogen, their most plentiful resource, to manufacture heavier elements like carbon, oxygen, and nitrogen. They do this in their pressure-cooker centers by the process called thermonuclear fusion—the same process that we humans use destructively to generate the explosive energy of the hydrogen bomb. Stars are formed when the force of gravity compresses large "globules" of gas (mostly hydrogen) into much smaller volumes. This compression raises the temperature of the gas sufficiently high to ignite the fusion reaction. The product of this fusion is a progression of heavier elements, including the elements of which our bodies are made. A bit of high-powered computation demonstrates that the relative abundance of the various chemical elements that we observe in the universe matches well with what we should expect from the "element factories" in stars.
Some of the products made in these element factories are expelled by aging stars back into space, where they become available once again to form second- and third-generation stars, usually accompanied by the planetary systems that are a noteworthy byproduct of star formation. To be sure, we are made of "the dust of the Earth," but the chemical elements of Earth dust are nothing other than stardust. It's a remarkable story, one that we've learned to tell only in the last century. It's a story told with warranted confidence by the natural sciences because so many portions of it can be empirically confirmed and because the portions that we can confirm fit together like pieces of a jigsaw puzzle that form an elegant and well-ordered picture.
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Why do we need stars (other than the Sun)? We need them to manufacture the elements of which our bodies are made. Remarkably, stars are equipped to do just that. Hydrogen is the most abundant element present in galaxies. The force of gravity gathers this hydrogen into star-sized spheres hot enough to ignite the "fires" of nuclear fusion. Fusion produces progressively heavier elements that are expelled by aging stars and made available for the formation of more stars; and not only of more stars, but also of the planets that orbit them; and not only of planets, but also of the living creatures that inhabit them.
Fully Equipped Creation
At the end of the day (or on a nighttime drive through the desert), what might we learn from this brief reflection on galaxies and space, and on elements and stars? Can we do more than just marvel that galaxies—among the largest of things—are visible to us because they are illumined by stars energized by atomic nuclei that rank among the smallest of things? That's an interesting observation, of course, but there's more. Two fundamental character traits of the universe strike me as especially worthy of note here. We have already hinted at both, but let's be more explicit.
The first has to do with here and now: the universe is a cosmos that is fully equipped with all of the resources and capabilities to provide for the needs of the day. Galaxies, we noted, function to craft the kind of space-time we need. The Sun provides the heat and light that make life on Earth possible. Atomic nuclei function to generate the Sun's wealth of luminous energy. We could fill a book with similar examples. We are members of a beautiful and harmonious system of resources and actions. As Christians we ought not be surprised at this. After all, if the universe is a creation that was given being by the One who is infinitely creative and who is characterized by the love of qualities like beauty and harmony, would we not expect the creation to be a cosmos?
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The second noteworthy character trait has to do with the manner in which we got to the here and now: the universe is richly gifted with remarkable capabilities for organizing itself, in the course of time, into new structures and forms.
Our universe has been equipped not only with the resources to meet the needs of this day, but also with the capabilities to form the structures that characterize this day in its history. The newborn universe was gifted with the capabilities to organize itself from a state of near uniformity into an array of galaxy-sized "lumps." The material within these lumps was gifted with the capability to collect into stars. The hydrogen within these stars was gifted with the capability to transform itself into the elements that would later be used to make earthy planets, plants, animals, and even us. Once again, we could fill a book with similar examples.
Although this wealth of formational gifts may astound us, surely we Christians shouldn't find it entirely unexpected. If the universe is a creation that was given being by the One who is generous beyond human comprehension, should we not expect to find that this creation is wondrously gifted with the capabilities needed for organizing and transforming itself into the structures and forms intended by its Creator? As Basil of Caesarea said more than 16 centuries ago in his homilies on the creation, "Our God has created nothing unnecessarily and has omitted nothing that is necessary." Although Basil had no knowledge of the astronomical matters that we are here considering, perhaps he was on the right track in expecting the creation to be gifted with all that it needed to carry out the Creator's intentions.
This concept of a fully-equipped universe is wholly consistent with our experience of God's action in our lives. We are not questioning the reality of God's providential action or of God's response to prayer. The question before us is not, Does God act in the universe? The question is, What is the character of the universe in which God acts and with which God interacts? Our scientifically informed concept of the creation may invite questions about the character of divine action, but not of its reality or of its necessity.
One final thought: Dare we take this expectation one step further and envision a creation so generously gifted that it has the formational capabilities to assemble even living creatures equipped to evolve into new forms through time? Or would that be expecting too much? Too much of ourselves (to envision so boldly)? Too much of God (to give so generously)?
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Some Christians look for evidence that the universe's "natural" capabilities were inadequate to the task of assembling some new biotic structure or life form in the past. If such "capability gaps" could be found, then, the argument goes, these gaps must have been bridged by occasional episodes of form-conferring divine intervention (sometimes called acts of "intelligent design"). But if the universe is a creation, as we Christians profess, then its natural capabilities are part of its God-given nature. That being the case, I am more inclined to look for the Creator's signature in the generosity with which the creation's formational gifts have been conferred. In other words, I think the Creator is better known by what the creation can do rather than by what it cannot.
Howard J. Van Till is emeritus professor of physics and astronomy at Calvin College in Grand Rapids, Michigan, and a coauthor of Science & Christianity: Four Views (InterVarsity, 2000).
Christianity Today's sister publication Books & Culture has a Science Pages section.
In 1997, Christianity Today columnist Philip Yancey wrote that the universe appears to be tuned with inconceivable precision and Christians look to Jesus for why that is.
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