The Privileged Planet
How Our Place In the Cosmos is Designed for Discovery
Guillermo Gonzalez and Jay W. Richards
p x In Introduction, quotes Sagan's "Pale Blue Dot" to typify the Copernican Principle, but "this melancholy assumption, despite its heroic pretense, is mistaken".
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But the authors reply "the conditions allowing for intelligent life on Earth also make our planet strangely well suited for viewing and analyzing the universe."
p xi "Scrutinize the universe with the best tools of modern science and you'll find that a place ith the proper conditions for intelligent life will also afford it inhabitants an exceptionally clear view of the universe."
p xi Sagan as advocate of the Copernican Principle or the Principle of Mediocraty "far more than the simple observation that the cosmos doesn't literally revolve around Earth. ...it is a metaphysical extension of that claim.."
p xi from Carl Sagan, the view that the material world is "all there is, or ever was, or ever will be ..." from "Cosmos".
p xi Following the Drake equation, Sagan "optimistically conjectured that our Milky Way galaxy alone might contain as many as one million advanced civilizations."
p xi After discussing the heroic tales of scientific discovery, comments "What you probably won't find is any discussion of the conditions necessary for such feats, conditions so improbably fine-tuned to allow discoveries that the beg for a better explanation than mere chance."
p xiii "Earth's conditions allow for a stunning diversity of measurements, ..."
p xiv "If we are to make discoveries in a variety of fields from geology to cosmology, our physical environment must be a good compromise of competing factors, an environment where a whole host of "thresholds" for discovery are met or exceeded."
Section 1. Our Local Environment
Chapter 1 Wonderful Eclipses
Interesting discussion of the fact of the almost exact match of sun and moon angular sizes, which makes the total eclips of the sun possible, which has given or prepared the way for some major discoveries. This match of sizes is just for the current era, the moon having been closer in the past and anticipated to be further in the future.
p 4 Physics of moon
- large moon stabilizes rotation axis between 22.1 and 24.5 over thousands of years, currently 23.5
- benefit of moderate seasons - seasonal rains which make more of Earth habitable
- tides - feed the oceans from tidal excursions, drive ocean currents
p 6 Model for moon formation, glancing blow with object a few times more massive than Mars
- melt iron, sink to center
- help form magnetic field
- removes excess iron from surface where it would trap oxygen and hinder plate tectonics
"if Earth had no moon, we wouldn't be here."
p10 Benefits of eclipses: general relativity confirmation, discover of hydrogen spect,
Chapter 2 At Home on a Data Recorder
p 22 Nature's data loggers - sedimentary layers, ice layers,
p 23 In Cold Storage - Vostok 2.25mi deep record covered 420,000 years.
p 24 Greenland ice cores 100,000 yrs.
p 25 Beryllium-10 as monitor of sunspot cycles, nitrate spikes for supernovas,
p 26 Biological data recorders - skeletal cells of single-celled marine organisms. Oxygen isotopic ratios as proxy for temperature, but also for global ice volume. But forams live near bottom and don't change temperature much, so code for global ice changes.
p 26 Lake Baikal 800,000 years.
p 28 Tidalites - repeating patterns in fossilized sediment, lunar cycle to 1% - backtrace 500 million years: day 20hr, lunar 27.5 current days.
p 28 Milankovitch cycles of eccentricity, obliquity, Axial precession
p 32 Life's chemistry - carbon - water -
p 33 Water's unique properties
- denser as liquid than solid
- Very high latent heats
- high surface tension
p 35 John Lewis "water is the best of all possible solvents, and carbon compounds are apparently the best of all possible carriers of complex information." Also cites Henderson's "The Fitness of the Environment" from 1913. Carbon and water also contribute to climate stabilization. "Together, they create a unified climate feedback system, and have kept Earth a lush planet for the past 500 million years."
p 36 "bacterium needs 17 elements, humans 27"
p 37 Essential are the oxidation reactions to provide energy, so hydrogen, carbon and oxygen offer the best source of chemical energy. From Henderson "The very chemical changes, which for so many other reasons seem to be best fitted to become the process of physiology, turn out to be the very ones which can divert the greatest flood of energy into the stream of life."
Chapter 3 Peering Down
p 48 Earthquakes let us visualize Earth's interior. Earth's magnetic field requires fast enough rotation and electrical conductivity. Cooling lava below Curie point freezes in the magnetic field, giving us evidence of field reversals, last one 780,000 years ago. The magnetism was the key to unraveling plate tectonics.
p54 Radio observation of quasars give relative drift of continents - information we couldn't get if our environment wasn't transparent to those frequencies used.
p 55 Plate tectonics essential to the carbon cycle. p57 preserves continents
p 62 Plate tectonics and hydrologic cycle indispensable for concentrating mineral ores.
p 64 Denton - only between 10 and 20% oxygen supports oxidative metabolism, and only in this range can fire occur.
Chapter 4 Peering Up
p 65 Blumenberg quote as intro.
p 66 We have dark nights and a clear atmosphere. "An eerie harmony among the range of wavelengths of light emitted by the Sun, transmitted by Earth's atmosphere, converted by plants into chemical energy, and detected by the human eye."
p68 Sun emits photons that pass through the transparency window of water vapor, and have the energy necessary for the life processes. "Our Sun ... is near the optimum for any plausible kind of life."
p69 Feedbacks and a clear view
p 73 Making long-term plans K/T asteroid,
p 74 Tunguska, Shoemaker-Levy, Hale-Bopp
p 75 Tagish Lake meteorites contain grains that predate the solar system, giving information abou the galaxy.
p 78 Role of the asteroids in preparing Earth for life - less and not enough carbon, more and too much bombardment to allow life to develop.
p 79 Nice summary paragraph. Quote it.
Chapter 5 Pale Blue Dot in Relief
Overview of Mars and Venus, Europa
p 92 Seismometers on moon recorded over 12,000 seismic events between 1969 ans 1977. Using 81 of them, the interior structure of the moon was mapped.
p 101 At the head of the pack. The best laboratory bench.
p
Chapter 6 Our Helpful Neighbors
p 106 Moon is only visible body that appears as more than a point of light, so gave a reference frame for learning, a "conceptual bridge" as he says.
p 107 Moon stabilizes axis tilt variations to 2.5 degrees vs much larger for Mars. This makes climate variations mild so that a reliable ice-layer record is laid down. It tides and the variations thereof recorded in the tidalites are long-term records.
p 108 Moon craters preserve history of solar system. Discusses late heavy bombardment at 3.8-3.9 billion years, when Earth fragments with early life might have been blasted off to moon.
p 109 "Moon serves as Earth's 'attic', where relics from the early history of the inner Solar System are stored and preserved"
p 110 Can measure Earth's albedo from the "earthshine" from the Moon's surface. Also gives us a spectral fingerprint of Earth from space, contributing to the search for other planets like Earth.
p 110 sharp limb of Moon allows us to measure occultation times precisely.
p 111 In Aristotle's time, they knew Earth was round by observing its shadow on the Moon during eclipses. More details about historical determinations of size of Earth, distance to Moon, etc.
p 114 Planetary protectors - Jupiter and Saturn helped shield Earth from sterilizing impacts.
Section 2 The Broader Universe
Chapter 7 Star Probes
p 120 Study of stars and development of H-R diagram.
p 122 oscillations of Sun, Cepheid variables, pulsars
p 123 stellar spectra
p 125 Doppler shift
p 126 "a real star contains and transmits information about its age, mass, position and velocity"
p 127 description of pulsar "Charged particles circulating around a pulsar's strong magnetic fields emit photons along narrow cones. This strong beaming allows us to measure a pulsar's rotation period precisely ..."
p 127 Circumstellar Habitable Zone (CHZ) "region around a star where liquid water can exist continually for at least a few billion years .."
p 128 details of CHZ, processes that help maintain liquid water, greenhouse effect, carbonate-silicate weathering, biological processes, ocean circulation, clouds, ice sheets, plate tectonics.
p 128 discussion of asteroid belt, useful way to characterize location 2AU out, 3AUs inside Jupiter. Role of Mars as inner boundary of asteroid belt and protector of Earth.
p 130 Detailed discussion of asteroids. "We probably have asteroids and some comets to thank for the few vvolitile compounds, such as water and carbon dioxide that abound in Earth's crust and outer mantle. Had Earth formed closer to the asteroid belt, however, is greater initial carbon and water endowment would probably have left a deep ocean, a thick carbon dioxide atmosphere, and a dead world."
p 132 Host star properties. Not more than 1.5 Msolar. Details problems of M dwarfs.
p 136 reflections on weak anthropic principle. Discussion of properties of Sun compared to other stars.
p 138 Latent ruler - Sun near optimum for life, Sun near optimum for extracting information from its spectrum. Also provides platform for parallax, and best platform - better than inner (too short a baseline) or outer (too long a period).
p O B stars as standard candles.
p 140 Sun as a good laboratory object.
p 142 last paragraph good summary Sun optimum for life, Sun great source of information
Chapter 8 Our Galactic Habitat
p 144 NGC 891 as model for our galaxy, diagram of Milky Way with Sun's position.
p 145 Face-on sketch of galaxy
p 145 see stars in all stages - see pairs, triplets and clusters. See giant clouds, discusses other variations.
p 146 halo, bulge, thick disk, thin disk , a plethora of objects, and we can see them all from our position. We are mid-plane, very little gas and dust,
p 149 globular cluster of Hercules, M 13 Couldn't see nearly as much there and there would be no night.
p 151 "In short, settings in the halo, a globular cluster, the bulge, a spiral arm, an isolated galaxy a dense cluster of galaxies, an irregular galaxy, or an elliptical galaxy would be less revealing than ours. We occupy the best overall place for observation in the Milky Way galaxy, which is itself the best type of galaxy to learn about ..."
p 152 discusses Galactic Habitable Zone (GHZ), which involves forming Earth-like planets with the needed planetary building blocks and the threats to complex life.
p 152-3 The "Ashes to Ashes, Dust to Dust section is a good summary of nucleogenesis of the elements - key section. "Metals" now 2% of galaxy's gas and dust.
p 154 Metal richness an important ingredient of habitability - more metal-rich cloud more likely to produce more low-mass stars.
p 155 need both gas giants and terrestrial planets - a tricky balance. The metal range may be quite narrow.
p 156 Metal content of stars in Sun's neighborhood is from 1/3 to 3 times that of the Sun. Metallicity increases with time in our neighborhood, decreases with distance from galactic center - more things that point to uniqueness of Sun, Earth.
p 157 Type Ia and II supernovae.
p 158 Supernovae graph
p 158 Role of radioactive elements for heating - later, less heating.
p 159 "A planet also must be largely free of threats to complex life over the long haul." discusses impacts and radiation from supernovae. Discusses extinction events.
p 160 comet discussion
p 164 Applying Weak Anthropic Principle Sun's metallicity just right for Earth type planets with large Jupiter companions. Place in galaxy just right. between spiral arms
p 166 Our "country club" location -- inner ghetto has radiation hazards, outer regions safer but less likely to form Earth type planets. Probably GHZ is ring around galactic center at our radius, but not in a spiral arm - on corotation circle? Also one of optimum locations for observation.
p 167 98% of nearby galaxies are more metal-poor,
p 168 "Precious few plots of galactic real estate are as amenable to complex life as ours, to say nothing of its value for observation. Our home is a fairly comfortable porch from which we can gaze out to the ends of space and the beginning of cosmic time. And as we will see, not all times in the history of the universe are like our present."
Chapter 9 Our Place in Cosmic Time
p 169 "Hubble was able to resolve individual Cepheid variable stars .. in .. M31 (Andromeda).
p 171 Discusses red shift, Hubble law Lemaitre, Einstein, Hubble - nice quote of the objections of Nernst as late as 1938 belief in a static and eternal universe. I love the part of Weizsacher's response "it was scientific to form hypotheses according to the hints given by experience " when Nernst insisted on an infinitely old universe.
p 172 Lemaitre's nice quote on looking back at the big bang, made from the evidence he saw before Hoyle's coining of "big bang".
p 172 Stellar standard candles, discusses Cepheids,
p 173 Type Ia supernovae as standard candles
p 174 Discovery of 3K CMB
p 177 Illustration of omega =1
p 178 Cosmic stew. Universe cooled too quickly to form anything past Lithium. The 3 independent supports for Big Bang: Hubble expansion, 3K CMB, H-He abundance.
p 179 Tests of cosmic expansion: Tolman test, broadening of curves of Type Ia supernovae, change in 3K temp with expansion, change of shape of 3K. Makes point that we can learn these things only because from our position we can see clearly to deep space. "That our time and place in the univers are fine-tuned not only for life but also for observation has, in one of the most important questions about the universe, made all the difference."
p 179 quasar probes - most distant and luminous objects - Hydrogen Lyman alpha test - 121.6nm Lyman alpha forest from different red shifts of intervening gas clouds. Has to shift to over 300nm to get through atmosphere.
p 181 Cosmic Habitable Age not before decoupling, not before essential elements formed in stars, not before "metals" distributed by supernovae, not so early that Earth-like planets would be in the dangerous inner galactic neighborhoods,
p 182 Milky Way massive enough to accumulate heavy elements relatively rapidly. Have to have the radioactive elements to heat the Earth - won't be as true later.
p 183 Optimum habitability in a narrow range of metalicity implies a window of time
p 191 Summary of evidence that we are optimum time for observability as well - CMB will redshift, etc .
p 192 Olber's Paradox
Chapter 10 A Universe Fine-Tuned for Life and Discovery
p 195 "There is for me powerful evidence that there is something going on behind it all ...It seems as though somebody has fine-tuned nature's numbers to make the Universe ...The impression of design is overwhelming." Paul Davies, The Cosmic Blueprint, Touchstone Books, 1989 p203.
p 195 Universe-creating machine
p 196 Illustration of control knobs on the machine. Only one combination that works.
p 196 "one of the most startling discoveries of the last century: the universe, as described by its physical laws and constants, seems to be fine-tuned for the existence of life."
p 197 Fine tuning in chemistry, Lawrence Henderson's 1913 book "The Fitness of the Environment" "reviewed the known properties of the environment particularly relevant to life, focusing on carbon and water."
p 198 "Carbon and Oxygen, Act II" Hoyle's prediction of an as yet unknown nuclear energy resonance. When two helium nuclei collide to form the unstable beryllium-8, it does so only because the energy of beryllium-8 is very close to that of the two Helium nuclei.The Be-8 has just 10
p 200 Diagram of the four interactions
p 201 Strong nuclear force. Because there are no stable elements with mass 5 or 8, carbon-12 can only be synthesized in stars by the process described above.
p 202 Potassium 40 is balanced on a razor's edge - enough to provide heat to drive plate tectonics but not enough to irradiate life.
p 202 Weak force . Roles in producing He-4, luminosity of stars,
p 203 Gravity Controls star formation. Also discusses dark energy.
p207 Multituning diagram
p208 Carbon and oxygen, Act III carbon dating and CO molecule tracing.
p212 Wigner's "unreasonable effectiveness of mathematics in natural science" built upon by Mark Steiner to describe the deep connections and uncanny predictive power of mathematics"
p212 cites Rees "Just Six Numbers"
p216 Sizes in the universe illustration.
p218 "the rare conditions required for habitability also provide excellent overall conditions for discovering the universe around us."
p "to reconsider our very purpose on this tiny speck orbiting a seemingly inconsequential star between the spiral arms of one ordinary galaxy among billions."
Section 3 Implications
Chapter 11 The Revisionist History of the Copernican Revolution
Rather passionate criticism of the distortion of history to portray science and faith as at war with each other.
p 221 "Our local environment, centering on the near-present time and Earth's surface, is exceptional and probably extremely rare, with respect to both its habitability and its measurability."
p 222 Good quote from a person who had swallowed all the bad history about Copernicus, et al and an appropriate blasting of the errors that are often made to create the myth of a war between science and faith in the time of Copernicus and thereafter.
p 224 Bertrand Russell about the Copernican Revolution. Other quotes and criticism of the "official story line" which is counter to the protests of hostorians of science.
p 228 War and Rumors of War - a good section on the contributions of the Judeo-Christian view to the development of science. Overall a good description of what they view as the distortions of history. A good treatment to use along with Dinesh D'Souza's treatment of the same subject.
p 231 Real Copernican revolution (Copernicus 1473-1543) Published his work on deathbed in 1543 - thought a system created by God should be precise and elegant, something the Ptolemaic system wasn't.
p 235 Interesting that Tycho Brahe was anti-Copernican, taking the earth to be stationary. But his careful data provided to Kepler the necessary precision to establish otherwise.
p 238 Kepler made the break from the mystical perfect circles and spheres and proposed elliptical orbits. Gonzales and Richards quote a passage from Kepler that resonates with their thesis of measurability by design. Keplers statement notes that in orbiting, the Earth gives diffferent measurement points, necessary for learning about the solar system.
p 239 Galileo's telescope observations
p 240 A little on the complications of the Galileo story.
p 242 Story of Bruno, executed by Church, to dismiss it as evidence of a war between science and faith.
p 244 In summary, their intent in this chapter has been to "expose the received version as so much mythology" "The great Copernican cliche'"
Chapter 12 Copernican Principle
p 247 Quotes Carl Sagan from "Pale Blue Dot" Also Lev Landau "Cosmologists are often wrong but never in doubt."
p 250 Still critical of the status accorded the Copernican principle, they propose predictioins of the principle that could be used to test it. 6 predictions in this chapter, all wrong, serve as a means for again highlighting the extraordinary nature of Earth.
p 251 Six predictions from Copernican principle, all wrong. Along lines of "Earth will be found unremarkable in suitability for ---
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Chapter 13 The Anthropic Disclaimer
Chapter 14 SETI and the Unraveling of the Copernican Principle
Chapter 15 A Universe Designed for Discovery
p 293 A discussion of what it takes to imply that something is designed.
p 295 An interesting discussion of Jocelyn Bell and the discovery of pulsars. Need to do some of that history in HyperPhysics in pulsar section.
p 297 In commenting on Ward & Brownlee's "lucky us" position regarding life on Earth, "The rarity of habitable conditions and complex life ifself weighs against the idea that life flows inevitably from the laws of physics and chemistry. But that rarity alone might suggest chance or design."
p 300 Has had several comments on Dembski's chance and specificity framework for implying design, and here discusses Del Ratzsch's work and his idea of "counterflow". He characterizes "counterflow" by "They contrast with the way nature will go if left to operate freely.".
p 303 Another approach to improbable events to help imply design is "value", which they try to define. But it is plausible to imply that living things have value.
p 304 In lots of ways, they explore the thesis that the fact that the most habitable regions also are the regions which are most favorable for learning about the universe can be used to make a case for design.
p 304 "As it is, we know that the laws of physics and initial conditions, themselves fine-tuned, are compatible with a wide range of local conditions, only a few of which are habitable. It's intrinsically interesting, and surprising, to find that those few habitable places are also the ones most conducive to diverse types of scientific discovery."
p 304 "to infer design reliably, normally a pattern must be independent from the event or object in question." Weak anthropic principle connections. They argue that being habitable and being measurable are distinct properties.
p 307 Good use of a Star Trek episode in which Kirk had all the components of gunpowder supplied to him in a test by an alien group. He recognizes a setup.
p 309 Quote from Michael Denton's Nature's Destiny, p262 "What is so striking is that our cosmos appears to be not just supremely fit for our being and for our biological adaptations, but also for our understanding."
p 310 Mendillo and Hart's whimsical proof of God from a perfect eclipse.
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