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Physics, Earth & Space Icon Physics, Earth & Space

University of London Astrobiologist: “Earth is Lucky” and “Almost the Perfect Place for Life”

While Cosmos is simply ignoring the life-friendly fine-tuning of our planet, other scientists see it as an important question to investigate. According to an article last month in The Scientist, “Is Earth Special?,” astrobiologist and geophysicist David Waltham argues that “Earth is a rare, beautiful, and very special place — one of the luckiest planets in the Universe.” He observes that, “Most planets are too hot or too cold; too wet or too dry; too small or too big; or just plain wrong for life in any one of a hundred other ways,” making our planet “almost the perfect place for life as we know it.”

Formerly the head of the Department of Earth Sciences at Royal Holloway College, University of London, Waltham recently wrote a book Lucky Planet: Why Earth is Exceptional–and What That Means for Life in the Universe which develops these arguments. But what are the implications of this fine-tuning? In his article in The Scientist he notes that there are three primary options available for explaining the life-friendly nature of our planet:

Firstly, it could be a fundamental principle that biogeochemical processes on inhabited worlds tend to stabilize climates. Thus, we shouldn’t be surprised by Earth’s suitability for life because the physical, chemical, and biological laws of the Universe guarantee the existence of many such worlds. Alternatively, it may be that life is extraordinarily adaptable and will thrive under a wide range of conditions. Again, we shouldn’t be surprised that Earth fits life because, in fact, life has adapted to fit Earth. Finally, perhaps planets suitable for complex organisms occur only rarely and purely by chance.

Waltham opts for the latter explanation, that “good fortune” is an important part of explaining why life exists on earth. He gives no indication that this necessarily points to intelligent design, for he believes:

Intelligent observers can only arise on planets where conditions allow complex life, even if such worlds are so unusual that we’d need to search a billion galaxies to find another. The tautology that we must inhabit a habitable world, even if such planets are extraordinarily peculiar, is an extreme example of the scientifically common problem of observational bias.

In other words, if earth was any different, we wouldn’t be here to see it. Waltham is right that this is a tautology, but does it really explain away the incredible fine-tuning of our planet? The following common illustration shows why it doesn’t.

Imagine that you are about to be executed by a 5-man firing squad. You hear the sergeant say “Ready, Aim, Fire,” and the guns go off. But you’re still there — your heart racing, your lungs breathing rapidly — very much alive. Now you say to yourself, “The gunners must have missed me, because if they hadn’t, I wouldn’t be here to realize it.” Perhaps that’s true — but that does not explain why they missed you. In the same way, the observation that we’re here on planet earth does nothing to explain why we are here on planet earth.

Indeed, the observation that we’re very lucky still doesn’t resolve the question of chance (or chance+law) vs. design. Sometimes apparently “lucky” things can happen when there are sufficient probabilistic resources, and don’t imply design. Sometimes events really are vastly improbable once you consider the available probabilistic resources. So was your survival of the firing-squad the result of chance, or design?

You decide to try to put some numbers on the problem. Let’s say you determine that a trained sharpshooter only misses its target 0.1% of the time. The odds of one sharpshooter missing you are thus 1 in 1,000, but the odds of five sharpshooters missing you, therefore, are 1 in 1,000,000,000,000,000, or one in a quadrillion.

Since there haven’t been a quadrillion people on earth, much less anywhere near a quadrillion executions, you decide that “chance” really isn’t a very good explanation here for why you survived the execution. In fact, a perfectly viable explanation is that the sharpshooters intentionally missed you so you would live — intelligent design.

We can do similar calculations for the life-friendly nature of our planet. I’m not going to do them here, but the point is this: the initial observation that our planet is “lucky” might point to chance, but it might also point to design. The mere fact that “we wouldn’t observe being ‘lucky’ if we weren’t here” does nothing to resolve the question; it doesn’t explain why we got lucky. That doesn’t mean these are intractable questions. We must assess the probabilistic resources available to produce such a life-friendly planet, and then ask whether our life-friendly earth is likely to exist given the known probabilistic resources available to chance+law.

The irony of all of this is that the investigation Dr. Waltham is undertaking is much the same as what Ball State University (BSU) physicist Eric Hedin was teaching in his class, “Boundaries of Science.” Now banned by BSU, Dr. Hedin’s course also explored the debate over whether earth, and life, are special, and whether they point to chance or intelligent design. These are legitimate scientific and philosophical questions that are not only worth asking — they are vital to ask if we’re to understand our own existence.

How ironic that while physicist Eric Hedin is being persecuted in the United States for discussing fine-tuning and intelligent design, a scientist from the UK is being granted the freedom to explore these same questions in a mainstream scientific journal. I’m glad for Dr. Waltham; I only wish the same Dr. Hedin.

Casey Luskin

Associate Director and Senior Fellow, Center for Science and Culture
Casey Luskin is a geologist and an attorney with graduate degrees in science and law, giving him expertise in both the scientific and legal dimensions of the debate over evolution. He earned his PhD in Geology from the University of Johannesburg, and BS and MS degrees in Earth Sciences from the University of California, San Diego, where he studied evolution extensively at both the graduate and undergraduate levels. His law degree is from the University of San Diego, where he focused his studies on First Amendment law, education law, and environmental law.



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