Holy Wars

Natural History Magazine

by Neil deGrasse Tyson

From Natural History Magazine, October 1999

At nearly every public lecture that I give on the universe, I try to reserve adequate time at the end for questions. The succession of subjects is predictable. First, the questions relate directly to the lecture. They next migrate to sexy astrophysical subjects such as black holes, quasars, and the big bang. If I have enough time left over to answer all questions, and if the talk is in America, the subject eventually reaches God. Typical questions include: Do scientists believe in God? Do you believe in God? Do your studies in astrophysics make you more or less religious?

Publishers have come to learn that there is a lot of money in God, especially when the author is a scientist and when the book title includes a direct juxtaposition of scientific and religious themes. Successful books include Robert Jastrow's God and the Astronomers, Leon M. Lederman's The God Particle, Frank J. Tipler's The Physics of Immortality: Modern Cosmology, God, and the Resurrection of the Dead, and Paul Davies's two works God and the New Physics and The Mind of God. Each author is either an accomplished physicist or astronomer and, while the books are not strictly religious, they encourage the reader to bring God into conversations about astrophysics. Even Stephen Jay Gould, a Darwinian pitbull and devout agnostic, has joined the title parade with his recent work Rock of Ages: Science and Religion in the Fullness of Life. The financial success of these published works indicates that you get bonus dollars from the American public if you are a scientist who openly talks about God. After the publication of The Physics of Immortality, which suggested the law of physics might allow you and your soul to exist long after you are gone from this world, Tipler's book-tour included many well-paid lectures to Protestant religious groups. This lucrative sub-industry has further blossomed in recent years due to efforts made by the wealthy founder of the Templeton investment fund, Sir John Templeton, to find harmony and reconciliation between science and religion. In addition to sponsoring workshops and conferences on the subject, Templeton seeks out widely published religion-friendly scientists to receive an annual award whose cash value exceeds that of the Nobel Prize.

Let there be no doubt that as they are currently practiced, there is no common ground between science and religion. As was thoroughly documented in the nineteenth century tome, A History of the Warfare of Science with Theology in Christendom, by the historian and one time president of Cornell University Andrew D. White, history reveals a long and combative relationship between religion and science, depending on who was in control of society at the time. The claims of science rely on experimental verification, while the claims of religions rely on faith. These are irreconcilable approaches to knowing, which ensures an eternity of debate wherever and whenever the two camps meet. Just as in hostage negotiations, it's probably best to keep both sides talking to each other. The schism did not come about for want of earlier attempts to bring the two sides together. Great scientific minds, from Claudius Ptolemy of the second century to Isaac Newton of the seventeenth, invested their formidable intellects in attempts to deduce the nature of the universe from the statements and philosophies contained in religious writings. Indeed, by the time of his death, Newton had penned more words about God and religion than about the laws of physics, all in a futile attempt to use the Biblical chronology to understand and predict events in the natural world. Had any of these efforts succeeded, science and religion today might be largely indistinguishable.

The argument is simple. I have yet to see a successful prediction about the physical world that was inferred or extrapolated from the content of any religious document. Indeed, I can make an even stronger statement. Whenever people have used religious documents to make accurate predictions about the physical world they have been famously wrong. By a prediction, I mean a precise statement about the untested behavior of objects or phenomena in the natural world that gets logged before the event takes place. When your model predicts something only after it has happened, then you have instead made a postdiction. Postdictions are the backbone of most creation myths and, of course, of the Just So stories of Rudyard Kipling, where explanations of everyday phenomena explain what is already known. In the business of science, however, a hundred postdictions are barely worth a single successful prediction.

Topping the list of predictions are the perennial claims about when the world will end, none of which have yet proved true. But other claims and predictions have actually stalled or reversed the progress of science. We find a leading example in the trial of Galileo (which gets my vote for the trial of the millennium) where he showed the universe to be fundamentally different from the dominant views of the Catholic Church. In all fairness to the Inquisition, however, an Earth-centered universe made a lot of sense observationally. With a full complement of epicycles to explain the peculiar motions of the planets against the background stars, the time-honored, Earth-centered model had conflicted with no known observations. This remained true long after Copernicus introduced his Sun-centered model of the universe a century earlier. The Earth-centric model was also aligned with the teachings of the Catholic Church and prevailing interpretations of the Bible, wherein Earth is unambiguously created before the Sun and the Moon as described in the first several verses of Genesis. If you were created first, then you must be in the center of all motion. Where else could you be? Furthermore, the Sun and Moon themselves were also presumed to be smooth orbs. Why would a perfect, omniscient deity create anything else?

All this changed, of course, with the invention of the telescope and Galileo's observations of the heavens. The new optical device revealed aspects of the cosmos that strongly conflicted with people's conceptions of an Earth-centered, blemish-free, divine universe: The Moon's surface was bumpy and rocky; The Sun's surface had spots that moved across its surface; Jupiter had moons of its own that orbited Jupiter and not Earth; and Venus went through phases, just like the Moon. For his radical discoveries, which shook Christendom, Galileo was put on trial, found guilty of heresy, and sentenced to house arrest. This was mild punishment when one considers what happened to the monk Giordano Bruno. A few decades earlier Bruno had been found guilty of heresy, and then burned at the stake, for suggesting that Earth may not be the only place in the universe that harbors life.

I do not mean to imply that competent scientists, soundly following the scientific method, have not also been famously wrong. They have. Most scientific claims made on the frontier will ultimately be disproved, due primarily to bad or incomplete data. But this scientific method, which allows for expeditions down intellectual dead ends, also promotes ideas, models, and predictive theories that can be spectacularly correct. No other enterprise in the history of human thought has been as successful at decoding the ways and means of the universe.

Science is occasionally accused of being a closed minded or stubborn enterprise. Often people make such accusations when they see scientists swiftly discount astrology, the paranormal, Sasquatch sightings, and other areas of human interest that routinely fail double-blind tests or that possess a dearth of reliable evidence. But this same level of skepticism is also being applied to ordinary scientific claims in the professional research journals. The standards are the same. Look what happened when the Utah chemists B. Stanley Pons and Martin Fleischmann claimed in a press conference to create cold nuclear fusion on their laboratory table. Scientists acted swiftly and skeptically. Within days of the announcement it was clear that no one could replicate the cold fusion results that Pons and Fleischmann claimed for their experiment. Their work was summarily dismissed. Similar plot lines unfold almost daily (minus the press conferences) for nearly every new scientific claim. You usually only hear about the ones that could affect the economy.

With scientists exhibiting such strong levels of skepticism, some people may be surprised to learn that scientists heap their largest rewards and praises upon those who do discover flaws in established paradigms. These same rewards also go to those who create new ways to understand the universe. Nearly all famous scientists, pick your favorite one, have been so praised in their own lifetimes. This path to success in one's professional career is antithetical to almost every other human establishment—especially to religion.

None of this is to say that the world does not contain religious scientists. In a recent survey of religious beliefs among math and science professionals, 65 percent of the mathematicians (the highest rate) declared themselves to be religious, as did 22 percent of the physicists and astronomers (the lowest rate). The national average among all scientists was around 40 percent and has remained largely unchanged over the past century. For reference, 90 percent of the American public claims to be religious (among the highest in Western society), so either nonreligious people are drawn to science or studying science makes you less religious.

But what of those scientists who are religious? Successful researchers do not get their science from their religious beliefs. On the other hand, the methods of science have little or nothing to contribute to ethics, inspiration, morals, beauty, love, hate, or aesthetics. These are vital elements of civilized life, and are central to the concerns of nearly every religion. What it all means is that for many scientists there is no conflict of interest.

When scientists do talk about God, they typically invoke him at the boundaries of knowledge where we should be most humble and where our sense of wonder is greatest. Examples of this abound. During an era when planetary motions were on the frontier of natural philosophy, Ptolemy couldn't help feeling a religious sense of majesty when he wrote, When I trace at my pleasure the windings to and fro of the heavenly bodies, I no longer touch the earth with my feet. I stand in the presence of Zeus himself and take my fill of ambrosia. Note that Ptolemy was not weepy about the fact that the element mercury is liquid at room temperature, or that a dropped rock falls straight to the ground. While he could not have fully understood these phenomena either, they were not seen at the time to be on the frontiers of science.

In the thirteenth century, Alfonso the Wise (Alfonso X), the King of Spain who also happened to be an accomplished academician, was frustrated by the complexity of Ptolemy's epicycles. Being less humble than Ptolemy, Alfonso once mused, Had I been around at the creation, I would have given some useful hints for the better ordering of the universe.

In his 1686 masterpiece, The Mathematical Principles of Natural Philosophy, Isaac Newton lamented that his new equations of gravity, which describe the force of attraction between pairs of objects, might not maintain a stable system of orbits for multiple planets. Under this instability, planets would either crash into the Sun or get ejected from the solar system altogether. Worried about the long-term fate of Earth and other planets, Newton invoke the hand of God as a possible restoring force to maintain a long-lived solar system. Over a century later, the French mathematician Pierre Simon de Laplace invented a mathematical approach to gravity, published in his four-volume treatise Célestial Méchanics, which extended the applicability of Newton's equations to complex systems of planets such as ours. Laplace showed that our solar system was stable and did not require the hand of a deity after all. When queried by Napoleon Bonaparte on the absence of any reference to an author of the universe in his book, Laplace replied, I have no need of that hypothesis.

In full agreement with King Alfonso's frustrations with the universe, Albert Einstein noted in a letter to a colleague, If God created the world, his primary worry was certainly not to make its understanding easy for us. When Einstein could not figure out how or why a deterministic universe could require the probabilistic formalisms of quantum mechanics, he mused, It is hard to sneak a look at God's cards. But that he would choose to play dice with the world is something that I cannot believe for a single moment. When an experimental result was shown to Einstein that, if correct, would have disproved his new theory of gravity Einstein commented, The Lord is subtle, but malicious he is not. The Danish physicist Niels Bohr, a contemporary of Einstein, heard one too many of Einstein's God-remarks and declared that Einstein should stop telling God what to do!

Today, you hear the occasional astrophysicist (maybe one in a hundred) invoke God when asked where did all our laws of physics come from, or what was around before the big bang. As we have come to anticipate, these questions comprise the modern frontier of cosmic discovery and, at the moment, they transcend the answers our available data and theories can supply. Some promising ideas, such as inflationary cosmology and string theory, already exist. These could ultimately give to the answers to those questions, thereby pushing back our boundary of awe.

My personal views are entirely pragmatic, and partly resonate with those of Galileo who, during his trial, is credited with saying, The Bible tells you how to go to heaven, not how the heavens go. Galileo further noted, in a 1615 letter to the Grand Duchess of Tuscany, In my mind God wrote two books. The first book is the Bible, where humans can find the answers to their questions on values and morals. The second book of God is the book of nature, which allows humans to use observation and experiment to answer our own questions about the universe.

I simply go with what works. And what works is the healthy skepticism embodied in scientific method. Believe me, if the Bible had ever been shown to be a rich source of scientific answers and understanding, we would be mining it daily for cosmic discovery. Yet my vocabulary of scientific inspiration strongly overlaps with that of religious enthusiasts. I, like Ptolemy, am humbled in the presence of our clockwork universe. When I am on the cosmic frontier, and I touch the laws of physics with my pen, or when I look upon the endless sky from an observatory on a mountaintop, I well up with an admiration for its splendor. But I do so knowing and accepting that if I propose a God beyond that horizon, one who graces our valley of collective ignorance, the day will come when our sphere of knowledge will have grown so large that I will have no need of that hypothesis.

Neil deGrasse Tyson, an astrophysicist, is the Frederick P. Rose Director of New York City’s Hayden Planetarium and a visiting research scientist at Princeton University.