This article points out the importance of the anthropic principles as it relates to earth. All the ingredients necessary for life are present on Titan, but the environment and mix is not right, nor is there a unique self-renewing source of water, making life impossible.
We also have to believe that life was created, and did not spring into existence from inanimate elements, because Titan, with all the ingredients and just as old as the rest of the solar system, still does not have life. If abiogenesis was a seasily explained as some would have us believe, why did it not happen on Titan?
A
Experts scratch heads over methane on Titan
January 27 2005 at 02:12PM
By Melissa Eddy
Frankfurt, Germany - Saturn's largest moon contains all the ingredients for life, but senior scientists studying data from a European probe on Wednesday ruled out the possibility that Titan's abundant methane stems from living organisms.
Weeks after the Huygens probe plunged through Titan's atmosphere, researchers continue to pore over data collected for clues to how the only celestial body known to have a significant atmosphere other than Earth came to be and whether it can provide clues to how life arose here.
Initial findings have revealed an abundance of methane on the surface of Titan - the first moon other than Earth's to be explored - which is crucial to supporting its thick atmosphere. But scientists are still puzzling over the origin of the methane.
"This methane cannot be coming from living organisms," Jean-Pierre Lebreton, mission manager for the Huygens probe that landed on the surface of Titan January 14, said.
Images snapped by the 340kg probe as it parachuted through Titan's atmosphere from the Cassini orbiter show the moon's surface was cut by a weather system leaving deep river beds and large reservoirs, implying activity by liquid methane.
But unlike water in the Earth's atmosphere that continually renews itself, methane is destroyed by ultraviolet light, so Titan must have a source deep inside, scientists said.
Based on data collected by Huygens' instruments, Sushil Atreya, a professor of planetary science at the University of Michigan in the United States, believes a hydro-geological process between water and rocks deep inside the moon could be producing the methane.
"I think the process is quite likely in the interior of Titan," Atreya said in a telephone interview.
The process is called serpentinisation and is basically the reaction between water and rocks at 100°C to 400°C, he said.
While these discoveries are breaking new ground - scientists have been surprised by the amount of data they were able to collect from Titan's surface during the mission - researchers are far from helping to explain how life may have formed during Earth's earliest years.
Titan has the ingredients for living organisms, including nitrogen, methane and water, but not in the right combinations. Far more information is needed to glean any insights into activity on young Earth, Atreya said.
"Just looking at the data we have now, I think it's a long shot," Atreya said.
Huygens was spun off from the Cassini mother ship on December 24. The €2,4-billion (about R20-billion) Cassini-Huygens mission to explore Saturn and its moons was launched in 1997 from Cape Canaveral, Florida - a joint effort between Nasa, the European Space Agency, and the Italian space agency.
Abiogenesis not explained from Titan
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Anonymous
Maybe too cold?If abiogenesis was a seasily explained as some would have us believe, why did it not happen on Titan?
It seems reasonable the actual probability for abiogenesis is a function of enviromental temperature.
Too cold => less reactions => more time needed
Too hot => too many reaction => too easy to destroy
Said that, who says that there is no life on titan?
All we know is that we didn't find carbon based evoluted lifeforms
(as expected).
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August
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Hi I,
The problem with non-carbon based life is again that it is virtually impossible for non-carbon elements to stick together in sufficient quantities to lead to life. Carbon right now seems to be the only element with the ability to form large molecules that can contain the information needed to create and sustain life. You also need water, in fact, just the combination of water and carbon contains at least six unique properties that make life possible from only those elements.
Furthermore, humans need 28, and bacteria 16, different elements in just the right proportions to live. There is no mention in the article if all of those elements are present on Titan, although it does state all the elements for life was there, and it is just that conditions were not right. Unclear at best, since we don't know what exact elements were present.
Maybe we will some day discover a life form based on another element, but from chemistry it seems rather unlikely.
The problem with non-carbon based life is again that it is virtually impossible for non-carbon elements to stick together in sufficient quantities to lead to life. Carbon right now seems to be the only element with the ability to form large molecules that can contain the information needed to create and sustain life. You also need water, in fact, just the combination of water and carbon contains at least six unique properties that make life possible from only those elements.
Furthermore, humans need 28, and bacteria 16, different elements in just the right proportions to live. There is no mention in the article if all of those elements are present on Titan, although it does state all the elements for life was there, and it is just that conditions were not right. Unclear at best, since we don't know what exact elements were present.
Maybe we will some day discover a life form based on another element, but from chemistry it seems rather unlikely.
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Mastermind
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Anonymous
all you arguments are based on a strict definition of life which is inspired by our limited knowledge of what is going on on Earth.
Life is an adaptative system and may develop in quite different situations in quite a different ways interacting and changing the enviroment in which it develop. EG on earth basically all complex carbon compounds you can find around wouldn't be there without life.
We don't even have a good definition for life!
Carbon is somehow preferred? Well for sure it was on Earth. Silicon has more or less the same ability of producing complex moleculae.
eg http://www.aist.go.jp/NIMC/publication/ ... /10_9.html
Can you prove that carbon is preferred in any environmental conditions?
No you cannot, just because you cannot clearly define wrt what it should be preferred.
BTW
http://wiki.cotch.net/index.php/Life
Life is an adaptative system and may develop in quite different situations in quite a different ways interacting and changing the enviroment in which it develop. EG on earth basically all complex carbon compounds you can find around wouldn't be there without life.
We don't even have a good definition for life!
Carbon is somehow preferred? Well for sure it was on Earth. Silicon has more or less the same ability of producing complex moleculae.
eg http://www.aist.go.jp/NIMC/publication/ ... /10_9.html
Can you prove that carbon is preferred in any environmental conditions?
No you cannot, just because you cannot clearly define wrt what it should be preferred.
BTW
http://wiki.cotch.net/index.php/Life
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Anonymous
Bacteria ADAPTS to live at high temperature.And by the way, I don't think temperature is that much of a factor. We have bacteria forming in extremely hot temperatures
Not for that it is relevant for abiogenesis.
Until we know which mechanisms can be behind it
we cannot have the slightest grasp on how these mechanisms depend
on the temperature.
Anyone familiar with chemestry knows that at different temperatures different reactions may be preferred staring with the same initial conditions. Biochemestry is not an exception.
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Kurieuo
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Kurieuo: Split robots becoming self-aware talk into a new thread at http://discussions.godandscience.org/vi ... php?p=3476
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August
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Yes, my arguments are based on carbon life forms. If you noticed in my earlier post I said as much. Somehow I don't believe we are alone in this universe, however, from a strictly scientific point of view, there is no empirical evidence to prove otherwise. On a philosophical level, I agree with you.all you arguments are based on a strict definition of life which is inspired by our limited knowledge of what is going on on Earth.
Life is an adaptative system and may develop in quite different situations in quite a different ways interacting and changing the enviroment in which it develop. EG on earth basically all complex carbon compounds you can find around wouldn't be there without life.
We don't even have a good definition for life!
More later.
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August
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"All life on Earth is built upon carbon and carbon-based compounds. Yet the possibility has been discussed that life elsewhere may have a different chemical foundation. In 1891, Julius Scheiner became perhaps the first to speculate on the suitability of silicon as a basis for life. This idea was taken up by James Emerson Reynolds who, in 1893, in his opening address to the British Association for the Advancement of Science,1 pointed out that the heat stability of silicon compounds might allow life to exist at very high temperatures (see thermophiles). In an 1894 article,2 drawing on Reynolds's ideas and also those of Robert Ball,3 H. G. Wells wrote:
One is startled towards fantastic imaginings by such a suggestion: visions of silicon-aluminium organisms - why not silicon-aluminium men at once? - wandering through an atmosphere of gaseous sulphur, let us say, by the shores of a sea of liquid iron some thousand degrees or so above the temperature of a blast furnace.
Thirty years later, J. B. S. Haldane suggested that life might be found deep inside a planet based on partly molten silicates, the oxidation of iron perhaps providing it with energy.
At first sight, silicon does seem a promising organic alternative to carbon. It is common in the universe and lies directly below carbon in the periodic table of elements, so that much of its basic chemistry is similar. For instance, just as carbon combines with four hydrogen atoms to form methane, CH4, silicon yields silane, SiH4. Silicates are analogues of carbonates, silicon chloroform of chloroform, and so on. Both elements form long chains, or polymers, in which they alternate with oxygen. In the simplest case, carbon-oxygen chains yield poly-acetal, a plastic used in synthetic fibers, while from a backbone of alternating atoms of silicon and oxygen come polymeric silicones.
Conceivably, some strange life-forms might be built from silicone-like substances were it not for an apparently fatal flaw in silicon's biological credentials. This is its powerful affinity for oxygen. When carbon is oxidized during the respiratory process of a terrestrial organism (see respiration), it becomes the gas carbon dioxide-a waste material that is easy for a creature to remove from its body. The oxidation of silicon, however, yields a solid because, immediately upon formation, silicon dioxide organizes itself into a lattice in which each silicon atom is surrounded by four oxygens. Disposing of such a substance would pose a major respiratory challenge.
Life-forms must also be able to collect, store, and utilize energy from their environment. In carbon-based biota, the basic energy storage compounds are carbohydrates in which the carbon atoms are linked by single bonds into a chain. A carbohydrate is oxidized to release energy (and the waste products water and carbon dioxide) in a series of controlled steps using enzymes. These enzymes are large, complex molecules (see proteins) which catalyze specific reactions because of their shape and "handedness." A feature of carbon chemistry is that many of its compounds can take right and left forms, and it is this handedness, or chirality, that gives enzymes their ability to recognize and regulate a huge variety of processes in the body. Silicon's failure to give rise to many compounds that display handedness makes it hard to see how it could serve as the basis for the many interconnected chains of reactions needed to support life.
The absence of silicon-based biology, or even silicon-based prebiotic chemicals, is also suggested by astronomical evidence. Wherever astronomers have looked - in meteorites, in comets, in the atmospheres of the giant planets, in the interstellar medium, and in the outer layers of cool stars - they have found molecules of oxidized silicon (silicon dioxide and silicates) but no substances such as silanes or silicones which might be the precursors of a silicon biochemistry."
David Darling - PhD Astronomy, Manchester University
Also: http://nai.arc.nasa.gov/astrobio/feat_q ... n_life.cfm
From Wikipedia
"Silicon-based life is regarded as improbable by most scientists. Superficially, the chemistries of carbon and silicon are similar; just as carbon can form methane (CH4), silicon can form silane (SiH4), and both elements can form long chains of polymers.
But silicon's affinity for oxygen means that it cannot easily be used for respiration. Whereas CO2 is a gas that can easily be removed from the organism, SiO2 is a solid that will instantly organize itself into lattices, making it hard to dispose of. On top of that, silicon fails to give rise to many compounds that exhibit chirality, which is a common feature of carbon-based molecules that are essential to the proper functioning of enzymes.
There is also astronomical evidence to suggest that silicon-based life is unlikely. Wherever astronomers have looked, they have failed to find the simplest precursors to silicon-based biochemistry. Complex carbon-based compounds are abundant in space, but in the case of silicon, most of what we have observed in space are simple oxides of silicon, with no record of more complex molecules such as silanes and silicones."
And: http://www.newton.dep.anl.gov/askasci/g ... n99709.htm
I know that silicon has been mentioned as an alternative. I like to be a little more eclectic here, and suggest that we have not yet discovered all elements in the universe, so there may very well be one with suitable characteristics to support life.
One is startled towards fantastic imaginings by such a suggestion: visions of silicon-aluminium organisms - why not silicon-aluminium men at once? - wandering through an atmosphere of gaseous sulphur, let us say, by the shores of a sea of liquid iron some thousand degrees or so above the temperature of a blast furnace.
Thirty years later, J. B. S. Haldane suggested that life might be found deep inside a planet based on partly molten silicates, the oxidation of iron perhaps providing it with energy.
At first sight, silicon does seem a promising organic alternative to carbon. It is common in the universe and lies directly below carbon in the periodic table of elements, so that much of its basic chemistry is similar. For instance, just as carbon combines with four hydrogen atoms to form methane, CH4, silicon yields silane, SiH4. Silicates are analogues of carbonates, silicon chloroform of chloroform, and so on. Both elements form long chains, or polymers, in which they alternate with oxygen. In the simplest case, carbon-oxygen chains yield poly-acetal, a plastic used in synthetic fibers, while from a backbone of alternating atoms of silicon and oxygen come polymeric silicones.
Conceivably, some strange life-forms might be built from silicone-like substances were it not for an apparently fatal flaw in silicon's biological credentials. This is its powerful affinity for oxygen. When carbon is oxidized during the respiratory process of a terrestrial organism (see respiration), it becomes the gas carbon dioxide-a waste material that is easy for a creature to remove from its body. The oxidation of silicon, however, yields a solid because, immediately upon formation, silicon dioxide organizes itself into a lattice in which each silicon atom is surrounded by four oxygens. Disposing of such a substance would pose a major respiratory challenge.
Life-forms must also be able to collect, store, and utilize energy from their environment. In carbon-based biota, the basic energy storage compounds are carbohydrates in which the carbon atoms are linked by single bonds into a chain. A carbohydrate is oxidized to release energy (and the waste products water and carbon dioxide) in a series of controlled steps using enzymes. These enzymes are large, complex molecules (see proteins) which catalyze specific reactions because of their shape and "handedness." A feature of carbon chemistry is that many of its compounds can take right and left forms, and it is this handedness, or chirality, that gives enzymes their ability to recognize and regulate a huge variety of processes in the body. Silicon's failure to give rise to many compounds that display handedness makes it hard to see how it could serve as the basis for the many interconnected chains of reactions needed to support life.
The absence of silicon-based biology, or even silicon-based prebiotic chemicals, is also suggested by astronomical evidence. Wherever astronomers have looked - in meteorites, in comets, in the atmospheres of the giant planets, in the interstellar medium, and in the outer layers of cool stars - they have found molecules of oxidized silicon (silicon dioxide and silicates) but no substances such as silanes or silicones which might be the precursors of a silicon biochemistry."
David Darling - PhD Astronomy, Manchester University
Also: http://nai.arc.nasa.gov/astrobio/feat_q ... n_life.cfm
From Wikipedia
"Silicon-based life is regarded as improbable by most scientists. Superficially, the chemistries of carbon and silicon are similar; just as carbon can form methane (CH4), silicon can form silane (SiH4), and both elements can form long chains of polymers.
But silicon's affinity for oxygen means that it cannot easily be used for respiration. Whereas CO2 is a gas that can easily be removed from the organism, SiO2 is a solid that will instantly organize itself into lattices, making it hard to dispose of. On top of that, silicon fails to give rise to many compounds that exhibit chirality, which is a common feature of carbon-based molecules that are essential to the proper functioning of enzymes.
There is also astronomical evidence to suggest that silicon-based life is unlikely. Wherever astronomers have looked, they have failed to find the simplest precursors to silicon-based biochemistry. Complex carbon-based compounds are abundant in space, but in the case of silicon, most of what we have observed in space are simple oxides of silicon, with no record of more complex molecules such as silanes and silicones."
And: http://www.newton.dep.anl.gov/askasci/g ... n99709.htm
I know that silicon has been mentioned as an alternative. I like to be a little more eclectic here, and suggest that we have not yet discovered all elements in the universe, so there may very well be one with suitable characteristics to support life.
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Anonymous
ok. I don't have scentific evidence pro or against myself.Yes, my arguments are based on carbon life forms. If you noticed in my earlier post I said as much. Somehow I don't believe we are alone in this universe, however, from a strictly scientific point of view, there is no empirical evidence to prove otherwise. On a philosophical level, I agree with you.
Of course we know all basic elements unless you believe you can have lifefroms based on Polonium.I know that silicon has been mentioned as an alternative. I like to be a little more eclectic here, and suggest that we have not yet discovered all elements in the universe, so there may very well be one with suitable characteristics to support life.
Silicon based life-forms have been suggested as a early stage of life on Earth. There are silicon peptides able to reproduce themseves as DNA moleculae, which could be a step towards life in a yet unknown process of abiogenesis.
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Mastermind
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