Life on other planets, a real possibility?
https://reasonandscience.catsboard.com/t232-life-on-other-planets-a-real-possibility
Brian C. Lacki: THE LOG LOG PRIOR FOR THE FREQUENCY OF EXTRATERRESTRIAL INTELLIGENCES September 21, 2016
This log log prior can handle a very wide range of PETI values, from 1 to 1010^122 while remaining responsive to evidence about extraterrestrial societies.
https://arxiv.org/pdf/1609.05931.pdf
Richard Dawkins on scientific truth, outgrowing God and life beyond Earth
28 de ago. de 2019
It's not totally obvious that there have to be other living creatures around but if we are unique then what that means is that there's something very very very very special about the origin of life on this planet if we are the only one that's developed life then the origin of life would then have to be a quite stupendously improbable event so much so that we're wasting our time trying to understand it but I don't believe that as a matter of fact, I believe that there is probably quite a lot of life around the universe even if there's only say as few as a billion other life-forms and I stress that word few because a billion is a tiny tiny number compared to 10 to 22 if that were the case then the different life forms might be so widely spaced out that none of them ever encounters any of the others.
https://www.youtube.com/watch?v=RKjiSu4zD5Y&t=6s
Because life has emerged on earth is no indication that it occurred anywhere else too. The statistical probability that life exists within the universe is less than the number of planets in the universe. The reason for this, is that Earth combines an extremely improbable number of factors that are required to produce and sustain life, which adds up to such a small likelihood that it’s more than likely that we are all there is. Earth’s moon is one of the huge factors, which is 160 times larger than a natural satellite for a planet of Earth’s size; and it keeps Earth’s rotation stable, to keep the equator from becoming the North and South pole — this would certainly preclude intelligent life from emerging; and it also creates the tides, which are helpful to the formation of life.
Paul Davies, the fifth miracle page 53:
There are indeed a lot of stars—at least ten billion billion in the observable universe. But this number, gigantic as it may appear to us, is nevertheless trivially small compared with the gigantic odds against the random assembly of even a single protein molecule. Though the universe is big, if life formed solely by random agitation in a molecular junkyard, there is scant chance it has happened twice.
RTB Design Compendium (2009)
https://reasons.org/explore/publications/articles/rtb-design-compendium-2009
Hugh Ross Probability Estimates for the Features Required by Various Life Forms 2008
Less than 1 chance in 10^1032 exists that even one life-support planet would occur anywhere in the universe without invoking divine miracles.
https://d4bge0zxg5qba.cloudfront.net/files/compendium/compendium_Part3_ver2.pdf
Hugh Ross Fine-Tuning for Intelligent Physical Life 2008
402 quantifiable characteristics of a planetary system and its galaxy that must fall within narrow ranges to allow for the possibility of advanced life’s existence. This list includes comment on how a slight increase or decrease in the value of each characteristic would impact that possibility. That includes parameters of a planet, its planetary companions, its moon, its star, and its galaxy must have values falling within narrowly defined ranges for physical life of any kind to exist.2
https://d4bge0zxg5qba.cloudfront.net/files/compendium/compendium_part2.pdf
Hugh Ross: 922 characteristics of a galaxy and of a planetary system physical life depends on and offers conservative estimates of the probability that any galaxy or planetary system would manifest such characteristics. This list is divided into three parts, based on differing requirements for various life forms and their duration. 3 and 4
Hugh Ross Probability Estimates on Different Size Scales For the Features Required by Advanced Life 2008
Less than 1 chance in 10^390 exists that even one planet containing the necessary kinds of life would occur anywhere in the universe without invoking divine miracles.
https://d4bge0zxg5qba.cloudfront.net/files/compendium/compendium_Part4_ver2.pdf
Hugh Ross: Exotic Life Sites: The Feasibility of Far-Out Habitats 2001
The data demonstrate that the probability of finding even one planet with the capacity to support life falls short of one chance in 10^140 (that number is 1 followed by 140 zeros)
https://reasons.org/explore/publications/facts-for-faith/read/facts-for-faith/2001/10/01/exotic-life-sites-the-feasibility-of-far-out-habitats
Quantifying the origins of life on a planetary scale
https://www.pnas.org/content/113/29/8127?fbclid=IwAR2lMvRxj5uJ8aHf-2Y1mDewShMHMzriFX-h7mddxK3U3B9l0WJAqCsTdKg
Dissolving the Fermi Paradox
When we take account of realistic uncertainty, replacing point estimates by probability distributions that reflect current scientific understanding, we find no reason to be highly confident that the galaxy (or observable universe) contains other civilizations, and thus no longer find our observations in conflict with our prior probabilities. We found qualitatively similar results through two different methods: using the authors’ assessments of current scientific knowledge bearing on key parameters, and using the divergent estimates of these parameters in the astrobiology literature as a proxy for current scientific uncertainty. When we update this prior in light of the Fermi observation, we find a substantial probability that we are alone in our galaxy, and perhaps even in our observable universe (53%–99.6% and 39%–85% respectively). ’Where are they?’ — probably extremely far away, and quite possibly beyond the cosmological horizon and forever unreachable.
https://arxiv.org/pdf/1806.02404.pdf
http://worldview3.50webs.com/mathproofcreat.html
Earth really IS special: None of the 700 million trillion planets in our known universe are similar to our own, study finds
Ellie Zolfagharifard For Dailymail.com
20 February 2016
There are believed to be 700 million trillion terrestrial planets in the known universe. Scientists have long believed that among them are worlds similar to our own. This is known as the 'Copernican principle', which states that our planet doesn't hold a privileged position in the cosmos. Now, a new study has turned that principle on its head by suggesting that Earth may well be one of a kind.
Exoplanet Census Suggests Earth Is Special after All
February 19, 2016
A new tally proposes that roughly 700 quintillion terrestrial exoplanets are likely to exist across the observable universe—most vastly different from Earth. …that means that either we are the result of a very improbable lottery draw or we don’t understand how the lottery works.” None of the known 700 quintillion possible planets look like Earth.
The Criterion : The "Cosmic Limit" Law of Chance
To arrive at a statistical "proof," we need a reasonable criterion to judge it by :
As just a starting point, consider that many statisticians consider that any occurrence with a chance of happening that is less than one chance out of 10^50, is an occurrence with such a slim a probability that is, in general, statistically considered to be zero. (10^50 is the number 1 with 50 zeros after it, and it is spoken: "10 to the 50th power"). This appraisal seems fairly reasonable, when you consider that 10^50 is about the number of atoms which make up the planet earth. --So, overcoming one chance out of 10^50 is like marking one specific atom out of the earth, and mixing it in completely, and then someone makes one blind, random selection, which turns out to be that specific marked atom. Most mathematicians and scientists have accepted this statistical standard for many purposes.
Sustaining the quest for other potential life sites, planetary scientist David Stevenson and origin-of-life researchers Jeffrey Bada and Christopher Wills go so far as to speculate that life might not require a home near a star.38-39 They suggest this scenario: A planet may be ejected from a normal planetary system before losing any of its light gases. If so, the planet may retain enough surface warmth (from interior radioactive decay) and a sufficiently heavy molecular hydrogen outer atmosphere (a heat-trapping blanket) to sustain life chemistry and metabolism.
To be capable of life support, however, such a hypothetical site would require super-enrichment by radioactive elements, and no mechanism or scenario exists to bring this enrichment about—none that would accomplish the job without simultaneously destroying the molecular hydrogen outer atmosphere. If the planet somehow acquired this enrichment, it still faces a problem: heat from the radioactive decay would decline exponentially through time. So, while such a planet might serve as a brief stopover for primitive life, it could not stay within the life-support range of temperature and other conditions long enough to serve as any conceivable home for intelligent life.
I do not dispute that life as we know it would not exist if any one of several of the
constants of physics were just slightly different.
thank you so much to let that clear.
The assertion that God can be
seen by virtue of his acts of cosmological fine-tuning, like intelligent design and earlier versions of
the argument from design, is nothing more than another variation on the disreputable God-of-thegaps
argument.
That is simply not true. Quit the oposit is the case. We use the fine-tune argument, because we KNOW the fine-tune constants.
These rely on the faint hope that scientists will never be able to find a natural
explanation for one or more of the puzzles that currently have them scratching their heads and
therefore will have to insert God as the explanation.
https://reasonandscience.catsboard.com/t232-life-on-other-planets-a-real-possibility
Brian C. Lacki: THE LOG LOG PRIOR FOR THE FREQUENCY OF EXTRATERRESTRIAL INTELLIGENCES September 21, 2016
This log log prior can handle a very wide range of PETI values, from 1 to 1010^122 while remaining responsive to evidence about extraterrestrial societies.
https://arxiv.org/pdf/1609.05931.pdf
Richard Dawkins on scientific truth, outgrowing God and life beyond Earth
28 de ago. de 2019
It's not totally obvious that there have to be other living creatures around but if we are unique then what that means is that there's something very very very very special about the origin of life on this planet if we are the only one that's developed life then the origin of life would then have to be a quite stupendously improbable event so much so that we're wasting our time trying to understand it but I don't believe that as a matter of fact, I believe that there is probably quite a lot of life around the universe even if there's only say as few as a billion other life-forms and I stress that word few because a billion is a tiny tiny number compared to 10 to 22 if that were the case then the different life forms might be so widely spaced out that none of them ever encounters any of the others.
https://www.youtube.com/watch?v=RKjiSu4zD5Y&t=6s
Because life has emerged on earth is no indication that it occurred anywhere else too. The statistical probability that life exists within the universe is less than the number of planets in the universe. The reason for this, is that Earth combines an extremely improbable number of factors that are required to produce and sustain life, which adds up to such a small likelihood that it’s more than likely that we are all there is. Earth’s moon is one of the huge factors, which is 160 times larger than a natural satellite for a planet of Earth’s size; and it keeps Earth’s rotation stable, to keep the equator from becoming the North and South pole — this would certainly preclude intelligent life from emerging; and it also creates the tides, which are helpful to the formation of life.
Paul Davies, the fifth miracle page 53:
There are indeed a lot of stars—at least ten billion billion in the observable universe. But this number, gigantic as it may appear to us, is nevertheless trivially small compared with the gigantic odds against the random assembly of even a single protein molecule. Though the universe is big, if life formed solely by random agitation in a molecular junkyard, there is scant chance it has happened twice.
RTB Design Compendium (2009)
https://reasons.org/explore/publications/articles/rtb-design-compendium-2009
Hugh Ross Probability Estimates for the Features Required by Various Life Forms 2008
Less than 1 chance in 10^1032 exists that even one life-support planet would occur anywhere in the universe without invoking divine miracles.
https://d4bge0zxg5qba.cloudfront.net/files/compendium/compendium_Part3_ver2.pdf
Hugh Ross Fine-Tuning for Intelligent Physical Life 2008
402 quantifiable characteristics of a planetary system and its galaxy that must fall within narrow ranges to allow for the possibility of advanced life’s existence. This list includes comment on how a slight increase or decrease in the value of each characteristic would impact that possibility. That includes parameters of a planet, its planetary companions, its moon, its star, and its galaxy must have values falling within narrowly defined ranges for physical life of any kind to exist.2
https://d4bge0zxg5qba.cloudfront.net/files/compendium/compendium_part2.pdf
Hugh Ross: 922 characteristics of a galaxy and of a planetary system physical life depends on and offers conservative estimates of the probability that any galaxy or planetary system would manifest such characteristics. This list is divided into three parts, based on differing requirements for various life forms and their duration. 3 and 4
Hugh Ross Probability Estimates on Different Size Scales For the Features Required by Advanced Life 2008
Less than 1 chance in 10^390 exists that even one planet containing the necessary kinds of life would occur anywhere in the universe without invoking divine miracles.
https://d4bge0zxg5qba.cloudfront.net/files/compendium/compendium_Part4_ver2.pdf
Hugh Ross: Exotic Life Sites: The Feasibility of Far-Out Habitats 2001
The data demonstrate that the probability of finding even one planet with the capacity to support life falls short of one chance in 10^140 (that number is 1 followed by 140 zeros)
https://reasons.org/explore/publications/facts-for-faith/read/facts-for-faith/2001/10/01/exotic-life-sites-the-feasibility-of-far-out-habitats
Quantifying the origins of life on a planetary scale
https://www.pnas.org/content/113/29/8127?fbclid=IwAR2lMvRxj5uJ8aHf-2Y1mDewShMHMzriFX-h7mddxK3U3B9l0WJAqCsTdKg
Dissolving the Fermi Paradox
When we take account of realistic uncertainty, replacing point estimates by probability distributions that reflect current scientific understanding, we find no reason to be highly confident that the galaxy (or observable universe) contains other civilizations, and thus no longer find our observations in conflict with our prior probabilities. We found qualitatively similar results through two different methods: using the authors’ assessments of current scientific knowledge bearing on key parameters, and using the divergent estimates of these parameters in the astrobiology literature as a proxy for current scientific uncertainty. When we update this prior in light of the Fermi observation, we find a substantial probability that we are alone in our galaxy, and perhaps even in our observable universe (53%–99.6% and 39%–85% respectively). ’Where are they?’ — probably extremely far away, and quite possibly beyond the cosmological horizon and forever unreachable.
https://arxiv.org/pdf/1806.02404.pdf
http://worldview3.50webs.com/mathproofcreat.html
Earth really IS special: None of the 700 million trillion planets in our known universe are similar to our own, study finds
Ellie Zolfagharifard For Dailymail.com
20 February 2016
There are believed to be 700 million trillion terrestrial planets in the known universe. Scientists have long believed that among them are worlds similar to our own. This is known as the 'Copernican principle', which states that our planet doesn't hold a privileged position in the cosmos. Now, a new study has turned that principle on its head by suggesting that Earth may well be one of a kind.
Exoplanet Census Suggests Earth Is Special after All
February 19, 2016
A new tally proposes that roughly 700 quintillion terrestrial exoplanets are likely to exist across the observable universe—most vastly different from Earth. …that means that either we are the result of a very improbable lottery draw or we don’t understand how the lottery works.” None of the known 700 quintillion possible planets look like Earth.
The Criterion : The "Cosmic Limit" Law of Chance
To arrive at a statistical "proof," we need a reasonable criterion to judge it by :
As just a starting point, consider that many statisticians consider that any occurrence with a chance of happening that is less than one chance out of 10^50, is an occurrence with such a slim a probability that is, in general, statistically considered to be zero. (10^50 is the number 1 with 50 zeros after it, and it is spoken: "10 to the 50th power"). This appraisal seems fairly reasonable, when you consider that 10^50 is about the number of atoms which make up the planet earth. --So, overcoming one chance out of 10^50 is like marking one specific atom out of the earth, and mixing it in completely, and then someone makes one blind, random selection, which turns out to be that specific marked atom. Most mathematicians and scientists have accepted this statistical standard for many purposes.
Sustaining the quest for other potential life sites, planetary scientist David Stevenson and origin-of-life researchers Jeffrey Bada and Christopher Wills go so far as to speculate that life might not require a home near a star.38-39 They suggest this scenario: A planet may be ejected from a normal planetary system before losing any of its light gases. If so, the planet may retain enough surface warmth (from interior radioactive decay) and a sufficiently heavy molecular hydrogen outer atmosphere (a heat-trapping blanket) to sustain life chemistry and metabolism.
To be capable of life support, however, such a hypothetical site would require super-enrichment by radioactive elements, and no mechanism or scenario exists to bring this enrichment about—none that would accomplish the job without simultaneously destroying the molecular hydrogen outer atmosphere. If the planet somehow acquired this enrichment, it still faces a problem: heat from the radioactive decay would decline exponentially through time. So, while such a planet might serve as a brief stopover for primitive life, it could not stay within the life-support range of temperature and other conditions long enough to serve as any conceivable home for intelligent life.
I do not dispute that life as we know it would not exist if any one of several of the
constants of physics were just slightly different.
thank you so much to let that clear.
The assertion that God can be
seen by virtue of his acts of cosmological fine-tuning, like intelligent design and earlier versions of
the argument from design, is nothing more than another variation on the disreputable God-of-thegaps
argument.
That is simply not true. Quit the oposit is the case. We use the fine-tune argument, because we KNOW the fine-tune constants.
These rely on the faint hope that scientists will never be able to find a natural
explanation for one or more of the puzzles that currently have them scratching their heads and
therefore will have to insert God as the explanation.
People often joke about the certainty of death and taxes. Astronomers can add another certainty to that short list: Sooner or later someone will ask, “What do you think about the possibility of life out there?”
Most questioners are looking for a particular answer. Science fiction novels, The Planetary Society, and countless movies, from E.T. to Contact to Planet of the Apes, suggest that extraterrestrial life is a given and help conjure images of how that life looks. To answer questions about such life takes as much diplomacy as answering my wife when she asks, “How do I look?”
Experience suggests a strategy for handling both questions. Step one: Make a positive statement, such as “You look great!” or “That’s a great question!” Step two: Provide amplification. This part is trickier. It can make or break the interaction. If it lacks sincerity or includes the word but, (e.g., “You look great, but I thought you were going to wear the blue dress”), my wife may walk away feeling hurt and deflated. A better answer adds some specific feedback (e.g., “You look great, and I especially like the way that color goes with your eyes”).
In the case of the life-elsewhere question, an honest, fact-based amplification acknowledges the “great question” as opening the door to three fascinating topics: life on other planets, life on other astronomical bodies, and life other than “life as we know it.” Step-by-step discussion of these subjects can lead to opportunities for spiritually significant conversation.
LIFE ON OTHER PLANETS
Technology and interdisciplinary research have enabled scientists to develop an extensive list of physical characteristics that must fall within limited ranges for a planet (or any other astronomical body) to be capable of life support. Those characteristics involve the planet’s star, moon(s), planetary companions, and galaxy, as well as the planet’s surface, interior, and atmospheric conditions. This list grows longer with every year. It started with two parameters in 1966,1 grew to eight by 1970, to twenty-three by 1980, to thirty by 1990, and to forty by 1995.2 Currently, the list includes more than 120 parameters and shows no signs of leveling off.3
The limits on some characteristics, especially on the essential-to-life features of a planet’s star, have been determined precisely. The limits on others, mostly on the features of the planet itself, presumably a terrestrial (rocky) planet, are less precisely known. Two reasons exist for this difference: First, trillions of stars are available for study while only 76 planets (9 in Earth’s solar system, 67 outside) have been discovered to date. Second, physical and chemical characteristics make stars, basically condensed balls of hot gas, much simpler systems than planets.
No one knows, of course, exactly how many planets exist. As recently as 1990, astronomers were divided between those who proposed that planets whirl around nearly every star and those who posited that the Sun alone possesses planets. Three research advances tilt the debate toward the latter scenario: (1) the availability of instruments and techniques capable of detecting and studying planets orbiting other stars; (2) the discovery that most, if not all, stars surrounded by disks of dust are young or still forming; and (3) the development of sophisticated theoretical models that explain how dust disks become planets.
Each of the 67 extrasolar planets discovered and studied to date orbits a relatively young, metal-rich star (a star rich in elements heavier than hydrogen and helium).4-8 This finding presents no surprise. The heavy elements needed to make planets and any type of life chemistry do not exist in sufficient quantity until at least two generations of stars have formed, burned out, and scattered their ashes, which then recycle to form more stars. Astronomers have learned that the longer a galaxy sustains star formation, the more metal rich its newly forming stars will be. In the case of the galaxy astronomers know best, the Milky Way galaxy (Earth’s own), only 2 percent of the stars possess metal richness adequate for planet formation.9
Of those Milky Way stars known to have planets, none formed as early as the Sun. The Sun benefited from a remarkable set of circumstances: it formed adjacent to two massive, star explosions (supernovae), each of which spewed out a different set of life-essential heavy elements.10-12 Those explosions occurred precisely at the right time and place for those heavy elements to be incorporated into the condensing solar nebula. Earth’s star may be the only star its age with an ensemble of both small rocky planets and gas giants. This finding implies that the probable number of life-site candidates falls far below 2 percent.
As for life-support planets in other galaxies, the odds look bleak. Astronomers have found that the Milky Way is exceptional for the longevity of its star formation processes. In 94 of every 100 galaxies, star formation shut down so long ago that few, if any, metal-rich stars reside there—hence few, if any, planets. The results of a Hubble Space Telescope (HST) study recently confirmed this conclusion. The HST searched for planets in an enormous cluster of old stars, 47 Tucanae, and found none.13
Observations indicate that the number of stars with planets, any kind or size of planets, adds up to only about 0.1 percent of all the stars in the cosmos. That number is at least a hundred times smaller than the estimate that launched the search for signals from extraterrestrial life.14 Small though that percentage may be, however, it still adds up to a lot of planets. If, for example, each star in that 0.1-percent group has ten planets around it, the number of planets would add up to a hundred million trillion (that is, 1020).
A hundred million trillion, then, is the number to which the data on various life-essential features must be applied. Some features fall within loose limits—others, within strict limits. Limits on the planet’s rotation period and its albedo (reflectivity) eliminate about 90 percent of the life-site candidates. Parameters such as the parent star’s mass and the planet’s distance from its parent star eliminate about 99.9 percent of all relevant candidates.
Dependency factors among certain of the parameters improve the odds somewhat, but many of these parameters must be kept within a specific range for long periods of time. Given how variable environments can be, this longevity requirement proves extremely limiting. The data demonstrate that the probability of finding even one planet with the capacity to support life falls short of one chance in 10140 (that number is 1 followed by 140 zeros).15
LIFE ON ALTERNATIVE SITES
The extreme improbability such a number indicates has driven some scientists to abandon the premise that life requires an Earth-like home. A satellite (moon) orbiting a giant planet that in turn orbits a star resembling Earth’s sun at the right distance could serve, they say, as a life site.16-18 The feasibility of such an alternative can be tested against a long list of recent findings.
None of the 67 “gas giant” planets found thus far outside Earth’s solar system orbit their stars in the zone life requires. Gas giants, which are many times larger than Earth, form under cold, low radiation conditions far from their stars. By gravitational interactions with interplanetary dust or with other planets and stars that pass by, most gas giants drift into the proximity of their stars. This drifting process drastically decreases their likelihood of retaining the nearly circular, stable orbit life demands.19-24 Of the known extrasolar gas giants, only two orbit anywhere near the life-habitable zone, and these two follow such an eccentric (i.e., elongated) orbital path as to make life on their satellites (moons), if they have any, impossible.25-28 The question remains unanswered as to whether or not giant planets can possibly retain the satellites during migration.
A satellite close enough to its planet to avoid enormous seasonal temperature fluctuations (caused by variations in the distance to the planet’s star, or heat source, as the satellite orbits its planet) becomes tidally locked to the planet—the same side always faces the planet. This tidal locking itself causes a host of life-destructive effects.
For example, tidal locking makes the satellite’s rotation period identical to the planet’s. Unless that period is short enough, day-to-night temperature differences become too extreme for life’s survival. However, the rotation period can only be that short if the satellite orbits closely. Within this sufficiently close range, however, another set of problems arises. For example, tidal forces generate drastic climatic and orbital instabilities (tidal torques force such a satellite to move farther and farther away from its planet), as well as massive and frequent volcanic eruptions (such as astronomers see on Jupiter’s moon Io).29 Any possible life-favorable conditions last briefly, at best.
A satellite with a highly improbable life-sustaining atmosphere most likely loses it in short order unless that satellite somehow possesses a strong magnetic field (similar to that of the Sun, Jupiter, and Earth). Otherwise, charged particles accelerated by the planet’s magnetosphere sputter away the satellite’s atmosphere. The magnetic field around Ganymede, the largest known planetary satellite and the only one with undisputed magnetism, measures less than 1 percent the strength of Earth’s.30-32
Another life risk for a satellite closely orbiting a large planet is that such a planet’s gravity significantly attracts asteroids, comets, and other debris passing nearby. This attraction increases the likelihood of bombardment, and such bombardment proves catastrophic to any possible life on the satellite.
A satellite cannot retain an adequate atmosphere for life unless its mass exceeds 12 percent of Earth’s mass. 33 At the same time, the satellite needs a mechanism to compensate for its nearby star’s increasing luminosity (brightness, thus light and heat radiation) as the star ages. The only known mechanism is the one seen on Earth, called the carbonate-silicate cycle. This cycle cannot operate, however, without lots of dry land (which eliminates ice-water environments such as Jupiter’s satellite Europa) and without a high level of plate tectonic activity.34, 35
Plate tectonics, in turn, require a certain minimum mass (0.23 Earth masses), and the demands of sustaining a carbonate-silicate cycle significantly increases that minimum. The best calculation to date sets the minimum mass of this hypothetical satellite at three times the mass of Mars, which is more than twelve times the mass of the solar system’s largest satellite. Of course plate tectonics also demand lots of liquid water (thus eliminating all dry satellites) and the precisely-timed introduction of just-right plant life in just-right amounts throughout the satellite’s history.36-37
MORE RADICAL PROPOSALS
Sustaining the quest for other potential life sites, planetary scientist David Stevenson and origin-of-life researchers Jeffrey Bada and Christopher Wills go so far as to speculate that life might not require a home near a star.38-39 They suggest this scenario: A planet may be ejected from a normal planetary system before losing any of its light gases. If so, the planet may retain enough surface warmth (from interior radioactive decay) and a sufficiently heavy molecular hydrogen outer atmosphere (a heat-trapping blanket) to sustain life chemistry and metabolism.
To be capable of life support, however, such a hypothetical site would require super-enrichment by radioactive elements, and no mechanism or scenario exists to bring this enrichment about—none that would accomplish the job without simultaneously destroying the molecular hydrogen outer atmosphere. If the planet somehow acquired this enrichment, it still faces a problem: heat from the radioactive decay would decline exponentially through time. So, while such a planet might serve as a brief stopover for primitive life, it could not stay within the life-support range of temperature and other conditions long enough to serve as any conceivable home for intelligent life.
If life claims a home anywhere in the vast cosmos, it must be on a planet like Earth orbiting a star like the Sun in a galaxy like the Milky Way. And, as ongoing studies shows, that possibility shrinks, rather than grows, as each year’s research adds to the harvest of data. Extraterrestrial life does indeed appear to be homeless—unless, of course, a transcendent, supernatural Being built that home. But that possibility points toward, rather than away from, belief in the biblical Creator.
ALTERNATIVE LIFE FORMS
One other possibility must still be addressed, a question that often hampers progress toward a realistic assessment of the chance for life elsewhere: To what degree might extraterrestrial life differ from “life as we know it”? At one time biologists speculated that extraterrestrial life might be based on exotic chemistry, something other than carbon.
So, biochemists went to work on the problem. Their research showed that only silicon and boron, besides carbon, can serve as the basis for adequately complex molecules—molecules capable of sustaining basic life functions, such as self-replication, metabolism, and information storage. This finding presents some significant problems, however. First, silicon can hold together a string of no more than a hundred amino acids—far too short a string to accommodate any conceivable life systems and processes. Second, throughout the universe boron is less abundant than carbon; so carbon always supersedes it. Third, concentrated boron is toxic to certain life-critical reactions.
The conclusion, published as early as 1961, still stands. Physicist Robert Dicke deduced at that time that if anyone wants physicists (or any other physical life forms, for that matter), carbon-based biochemistry is a must.40 The key word, here, is physical. What about life that is not physical?
THE SPIRITUAL OPPORTUNITY
Both science and the Bible offer helpful information on this topic of non-physical reality. Science points to the existence of a transcendent (beyond space and time), personal Creator, demonstrably the same Creator revealed in the pages of Scripture. The Bible, in turn, reveals the existence of life forms other than Earth life, other than physical life. This life may be described as spiritual life, and yet it possesses the capacity for at least some physical expression or manifestation.
The Bible calls these creatures (in English translations) “angels,” “ministering servants,” or “ministering spirits.” Three specific names are given in the text: Michael, Gabriel, and Lucifer. The latter, also called Satan, led a rebellion against God. Scripture refers to the angels who rebelled with him (about a third of the total number) as “evil spirits,” “devils,” or “demons.” The one reliable source of information about this other kind of life is the Bible, and further study is highly recommended.
The possibility for life elsewhere is in fact great, as great as the certainty that the Bible is a true, trustworthy, and relevant revelation from the Creator. Any question that leads to an opportunity to talk about the word of God as well as the work of God, the Creator, deserves to be called a great question.
Most questioners are looking for a particular answer. Science fiction novels, The Planetary Society, and countless movies, from E.T. to Contact to Planet of the Apes, suggest that extraterrestrial life is a given and help conjure images of how that life looks. To answer questions about such life takes as much diplomacy as answering my wife when she asks, “How do I look?”
Experience suggests a strategy for handling both questions. Step one: Make a positive statement, such as “You look great!” or “That’s a great question!” Step two: Provide amplification. This part is trickier. It can make or break the interaction. If it lacks sincerity or includes the word but, (e.g., “You look great, but I thought you were going to wear the blue dress”), my wife may walk away feeling hurt and deflated. A better answer adds some specific feedback (e.g., “You look great, and I especially like the way that color goes with your eyes”).
In the case of the life-elsewhere question, an honest, fact-based amplification acknowledges the “great question” as opening the door to three fascinating topics: life on other planets, life on other astronomical bodies, and life other than “life as we know it.” Step-by-step discussion of these subjects can lead to opportunities for spiritually significant conversation.
LIFE ON OTHER PLANETS
Technology and interdisciplinary research have enabled scientists to develop an extensive list of physical characteristics that must fall within limited ranges for a planet (or any other astronomical body) to be capable of life support. Those characteristics involve the planet’s star, moon(s), planetary companions, and galaxy, as well as the planet’s surface, interior, and atmospheric conditions. This list grows longer with every year. It started with two parameters in 1966,1 grew to eight by 1970, to twenty-three by 1980, to thirty by 1990, and to forty by 1995.2 Currently, the list includes more than 120 parameters and shows no signs of leveling off.3
The limits on some characteristics, especially on the essential-to-life features of a planet’s star, have been determined precisely. The limits on others, mostly on the features of the planet itself, presumably a terrestrial (rocky) planet, are less precisely known. Two reasons exist for this difference: First, trillions of stars are available for study while only 76 planets (9 in Earth’s solar system, 67 outside) have been discovered to date. Second, physical and chemical characteristics make stars, basically condensed balls of hot gas, much simpler systems than planets.
No one knows, of course, exactly how many planets exist. As recently as 1990, astronomers were divided between those who proposed that planets whirl around nearly every star and those who posited that the Sun alone possesses planets. Three research advances tilt the debate toward the latter scenario: (1) the availability of instruments and techniques capable of detecting and studying planets orbiting other stars; (2) the discovery that most, if not all, stars surrounded by disks of dust are young or still forming; and (3) the development of sophisticated theoretical models that explain how dust disks become planets.
Each of the 67 extrasolar planets discovered and studied to date orbits a relatively young, metal-rich star (a star rich in elements heavier than hydrogen and helium).4-8 This finding presents no surprise. The heavy elements needed to make planets and any type of life chemistry do not exist in sufficient quantity until at least two generations of stars have formed, burned out, and scattered their ashes, which then recycle to form more stars. Astronomers have learned that the longer a galaxy sustains star formation, the more metal rich its newly forming stars will be. In the case of the galaxy astronomers know best, the Milky Way galaxy (Earth’s own), only 2 percent of the stars possess metal richness adequate for planet formation.9
Of those Milky Way stars known to have planets, none formed as early as the Sun. The Sun benefited from a remarkable set of circumstances: it formed adjacent to two massive, star explosions (supernovae), each of which spewed out a different set of life-essential heavy elements.10-12 Those explosions occurred precisely at the right time and place for those heavy elements to be incorporated into the condensing solar nebula. Earth’s star may be the only star its age with an ensemble of both small rocky planets and gas giants. This finding implies that the probable number of life-site candidates falls far below 2 percent.
As for life-support planets in other galaxies, the odds look bleak. Astronomers have found that the Milky Way is exceptional for the longevity of its star formation processes. In 94 of every 100 galaxies, star formation shut down so long ago that few, if any, metal-rich stars reside there—hence few, if any, planets. The results of a Hubble Space Telescope (HST) study recently confirmed this conclusion. The HST searched for planets in an enormous cluster of old stars, 47 Tucanae, and found none.13
Observations indicate that the number of stars with planets, any kind or size of planets, adds up to only about 0.1 percent of all the stars in the cosmos. That number is at least a hundred times smaller than the estimate that launched the search for signals from extraterrestrial life.14 Small though that percentage may be, however, it still adds up to a lot of planets. If, for example, each star in that 0.1-percent group has ten planets around it, the number of planets would add up to a hundred million trillion (that is, 1020).
A hundred million trillion, then, is the number to which the data on various life-essential features must be applied. Some features fall within loose limits—others, within strict limits. Limits on the planet’s rotation period and its albedo (reflectivity) eliminate about 90 percent of the life-site candidates. Parameters such as the parent star’s mass and the planet’s distance from its parent star eliminate about 99.9 percent of all relevant candidates.
Dependency factors among certain of the parameters improve the odds somewhat, but many of these parameters must be kept within a specific range for long periods of time. Given how variable environments can be, this longevity requirement proves extremely limiting. The data demonstrate that the probability of finding even one planet with the capacity to support life falls short of one chance in 10140 (that number is 1 followed by 140 zeros).15
LIFE ON ALTERNATIVE SITES
The extreme improbability such a number indicates has driven some scientists to abandon the premise that life requires an Earth-like home. A satellite (moon) orbiting a giant planet that in turn orbits a star resembling Earth’s sun at the right distance could serve, they say, as a life site.16-18 The feasibility of such an alternative can be tested against a long list of recent findings.
None of the 67 “gas giant” planets found thus far outside Earth’s solar system orbit their stars in the zone life requires. Gas giants, which are many times larger than Earth, form under cold, low radiation conditions far from their stars. By gravitational interactions with interplanetary dust or with other planets and stars that pass by, most gas giants drift into the proximity of their stars. This drifting process drastically decreases their likelihood of retaining the nearly circular, stable orbit life demands.19-24 Of the known extrasolar gas giants, only two orbit anywhere near the life-habitable zone, and these two follow such an eccentric (i.e., elongated) orbital path as to make life on their satellites (moons), if they have any, impossible.25-28 The question remains unanswered as to whether or not giant planets can possibly retain the satellites during migration.
A satellite close enough to its planet to avoid enormous seasonal temperature fluctuations (caused by variations in the distance to the planet’s star, or heat source, as the satellite orbits its planet) becomes tidally locked to the planet—the same side always faces the planet. This tidal locking itself causes a host of life-destructive effects.
For example, tidal locking makes the satellite’s rotation period identical to the planet’s. Unless that period is short enough, day-to-night temperature differences become too extreme for life’s survival. However, the rotation period can only be that short if the satellite orbits closely. Within this sufficiently close range, however, another set of problems arises. For example, tidal forces generate drastic climatic and orbital instabilities (tidal torques force such a satellite to move farther and farther away from its planet), as well as massive and frequent volcanic eruptions (such as astronomers see on Jupiter’s moon Io).29 Any possible life-favorable conditions last briefly, at best.
A satellite with a highly improbable life-sustaining atmosphere most likely loses it in short order unless that satellite somehow possesses a strong magnetic field (similar to that of the Sun, Jupiter, and Earth). Otherwise, charged particles accelerated by the planet’s magnetosphere sputter away the satellite’s atmosphere. The magnetic field around Ganymede, the largest known planetary satellite and the only one with undisputed magnetism, measures less than 1 percent the strength of Earth’s.30-32
Another life risk for a satellite closely orbiting a large planet is that such a planet’s gravity significantly attracts asteroids, comets, and other debris passing nearby. This attraction increases the likelihood of bombardment, and such bombardment proves catastrophic to any possible life on the satellite.
A satellite cannot retain an adequate atmosphere for life unless its mass exceeds 12 percent of Earth’s mass. 33 At the same time, the satellite needs a mechanism to compensate for its nearby star’s increasing luminosity (brightness, thus light and heat radiation) as the star ages. The only known mechanism is the one seen on Earth, called the carbonate-silicate cycle. This cycle cannot operate, however, without lots of dry land (which eliminates ice-water environments such as Jupiter’s satellite Europa) and without a high level of plate tectonic activity.34, 35
Plate tectonics, in turn, require a certain minimum mass (0.23 Earth masses), and the demands of sustaining a carbonate-silicate cycle significantly increases that minimum. The best calculation to date sets the minimum mass of this hypothetical satellite at three times the mass of Mars, which is more than twelve times the mass of the solar system’s largest satellite. Of course plate tectonics also demand lots of liquid water (thus eliminating all dry satellites) and the precisely-timed introduction of just-right plant life in just-right amounts throughout the satellite’s history.36-37
MORE RADICAL PROPOSALS
Sustaining the quest for other potential life sites, planetary scientist David Stevenson and origin-of-life researchers Jeffrey Bada and Christopher Wills go so far as to speculate that life might not require a home near a star.38-39 They suggest this scenario: A planet may be ejected from a normal planetary system before losing any of its light gases. If so, the planet may retain enough surface warmth (from interior radioactive decay) and a sufficiently heavy molecular hydrogen outer atmosphere (a heat-trapping blanket) to sustain life chemistry and metabolism.
To be capable of life support, however, such a hypothetical site would require super-enrichment by radioactive elements, and no mechanism or scenario exists to bring this enrichment about—none that would accomplish the job without simultaneously destroying the molecular hydrogen outer atmosphere. If the planet somehow acquired this enrichment, it still faces a problem: heat from the radioactive decay would decline exponentially through time. So, while such a planet might serve as a brief stopover for primitive life, it could not stay within the life-support range of temperature and other conditions long enough to serve as any conceivable home for intelligent life.
If life claims a home anywhere in the vast cosmos, it must be on a planet like Earth orbiting a star like the Sun in a galaxy like the Milky Way. And, as ongoing studies shows, that possibility shrinks, rather than grows, as each year’s research adds to the harvest of data. Extraterrestrial life does indeed appear to be homeless—unless, of course, a transcendent, supernatural Being built that home. But that possibility points toward, rather than away from, belief in the biblical Creator.
ALTERNATIVE LIFE FORMS
One other possibility must still be addressed, a question that often hampers progress toward a realistic assessment of the chance for life elsewhere: To what degree might extraterrestrial life differ from “life as we know it”? At one time biologists speculated that extraterrestrial life might be based on exotic chemistry, something other than carbon.
So, biochemists went to work on the problem. Their research showed that only silicon and boron, besides carbon, can serve as the basis for adequately complex molecules—molecules capable of sustaining basic life functions, such as self-replication, metabolism, and information storage. This finding presents some significant problems, however. First, silicon can hold together a string of no more than a hundred amino acids—far too short a string to accommodate any conceivable life systems and processes. Second, throughout the universe boron is less abundant than carbon; so carbon always supersedes it. Third, concentrated boron is toxic to certain life-critical reactions.
The conclusion, published as early as 1961, still stands. Physicist Robert Dicke deduced at that time that if anyone wants physicists (or any other physical life forms, for that matter), carbon-based biochemistry is a must.40 The key word, here, is physical. What about life that is not physical?
THE SPIRITUAL OPPORTUNITY
Both science and the Bible offer helpful information on this topic of non-physical reality. Science points to the existence of a transcendent (beyond space and time), personal Creator, demonstrably the same Creator revealed in the pages of Scripture. The Bible, in turn, reveals the existence of life forms other than Earth life, other than physical life. This life may be described as spiritual life, and yet it possesses the capacity for at least some physical expression or manifestation.
The Bible calls these creatures (in English translations) “angels,” “ministering servants,” or “ministering spirits.” Three specific names are given in the text: Michael, Gabriel, and Lucifer. The latter, also called Satan, led a rebellion against God. Scripture refers to the angels who rebelled with him (about a third of the total number) as “evil spirits,” “devils,” or “demons.” The one reliable source of information about this other kind of life is the Bible, and further study is highly recommended.
The possibility for life elsewhere is in fact great, as great as the certainty that the Bible is a true, trustworthy, and relevant revelation from the Creator. Any question that leads to an opportunity to talk about the word of God as well as the work of God, the Creator, deserves to be called a great question.
Last edited by Otangelo on Sat May 25, 2024 7:26 am; edited 28 times in total