The Privileged Planet Part 3: The Anthropic principle

[size=200%]Anthropic Principle[/size] My claim is that it is exactly in areas where life and science develop were expect to see science discover a correlation between habitability and measurability. Without habitability we would not have been here, without measurability we would not have science to lead us to this conclusion. Does this mean that there was purpose involved, or just a matter of fact statement?
Isn't a beach well adapted for sun bathing, digging holes in the sand, beach volley ball and wading. Isn't it miraculous that we go to beaches, which provide for easy access to the ocean, with sand allowing us to spend our sun bathing in relative comfort and play beach games. In addition a slowly deepening bottom allows us to wade in the ocean without the immediate risk of drowning. As icing on the cake, the waves seem to approach the beach in perpendicular to the coast line adding to our enjoyment. And in addition to all this, what surely must seem to be a miraculous environment, also provide us with protection from flooding (dunes). One cannot escape the conclusion that these beaches were designed with a purpose in mind. (I would like to thank my unnamed colleague who came up with these excellent observations). [size=150%]Opacity, habitability and measurability[/size] Assume that a habitable environment exists with an opaque atmosphere, or at least opaque to �visible' light (visible to us that is). Would it not be reasonable to expect that the local life forms might evolve a �vision' in a range in which the atmosphere is not opaque? What exciting discoveries could such an organism make in these wavelengths? And how would they lament these poor creatures on planets with opaque atmospheres. So is measurability not in the eyes of the beholder? [size=150%]A review of critiques[/size] In 2002, a five-part debate on the hypothesis of 'Rare Earth' took place on website. One of the participants, David Grinspoon remarked David Grinspoon: I think it is a mistake to look at the many specific peculiarities of Earth's biosphere, and how unlikely such a combination of characteristics seems, and to then conclude that complex life is rare. This argument can only be used to justify the conclusion that planets exactly like Earth, with life exactly like Earth-life, are rare. My cat "Wookie" survived life as a near-starving alley cat and wound up as a beloved house cat through an unlikely series of biographical accidents, which I won't take up space describing but, trust me, given all of the incredible things that had to happen in just the right way, it is much more likely that there would be no Wookie than Wookie. From this I do not conclude that there are no other cats (The Rare Cat Hypothesis), only that there are no other cats exactly like Wookie. Life has evolved together with the Earth. Life is opportunistic. The biosphere has taken advantage of the myriad strange idiosyncrasies that our planet has to offer. Not only that, life has created many of Earth's weird qualities. So it is easy to look at our biosphere, and the way it so cleverly exploits Earth's peculiar features, and conclude that this is the best of all possible worlds; that only on such a world could complex life evolve. My bet is that many other worlds, with their own peculiar characteristics and histories, co-evolve their own biospheres. The complex creatures on those worlds, upon first developing intelligence and science, would observe how incredibly well adapted life is to the many unique features of their home world. They might naively assume that these qualities, very different from Earth's, are the only ones that can breed complexity. Darling published a detailed criticism of the 'Rare Earth' hypothesis in his book "Life Everywhere: The Maverick Science of Astrobiology." Much of his comments apply to the Privileged Planet claims as well. But there are some differences between the arguments in Privileged Planet and Rare Earth, which I will discuss. Darling quotes Athena Andreadis, a neuro surgeon at Harvard Medical School who points out that: In science, theories cannot be identical to their predictions, nor can that prediction be trivial. In fact, the Rare Earth theory is neither hypothesis nor prediction, but a description of how life arose on earth... Their (Ward and Brownlee's) oft repeated statement that both Earth and humans are unique is neither novel not contested - nor helpful in predicting life elsewhere. While these objections are about Ward and Brownlee's book 'Rare Earth' they appear to apply equally well to the "Privileged Planet". Darling continues to argue that But Ward and Brownlee go further, they actually pick and choose the factors that best suit their case. In "Privileged Planet" the authors argue that a large moon is both required for habitability and measurability. A claim which I intend to more in depth show to be erroneous. [size=200%]The arguments in more detail[/size] First some definitions Habitability: A habitable planet is a "terrestrial planet that supports complex carbon- and water-based life", a "planet in "Circumstellar Habitable Zone"" and "Planetary system in "Galactic Habitable Zone"" The main argument proposed is that: "Habitability correlates with measurability". Or in other words "The same narrow circumstances that allow us to exist also provide us with the best overall setting for making scientific discoveries." "Therefore, there is a God." or "A More Modest Conclusion: The universe is fine-tuned so that environments habitable to observers will provide the best overall conditions for observation and discovery. The universe is designed for discovery" Examples of these correlations include 1. Perfect solar eclipses 2. Layering processes 3. Plate tectonics 4. Transparency of atmosphere 5. Planetary neighbors 6. Stars 7. Galactic location 8. Cosmic time 9. Fine tuned cosmos Gonzalez and Richards argue that the following requirements need to be met for a habitable planet 1. Right terrestrial planet 2. Stabilizing moon 3. Right atmosphere 4. Right planetary neighbors 5. Right single star 6. Galactic location 7. Right cosmic time 8. Universe fine tuned for life A side claim What does design tell us about God? Design confirms theism: The correlation is more likely given theism than given naturalism. [size=200%]A devastating rebuttal[/size] Kyler Kuehn has presented a very compelling thesis why the arguments proposed by Gonzalez and Richards should be rejected. Kuehn's primary thesis is Habitability + Measurability do not warrant an inference to design (Divine or otherwise). His secondary Thesis is Habitability + Measurability cannot provide warrant for a design inference. Therefore: Habitability + Measurability are not the right tools for empirically detecting design. Kuehn argues that optimal measurability is trivially true, in other words science will use the best observations/measurements and thus will be biased. In order to know the true distribution one needs to know good/bad measurability examples and show that there is a preponderance of good. By its nature however measurability is biased because we are ignorant of those things that are NOT measurable. Kuehn then argues that based on physical law "constraints on measurability are entailed by constraints on habitability" Habitability requires appropriate stellar (and electromagnetic energy) density--necessarily, we can see more than if we were located in a globular cluster or the galactic center Kuehn then argues that several generations of stellar nucleosynthesis are required to form biologically relevant and necessary elements thus we can by definition observe a lot of stellar history. Kyler then pursues the possibility that the correlation is law like? Thus a regularity pathway blocks a design inference. ID can of course argue that the designer designed the laws but Kyler argues: Specific design input in the initial stages of the universe would then have to be proven (beyond simply the ontological or cosmological argument for God). Such an argument does not pass through Dembski's design filter--is there a better design detection algorithm for this job? Kuehn then argues that measurability may not even be measurable Optimality Measure = Nopt/Ntot But if Ntot is unknown then we cannot argue that a particular value of Nopt is 'special' Then of course there are many confounding factors such as Nopt being a measurement of intrinsic properties of the universe or Nopt is biased by sociological factors such as funding. And then Kuehn gives the final blow: Science flounders towards truth: Many physical objects are hideously difficult to observe properly (e.g. neutrinos). Many measurements require significant manipulation of our environment (e.g. placing satellites beyond the absorption effects of Earth's atmosphere). How are quantities optimally measurable if most of humanity's scientific knowledge has been accumulated only recently? Kyler concludes: A Design Inference based on the correlation of measurability and habitability is at best only trivially true. Quantifying measurability is a formidable (impossible?) task which must be completed prior to any potential design inference based on the Privileged Planet Hypothesis. A Critique of the Privileged Planet Hypothesis by Kyler Kuehn presented at the "The Heavens Declare the Glory of God" ASA Annual Meeting, July 25-28, 2003 Colorado Christian University [size=200%]Well positioned earth[/size] Mankind is unusually well positioned to decipher the cosmos. From: Gonzalez and Richards, The Privileged Planet: How our place in the cosmos is designed for discover. But Gonzalez et al provide no quantifiable measures that help us determine if their claim is correct. What they do argue, again without much supporting evidence, is that habitability and measurability correlate in zones that are called galactic �habitable zones". They argue that these zones are �rare' but present no quantifiable information as to how many stars would be involved. The statement that habitability and measurability correlate in (significantly sized) zones in the universe undermines the argument that habitability and measurability are improbable and even seems to argue that measurability and habitability naturally correlate. Even more mysterious than the fact that our location is so congenial to diverse measurement (what is so mysterious about this? Other than that the authors have failed to make their case that the earth is uniquely congenial to diverse measurements) and discovery is that these same conditions appear to correlate with habitability (appear to correlate. That's the risk of not really providing for hard estimates). This is strange because there is no obvious (to the authors at least) reason to assume that the very rare (unsupported) properties that allow for our existence (anthropocentric) would also provide the best overall (and yet the authors provide NO evidence for this optimality) setting to make discoveries about the world around us. So lets look at some of the examples of measurability they quote from a variety of disciplines. Their article include perfect solar eclipses (astronomy), ice cores in Greenland and Antarctica (geology), deep sea cores (geology), tree rings (biology), stellar trigonometric parallax (astronomy). Stars as isotropic emitters of highly specific information (any ID paper seems to have as a requirement a reference to information and specificity J), supernovae and Cepheids (astronomy), our place in the Milky way and dust extinction (astronomy), the capacity to observe the maximum diversity of star types and the distant universe (astronomy) background radiation (astronomy) and the particle and event horizons of the universe (astronomy). Not as diverse as one may have hoped for and in fact the authors fail to show that the earth is somehow unique in these aspects So is the earth �the best overall bench in the lab'? The authors do little to support this conclusion other than by pointing out that the earth has certain characteristics but are they optimal? Are they the best bench in the universe? How will we know? Little guidance is provided here. [size=150%]Big Moons and solar eclipses[/size] Gonzalez suggests that there is a link between life (on earth) and perfect solar eclipses. The moon and sun appear to be of similar size in the sky allowing �perfect' solar eclipses to occur. Not only is a big moon essential for stabilizing the planet (helpful perhaps but not necessarily essential)but it also was essential for the validation of Einstein's theory of relativity and the study of the solar corona. Thus linking habitability with measurability. But was the solar eclipse of 1919 required for the scientific discover of Einstein? It's hard to argue that this confirmation hurt Einstein's case but lest point out that first of all, Einstein did not base his theory on the solar eclipse so the origins of the theory are not dependent on the solar eclipse but what about its verification? To understand the relevance of the 1919 solar eclipse we need to remember that Einstein provided in his 1915 paper three experimental tests. Would the precession of the perihelionof Mercury not have been sufficient? Would the solar eclipse data have been sufficient without the Mercury prediction? In fact to Einstein "This discovery was, I believe, by far the ]strongest emotional experience in Einstein's scientific life, perhaps in all his life. Nature had spoken to him." Abraham Pais (EM, p. 202)" ". Einstein commented These equations, which proceed, by the method of pure mathematics, from the requirement of the general theory of relativity, give us, in combination with the [geodesic] equations of motion, to a first approximation Newton's law of attraction, and to a second approximation the explanation of the motion of the perihelion of the planet Mercury discovered by Leverrier. These facts must, in my opinion, be taken as a convincing proof of the correctness of the theory. Source The same link reports that To his friend Paul Ehrenfest in January 1916 he wrote that "for a few days I was beside myself with joyous excitement", and to Fokker he said that seeing the anomaly in Mercury's orbit emerge naturally from his purely geometrical field equations "had given him palpitations of the heart". But of course Mercury and habitability arguments just do not seem to be as impressive as trying to present a case that the moon provides for stability of the earth axis (habitability) and allows for discovery (measurability). Certainly the perihelion of Mercury was an earlier event than the 1919 solar eclipse. We may never know to what extent the solar eclipse data sealed the case for Einstein's theory but it does show how the data appear to be carefully selected to support the thesis. Here we also encounter another peculiarity of Earth namely that the requirement for habitability (nearly circular orbit) made the earth orbit unreliable for perihelion precession measurements.
             Predicted   Observed
   Mercury     43.0     43.1 +/- 0.5
   Venus        8.6      8.4 +/- 4.8
   Earth        3.8      5.0 +/- 1.2
   Icarus      10.3      9.8 +/- 0.8
The large tolerances for Venus and Earth are mainly due to the fact that their orbits are so nearly circular, making it difficult to precisely determine the axes of their elliptical orbits. So when Gonzalez et al claim that: The requirements for producing perfect solar eclipses, which provide scientific insight, also contribute to the Earth's habitability. This is only one example where the conditions for habitability overlap the conditions for measurability. it seems that this overlap depends on what data we include and what data we ignore. Now the argument for habitability. Is the moon essential for the stability of the earth and habitability? Recent computer simulations by Eugenio Rivera of NASA AMES and his colleagues suggest that small planets with big moons are likely to be quite common. As many as one in three earth like planets in their infancy may be struck hard enough by other large objects to make big moons, and one in twelve struck at a time when its tilt is sufficiently mild for it to be stabilized at a terrestrial angle (currently 23.5 degrees) or less. Page 97 Darling, Life Everywhere: The Maverick Science of Astrobiology Rivera reports that In my Ph.D. dissertation, I explored the plausibility of having five terrestrial planets for 8 -- 200 Myr, having two of them collide in this time, and leaving a planetary system with small orbital eccentricities as in the Solar System. I performed 191 N-body simulations which started with the planets Mercury through Neptune with their current orbits and masses except that the Earth and Moon were replaced with two bodies (the Earth-Moon progenitors), each in its own heliocentric orbit between the orbits of Venus and Mars, such that mass and angular momentum were conserved. I varied the mass ratio of the Earth-Moon progenitors, their initial eccentricities, inclinations, and semi-major axes. When a collision occurred, the bodies were simply merged into one. Slightly over one-half of the simulations ended with a collision between two planets before 200 Myr had elapsed, and about one-third of the systems which started with five terrestrial planets were stable for 200 Myr. Out of the 191 simulations, 16 ended with a collision between the Earth-Moon progenitors in the right time interval; four of these 16 resulting systems resembled the Solar System in that the terrestrial planets were on nearly circular, coplanar orbits. An additional 27 simulations ended with a collision at the right time which left four terrestrial planets with a mass distribution similar to that in the Solar System. Four of these 27 resulting systems resembled the Solar System. Thus, the scenario I explored does seem plausible. Link But not only is the moon exactly the right 'size' for perfect eclipses, Gonzalez et al also argue that the moon is "just massive enough to stabilize this planet's 23.5-degree axial tilt. If the moon were any smaller, the tilt of our planet could vary as much as 30 degrees over the course of a year. " But is this argument correct? "A Moon-less Earth with the same mass, rotation rate, and orbit as today would have the direction of its spin axis vary chaotically between 0 and 90 degrees on time scales as short as 10 million years," says Darren Williams, Assistant Professor of Physics and Astronomy at Penn State University and NAI member. "At high obliquity, temperatures over mid-to-high latitude continents would reach near boiling 80 to 100 Celsius around the summer solstice under a 1-bar nitrogen- dominated atmosphere. Such temperatures would be damaging to all forms of water-dependent life on Earth today." Link In addition without a moon the earth would be spinning faster, fast enough to stabilize the earth. In addition calculations have shown that the tidal friction increases the distance between the earth-moon, eventually causing the earth to come under the influence of chaos. Neron de Surgy and Laskar report in "On the long term evolution of the spin of the Earth" that in the next 5 billion years, the obliquity of the earth can reach a chaotic stage in about 1.5 billion years from now. One may also ask why the moon adds to measurability when its dark-side has remained invisible to us from earth? But that may seem to be nitpicking, or does it? Similar arguments for design based on the earth moon system can be found God and Science website A collision which would have ejected material less than the Roche limit would have formed only rings around the earth. Computer models show that a collision of a small planet with the earth must have been very precise in order for any moon to have been formed at all (coincidence or design?). (see What If the Moon Didn't Exist?, by Neil F. Comins, professor of Astronomy and Physics). For a moonless earth, the time scales for fluctuation would be as short as 10 million years. Quite a different perspective. Gonzalez et al reference Michael Mendillo and Richard Hart (Boston University), "Resonances," Physics Today 27:2 (1974), p. 73: Based on the solar eclipses they reach the following conclusion A planet/moon system will have exactly total solar eclipses only if there is someone there to observe them. As only Earth meets this requirement, there is no extraterrestrial life in the solar system. Corollary In a system composed of nine planets and 32 moons, for only Earth with its single moon to have exactly total solar eclipses is too remarkable an occurrence to be due entirely to chance. Similar arguments can be found in the Creation Research Society Quarterly Journal by Danny R. Faulkner (The Angular Size of the Moon and Other Planetary Satellites: An Argument For Design CRSQ Volume 35(1) June 1998) For generations astronomers have traveled to exotic locations to observe total solar eclipses because total solar eclipses are such rare events. On average a total solar eclipse is visible from any location only once every few centuries. Therefore without planning it is unlikely that a typical person will ever view a total solar eclipse, let alone more than one. Whitcomb and DeYoung (1978, p. 132-136) and Mendillo and Hart (1974) have previously called attention to the interesting circumstance necessary for total solar eclipses as an argument for design in the earth-moon-sun system. More recently Englin and Howe concluded that the unique geometry of the earth-moon system that gives us total eclipses is no accident. No other moon in the solar system has such a close balance between the rarity and stark beauty of eclipses. Many have no eclipses at all. In the two decades since the work of Whitcomb and DeYoung the number of known satellites in the solar system has nearly doubled. At the same time the orbital parameters and measured sizes of most of the others have been greatly improved. Let us examine the latest values to determine how unique our moon is in this respect. or in the Institute for Creation research article "THE MOON: A FAITHFUL WITNESS IN THE SKY* - IMPACT No. 68 February 1979 by Donald B. DeYoung, Ph.D.** The combination of size and distance of the moon from the earth results in the special situation that the 0.5� angular size of the sun and moon as seen from earth are the same. The moon is 400 times smaller than the sun but it is likewise 400 times closer to the earth. Because of this purposeful situation the moon is able to occasionally eclipse the sun exactly, providing a precise time record. Computer studies furthermore show that this perfect eclipse condition is unique among all the known moons of the solar system.5 The significance of eclipse data for Biblical studies is great, for it provides confirmation that the chronological systems employed by Old Testament scribes were perfectly accurate. An interesting side note: Faulkner mentions that "On average a total solar eclipse is visible from any location only once every few centuries.", undermining the measurability argument proposed by Gonzalez et al. Earth-Like Planets Common, Computer Simulation Suggests 11 December 2003 A new computer model designed to explore the range of possibilities for planet formation around other stars had no trouble coming up with worlds similar to Earth. The simulations generated planets in similar orbits, planets with and without water, and a range of other virtual places that resemble Earth and the other inner, rocky planets. The effort was designed to determine whether the four inner planets in our solar system, called terrestrials, represent a typical or extreme evolutionary scenario compared to what might develop around a Sun-like star with slightly different dynamics, explained said Sean Raymond, a University of Washington doctoral student in astronomy. "We found there's a much wider possible range of masses and water content on terrestrial planets," Raymond said in a telephone interview. "You can have planets that are half the size of Earth and are very dry, like Mars, or you can have planets like Earth, or you can have planets three times bigger than Earth, with perhaps 10 times more water," Raymond said. 43 planets formed between 0.8 and 1.5 AU with the following distribution and the authors reach the conclusion that: 1. Most of Earth's water was accreted during formation from bodies past snow line 2. Terrestrial planets have a large range in mass and water content 3. Habitable planets common in the galaxy earth.JPG see original here Scientists estimate 30 billion Earths Monday, 1 July, 2002 Scientists say they are now in a position to try to estimate how many planets may exist in the galaxy and speculate on just how many could be like the Earth. The answer in both cases is billions. Virtually all the stars out to about 100 light-years distant have been surveyed. Of these 1,000 or so stars, about 10% have been found to possess planetary systems. So, with about 300 billion stars in our galaxy, there could be about 30 billion planetary systems in the Milky Way alone; and a great many of these systems are very likely to include Earth-like worlds, say researchers


If the solar system were designed for our benefit, the solar year would have an even number of days in it. It doesn’t. Therefore the solar system was not designed.

That may not be an iron-clad argument, but it is no worse than the various “If it doesn’t fit, you must acquit” riffs mass produced by the other side of the debate.

One thing I’d like to emphasize is the evolution of the Earth-Moon system. The recession of the Moon means that eclipses are more a case of coincidence than design.

You could use the same logic to assume that the modern horse evolved specifically just so human beings would have a form of transport.

Those simulations are *cool*.

One thing I’d like to emphasize is the evolution of the Earth-Moon system. The recession of the Moon means that eclipses are more a case of coincidence than design.

I guess IDologists must believe that God timed the recession of the moon so it would be just the right distance from the Earth just when humans evolved (or vice versa).

One of the problems with the Anthropic Principle is that it typically relies on a very restricted conception of what universes are possible. It’s normally assumed that a few of the basic physical constants could have had different values and that in other superficial ways the cosmos could have been different (but luckily it turns out just the way it is).

But we have no deep metaphysical theory which tells us how the universe could have been. We suspect that logic and probably maths must be valid in all possible universes, but that’s about it. Maybe there could have been universes without matter, energy or space, as we understand them, but with lots of entirely different, mathematically consistent stuff we can’t even guess at, and with all sorts of potential for life and intelligence in forms we can’t remotely imagine. Perhaps, in fact, we got an unusually sterile and wretched cosmos, rather than the only possible life-supporting one: but until we have the deep metaphysical theory that tells us what universes are possible (and I’m not holding my breath), there is simply no way of knowing.

While it’s true that the universal constants, planetary orbits, amount of rhubarb in North America, etc. had to be within very narrow constraints in order for “life as we know it” to have arose, my take on things is that different values for those variables would not necessarily have prevented life from forming at all.

We see it in evolution. Halophiles grow in incredibly osmotic salt solutions, thermophiles grow where its boiling hot - all examples of living things adapting to their environments. Why would it have to be the case that the only life one considers as a notable result has to be anthropic? If a universe with a strong force that was 3 units more than it is now is even possible, why would it necessarily preclude life of any sort?

I recognize that these are not original ideas.


I’ve pointed out elsewhere here that the Moon would be a better eclipser of the Sun if it had a larger angular diameter (either closer or bigger or both).

Also, Galactic Habitable Zones are wider than what most Privileged Planet advocates seem to be implying; they still contain enormous numbers of stars.

And the transparency of our atmosphere may be a necessary condition for the emergence of complex multicellular organisms and ecosystems. This is because:

* Photosynthesis requires zero chemical processing to supply energy, meaning that it does not require exploitable chemical disequilibrium, as chemosynthesis does. This means more energy to spare for the assembly of complex structures.

* Photosynthesis can release molecular oxygen, while doing so would be very wasteful for chemosynthesis.

* Aerobic chemical reactions typically provide much more energy per unit mass than anaerobic ones, making more energy available for assembling complex structures.

I’d elsewhere commented on the difficulty of finding the ultimate constituents of matter. The fundamental physical theories, general relativity and the Standard Model, require some rather elaborate mathematics to understand, and a favorite candidate for the “Theory of Everything”, superstring theory, only gets worse.

So one would have to be Dr. Pangloss’s #1 fan to support the “Privileged Planet” hypothesis.

All this the pseudoscience in the worl will make me believe in a Celestial Micromanager.


All four gas giant planets and Pluto have moons large enough to completely eclipse the sun. Their moons are even bigger than the sun as seen from the planet, giving what I expect would be longer observation times during eclipses. I see no “measurability” value in having the moon be equal in size to the sun, except maybe for viewing the solar corona. Even then, an observer would still be able to see parts of the solar corona at various points during an eclipse caused by a moon with a larger apparent diameter.

You can compare diameter sizes using the Solar System Simulator at:

So… are we alone in the universe? Is the Earth indeed unique? If not why arent they here?

Actually, Im more interested in the Rare Earth rather than the Anthropic Principle side of the discussion .

In one story that was serialized through Analog, there appeared a race that had developed on a planet with an opaque (permanently cloudy) atmosphere. They had, through very careful measurement of oceanic tides, deduced the existence of all the major planets in their solar system.

I don’t know if the signal/noise ratio in a real-world body of water is high enough to allow this in reality, but it does serve to do at least plausible damage to the notion that any set of conditions are essential for making discoveries.


I remember thinking of something like that myself, when I considered what one would see if one was living on Saturn’s largest satellite, Titan.

If one does large-scale surveying, one would eventually find out that one is living on an approximately spherical world. This would be from the polygon-angle excess:

(Polygon angle sum) = (180 deg)*((# sides) - 2) + (curvature)*(area)

This result is exact for a sphere:

(curvature) = 1/(radius)^2 (area) = (polygon solid angle)*(radius)^2

The ultimate demonstration would be to travel in a complete Great Circle, going as straight as possible from one’s starting position and reaching it after going all the way around.

One could also find out that one’s world is rotating by performing the Foucault experiment – letting a pendulum swing for a long time and watching its plane of swinging rotate. One might initially be motivated to perform it by wanting to test the hypothesis that one’s residence moves in an inertial fashion, without acceleration or rotation. So discovering rotation would be a surprise.

One could then perform this experiment elsewhere, and discover that the measured rotation rates are functions of position that are consistent with one’s world having a constant rigid-body rotation.

I also considered what one would see if one could fly a balloon above Titan’s clouds.

Due to Titan’s orbit, Saturn’s most famous feature, its rings, would be edge-on and thus nearly invisible. However, their shadows on Saturn would be easily visible.

Saturn’s other satellites would be difficult to resolve without a telescope, but with sufficient observation of them, one could discover some interesting resonance effects in their orbits.

Jupiter would be easy to see, but the inner planets would be rather difficult to see. And even with a telescope, it would be difficult to resolve surface details of the inner planets.

Parallaxes of stars would be 10 times larger than from Earth, though they’d take 30 times longer to observe.

For anyone that is really interested in this subject, there is a new theory that cuts right down the middle of the debate and will throw a serious monkey wrench into the ID movement, but it will also leave a very bitter taste in the mouths of chaos oriented evolutionists, since it defines a purposeful universe that requires intelligent human life as a means to maximize entropic efficiency.

There are now two separate and independent derivations of this theory:

One can be found in the article here:[…]0/2003204990

and here…[…]hp?id=165454

But the complete theory was written down prior to that, and can be found here:[…]ontents.html

Shaun Rose Wrote:

So … are we alone in the universe? Is the Earth indeed unique? If not why arent they here?

Actually, Im more interested in the Rare Earth rather than the Anthropic Principle side of the discussion .

See the book Rare Earth, page 251 if I recall correctly. The authors state essentially “There are probably other civilizations with radio telescopes in the galaxy…” They just think these are are too sparse for the SETI project to have a decent chance.

How many galaxies are there?

They had, through very careful measurement of oceanic tides, deduced the existence of all the major planets in their solar system.

It’s an interesting idea, but not reasonable. You could deduce the moon, and you could probably put the sun on the ecliptic. Jupiter exerts about 1% the tidal influence as the moon, so maybe you could barely detect that. Since Venus only gets as close as 40 million km, and mars 60 million, you probably wouldn’t be able to detect them. Given all that, would you be able to deduce heliocentrism? I doubt it, but i don’t know. other moons, mercury, cruithne, all that stuff would be right out. But wrong ideas are often interesting and productive to think about. Indeed some physics professors use wacko ideas to enhance the right ideas. Years ago I had an intro EM class where we were required to think up, say, 3 experiments which would invalidate a given loony idea, like the one that gravity doesn’t exist, and apparent gravity is an induced-dipole effect. And my thermo class made use of wackos, because of course half the senseless pseudoscientific notions in the world attempt to use the SLOT. Just as I’m sure some intro bio classes use these nutcase probability-of-this-protein arguments to illuminate basic protein structure and function.

One consequence of Gonzalez et. al.’s failure to include much in the way of actual numbers is that an unsophisticated reader is left with no way to evaluate their claims without recourse to external data. For example, Gonzalez et. al. claim (pg 258) that the Milky Way is an especially well-suited home for life (implying that few or no other galaxies are also suited for life). But the Milky Way is a relatively common spiral galaxy. There are billions of other spiral galaxies in the universe (a reality uncommented on by Gonzalez et. al.) . Is it really true (even if one accepts the argument that only spiral galaxies are hospitable to life) that the Milky Way is the ONLY spiral galaxy out of billions that is hospitable to life?

Gonzalez et. al. also claim that sunlike (i.e., G2) stars are rare in the Milky Way (which is true) and that only sunlike stars are hospitable to life (which may be true or may not be). But if sunlike (i.e., G2 stars) are only 1% of the Milky Way’s population, that still means there are a billion of them (which doesn’t exactly make them rare in an absolute sense). Once more, Gonzalez et. al don’t provide any estimate of the total number of stars in the Milky Way, let alone the number of sunlike stars. They leave the naive reader with the impression that the sun is unique (or nearly so) in every way that matters for life, which is almost certainly untrue.

There are something like 10 ^ 22 stars in the universe. What if only one in a quadrillion supports intelligent life? That would hardly make earth unique. It might seem odd to have a universe this size with only ten million intelligent-life-supporting planets, but it would certainly undermine the arguments made in “The privileged Planet.”

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This page contains a single entry by PvM published on April 17, 2004 6:26 PM.

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