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Life on Other Planets? A Writer at Slate Takes Us to Task

Daniel Bakken

Saturn and Titan.jpg

Over at Slate, Mark Strauss has contributed some comments about the possibility of life on other planets. His article, “God’s Chosen Planet: Why Creationists are Praying We Never Find Alien Life,” is a confusing rebuttal of sorts to the Rare Earth hypothesis, as well as to articles here at Evolution News & Views.

First, I must congratulate Strauss for actually reading our coverage at ENV, which not everyone who tries to answer us actually does. He understands the relevant arguments, and demonstrates his comprehension in the article. If it weren’t for the ad hominems and other juvenile remarks sprinkled in, you might not realize it was intended as a rebuttal at all.

He begins with Titan, the large moon of Saturn:

Could primordial soup be served ice-cold and made with a liquid other than water? Astrobiologists believe that it’s possible on Titan. Although the temperature on Saturn’s massive moon is a chilly minus 179 degrees Celsius, it has a thick nitrogen atmosphere rich in organic molecules and a surface speckled with methane lakes. These ingredients, according to computer simulations recently conducted at Cornell University, could combine to form cellular membranes, which are crucial for the evolution of complex cells.

This refers to a proposal of workable membrane walls in liquid methane, and it certainly is interesting. But it addresses only one of a host of problems in the origin of life. The big problem isn’t a potential cell wall, which in itself is complex — much more complicated than a membrane. The real difficulty is the biological information required for even the simplest cell. In addition, water possesses unique properties that liquid methane does not. But no matter — a spherical membrane looks like a cell, so I guess we should think they’ve got it pretty much all figured out, and consequently there must be cryo-organisms on Titan. This is why Strauss believes we should spend billions of dollars to go look.

Strauss then accuses Discovery Institute of ridiculing astrobiology. On the contrary, Discovery is one of the few outlets publicizing the results of astrobiologists. The trouble for Mark Strauss is that the field has been giving us a lot of results that he doesn’t like. What may merit ridicule is the unwarranted optimism of those who would direct precious research funding to unrealistic projects seeking to demonstrate the existence of life elsewhere. We need to be sober about these things: bubbles in liquid methane aren’t enough to convince a reasonable person that there is life on Titan.

After presenting some of the evidence for the Rare Earth hypothesis, and for the Privileged Planet hypothesis advanced by Guillermo Gonzalez and Jay Richards, Strauss then throws up his hands: “It’s the sort of circular reasoning that can give you an ice cream headache.”

He fails to understand that there aren’t just a few factors that make the earth special — there are many. The argument is cumulative: you can’t just take a couple of them, and say that is the whole of it. But then he thinks “creationists” are all stuck in the fantasy that Copernicus demoted the earth from the center of the universe, and so we’re trying to put it back. As a historical matter, the truth is that the center of the universe was never understood by the ancients to be a special position. The center was the sump of the universe, where all decay, corruption, and imperfection collected, while the heavens were perfect. In reality, Copernicus promoted the earth to the same status as the heavens. If, as some have suggested, the earth is unique in the visible universe, then our planet would seem to hold something of a special position in that sense.

Strauss makes the point that maybe a tidally locked planet could support life — that is, if it has ocean currents to transport heat to its cold side. If so, that would help boost the number of potentially habitable worlds, since it’s likely that many planets circle the very common red dwarf type stars. For these planets to be in the habitable zone of their stars, they need to be so close that they become tidally locked, as our moon is to the earth, with one side always facing the star.

These planets would not rotate very quickly, and models show that, even in their twilight areas, habitable zones would be very small if they existed at all. In the oceans, as he suggests, there may be greater distribution of heat, but it doesn’t seem likely that technology could ever develop there.

There are many other problems Strauss doesn’t even hint at. The closer a planet is to a red dwarf star, the stronger the effects of stellar flares on the atmosphere of that planet. Its slow rotation would likely rule out any strong magnetic field to shield it from flares. To have an ocean at all requires a stable atmosphere that can keep liquid on its surface. With extreme temperature differences between the day and night sides, a tidally locked planet makes that difficult.

Strauss then executes a mighty leap. He claims we’ve found habitable zones on Titan, and Europa, the moons of Saturn and Jupiter. This is the faith of a true believer, not the objectivity of a scientist, since we don’t know if they are, in fact, habitable. In any event, our solar system isn’t a very good place to look for independently evolved life. Why? Because the earth has contaminated it with microbes that hitched rides on the ejecta from asteroid collisions since life first appeared here. Due to this transfer mechanism, we should positively expect the remains of earth life on Mars, and even throughout the solar system.

Strauss seems incredulous that the Rare Earth hypothesis allows for the possibility of microbes in the universe. He writes:

The intelligent design crowd doesn’t rule out the existence of what it calls “simple life” on other worlds. However, as the Discovery Institute sniffs, “we likely won’t be satisfied with microbes barely surviving on a moon. … We are looking for much more complex life, with a brain capacity similar to our own, and the ability to modify its surroundings into complex technology.”

It’s stunning that even critics of astrobiology could be witless enough to write those words. We’d be quite satisfied with microbes eking out an existence on an alien moon. In fact, evidence that life can emerge on other worlds would be the most significant discovery of the millennium.

The writer doing the “sniffing” there was me (see “In Search of Exoplanets: Defining Habitable Space Bodies“). I agree that if we found microbes barely surviving on a moon outside our solar system, that would be a great discovery. But Mark has wrenched my comments out context. As I’m sure he is smart enough to understand, I was writing there about the natural curiosity about intelligent life elsewhere in the cosmos. We can’t talk to microbes, much less discuss the meaning of life and the purpose of the universe with them, because they aren’t capable of a technological civilization. That’s what it takes for interplanetary communication. This isn’t hard to understand.

Strauss offers an unintended confirmation of the design hypothesis when he says, “But there is nothing simple about life itself.” No, there isn’t. Advocates of ID argue that life in fact reveals hallmarks of design associated with the activity of an intelligent agent. Yet Mark Strauss doesn’t seem to fully appreciate the orders of magnitude of complexity that separate microbes from humans. The attendant narrowing of the fine-tuning of habitability factors for technological civilizations is such that we can justifiably assume that the earth is incredibly rare, possibly even unique in the visible universe, in its ability to support technological civilization.

One point that I explicitly laid out in my series of articles on exoplanets has to do with Fermi’s paradox. In brief, Fermi’s paradox asks, if technological life is common in the galaxy, then where are they? At modest speeds, relative to the history of life on the earth going back billions of years, the time needed for colonizing a planet like ours is only 50 million years or less. If alien life is out there, then why have we not been colonized or at least contacted by now? Occam’s razor suggests that the simplest reason is the best: we are alone.

Mark’s parting shot is to suggest that anyone who argues for intelligent design in the universe must be afraid of finding life out there. This is a straw man. We argue from the data available: that earth is statistically a miracle in its ability to support a technological species like humans. If there is another found that’s like it, who is to say an intelligent designer didn’t decide to make more than one?

Image: Titan and Saturn, by NASA/JPL-Caltech/Space Science Institute.