Earth unique in cosmos

Earth rises above the horizon of the Moon before the crew of Apollo 11
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Earth is unique in the cosmos as a harbor of intelligent life. A secular science writer admits this and describes what makes Earth special.

Earth unique or commonplace?

As long as men have built cities, they have wondered whether they are alone in the universe. Religious men, of course, usually assume that we are alone. (C. S. Lewis briefly suggested that if we are not alone, then God has instructed other races to leave us alone, because we are fallen and they are not.) But even secular men, beginning with Plato, have claimed that man is alone.

Most secular men today reject the notion of a unique Earth. They reason thus: the universe is so vast, and has so many stars, that some of those stars must have planets, and some of those planets must have given rise to beings that could someday meet, talk, trade (or fight) with humans. Usually, those who speculate about non-human intelligences, place them just beyond the reach of human knowledge about the sky and the objects in it. Thus H. G. Wells speculated about civilizations on Mars and even on the Moon. People stopped speculating when explorers (on the Moon) or their robotic proxies (on Mars and elsewhere) found other bodies in the solar system hostile and inhospitable to life. So today people speculate about civilized life in other “solar systems.” How convenient! Even trying to go to such a star to find out would cost more than any government could raise with the most optimistic bond sales. Worse, getting a message back would usually take longer than the life, much less the career, of any flight director. CNAV doubts that any launch authority would last long enough.

Now comes a new book, Alone in the Universe, that says that looking for non-human trading (or sparring) partners is useless.

Conditions for life unique to Earth

John Gribbin (born 1946) has written about scientific hypotheticals for years. In his latest work (see here for the review by Alan Hirschfeld), Gribbin says flatly that the Earth is the only planet in the galaxy, at least, that can harbor intelligent life. Gribbin argues from conventional theories about the origin of the Earth and the solar system. This includes every theory that any secular scientist has advanced to explain various features of the Earth: a giant impactor to create the Moon, a “dynamo” in the earth’s core to generate the magnetic field, etc. Each of those theories has its own unique problems. But Gribbin observes several features that, he says, made human life possible. They include:

  • A relatively thin crust.
  • A powerful magnetic field, to protect against most cosmic radiation.
  • A moon one-fourth as big around as the Earth, with a mass to match. (Without this, says Gribbin, giant Jupiter would have shifted the poles dozens of times.)
  • A remarkably temperate climate.

Earth rises above the horizon of the Moon before the crew of Apollo XI

Earth rises above the horizon of the Moon as the crew of Apollo XI return from the Moon's far side. Photo: NASA/JSC

How the Earth came to have these features is less important than how likely this was to happen. The point is that, taken together, those features are a rigorous set of requirements. So rigorous are they that the galaxy has room for only one planet to satisfy them. That planet is Earth.

Gribbin lays out one more argument from what he supposes is the great age of the galaxy. If the galaxy is that old, then a civilized society should have arisen long before now. And if that society could survive and solve its own problems from environmental stress, crime, and war, then they should have conquered the galaxy long before this. Yet no explorer or observer has ever seen anything he could rely on to show that non-human intelligent life exists or existed. (If non-human life did arise on a world other than Earth, then it killed itself long ago, so that we would neither see nor hear from them today.)

A planet made to order

Creation advocates have no problem with Earth being unique. This is a variation on the anthropic principle. This principle holds that the cosmos is literally made to order for man.

…our existence in this universe depends on numerous cosmological constants and parameters whose numerical values must fall within a very narrow range of values. If even a single variable were off, even slightly, we would not exist.

These constants include the strengths of everything from the charge on a single proton or electron to the Four Basic Forces (strong and weak nuclear, electromagnetic, and gravity). Likewise, John Gribbin has shown that the Earth itself is made to order for man. In addition to the features Gribbin named, many other facts make Earth a remarkably hospitable place for man to live and thrive:

  • Ice being less dense than liquid water
  • The total mass, and the proportions, of the gases in the atmosphere
  • The proportion of the sun’s light that Earth reflects
  • The distance from Earth to the sun
  • The color of the sun
  • The distance of the sun to the center of the galaxy (Not even many scientists realize that the galaxy has its own narrow “habitable zone.” Beyond it, radiation would kill all life on Earth.)

And now the problem of how Earth came to have these features becomes acute. By any reasonable standard whatsoever, Earth should not exist, either. Furthermore, the “fine-tuning” of the universe is an even worse problem than the fine-tuning of Earth within a fine-tuned universe.

In short, the cosmos, and the Earth, are miracles.

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Terry A. Hurlbut has been a student of politics, philosophy, and science for more than 35 years. He is a graduate of Yale College and has served as a physician-level laboratory administrator in a 250-bed community hospital. He also is a serious student of the Bible, is conversant in its two primary original languages, and has followed the creation-science movement closely since 1993.

40 Responses to Earth unique in cosmos

  1. Fergus Mason says:

    Oh dear, where to start?

    “Ice being less dense than liquid water”

    This applies everywhere, not just on Earth.

    “The total mass, and the proportions, of the gases in the atmosphere…”

    …is itself largely a product of life.

    “The proportion of the sun’s light that Earth reflects…”

    …is wildly variable; in fact Earth’s albedo varies at least twice a year.

    “The distance from Earth to the sun…”

    …is irrelevant. What matters is the energy density per m^2 at Earth’s surface.

    “The color of the sun…”

    …is typical of a G2 star, which is hardly rare; about 8% of all stars are in this class, which means there are about 32 BILLION in our galaxy alone.

    “Not even many scientists realize that the galaxy has its own narrow “habitable zone.””

    Of course they do. As you prefer books to papers, try “Death from the Skies” by Dr Phil Plait for an explanation of how the Sun’s orbit leads to mass extinctions on Earth.

    • Terry A. Hurlbut says:

      The point is that when you add these all up, you still get a vanishingly small probability that either Earth or cosmos would exist as they do.

      Sorry, mate, but Star Trek is all wet. You might want to try John Gibbin’s suggestion: search for signatures in the infrared spectrum consistent with an atmosphere containing water vapor. Let me know whether you or any other observer finds any…

      • Fergus Mason says:

        “You might want to try John Gibbin’s suggestion: search for signatures in the infrared spectrum consistent with an atmosphere containing water vapor.”

        That’s being done already. The problem is technological; not many exoplanets are close enough for existing telescopes to pick that up and discriminate it from the IR signatures of other greenhouse gases.

        “Let me know whether you or any other observer finds any”

        OK, here’s one; HD209458b. As it’s a hot Jupiter it certainly won’t have Earthlike life, but it does have water vapour. However not all that many have been checked yet, and of course we’ve only found a few hundred exoplanets out of the hundreds of millions that probably exist in this galaxy. I expect the Spitzer telescope will find others in the next few years.

        • Fergus Mason says:

          Sorry, that should be hundreds of BILLIONS that probably exist in this galaxy.

  2. Fergus Mason says:

    “If the galaxy is that old, then a civilized society should have arisen long before now.”

    Why?

    “And if that society could survive and solve its own problems from environmental stress, crime, and war, then they should have conquered the galaxy long before this.”

    You forgot to mention that Gribbin – and, far more eloquently, Carl Sagan – pointed out that a civilised society probably WOULDN’T overcome these problems. Given the state of affairs on Earth, where people are quite prepared to start a nuclear war over issues as trivial as the 1947 India/Pakistan partition line or the Book of Revelation, I tend to agree.

  3. Fergus Mason says:

    “a vanishingly small probability that either Earth or cosmos would exist as they do.”

    Now, let’s look at how small this probability actually is. Of the eight planets in our own solar system, four (50%) are terrestial planets, of which three (75%) lie within the habitable zone; of these three, two (66.6%) and perhaps three (100%) are large enough to hold an atmosphere and sustain life. All three plus our moon (100%) hold water and two (66.6%) have water vapour in the atmosphere. None of these probabilities, it seems to me, are vanishingly small – especially in a galaxy with hundreds of billions of planets.

  4. Fergus Mason says:

    “A moon one-fourth as big around as the Earth, with a mass to match. (Without this, says Gribbin, giant Jupiter would have shifted the poles dozens of times.)”

    Does he have any explanation for why that hasn’t happened to Mars?

    Gribbin is a decent enough astronomer, but he does have a reputation for writing wildly speculative books, which of course being mere books are popular rather than scientific. This is one of them.

    • Terry A. Hurlbut says:

      Do you have an explanation for why, according to the theories you favor, that did not happen to Mars? Or Venus, which is nearer Earth’s size?

      • Fergus Mason says:

        “Do you have an explanation for why, according to the theories you favor, that did not happen to Mars? Or Venus, which is nearer Earth’s size?”

        As it happens yes, I do: Jupiter’s gravity simply isn’t strong enough.

      • Fergus Mason says:

        Anyway, do you have any comment on the fact that I’ve named two planets which have water vapour in their atmospheres? After all, you DID ask me to.

        • Terry A. Hurlbut says:

          Of course, those are Jovian-type planets. Any wet Earths out there? Not yet, there aren’t.

          • Fergus Mason says:

            “those are Jovian-type planets.”

            Well, Venus isn’t.

            “Any wet Earths out there?”

            None that have been found yet. Of course we’ve barely spotted ANY Earth-sized planets, because they’re a lot harder to find than gas giants, and none that I know of have had detailed scans of their atmospheres.

            When we find terrestrial planets with water vapour, will it change your opinions at all? Or will you just “refuse to accept it”?

          • Fergus Mason says:

            “Any wet Earths out there?”

            By the way, I assume that scraping sound I hear is you moving the goalposts. You asked me for planets with water vapour in the atmosphere. I named two. Now you want earthlike planets (except Venus, apparently) with water vapour in the atmosphere. Well, if a hot Jupiter only 4 million miles from its star can hold on to water vapour, that just makes it MORE likely that a terrestrial planet in the Goldilocks zone can.

            The fact is, Terry, water is common in the universe. Planets are common in the universe. Organic molecules are common in the universe. What are you going to say ten or fifteen years from now if a probe finds life on Europa?

          • Terry A. Hurlbut says:

            If you click through to the Hirschfeld review, you’ll see the mention of a wet Earth.

          • Shran says:

            “Any wet Earths out there? Not yet, there aren’t.”

            With an estimate of 3-100 times 10^22 stars in the observable universe checking 1 star every millisecond still takes about 10.000.000.000 years to check ‘m all in the best case scenario.

            So… when and how did you… check ?

          • Terry A. Hurlbut says:

            The point that even this secular author was making was that even with the number of stars you mentioned, the events that could have shaped our Earth were highly unlikely.

          • Fergus Mason says:

            “The point that even this secular author was making was that even with the number of stars you mentioned, the events that could have shaped our Earth were highly unlikely.”

            Well, he’s very much a minority voice and a lot of people don’t agree. As Panegg said, only an idiot would state positively that life does or doesn’t exist elsewhere in the universe, but given the statistics I gave you earlier about water and habitable zones just in our own solar system I don’t think it’s unlikely at all. Remember, this solar system alone has three water-bearing planets in the habitable zone, plus very interesting moons like Europa. That’s one star. There are 400 billion stars in this galaxy and at least a hundred billion galaxies in the observable universe. That’s a lot of planets, and even highly unlikely things may well happen billions of times.

          • Geno says:

            Terry comments:
            Of course, those are Jovian-type planets. Any wet Earths out there? Not yet, there aren’t.

            Geno points out:
            Exactly…. “not yet.”

            When I was younger, the creationist argument was that our sun was unique in that it was the only star that has planets.

            Then we discovered extra-solar planets and the argument became: “Well, there are no other planet systems.”

            Then we discovered stars with planetary systems and the argument became: “Well, all the planets are too big.”

            Then we discovered Earth size planets and the argument became: “Well, none of them are in the habitable zone.”

            Now we have discovered Earth size planets in the habitable zone and the argument becomes: “Well, none of them are ‘wet Earths.'”

            One can only wonder what the new argument will be when “wet Earths” are discovered. After all, water isn’t all that unusual in the universe.

            As I see it, even if there is what we would call “intelligent” extra-terrestrial life, it isn’t a problem as the Bible is silent on the topic of other civilizations on other worlds.

            But that’s just me……

  5. Jason Samoa says:

    But… What if god had a side project?

    • Terry A. Hurlbut says:

      Why would He? Even speculation ought to have a foundation.

      • Panegg says:

        I think the absurdities of yes and no clash so much that the middle ground can’t be found easily.

        In other words, you have UFO believers (akin to Sasquatch and Loch Ness believers) that feel that aliens have already visited Earth and life is certainly out there. The other side is user Conservative of Conservapedia, stating: “Bible believers know there are no ETs/little green men.”

        One side believes with nothing more than possibly forged evidence that won’t convince any skeptic (extraordinary claims require extraordinary evidence, as the old saying goes), while the other flatly denies it based on their apparent religion.

        The middle ground, as I see it being done, is that scientists simply don’t know if life exists out there, and they want to find out. It makes sense that the best way to look for life is to search out other planetary bodies that match Earth’s requirements to sustain life. There’s more planets out there than one can imagine, so no matter how minute the chances are to finding a planet similar to Earth’s, there may be one (if not already found) out there. Then, they’ve got to somehow find evidence of life (hah, good luck with that, given out current technology). I have my doubts that scientists would even be able to specifically search for life out there in our lifetimes, but hey, they’re scientists and I’m not.

        But anyway, to claim yes or no that life exists out there beyond our earth when searching has basically just begun is just a naive hope of being right.

      • Panegg says:

        As to whether God may have had a “side project” (that’s funny how it’s said that way), the best answer should be “we don’t know, because God hadn’t mentioned anything about another planet”.

        But then, if the answer were a definitive “yes” or “no”, what if life were found? Perplexing.

  6. Alex M says:

    Earth sized planets orbiting at the proper distance from their parent star are indeed very rare. However, if Earth wasn’t where it is, then life couldn’t have developed and we wouldn’t be here today talking about it. Now THAT is the anthropic principle.

    We have a very good understanding of why Venus and Mars are not Earth-like. In short, Venus underwent a runaway greenhouse effect (liquid water did not develop on its surface due to it being hotter than the Earth [closer to the sun], and this prevented the formation of a granitic crust necessary for plate tectonics) and Mars was not large enough to maintain an active hot mantle.

    Several hundred years ago the consensus was that stars were actually holes in the sky that let in light from Heaven. Several decades ago it was that there were many stars but hardly any planets. We now know that many stars have orbiting planets, and several of these are within the “Goldilocks” zone. Give it more time (and continued funding for the Kepler mission) and I assure you we’ll find Earth like planets.

    It may interest you that the Vatican (yes, THE Vatican) came forth several years saying that it is highly probable that there are other habitable worlds in the galaxy that likely contain life.

    • Terry A. Hurlbut says:

      Yes, and the Vatican also swallowed the uniformitarian/abiogenetic/commonly descending paradigm. So what?

      • Alex says:

        As usual, you ignore everything in a post which disputes what you’re saying and only address a minor tidbit which is really inconsequential to the rest of the comment. I love it! It really says something about how well you can defend your ideas against well-understood scientific facts.

        I would argue that Vatican scholars have studied the Bible more thoroughly than any other institution on Earth (there may be some Jewish institutions that have done more with the Old Testament but you would be hard pressed to find any other group that has more expertise than the Vatican when it comes to the New Testament). They alone have access to countless documents dating back thousands of years which people of all the Abrahamic faiths use to justify the historical accuracy of their respective religions. Therefore, if the Vatican comes up with an idea, perhaps it is worth looking into.

        If your going to base an entire article off of what Gribbin says, perhaps you would do well to read some other things by him. Like his several books on the truth of human-caused global warming. Or the irrefutable evidence for God-less evolution (he is a fan of Dawkins). But I suppose its easier to just play ignorant and just pick and choose what you are actually going to read, since you would otherwise be stuck having to actually learn something about the natural world we live in.

        To drill in the point once again, it doesn’t matter how rare planets like the Earth are, because if the Earth wasn’t hospitable to life, we couldn’t have developed to be here today. Its really not that complicated.

        What I really cant wrap my mind around is how people like you are completely content with assuming that we already know everything that there is to know so we should just stop doing exploring for science. If you all were in charge we would still think that there were only seven entities (Earth, Moon, Sun, Venus, Mars, Jupiter, Saturn) in the entire universe and that the sun orbits the Earth, plus all the other absurd ideas we used to think were true.

        • Fergus Mason says:

          Harsh, but undeniably true. I’ve also noticed that Terry has a habit of ignoring points he can’t answer and picking up on something else.

          • Terry A. Hurlbut says:

            That’s because I don’t have time to repeat the obvious.

          • Fergus Mason says:

            No Terry, I don’t think so. For example you’ve completely ignored several statements which have been made about just how common water is in the universe. You’ve ignored the fact that we’ve barely started to look at exoplanets and already several have been found in habitable zones. So OK, we haven’t found a planet with all the life-friendly conditions that Earth has – YET. However there is no reason whatsoever to think that such planets don’t exist; do you have any idea at all how small the proportion of exoplanets we’ve studied is?

          • Terry A. Hurlbut says:

            However common water is, what is not common is the earth’s kind of temperate climate and breathable air.

            And one thing more: we only infer these extra planets from very small stellar motions and other signals. The signal-to-noise ratio must be very low. And neither you nor anyone else have any way to test whether the signals you’re getting mean what you think they mean. You can’t send a probe to any of these systems and expect to hear back from it. Not in your lifetime, and maybe not in the “lifetime” of any launch authority.

          • Fergus Mason says:

            Also, on the discussion about Noah’s Barge you ignored several points I made about the flaws in Lovett’s proposed “steering” mechanism, which of course wouldn’t actually work. Unpowered ships caught in large waves broach and capsize. This is especially true for unfeasibly large wooden ships, because they’re taking on huge amounts of water from their flexing seams and this sloshes around inside the disintegrating hull, amplifying the instability.

          • Terry A. Hurlbut says:

            So now you are also an expert in naval architecture?

          • Fergus Mason says:

            “what is not common is the earth’s kind of temperate climate and breathable air.”

            How do you know? What percentage of exoplanets have you studied? What do you even mean “breathable air”? Breathable by US (who evolved to breathe it – Earth’s “breathable air” wiped out the vast majority of its early anaerobic life) or breathable by SOMETHING ELSE?

            “And one thing more: we only infer these extra planets from very small stellar motions and other signals.”

            Uh, no. That was teh case a few years ago, but now several have been directly imaged. It turns out that of you point a modern space telescope at exactly where a planet has been “inferred” by other methods, lo and behold, tehre’s a planet there!

            “And neither you nor anyone else have any way to test whether the signals you’re getting mean what you think they mean.”

            Sure we do; it’s called “science.” As I said, we’ve tested the accuracy of our methods of finding exoplanets by pointing the latest space telescopes at the predicted locations and SEEING PLANETS. As for the “signals,” I assume you mean emission and absorption spectra. We can test these easily with a light source, a jar of gas and a spectroscope.

          • Terry A. Hurlbut says:

            Direct images? All I’ve seen are artists’ concepts.

          • Fergus Mason says:

            “So now you are also an expert in naval architecture?”

            No, just an interested amateur and keen sailor. However I’m not asking you to take my word for it; just ask any seaman what’s going to happen to an unpowered 450 foot ship in a fully developed sea state. [Libelous content deleted]

  7. Fergus Mason says:

    “Direct images? All I’ve seen are artists’ concepts.”

    There are images. However people generally use artist’s impressions to illustrate articles because the actual images aren’t glossy hi-res colour photos. You’ll find some here:

    http://dsc.discovery.com/space/im/exoplanet-image-sara-seager.html

    • Terry A. Hurlbut says:

      Yes, I can see how an atheistic astronomer might find those images breathtakingly impressive. Of course, that’s as close as anyone is likely to get.

      • Fergus Mason says:

        “Of course, that’s as close as anyone is likely to get.”

        Of course that statement is idiotic. Those are images – only the visible spectrum images, at that – of things that are far beyond the resolution limit of the Hubble scope, one generation behind. The next generation of space telescopes will start going up in a few years and their resolution will be an order of magnitude better. Next comes long-baseline interferometry, probably by 2025 at the latest; that will REALLY push telescope performance. Don’t forget that 150 years ago cameras could produce family portraits at ten feet with a 30-second exposure; now I can photograph Saturn’s rings with an amateur telescope and a $100 pocket camera, and the NSA can read car number plates from orbit.

      • Fergus Mason says:

        Anyway, I’m going to bed because I have a plane to catch later, but I’ll leave you with this:

        http://www.cfa.harvard.edu/news/2009/pr200924.html

        Feel free to be as fascinated and excited as I am at what astronomers are discovering. It would be inexpressibly sad if your only reaction to things like this was to make up increasingly flimsy reasons to not believe them.

  8. Dasch_dude says:

    Wow! This is really interesting.

    On one side you have a secular author, who believes in man-made global warming, and god-less evolution, (making him a card-carrying atheist), arguing that life in the cosmos is vanishingly rare.

    On the other side you have (supposedly) sensible people committing such logical errors as appeals to the majority, (scientific truths by consensus?) and using “The Vatican” as their source. Yes, if someone doubts the existence of life on other planets, that HAS to be a religious objection, of course. So bring out The Vatican, they’ve been right about so many other scientific facts, amiright?

    Very interesting.

    • Terry A. Hurlbut says:

      Very interesting indeed. You are one of the few readers of the article who got my point.

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