Lawrence M. Krauss, a theoretical physicist, is president of the Origins Project Foundation, and the author of books including A Universe from Nothing, and most recently, The Physics of Climate Change.
As a scientist who has written at length about science and religion, I nevertheless remain surprised by the continued appearance of articles by people of faith, ranging from New York Times columnist Ross Douthat to the religious Discovery Institute spokesman Stephen C. Meyer, about how the “strange fittedness of the universe for life” helps support their belief in God.
While inferring evidence for a hypothesis when no such evidence exists – misinterpreting coincidence as intent, for example – is a common and understandable human error, inferring evidence in the face of massive counterevidence seems to be more restricted to the truly faithful.
Modern science has revealed that most of the universe appears to be uninhabitable for life forms like us. And even here on our remote living oasis on Earth, the universe continues to generate new opportunities to hasten our demise. If we are not annihilated by a roving asteroid or comet, or a nearby exploding star, or by the eventual demise of our own sun, the evolution of intelligent life on Earth may itself pose a threat to continued terrestrial habitability, either through nuclear weapons or owing to the long-term effects of climate change.
In our own solar system, Earth is uniquely positioned to have allowed the evolution of intelligent life. Microbes may exist under the surface of Mars or in the oceans under the frozen surfaces of planetary moons such as Europa or Enceladus, and it would be a profound scientific development to discover evidence for such life, but none of these systems are naturally habitable for humans.
On larger scales, in our own galaxy, with 100 billion stars, most of which may have planetary systems around them, the majority of these systems are nevertheless unfit for the evolution of Earth-like life. Those close to the centre of the galaxy will experience frequent stellar encounters that will alter the orbital dynamics of their planetary systems, making potentially habitable planets uninhabitable, or, ejecta from nearby supernovae will either evaporate planetary surfaces or sterilize them. While many potentially habitable planets (i.e. those that contain liquid water on the surface) might still exist, most of these are located in close proximity to stars far smaller than our sun. Extreme tidal effects and solar eruptions are likely to pose grave threats to the long-term evolution of life on these systems. It is possible that out of 100 billion solar systems, our Earth might be the only planet possessing intelligent life.
On still larger scales, galaxies themselves are few and far between. Most of space is cold and dark and uninhabitable for us. Many galaxies contain supermassive black holes, thousands of times larger than the relatively tame black hole at the centre of our galaxy, that emit unfathomably deadly and energetic jets of radiation, sterilizing or vaporizing systems in their path.
On the scale of our whole observable universe, much has been made of the fact that if the recently discovered energy of empty space, so-called “dark energy,” the dominant energy in the universe in fact, were much larger than its minuscule value, galaxies would never have formed, and with them stars, planets and Earth. But, if the energy of empty space were zero, a value most physicists thought would be most natural in advance of observations to the contrary, the universe would be more hospitable to life. As it is, the formation of structures on scales larger than clusters of galaxies, which could result in the formation of new galactic systems that might house life, stopped more than five billion years ago once dark energy began to dominate the expansion of the universe.
In the face of all of this evidence against fitness, why do so many people like Mr. Douthat, Mr. Meyer and others who lean toward the notion of a divine designer continue to think the opposite is true? It is probably easiest to answer this statement by returning to a mindset before the results of Charles Darwin’s successful realization that natural selection is the mechanism that governs to evolution of the diversity of life on Earth.
Before Darwin, the remarkable compatibility between diverse living things and their local environments seemed certain evidence for divine creation. After Darwin, it was realized that focusing on the apparent strange fitness of the Earth for life was putting the cart before the horse. Instead, natural selection produces forms of life that are fine tuned to fit their environment, and not the other way around.
So too, as we examine our universe, focusing on the qualities of our universe that appear to make it fit for life is misplaced. Life on Earth is fine-tuned to fit the characteristics of our region of the universe. One should expect no less. It would be remarkable to find life evolving qualities incompatible with its environment.
Focusing on the seeming unlikeliness of all the coincidences that allowed life to evolve on Earth is bound to lead to a misplaced notion of compatibility. Listing all of the precursors that were required so I would exist today to type these words – from the unbelievably unlikely successful couplings of eons of my human and pre-human ancestors, to the fact that Steve Jobs created a computer that ultimately allowed me to type these words today – might make this essay itself seem miraculous. It is not.
Exotic terrestrial extremophile forms of life exist only in boiling acidic environments. An intelligent extremophile living in a cave might marvel about the strange fitness of the cave for their existence. But a more intelligent extremophile, who created tools to explore the outside world, would realize that most of the Earth is hostile.
It is also true that if our universe were different, even in potentially minute ways, we might not exist. But that is not to say that some other forms of life could not evolve, tuned to the features of their own universe. The late great physicist Freeman Dyson, with whom I had a long and enjoyable academic debate about the possible future of life in our universe, considered possible lifeforms about as far away from our current forms as one could imagine, including ones like those in Fred Hoyle’s science-fiction story The Black Cloud, containing a diffuse gas of particles whose movements encoded intelligence. Would such lifeforms, which could exist even in a universe without stars, or even heavy elements, ponder the largess of their own Gods?
We can choose, as the late Nobel Prize-winning physicist Steven Weinberg did, to suggest that the more the universe seems comprehensible, the more it seems pointless, even as we rejoice that life found an accidental hospitable niche here on Earth. Or one can choose to believe that God created such a niche. But either way, it is simply false to claim the universe in which that niche exists is kind or welcoming, and as a result, designed.
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