Village Journals
Resonate your identity with Naseeb journals. Express your opinions, share your thoughts, post your writings and connect with like minded people through the power of expression.
Resonate your identity with Naseeb journals. Express your opinions, share your thoughts, post your writings and connect with like minded people through the power of expression.
The Privileged Planet
?Say, "Have you thought: if God made the night perpetual until the Day of Resurrection, which god besides God would have provided you with light? Do you not hear?" Say, "Have you thought: if God made the daylight perpetual until the Day of Resurrection, which god besides God would have provided you with a night for your rest? Do you not see?" -Quran 28:71-72
?In the creation of the heavens and the earth and the alternation of night and day, there are signs for those who understand.? -Quran 3:190
?We showed Abraham the kingdom of the heavens and the earth so that he may attain certainty.? ?Quran 6:75
For the first time in 1992, planets outside the solar system (exoplanets) were discovered orbiting a radio pulsar, a rotating neutron star www.nature.com). The first definitive confirmation of an exoplanet orbiting an ordinary main-sequence star came forth in 1995 www.nature.com). About 200 exoplanets, mostly hot gas giants, have been discovered since then. NASA's Kepler Mission, Space Interferometry Mission, Terrestrial Planet Finder, European Space Agency's Darwin and Gaia, and France's COROT are all gearing up for a thrilling celestial hunt for exoplanets. For instance, the Kepler Mission www.kepler.arc.nasa.gov) is scheduled to lift off in November 2008 to search for Earth-like planets in habitable orbital zones around stars:
?The Kepler satellite will orbit the Sun and study some 100,000 stars for four years, looking for planets that are similar in size to Earth and in similar orbits around their stars. Only planets with orbits in this so-called "habitable zone," where it is not too hot and not too cold, could have liquid water, scientists say. And liquid water is seen as a necessary ingredient for life as we know it? www.space.com).
The Privileged Planet: How Our Place in the Cosmos is Designed for Discovery proposes that the rare conditions that allow intelligent life to flourish on Earth (habitability criteria) also make the planet a uniquely well suited platform that permits intelligent life to study the universe (measurability criteria). From the Privileged Planet website:
?Elsewhere, you might learn that Earth and its local environment provide a delicate, and probably exceedingly rare, cradle for complex life. But there's another, even more startling, fact, described in The Privileged Planet: those same rare conditions that produce a habitable planet-that allow for the existence of complex observers like ourselves-also provide the best overall place for observing. What does this mean? At the least, it turns our view of the universe inside out. The universe is not "pointless" (Steven Weinberg), Earth merely "a lonely speck in the great enveloping cosmic dark," (Carl Sagan) and human existence "just a more-or-less farcical outcome of a chain of accidents" (Steven Weinberg). On the contrary, the evidence we can uncover from our Earthly home points to a universe that is designed for life, and designed for discovery? www.privilegedplanet.com).
Allow me to illustrate a few instances of the correlations between habitability and measurability:
1. The atmospheric mixture (the right proportion of the right chemicals such as ozone, oxygen, carbon dioxide, etc.) of Earth protects and flourishes life (habitability criterion), and the same mixture is stunningly so clear and transparent that it allows observers to use the night sky to study moons, planets, stars, celestial mechanics, nebulae, supernovae, and other astronomical phenomena even in the distant reaches of the visible universe (measurability criterion). Many planets seem to either lack clear and transparent atmospheres or lack atmospheres altogether.
Did anyone watch the sci-fi movie Pitch Black imdb.com)? Three suns would continuously illuminate the exoplanet for 22 years. The three suns would then align in such a way that the planet would get eclipsed by another giant, ringed planet in the system, tossing the eclipsed planet into uninterrupted pitch darkness for another 22 years. Planets like that in multiple-star systems are gravitationally unstable, yet are possible, given a certain celestial setup. If there were no night sky, no reasonably frequent alternation of day and night (i.e., in reasonable relation to a certain length of average human lifetime), or no transparent atmosphere, would we have ever learnt Kepler?s laws of planetary motion, discovered Galileo?s moons of Jupiter, confirmed Einstein?s general relativity, landed on the moon, known the Big Bang, launched satellites to study the cosmic microwave background radiation (the remnant of the explosive creation of space-time), and postulated possible cosmological geometries, to name a few? Reasonably frequent alternation of dark nights and lighted days and a transparent atmosphere promote scientific progress of intelligent life on a planet.
2. The solar system is located about halfway between the galactic center and the edge of the galactic disk and in the mid-plane of the Milky Way galaxy when viewed edge on. As we approach the galactic center, the risk of supernovae, short-lived stars, black holes, quasars, gamma ray bursts, and other violent cosmic events proportionally increases. Also, closer to the center, the night sky would be much brighter and thus would obscure the view of background stars and other celestial objects from observation. As we travel out from the center, the metallicity of stars proportionally declines, resulting in increasingly lower likelihood of terrestrial planet formation. The solar system?s location within the Milky Way galaxy is exceptional. Our planet is not located in the violent central galactic bulge, not near a source of gamma radiation, not in a gravitationally unstable multiple-star system, not near a pulsar, and not near a star too small, too large, or soon to explode into a supernova (habitability criterion). Our planet is located precisely in that region of the Milky Way?s spiral arm that permits telescopes to pierce into the background stars and the farthest reaches of the visible universe. Our view of the cosmos from Earth is free of obstruction by dense star clusters and by diffuse gas found in other regions of the galaxy (measurability criterion).
3. The Earth has a magnetosphere that shields life from solar flares (habitability criterion), and the stable magnetic field facilitates terrestrial and aerial navigation (measurability criterion). Can we imagine leading the expansion of the Arabian Empire through the African Sahara in the 8th century AD without a compass, or flying United Airlines from Los Angeles to Sydney on an Earth without a magnetic field?
I have offered a brief and an admittedly incomplete analysis of many such exceptional and fascinating correlations between habitability and measurability. Our planet seems to be exquisitely fit not only to support life but also to offer us the best platform or laboratory for probing the universe. It is as if the Earth were specially designed both for life and for scientific discovery (Privileged Planet hypothesis). The Privileged Planet hypothesis undermines the Copernican Principle and the Principle of Mediocrity in the philosophy of science. The Principle of Mediocrity holds that there is nothing special about Earth and the human race. It is a Copernican Principle, which maintains that no special observers should be proposed.
The data from exoplanet space missions serves as a test of the Privileged Planet hypothesis. Are there more Earth-like planets that have conditions suitable for intelligent life to flourish and conditions suitable for the life forms to discover the marvels of the universe? Is there something strangely extraordinary about the correlation between the Earth?s habitability and measurability conditions? Are our planet and our existence special and purposeful? With forthcoming data from exoplanet space missions, it would be interesting to see how the hypothesis fares against orthodox philosophical notions that maintain that the human race?s existence is unexceptional in the cosmos. Stay tuned.
Nadeem
References (excludes web links)
Gonzalez, Guillermo, and Jay W. Richards. The Privileged Planet: How Our Place in the Cosmos is Designed for Discovery. Washington, DC: Regnery Publishing, Inc., 2004.
Lead Author's Bio www.public.iastate.edu www.discovery.org)
Guillermo Gonzalez is an Assistant Professor of Astronomy at Iowa State University. He received his Ph.D. in Astronomy in 1993 from the University of Washington. He has done post-doctoral work at the University of Texas, Austin and at the University of Washington and has received fellowships, grants and awards from such institutions as NASA, the University of Washington, Sigma Xi (scientific research society) and the National Science Foundation.
Gonzalez has extensive experience in observing and analyzing data from ground-based observatories, including work at McDonald Observatory, Apache Point Observatory and Cerro Tololo Interamerican Observatory. He is a world class expert on the astrophysical requirements for habitability and on habitable zones and a co-founder of the Galactic Habitable Zone (GHZ) concept. Astronomers and astrobiologists around the world are pursuing research based on my work on extra solar planets host stars, the GHZ, and several discoveries pertaining to stellar abundances.
Gonzalez has also published over sixty articles in refereed astronomy and astrophysical journals including Astronomy and Astrophysics, Monthly Notices of the Royal Astronomical Society, Astrophysical Journal and Solar Physics. His current research interests in astrobiology focus on the "Galactic Habitable Zone" which captured the October 2001 cover story of Scientific American, and the properties of the host stars of extra solar planets. He also is the co-author of the second edition of "Observational Astronomy" an advanced college astronomy textbook.
In 2004 he co-authored The Privileged Planet: How Our Place In The Cosmos is Designed For Discovery with Jay W. Richards.
?In the creation of the heavens and the earth and the alternation of night and day, there are signs for those who understand.? -Quran 3:190
?We showed Abraham the kingdom of the heavens and the earth so that he may attain certainty.? ?Quran 6:75
For the first time in 1992, planets outside the solar system (exoplanets) were discovered orbiting a radio pulsar, a rotating neutron star www.nature.com). The first definitive confirmation of an exoplanet orbiting an ordinary main-sequence star came forth in 1995 www.nature.com). About 200 exoplanets, mostly hot gas giants, have been discovered since then. NASA's Kepler Mission, Space Interferometry Mission, Terrestrial Planet Finder, European Space Agency's Darwin and Gaia, and France's COROT are all gearing up for a thrilling celestial hunt for exoplanets. For instance, the Kepler Mission www.kepler.arc.nasa.gov) is scheduled to lift off in November 2008 to search for Earth-like planets in habitable orbital zones around stars:
?The Kepler satellite will orbit the Sun and study some 100,000 stars for four years, looking for planets that are similar in size to Earth and in similar orbits around their stars. Only planets with orbits in this so-called "habitable zone," where it is not too hot and not too cold, could have liquid water, scientists say. And liquid water is seen as a necessary ingredient for life as we know it? www.space.com).
The Privileged Planet: How Our Place in the Cosmos is Designed for Discovery proposes that the rare conditions that allow intelligent life to flourish on Earth (habitability criteria) also make the planet a uniquely well suited platform that permits intelligent life to study the universe (measurability criteria). From the Privileged Planet website:
?Elsewhere, you might learn that Earth and its local environment provide a delicate, and probably exceedingly rare, cradle for complex life. But there's another, even more startling, fact, described in The Privileged Planet: those same rare conditions that produce a habitable planet-that allow for the existence of complex observers like ourselves-also provide the best overall place for observing. What does this mean? At the least, it turns our view of the universe inside out. The universe is not "pointless" (Steven Weinberg), Earth merely "a lonely speck in the great enveloping cosmic dark," (Carl Sagan) and human existence "just a more-or-less farcical outcome of a chain of accidents" (Steven Weinberg). On the contrary, the evidence we can uncover from our Earthly home points to a universe that is designed for life, and designed for discovery? www.privilegedplanet.com).
Allow me to illustrate a few instances of the correlations between habitability and measurability:
1. The atmospheric mixture (the right proportion of the right chemicals such as ozone, oxygen, carbon dioxide, etc.) of Earth protects and flourishes life (habitability criterion), and the same mixture is stunningly so clear and transparent that it allows observers to use the night sky to study moons, planets, stars, celestial mechanics, nebulae, supernovae, and other astronomical phenomena even in the distant reaches of the visible universe (measurability criterion). Many planets seem to either lack clear and transparent atmospheres or lack atmospheres altogether.
Did anyone watch the sci-fi movie Pitch Black imdb.com)? Three suns would continuously illuminate the exoplanet for 22 years. The three suns would then align in such a way that the planet would get eclipsed by another giant, ringed planet in the system, tossing the eclipsed planet into uninterrupted pitch darkness for another 22 years. Planets like that in multiple-star systems are gravitationally unstable, yet are possible, given a certain celestial setup. If there were no night sky, no reasonably frequent alternation of day and night (i.e., in reasonable relation to a certain length of average human lifetime), or no transparent atmosphere, would we have ever learnt Kepler?s laws of planetary motion, discovered Galileo?s moons of Jupiter, confirmed Einstein?s general relativity, landed on the moon, known the Big Bang, launched satellites to study the cosmic microwave background radiation (the remnant of the explosive creation of space-time), and postulated possible cosmological geometries, to name a few? Reasonably frequent alternation of dark nights and lighted days and a transparent atmosphere promote scientific progress of intelligent life on a planet.
2. The solar system is located about halfway between the galactic center and the edge of the galactic disk and in the mid-plane of the Milky Way galaxy when viewed edge on. As we approach the galactic center, the risk of supernovae, short-lived stars, black holes, quasars, gamma ray bursts, and other violent cosmic events proportionally increases. Also, closer to the center, the night sky would be much brighter and thus would obscure the view of background stars and other celestial objects from observation. As we travel out from the center, the metallicity of stars proportionally declines, resulting in increasingly lower likelihood of terrestrial planet formation. The solar system?s location within the Milky Way galaxy is exceptional. Our planet is not located in the violent central galactic bulge, not near a source of gamma radiation, not in a gravitationally unstable multiple-star system, not near a pulsar, and not near a star too small, too large, or soon to explode into a supernova (habitability criterion). Our planet is located precisely in that region of the Milky Way?s spiral arm that permits telescopes to pierce into the background stars and the farthest reaches of the visible universe. Our view of the cosmos from Earth is free of obstruction by dense star clusters and by diffuse gas found in other regions of the galaxy (measurability criterion).
3. The Earth has a magnetosphere that shields life from solar flares (habitability criterion), and the stable magnetic field facilitates terrestrial and aerial navigation (measurability criterion). Can we imagine leading the expansion of the Arabian Empire through the African Sahara in the 8th century AD without a compass, or flying United Airlines from Los Angeles to Sydney on an Earth without a magnetic field?
I have offered a brief and an admittedly incomplete analysis of many such exceptional and fascinating correlations between habitability and measurability. Our planet seems to be exquisitely fit not only to support life but also to offer us the best platform or laboratory for probing the universe. It is as if the Earth were specially designed both for life and for scientific discovery (Privileged Planet hypothesis). The Privileged Planet hypothesis undermines the Copernican Principle and the Principle of Mediocrity in the philosophy of science. The Principle of Mediocrity holds that there is nothing special about Earth and the human race. It is a Copernican Principle, which maintains that no special observers should be proposed.
The data from exoplanet space missions serves as a test of the Privileged Planet hypothesis. Are there more Earth-like planets that have conditions suitable for intelligent life to flourish and conditions suitable for the life forms to discover the marvels of the universe? Is there something strangely extraordinary about the correlation between the Earth?s habitability and measurability conditions? Are our planet and our existence special and purposeful? With forthcoming data from exoplanet space missions, it would be interesting to see how the hypothesis fares against orthodox philosophical notions that maintain that the human race?s existence is unexceptional in the cosmos. Stay tuned.
Nadeem
References (excludes web links)
Gonzalez, Guillermo, and Jay W. Richards. The Privileged Planet: How Our Place in the Cosmos is Designed for Discovery. Washington, DC: Regnery Publishing, Inc., 2004.
Lead Author's Bio www.public.iastate.edu www.discovery.org)
Guillermo Gonzalez is an Assistant Professor of Astronomy at Iowa State University. He received his Ph.D. in Astronomy in 1993 from the University of Washington. He has done post-doctoral work at the University of Texas, Austin and at the University of Washington and has received fellowships, grants and awards from such institutions as NASA, the University of Washington, Sigma Xi (scientific research society) and the National Science Foundation.
Gonzalez has extensive experience in observing and analyzing data from ground-based observatories, including work at McDonald Observatory, Apache Point Observatory and Cerro Tololo Interamerican Observatory. He is a world class expert on the astrophysical requirements for habitability and on habitable zones and a co-founder of the Galactic Habitable Zone (GHZ) concept. Astronomers and astrobiologists around the world are pursuing research based on my work on extra solar planets host stars, the GHZ, and several discoveries pertaining to stellar abundances.
Gonzalez has also published over sixty articles in refereed astronomy and astrophysical journals including Astronomy and Astrophysics, Monthly Notices of the Royal Astronomical Society, Astrophysical Journal and Solar Physics. His current research interests in astrobiology focus on the "Galactic Habitable Zone" which captured the October 2001 cover story of Scientific American, and the properties of the host stars of extra solar planets. He also is the co-author of the second edition of "Observational Astronomy" an advanced college astronomy textbook.
In 2004 he co-authored The Privileged Planet: How Our Place In The Cosmos is Designed For Discovery with Jay W. Richards.
Comments on this journal
?But new simulations of the climate on Gliese 581c created by Werner von Bloh of the Institute for Climate Impact Research in Germany and his team suggest the planet is no Earthly paradise, but rather a faraway Venus, where carbon dioxide and methane in the atmosphere create a runaway greenhouse effect that warms the planet well above 212 degrees Fahrenheit (100 Celsius), boiling away liquid water and with it any promise of life.? bcast1.imaginova.com)
?When an international team of physicists led by Werner von Bloh of the Potsdam Institute for Climate Impact Research in Potsdam, Germany, applied computer climate models to Gliese 581c, it found that even if the planet contained life-giving carbon dioxide, Gliese 581c's close proximity to its parent star would cause high levels of the greenhouse gas to build up in the atmosphere. That would likely warm the planet above 100?C, boiling off any water.? sciencenow.sciencemag.org)
Bloh?s study, published in last month?s May 25 issue of Astronomy & Astrophysics arxiv.org), seems to better appreciate the delicate intricacy of planetary habitability conditions, as he bases his climate model on a more realistic and a more accurate depiction of habitability that incorporates both atmospheric and geophysical properties of a planet, and not just size, luminosity, and other parameters of the host star:
?Here habitability (i.e., presence of liquid water at all times) does not just depend on the parameters of the central star, but also on the properties of the planet. In particular, habitability is linked to the photosynthetic activity of the planet, which in turn depends on the planetary atmospheric CO2 concentration, and is thus strongly influenced by the planetary dynamics. In principle, this leads to additional spatial and temporal limitations of habitability, as the stellar HZ (defined for a specific type of planet) becomes narrower with time due to the persistent decrease of the planetary atmospheric CO2 concentration.?
Basing his calculations on a more comprehensive portrayal of habitability, Bloh concludes that ?Gl 581c is clearly outside the habitable zone.? Eyes are zooming in for ?at least some primitive forms of life,? however, on GI 581 d ? a rather unsurprising discovery if materialized. Bloh concludes:
?In conclusion, one might expect that life may have originated on Gl 581d. The appearance of complex life, however, is unlikely due to the rather adverse environmental conditions. To get an ultimate answer to the profound question of life on Gl 581d, we have to await the TPF/Darwin missions. They will allow for the first time to detect biomarkers (Grenfell et al. 2007) in the atmospheres of the two super-Earths around Gl 581.?
Thus, both the much-touted ?Earth-like? planet and its sister, GI 581 d (?super-Earth?), have been officially classified uninhabitable for complex life. After all the initial misreported frenzy, how many in the media are now reporting Bloh's study? Maybe it is not as exhilarating to draw a bandwagon around the news of an uninhabitable dead world previously declared ?habitable.?
Udry obswww.unige.ch): ?The HARPS search for southern extra-solar planets*? (title). ?XI. Super-Earths (5&8M ) in a 3-planet system? (sub-title).
ESO www.eso.org): ?The HARPS search for southern extra-solar planets : XI. An habitable super-Earth (5 MEarth) in a 3-planet system?
Why would ESO misquote the title? Did the media follow ESO?s lead and tag on the word ?habitable? in news headlines? GI 581 c is deemed ?habitable? and the other massive planet is not also labeled ?super-Earth? as Udry?s title declared. ESO?s title gives the false impression that this one planet is ?habitable? and is the only Earth, albeit super, in the 3-planet system. Why does ESO?s press release glamorize GI 581 c at the center of public theatrics? Udry et al. correctly and cautiously note that the planet is ?probably the most Earth-like of all known exoplanets? (not that it actually is in fact Earth-like) and even so in terms of radius and temperature parameters only, that ?the actual surface temperature of the planet very much depends on the highly uncertain composition and thickness of its atmosphere,? and that a ?detailed study will also need to consider the possible tidal locking of the planetary rotation to the orbital period.? Such vigilant qualifications, barely reported by the media, apparently were not enough to prevent a supposedly scientific organization from misquoting the title, claiming that the planet is ?habitable.? ESO?s misquotation might have contributed to igniting the frenzied chain reaction.
Although a few headlines do use the accurate clause (?most Earth-like planet found to date?), many headlines (including that from the European Organization for Astronomical Research) proclaim that the planet is a ?super-Earth? or is or could be ?Earth-like? (even though it is 5 times more massive than Earth), and other headlines illicitly equate ?Earth-like? with ?habitable? and ?life?:
?Astronomers Find First Earth-like Planet in Habitable Zone? -European Organization for Astronomical Research in the Southern Hemisphere
?All Wet? Astronomers Claim Discovery of Earth-like Planet? -Scientific American
?New 'Super Earth' found in space? -BBC
?New Planet Could Be Earthlike, Scientists Say? -New York Times
?Astronomers Discover an Earth-Like Planet? -Newsweek
?New Earth-like Planet 'Habitable'? -Discovery Channel
"Gliese 581c Discoverer: More Earth-Like Planets to Come" -Wired Science
?Astronomers Find Habitable Earth-like Planet? -Astrobiology Magazine
?Astronomers Find First Habitable Earth-Like Planet? -Space Daily
?Earth-like planet found that may support life? -CTV News
?Scientists find earth-like planet? -Los Angeles Times
?Search for Life Next on Habitable Earth-Like Planet? -Sci-Tech Today
?Earth-like planet discovery 'may support life'? -Ireland Online
??Earth-like? planet found? -Glasgow Evening Times, UK
?Scientists Find Planet Like Earth? -The Moscow Times, Russia
?First habitable 'Earth-like' planet found? -National Post, Canada
?Red dwarf is mother to an Earth-like planet? -Manila Bulletin, Philippines
?New Earth-like planet 'habitable'? -ABC Science Online, Australia
?Scientists find planet like Earth that may have life? -Shanghai Daily, China
?Earth-like planet discovered? -iAfrica.com, South Africa
?Astronomers find Earth:like planet? -NZZ Online, Switzerland
?Earth-like planet discovered? -Gulf News, United Arab Emirates
?First habitable Earth like planet outside Solar System discovered? -Zee News, India
The research paper itself (?The HARPS search for southern extra-solar planets: XI. An habitable super-Earth (5 MEarth) in a 3-planet system,? by S. Udry et. al.) seems to have hastened to declare the planet ?habitable.?
What an outstanding bandwagon! This appears to be an even bigger bandwagon than the one that ballyhoos discoveries of fossilized skulls and fragments in favor of evolution. The term ?Earth-like? seems to solely refer to ?Earth-like? average surface temperatures that permit water in its liquid state. The planet is deemed ?habitable? primarily due to the essentially trivial fact that its orbit is confined to the circumstellar habitable zone, which allows planetary surface temperature to accommodate liquid water. But that is not a sufficient criterion for habitability.
The media and the scientists alike neglected to clearly define the term. It was evident that they neither understand nor appreciate the host of factors crucial to habitability (On a side note, it is no wonder that the Quran states that there exist many ?signs,? throughout the heavens and the Earth, for ?those who understand.?) How can this planet be Earth-like if it is 5 times more massive than Earth? For instance, consider this: ?the fact that it has a mass at least 5x Earth's means that it will have a high surface gravity and less surface relief than the Earth -- meaning no dry land,? according to astronomer Dr. Guillermo Gonzalez www.evolutionnews.org). This is not to imply that life cannot thrive on a planet more massive than Earth, though too massive a planet would be an unlikely cradle for complex (animals and higher plants) and intelligent (technological) life. The point is this: surely, must we reckon that this particular planet is ?Earth-like? after all? And the ETs, if any, are probably fish-like, but intelligent, aquatic vertebrates that must have evolved the needed faculties to live under-water in higher gravity and higher pressure world of ?liquid water.? Or, maybe the ETs are intelligent invertebrates that resemble some combination of jellyfishes, sponges, giant squids, platyhelminthes, nematodes, and sea cucumbers.
Gl 581 b: 15.6 Earth-masses, 0.041 AU
Gl 581 c: 5.06 Earth-masses, 0.073 AU
Gl 581 d: 8.3 Earth-masses, 0.25 AU
Wherever possible, I calibrated the data from the perspective of our solar system (cf. www.solarviews.com):
Gl 581 b: nearly the mass of Neptune (17.1 Earth-masses), 11% of AU from sun to Mercury (0.39 AU)
Gl 581 c: 5.06 Earth-masses, 19% of AU from sun to Mercury
Gl 581 d: 8.3 Earth-masses, 64% of AU from sun to Mercury
Three noteworthy points:
1. A relatively massive giant nearly the mass of Neptune and at least two other planets more massive than Earth are tightly packed into orbits much smaller than the orbit of Mercury.
2. Ignoring the orbits of Neptune and Pluto, the shortest average distance between the orbits of any two planets in the solar system is between the orbits of Earth and Venus (0.277 AU). The distance between the orbits of Gl 581 c and the massive Neptune-sized giant is within a stunning 12% of the Earth-Venus orbit! Based on this orbital spacing parameter alone, it is almost as if GI 581 c is a moon of the giant, or might anytime, upon close encounter with the giant, be gravitationally captured into an orbit around the giant if it has not done so already (or, at worst, possibly crash into the giant)! The Privileged Planet hypothesis makes the predictive, testable, and falsifiable scientific argument that it is unlikely that intelligent life will be found on a moon.
3. The distance between the orbits of GI 581 c and GI 581 d is within 64% of the Earth-Venus orbital spacing.
Do these jam-packed orbits and proximity of Gl 581 c to a relatively massive giant undermine, due to potential gravitational perturbation, the habitability of Gl 581 c, the ?best candidate? that we have discovered so far? Even if life, in any form whatsoever, currently exists on the planet, it is hard to believe how life could persist for billions of years on a planet with potentially unstable, gravitationally perturbed orbit. The slightest perturbation of a planetary orbit could result in considerable global climate change, including cryogenic deep-freeze. On the other hand, stable and nearly circular orbit of Earth, spaced far apart from the Jovian gas giants (and the gas giants themselves spaced far apart), has contributed to flourishing habitable conditions for life on Earth for more than 3.5 billion years. Do the orbits of the planets and the spacing between them really rival the life-friendly orbits and spacing of the planets in the solar system?
A stable orbit over vast tracts of time is only one of many other habitability criteria for life. Have SETI folks evaluated these criteria in an unbiased manner? Or, due to the nature of their paid profession, are they inherently biased in favor of the possibility of finding intelligent life at the slightest likelihood of the presence of mere liquid water? Are they inherently liable to be unappreciative of life-friendly conditions on and around Earth? Do they really understand and appreciate the assortment of life-friendly conditions that enable their subsistence?
>> ? the planet nevertheless lies in the habitable zone, the region around a star where water could be liquid! www.eso.org)
A circumstellar habitable zone is defined as the space around a star where planetary surface temperature might accommodate liquid water. Since liquid water is a necessary but not a sufficient criterion for life, the confinement of a planetary orbit to the circumstellar habitable zone is a necessary but not a sufficient criterion for complex or intelligent, if not extremophilic microbial, life. Contrary to the SETI Institute, there has not been sufficient reason so far to get thrilled about the odds of finding complex or intelligent life on GI 581 c. Further studies are needed to determine whether conditions there are habitable enough to increase the odds of the presence of complex or intelligent life.
I have quoted below the space.com article.
>> An Earth-like planet spotted outside our solar system is the first found that could support liquid water and harbor life, scientists announced today.
>> ?It means there probably are many more such planets out there,? Charbonneau said in a telephone interview.
The term ?Earth-like? is deceptive and vague. The Privileged Planet hypothesis is more explicit. The real contention is whether this ?best candidate? for life nurtures conditions suitable for intelligent life to flourish and conditions suitable for the life forms to unravel the universe.
>> Liquid water is a key ingredient for life as we know it.
Liquid water is a necessary but not a sufficient requisite for life. Also, it must be clearly spelled out whether ?life? means simple (microbial) life, complex life, or intelligent life.
>> Shostak said he was ?jazzed? by the discovery. ?This is pointing to something that in the past has only been an assumption, namely that Earth-sized worlds are not rare,? he said. ?We know of only two . We know this one and we know our own. But two is better than one.?
It is not contested whether the size of the Earth is rare. There may be many more Earth-sized worlds out there. The issue is whether there are other planets that nurture conditions suitable for intelligent life to flourish and conditions suitable for the life forms to unravel the universe.
Despite the publicized thrill behind this discovery, certain key conditions that permit intelligent life on a planet have been apparently overlooked, at least so far. Just a few brief examples. First, the planet, which orbits a red dwarf star, is located ?14 times closer to its star than the Earth is from the Sun.? A planet in proximity to a star faces the risk of rotational braking induced by the gravitational field of its host star, permanently halting the planet?s rotation and freezing potential water and atmosphere on the planet?s dark side. Second, if the planet lacks stable and protective magnetic field, the stronger solar flare intensity of the red dwarf would threaten planetary life, and occasional flare bursts could damage protective chemicals such as ozone in the planet?s atmosphere. In contrast, the Earth?s atmosphere has protected life for billions of years. Third, the spectrum of a star is vital for photosynthetic activity. Is the spectrum of the planet?s red dwarf star hospitable to life? Fourth, if spacing between this planet and the other large planets in the system is not far enough (as it is in the Earth-Jupiter-Saturn system), the system risks gravitational perturbation, which could toss, like billiard balls, one or more of the planets out into cosmic void. This is by no means an exhaustive list of the many obstacles relevant to planetary habitability, let alone measurability. Yet, Shostak is ?jazzed? by the discovery.
It may be intuitive that the fact that the universe is so old and so vast means that the Earth is insignificant and that there may be "around a million technical civilizations" in our galaxy alone (cf. Carl Sagan's famous argument from the Drake Equation). However, the Weak Anthropic Principle (WAP) proposes a distinctively divergent view. There exists a physical requirement that enough time pass for cosmic expansion to suitably cool after the Big Bang in order to permit the existence of observers and to produce life-supporting elements. This requirement automatically ensures that before observers come on board to contemplate over the universe: (1) the universe must be as old as it is, and (2) because the outer limit of the universe expands at the speed of light, the universe must be as large as it is. Therefore, the age and the size of the universe are no surprise because we exist (WAP). We can exist precisely at the time in cosmic evolution that permits us to exist, and that life-friendly cosmic time is roughly the present age of the universe. Apart from being stunned by cosmic vastness, an observer should not be surprised then that the universe is so old and so vast and that the Earth is a comparatively infinitesimal speck.
The heavy nuclei (carbon, nitrogen, oxygen, phosphorus, etc.) take time to cook from the lighter nuclei (hydrogen and helium) in the interiors of stars. When a star ends its life cycle and goes supernova, the biological elements are scattered throughout space and some gravitationally clump together to form terrestrial planets. The long time required for life-supporting planets and life-forming elements to be produced in this way has been calculated. The time roughly equals the lifetime of a main-sequence star, such as our sun, in its evolution. Thus, in order that "the Universe contain the building-blocks of life, it must be at least as old as t* and hence, by virtue of its expansion, at least ct* light-years in extent." No observer should be surprised to find the universe as large as it is because it has to be that old and that huge in order to have the slightest chance to produce the physical conditions necessary for our existence (WAP). The WAP shows that "the argument that the Universe should be teeming with civilizations loses much of its persuasiveness; the Universe has to be as big as it is in order to support just one lonely outpost of life." Refer to The Anthropic Cosmological Principle (p. 18) in which John Barrow (British cosmologist, theoretical physicist, and mathematician) and Frank Tipler (American mathematician and physicist) present the analyses in more mathematical and astronomical detail.
>> I guess this hypothesis will fall to the ground as soon as something equitable or better is found, which is at least not beyond imagination statistically speaking...
All scientific ideas are susceptible to fall (falsification). Otherwise, the idea would be considered to have ventured into philosophy. In contrast to the Copernican Principle, which is an unproven philosophical assumption, the Privileged Planet hypothesis is founded on scientific observation and evidence (see my original post above) and is open to falsification.