Skyhooks and cranes-1: Why skyhooks are appealing

I occasionally meet people who, knowing something about my interests with science and religion, say something like “I am not religious but I am skeptical of the theory of evolution.” These people are often well-educated but not biologists or archeologists or paleontologists or anthropologists, so it is unlikely that they have done any kind of scholarly study of the evidence in favor of evolution and found it wanting. Their skepticism of evolution seems to spring from a different well.

When questioned, it usually turns out that the major reason for their doubts is that we live in a world that has an amazing array of diverse and complex organisms. If one doesn’t look closely into the science and mathematics of evolutionary theory, it can seem quite incredible that all this could have emerged by purely natural causes. So for some people, skepticism about evolution arises purely from a sense, a gut feeling if you will, that it is highly unlikely that life arose in the unguided way that evolution proposes. Just last week I had a discussion with a professor of chemistry who argued in precisely this way, that he could not imagine that all this could have come about without some kind of guiding intelligence, and what could that be but a supernatural agency of some kind?

I have argued before that evolution by natural selection, though unguided, is very far from something that happens purely by chance. While it is chance that produces the variations, the process of natural selection is highly focused. Furthermore, people’s intuitions about probability are notoriously poor, and people should be wary of placing too much weight on them.

The other major source of discomfort is that people cannot properly conceive of very long timescales, especially the hundreds of millions of years that are involved in evolutionary processes. Things that are unlikely over shorter time periods can become likely, even inevitable, if you wait long enough, but people have no real feel for that. For example, we all know that the chance of winning a big lottery prize is very small. But if I were willing to play for a very, very long time, the probability of my winning becomes very high, almost inevitable. But of course, the amount I would have bet would be almost certainly be much more than my winnings and I would be long since dead anyway, so the whole exercise would be pointless. But our tendency is to take the probability over our short lifetimes, and erroneously assume it remains the same over very long time scales.

But even allowing for that, there is something strange about the theory of evolution being singled out for skepticism. After all, all manner of small probabilities and long time scales are involved in the Big Bang theory, involving the way that the primordial matter coalesced to form the stars, planetary systems, and galaxies. Why aren’t people similarly skeptical about how the Earth and our Solar system came into being? Some religious fundamentalists, of course, do argue that god created everything and reject pretty much all of science, but I am not talking about them. I am talking about people who have no problem accepting scientific theories of how the entire universe came to be, but yet remain unconvinced that scientific theories can explain how all of life came into being.

There is another possible reason for this focused skepticism against evolution. The Big Bang is a spectacular thing to visualize. There is a magnificence to it that is commensurate with the importance we attach to something that happened at the very beginning of time. But the theory of evolution is the very opposite, saying that life in all its grandeur came about very slowly as a result of a vast number of tiny little plodding steps, each too small to observe. There is no arresting visual image that we can seize upon.

Daniel Dennett’s book Darwin’s Dangerous Idea (1995) says that the basic idea of Darwin’s theory, that everything is a product of an algorithmic process, a simple set of rules mindlessly applied, is what many people find hard to accept.

Among the controversies that swirl around us, most if not all consist of different challenges to Darwin’s claim that he can take us all the way to here (the wonderful world we inhabit) from there (the world of chaos or utter undesignedness) in the time available without invoking anything beyond the mindless mechanism of the algorithmic processes he proposed. (p. 74)

As a result of this skepticism, people have consistently, over time, invoked what Dennett calls skyhooks as explanations. A skyhook is defined as an “imaginary contrivance for attachment to the sky” that can be used for lifting things easily. The skyhook concept is similar to the deus ex machina (“god from a machine”) literary device used by inferior Greek dramatists to suddenly swoop down and lift their characters out of a tight spot. So a skyhook is basically a mysterious and advanced mechanism that can be invoked as an explanation. The existence of skyhooks as explanatory mechanism leads naturally to an acceptance of the existence of a designer, since someone had to have created the skyhook.

The search for skyhooks has historically taken many forms. In the early days, skyhooks were used to explain the appearance of every species. This was the theory of ‘special creation’, popular up to Darwin’s day, where god (the ultimate skyhook) created species to fit into the various ecological niches. As time went by and science explained more and more of what was previously inexplicable, the number of skyhooks needed as explanatory devices has decreased, but never gone away.

The ‘God of the Gaps’ that I have written about earlier is a manifestation of this desire for skyhooks.

The idea of skyhooks is seductive and is what draws many of us in to believing in a creator, especially when we are young. It is a form of magical thinking that all young children find attractive and which is what makes believing in a god easy.

But why do people continue to feel the need for skyhooks as adults when there are other good explanations?

Next: Replacing skyhooks with cranes.

POST SCRIPT: The appeal of skyhooks for children

In this interview with Jonathan Miller, Richard Dawkins says that as a boy he accepted the need for skyhooks for the creation of life, before he discovered that the theory of evolution solved the problem, and the sense of intellectual freedom and liberation that it generated.


  1. says

    Man, you had me going. I thought you were going to talk about thephysics and engineering of literal skyhooks and space elevators (and those extra-ridiculous space fountains). Too bad 🙁 Oh well, this is a good topic too.

  2. says

    Hi sorry if this is a little off topic, but having just watched Dawkins’ interview where he talks about science providing the answers to the nature of reality, and having read New Scientist last week, I have a question…

    It is becoming more accepted that ’empty’ space actually has a fabric, observations reported in New Scientist recently have shown that high energy photons have been slowed down more than their low energy cousins by just a few minutes over distances of several billion light years, this slowing is credited to the fabric of space.

    These bursts of photons are believe to come from some poorly understood but evidently massive stellar activity in distant galaxies, possibly to with black holes, but the consensus is that all the photons are emitted at the same time but arrive at our telescopes several minutes apart.

    My question is, how does this square with the concept of relativity whereby there is no such notion of (an object in space) being at absolute rest or in absolute motion, rest or motion being only ‘relative’ to other objects. Can an object not be said to be at rest or in motion relative the fabric of space? Could two objects closing on each other at, say, 100 miles an hour now be given absolute speeds individually (rather than just a relative speed of 100mph) relative to their motion against the fabric of space. Does the fabric of space fundamentally challenge relativity theory?


  3. says

    Hi Ray,

    Is this the article you are referring to?

    I think I can answer your question, but as a disclaimer, I am not a real physicist. In my reading the term “fabric of reality” is a conceit of the author and not an actual thing in the way that people thought “the luminiferous aether” was before the advent of relativity. Instead I think he is just referring to the curvature of space-time. As a general concept, curved space-time is an integral part of general relativity and does not conflict with it.

    Here is the actual paper by the researchers who first observed the phenomenon in question. I don’t really understand quantum gravity, but as far as I can tell the paper makes no claim about an underlying fabric of reality aside from regular space-time.

    So in conclusion the discovery does not likely contradict the underlying assumptions of general or relativity. However, I can see how you would read it the other way based on the New Scientist article. I mean no disrespect to science reporters, but it isn’t uncommon to see one to get a little overzealous and make outrageous claims.

    I hope this answers your question, and if anybody more knowledgeable in the subject has any additions feel free to contradict me. 🙂


  4. says

    Hi Ray,

    Thanks for the question and Jared for for the link to the article.

    We have known for some time that “empty” space need not be that empty. It is possible for a particle-antiparticle pair (say an electron and a positron) to emerge out of nothing and recombine to form nothing again. Wouldn’t this violate the law of conservation of energy, since something has been created out of nothing? Yes. But the uncertainty principle allows for that. The catch is that the larger the violation of energy conservation, the smaller the time interval that the violation can exist.

    So the modern picture of a vacuum is that of a foamy sea of particle anti-particle pairs being created and annihilated, each pair existing for very tiny times.

    This means that when photons travel through space, they may occasionally hit one of these fleeting particles and thus be slowed down. The likelihood of this happening depends on the energy of the photon, which is what this study is suggesting.

    Does the existence of this foamy sea violate the relativistic idea that there is no such thing as absolute motion or rest? Not that I can see. All it means that we can specify speeds with respect to the frame of the foamy sea, but the consequences are no different from being able to specify speeds with respect to any other inertial frame, such as that of the distant stars.

    Just as with those those other frames, if two objects are approaching each other, each having a speed of 0.9c with respect to the foamy sea, the laws of special relativity says that the speed of one relative to the frame of the other will still be less than c, and not 1.8c. The latter result would violate special relativity, while the former would not.

  5. says

    Hi, thanks Jared and Mano,

    I will look up the article that Jared suggested.

    I understand most of what you said, I am not a physicist myself but took ‘nature of matter and the universe’ as my complimentary subjects during my degree in ‘Biology of Man and His Environment’ 1977 -- 1980 at the University of Aston in Birmingham (UK). I have been fascinated by the subject ever since. The selfish Gene was a new publication then and I have been a fan of Dawkins ever since! I have continued to read many the ‘laymans’ books on both subject areas.

    I understand how the relativistic speed of two objects closing on each other do not violate the relativity principle of the light speed limit, even though the sum of their velocities, as measured against another distant object would seem to exceed light speed, this is through the dilation of time and the ‘elasticity’ of space which occur with the relative speed on one object to another.

    But if we deal with objects that are moving relatively slowly to one another so that the relativistic effects of time dilation and space stretching are insignificant then we can examine the concept of absolute rest or absolute motion of an object.

    My understanding of relativity is that, if there were only one object in the universe it would be impossible to say whether or not it were at rest or moving. Introduce another object and we can now say whether the two objects are at rest or moving relative to each other. If they are at rest relative to each other then they may well both be moving at the same speed and in the same direction, relative to a hypothetical third object which may exist somewhere else in the universe -- so there is still no ‘absolute’ rest or movement.

    Am I right so far?

    Now, this is where my understanding breaks down…

    If space is filed with particle anti particle pairs spontaneously emerging and then annihilating each other, then each of the two objects would have a speed ‘relative’ to this framework -I think that this is what Mano confirmed.

    So, let’s assume that the closing speed of the two objects is just 100 miles per hour -- too slow to invoke any significant time or space dilation / stretching, yet we could still determine the relative speed of each object against the background of the ‘foamy sea’ of virtual particle anti-particle pairs. So we may discover that one particle is doing, say 20mph relative to this and the other 80mph or that one is at rest relative to the foamy background and one is doing all of the 100mph. So what I don’t get is, if this is the case, are we not now able to determine a case of absolute rest in space? I guess my question could be interpreted as, ‘isn’t the foamy sea of virtual particle pairs synonymous with space itself?’

    So, if there were only one object in the universe with no other objects that it can move relative to, doesn’t the ‘framework’ of the particle -- anti particle pairs give us something to determine absolute motion or absolute rest against? The only way that I can see that the answer would be ‘no’ is if all these particle -- anti particle pairs were, themselves moving in different directions thus making it impossible to determine a single speed for the only ‘real’ object. But, even then if we were to only consider the point of origin of these virtual particles and in our minds eye plot a framework in space where each originate, does this not give us an absolute framework in space against which we can determine absolute motion or state of rest?

    Another consideration here is the background radiation. I read once that if we were ever able to move at very high velocities through space, say 99% of the speed of light -- relative to the earth’- then we would observe the frequency of the background radiation to be much higher than an observer on earth, so could an object not measure the frequency of the background radiation and use that as a way of determining its absolute velocity in space, without reference to another material object like the earth?

    Sorry if my understanding of these things is rather basic and I really do appreciate your trouble in answering my question


  6. Paul Jarc says

    The transitory particles are indeed moving with respect to each other—as I understand it, each pair begins at a single point (a different point for each pair), the two particles move apart, then back together, and annihilate each other ending at another single point. At any given time, we can add all the velocity vectors of the transitory particles existing at that time to come up with an aggregate reference frame. (Or we could, if it were practically possible to measure all their velocities.) Since different particles with different velocities exist at different times, the aggregate result could be different at different times. But we could also do that for any other arbitrarily-defined collection of particles, and get yet another different result. The fact that they are transitory or widespread may make these particles seem like a more absolute reference point than other particles, but it doesn’t make the universe really act that way.

  7. says

    Thanks Paul,
    My understanding is growing.
    Should I be viewing this as if these particles existing IN space rather than being part of the fabric of space itself? If so, what about the space between the (virtual) particles? does this have a fabric of its own? typically, how far apart are these particles? I mean if you were to take an arbitrary cubic meter of space would you be lucky to find one or two virtual particle pairs popping in and out of existence at any one point in time or would that space be typically filled with particle pairs about a plank length apart or something inbetween?

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