Revisiting the anthropic principle


Here’s another view captured along the Falls Trail at Rickett’s Glen State Park. I particularly like the illuminations in the foreground. If you click on the image for a higher resolution view you will see several thin squiggles on the left side of the foreground. These are the recorded movements of insects as each skimmed across the surface of the water during the 10 second exposure required to capture this image. Whenever I stand by water, whether it be a waterfall such as this, an ocean shoreline, a creek side, or the large tank from which our sheep draw sustenance, I cannot help but return to some thoughts about water that I have quite often; that few of us have a true appreciation of the fact that water sustains life as we know it, and water is really amazing stuff.


Much has been written about the narrow physical and chemical limits within which liquid water can exist. I recently read a fascinating discussion of the strength of the hydrogen bond the conclusion to which was that it must exist within a narrow window (5-30 kJ/mole)  for life to exist. The dashed lines in the image above show how these bonds form between water molecules. It is unsettling to consider that a 29% decrease in the strength of the H-bond would cause water to boil at 98.6ºF and an 18% increase in its strength would cause water to freeze at 98.6ºF. Hydrogen bonds are weak interactions which occur between a hydrogen atom attached to an electronegative atom, such as oxygen, and an electronegative atom of another molecule. Such bonds are responsible for the phenomena of surface tension (allowing leaves to rest upon a pond’s surface and certain insects to walk-on-water) and capillary action (drawing water up thin tubes and against the downward force of gravity). Water’s high specific heat and its high heat of vaporization allow the earth’s oceans to buffer and to protect the planet from dramatic changes in temperature. One of water’s most unusual properties is that it reaches its maximum density at 4°C while it freezes at 0°C. Ice is less dense than fluid water at 4°C because in the liquid state water molecules are, on average, bonded to 3.4 other water molecules while as a solid they are bound to four other water molecules. The physical interactions among four players, rather than 3.4, dictate that these can pack less closely and solid water is therefore less dense than liquid water. And all of us can remember learning in grade school that if water did not display this unusual property the world’s high latitude fresh waters would freeze from the bottom-up with negative consequences for all resident organisms. Even DNA, the genetic material itself, relies on hydrogen bonds to hold its complementary strands together. Although the animated DNA looks pretty it does not show these important bonds which form between the bases (in purple and in the center of the rotating molecule). For a split second the void between adjacent bases can be seen and this is where the H-bond should be. Unfortunately, the modelers left this detail out. These tenuous attractions are key to keeping DNA together and, ultimately then, the transmission of genetic traits, reproduction, and life.The fact that water’s remarkable properties allow life to flourish on this planet is undeniable. Does it then follow that the planet was made for us? Indeed, this argument has been called the Anthropic Principle by some and the Principle of the Fine-Tuned Universe by others. Does evidence of preordination or mindfulness imply the existence of a larger consciousness somewhere among the stars? As the philosopher would say, these are explananda in need of explanana. Mark Twain’s wonderfully irreverent essay Was the World Made for Man? was written in response to the claims of Alfred Russell Wallace, with whom Darwin shared claim to being the first to describe the mechanism of Natural Selection, that intelligent life lay foreshadowed in the laws of nature. I have taken the following quote from it. Forgive Twain his 1903 view of Earth history. I have added, in square brackets, more current estimates of these numbers.

… Man has been here 32,000 [200,000] years. That it took a hundred million [4.5 billion] years to prepare the world for him is proof that that is what it was done for. I suppose it is. I dunno. If the Eiffel Tower were now representing the world’s age, the skin of paint on the pinnacle-knob at its summit would represent man’s share of that age; and anybody would perceive that that skin was what the tower was built for. I reckon they would. I dunno.

Postscript. Soon after this post was published my favorite physicist Elke, at Theory and Practice of Trying to Combine Just Anything,  provided a link to a nicely presented synopsis of the Anthropic Principle provided by  two theoretical physicists, Sabine and Stefan, at Backreaction. The internet a wonderful thing indeed. Thanks Elke, Sabine, and Stefan.

26 thoughts on “Revisiting the anthropic principle

  1. Water really is a miracle, and like you I’m always pulled off into wonder when I sit and watch it at play. I love your question at the end, was earth created for us … but I have to say no, to my mind it’s just a wonderful cascade of happenings and facts, which leads to the wonderful and incredible jigsaw of life. Each piece slots and fits because of the others 🙂 The link was really interesting reading.

    1. I just wrote, in reply to another comment, the following … I cannot take credit for this wonderful line of reasoning, one or another well-known ecologist said it I think. Man has been here, in this (modern) form, for perhaps 200,000 years. The earth is known to be 4.54 billion years old. So we have been here for just 0.004% of earth time, and if we round that number we discover that we haven’t even been here! Poof! Seonaid, I agree with you entirely! The fact of our existence shouldn’t motivate us to look to the heavens for explanation … rather, it should stimulate in us simple appreciation for the fact that we exist at all. We should revel in this opportunity we have and the improbability of it all. Does the fact that we are a happy accident make life any less wondrous? No, in fact it makes it more so! D

  2. I know how precious the water is. Your blog makes me actually THINK about that every now and then when I am usually so preoccupied with my own mundane life! Love your easy-to-understand examples and of course, this is another lovely image. The rushing water is very soothing to look at. Now I return to my usual life … waiting for the oil burner man to come and clean the furnace. Hope your weather is as gorgeous there as it is here.

    1. I will take your second sentence as a complement – thank you. I am glad that the combination of words and images is making you pause … if even for only for a moment. D

    1. I have said before Leanne that your approbation means much to me. Thank you for taking the time to take a look and to click the comment. I have been keeping close tabs on your work and am always amazed at your range of talents. Bike races, theater, portraiture, landscapes, still life, and the list goes on. You are, by all measures, a talented artist. I’m always intrigued to see what will be next. Keep it up, and thanks again. D

  3. A particularly beautiful and thoughtful post for a beautiful fall morning in my part of the world. It got down to 3C last night and was only at 5C when I dropped the boys in to University for the day. Since fall is my favourite time of the year and crisp days like this are the best of all I decided that a good walk in the outdoors would take precedence over anything else I might want to do. While I’m out there I’ll be thinking of what you just posted. One of the things I have come to terms with over the years is a sense of comfort in knowing, beyond doubt, that the universe was not created to be my (or any one else, for that matter) plaything. We are of it – the product of a series of ‘happy coincidences’ that can be explained, fairly easily, through a knowledge of interactions related to entropy. Google “Richard Dawkins explains the evolution of the eye,” for example, to find a particularly well done video refutation of one of the most oft-touted pieces of so-called evidence to the contrary. That won’t detract in any way, though, from the sense of awe, wonder and joy I will feel once I lace up the boots and get out there. 🙂

    1. Thank you. Really. Thank you Maurice for this thoughtful, honest, and introspective comment. Dawkins has always been one of my absolute favorites. His discussion of the evolution of the eye is only part of a much larger problem, that which has been called The Problem of Perfection. Objects of extreme perfection have always been problematic for those of us who can appreciate evolutionary theory because they smack of divine intervention. This argument gained traction in 1802 when the Reverend William Paley forwarded a most English sort of scientific reasoning called the Argument from Design. The evidence for elegance of design in nature was reflective, in his view, of conscious design and of a conscious (divine) designer. This is now called Intelligent Design Theory. [The title of Paley’s original work was “Natural Theology: or, Evidences of the Existence and Attributes of the Deity, Collected from the Appearances of Nature”. Here is a link (isn’t the internet grand?), You only need to read Chapter One, State of the Argument (this is the classic ‘Watch’ argument … and herein you will discover the play-on-words that Dawkins used in his title of his book ‘The Blind Watchmaker’).] You must be channeling Stephen Gould when you use the words ‘happy coincidences’ for he used this turn of phrase as well; it must be true then that great minds think alike. So Maurice, do enjoy your walk and be grateful for the seemingly infinite number of happy accidents that have culminated in your ability to do so .. and be aware of it! D

      1. Well said, Maurice and Dave. I do admire Dawkin’s irreverent and discerning writing, too.
        Right now I have stumbled upon another post reflecting on ‘Intelligent Design’, quoting a funny (or actually not so funny) satirical article that showed a protester with a sign saying ‘I Don’t Accept the Fundamental Tenets of Science and I Vote’.
        As a European, this topic and related discussions had always appeared remote and alien to me – until I accidentally run into a ‘convention’ or ‘trade fair’ (or whatever it was) held by hardcore creationists in Austria. There was a seller of devotional objects who told potential buyers that ‘evolution is just an ideology, too… and therefore it is going to be forbidden in some US states’. I was flabbergasted.
        It’s a different thing to read about those things happening at another continent and realizing that people thinking that way live near you. Well, and vote.

          1. Yes, I had seen this before. I tried to find some statistics after my traumatic encounter, but that made things worse. The numbers for Austria are seriously disturbing, 25% say that human beings did not develop from earlier species of animals. Leaves me speechless. It seems we are rather the headquarters of creationism in Europe.

          2. I am also reminded of one my favorite quotes by Richard Feynman (Physics Lectures, Vol.1, in a footnote):

            “Poets say science takes away from the beauty of the stars – mere globs of gas atoms. Nothing is “mere.” I too can see the stars on a desert night, and feel them. But do I see less or more? The vastness of the heavens stretches my imagination – stuck on this carousel my little eye can catch one million year old light… What is the pattern, or the meaning, or the why? It does not do harm to the mystery to know a little about it. For far more marvelous is the truth than any artists of the past imagined! Why do the poets of the present not speak of it? What men are poets who can speak of Jupiter as if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?”

                1. I think the two of you would love the writing of Rebecca Grambo. Her science articles are really amazing for the way that she can make science sing. If I can find some links or sources to her published work I will share them. In the meantime, is the website she shares with her husband Glen, a photographer whose work is stunning.

          3. I use this graphic at the beginning of my evolution lectures because I think it is a good place to start a discussion of misconceptions (in my opinion, they’re a big reason why the United States is so far behind). I wonder if the graphic would be different, at least with regard to respondents in the U.S., if the survey question had been phrased differently? There are many people who think evolutionary theory is true but do not think that it applies to humans. In this case, the “disagree” bar here may include people who accept evolutionary theory in part. Certainly this dichotomy is false – people are animals – but I think that there is more to evolutionary theory than just ‘where people come from.’ Presenting it as such can repel people. In my classes, when I go through microevolution many students are surprised to discover that they actually do agree with evolutionary theory; they had just always thought it was ‘where people come from’ or ‘people came from monkeys.’

            Ah, I have work to do! Thank you for the thought-provoking posts.

            1. You sound like the voice-of-reason. I hope, however, you have done your very best to dispell the ‘people came from monkeys’ myth. But you do make a good point when you describe the dichotomy in understanding. I suppose if folks are willing to accept the argument and hold humans to particular scrutiny and make them a special case … so be it. I’ll take half the cake rather than none at all! I noticed you posted at 4:34 PM saying that you had work to do! I hope you’re not arriving early and staying late! Please keep in touch. D

    2. I love that this is the post for today! I was up late last night discussing this topic with someone and the words I used were similar to the sentiments you express here, Maurice (mine were less eloquent, but similar). I think that life is amazing – the more I learn, the more fascinated I am. I don’t need to think that the world was made for me in order to feel this sense of wonder.

      1. A most excellent expression of a very reasonable point-of-view. The fact (in our view) that life is unplanned, not preordained, chancy, and entirely unpredicted should make us marvel all-the-more that it happened and that we are here to have a conversation such as this! Isn’t it wonderful? D

  4. Fascinating stuff. I know of some current accounts of the anthropic principle by physicists, it is a hotly debated subject. On the one hand, it should support a fundamental explanation of our world in terms of multiverse or multiple universe theories because if our seemingly arbitrary universe is only one of many, balance is restored and there is no need to invoke an intelligent designer, for example. On the other hand some authors state that focusing on one combination of parameters and varying them one by one and then ‘proving’ that this is the only working combination disregards other combinations (jumping into a different place in parameter hyperspace) that would allow for life – probably life very different from us.
    This is one of the best summaries i have read recently,

  5. Oh Twain, so cleverly snide! Have you ever read Letters to the Earth? This makes me want to go back and re-read some of his really top shelf sarcasm. It is mind boggling that our continued existence is predicated on such narrow parameters being met.

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