thesis
Faith, chemistry and extraterrestrial life NASA/JPL-CALTECH/MALIN SPACE SCIENCE SYSTEMS
Bruce Gibb wonders whether our faith in chemistry — and what it can teach us about the Universe beyond our Earthly bounds — will have a role to play in the search for alien life.
Scientists and religious leaders have argued about the importance of, and relationship between, science and religion since time immemorial. Against this backdrop, both science and religion have changed as the body of human knowledge has increased. For example, thanks to the likes of Nicolaus Copernicus most religions no longer accept the Ptolemaic model of the cosmos in which Earth is the centre of the Universe (although between 10–20% of people polled in the US do believe this1), and courtesy of Albert Einstein, our scientific view of the Universe has changed considerably since the days of Isaac Newton. What drives these changes? In science, of course, it is the perpetual feedback cycle between new thoughts and new technologies. New thoughts lead to new abstractions (models) that allow us to define and build new technologies that lead to new thoughts and abstractions… And over time these abstractions become accepted scientific knowledge; consider for example the simple atomistic view of matter put forth by the Greeks and how our understanding of the structure of the atom fits into the current bedrock of knowledge. (I’ll leave the thought of how an abstraction transforms into bedrock knowledge to the epistemologically inclined readers.) Some of the new abstractions rub off onto religion, which in turn contributes to the slower — but analogous — change that it experiences. Correspondingly of course, these changes to scientific and religious
understanding open up new areas in which scientists and theologians can engage with one another; it was the case when Eratosthenes used maps and gnomons to demonstrate that Earth was round rather than flat, and it is the case today with the likes of the Large Hadron Collider. The latter example has provided ample opportunity for scientific abstractions to clash with theological ones; you’re kind of asking for it if you label the Higgs boson the ‘God particle’ (the origin of which is Nobel Laureate Leon Lederman’s 1993 book The God Particle: If the Universe is the Answer, What is the Question?). Scientists who lie within the central science — that’s us chemists of course — are somewhat insulated from this sort of thought. Between us and the meaning of the Universe are the physicists, between us and the meaning of life are the biochemists and molecular biologists, and between us and the contemplation of the existence of the soul are the neuroscientists. So chemists don’t have to spend much of their job contemplating how their abstractions and models clash with religious doctrine, faith and why we and the rest of the Universe actually exist. Compare and contrast, for example, the abstractions/knowledge of an organic chemist (atomic orbitals, molecular orbitals, valence-shell electron-pair repulsion, induction, resonance and so on) with the God particle. There really is no comparison; most people don’t care about the former, whereas the latter is for the philosopher in everyone. Chemistry still influences
NATURE CHEMISTRY | VOL 6 | NOVEMBER 2014 | www.nature.com/naturechemistry
© 2014 Macmillan Publishers Limited. All rights reserved
almost everyone on the planet, and there can be plenty of philosophical discussions around diverse topics such as health care and pharmaceutics, the cornucopia of materials around us, greenhouse gases and global warming… the list goes on. But it’s hard to imagine contemporary abstractions from chemistry engaging with something as metaphysically heavy as the meaning of life in the same way as alchemy did with religions that arose in China and India (and to a lesser extent those of the West). That is not to say that there aren’t any future possibilities. Now, my crystal ball is as murky as the next person’s, but a couple of recent — and at first glance disparate — events made me think of one possibility where chemical abstractions and knowledge might intertwine with weighty philosophical thoughts. The first of these was a map; not a map of the world, but a map of where our galaxy fits into the greater scheme of things2. For those of you who missed the article, your complete address is now something like: 59 Smith Street, Indianapolis, Indiana, USA, Planet Earth, The Solar System, Milky Way, Laniakea, The Universe. Mentioning this to my younger daughter led to a look of youthful wonderment quite impossible to encapsulate in words. ‘Ineffable’ — a word that represents the greatest linguistic opt-out possible — is what comes to mind. The second event was when I stumbled across two related conference abstracts3,4; no, not from the American Chemical Society, but 943
thesis from the International Conference on Mars and the 45th Lunar and Planetary Science Conference. (Don’t these conferences sound much more fun than your average ACS meeting?) On one level, to an organic chemist the topics of these papers are fairly mundane: the detection of chlorobenzene and, assuming this data to be true, the source of this simple aromatic compound. But as the titles of the conferences suggest, the real tricky part to these questions is the location of the sensor that collected the data; the sensor is on the Curiosity rover on Mars.
Chemists don’t have to spend much of their job contemplating how their abstractions clash with religious doctrine, faith and why we exist. One component of the rover is the Sample Analysis at Mars (SAM) instrument designed to determine which organic and inorganic volatiles thermally evolve from collected solid samples. Of primary note are an evolved-gas analysis system and a pyrolysis gas-chromatography mass spectrometer. Using these tools, the rover seems to have discovered chlorobenzene on Mars. And so, many questions emerge: Does it arise from the reaction of Martian oxidants with the polymer in the hydrocarbon trap of the instrument or with known terrestrial organics in the instrument such as the silylating agent N-methyl-N(t-butyldimethylsilyl)trifluoroacetamide? Perhaps it is derived from Martian organics or simply from thermal desorption of chlorobenzene directly from the samples? So far it has been established that it doesn’t arise from the instrument in the rover, although polymers may be responsible for a small fraction of the observed signal. Although the source of chlorobenzene remains unclear, it seems to be present either in Martian soil samples or formed by other organics in the famous red sand that react with Martian oxidants during pyrolysis. In either case, it’s natural to wonder what the precursor to this extraterrestrial chlorobenzene is. The confluence of these events stirred two thoughts. First, faith is alive and well in chemistry. Now when I say ‘faith’, I should note that I’m not a believer in digital faith (it’s either on or off, you either have it or you don’t) but on the fine balance between faith and trust from theoretical and evidence-based underpinnings. Take NMR spectroscopy for example. This is 944
a technique that our research team uses routinely. However, I must admit to being a bit rusty regarding the finer mathematical details of the subject. To be honest, I would probably fail — if I took it right now — a graduate-level exam on NMR theory. I don’t really have much choice; apart from the NMR experts, to function in this world we all take the theoretical nitty-gritty of NMR for granted. Some have argued that in this situation, where I don’t know the subject down to the subtlest mathematical minutia, I am acting on faith5. That may be so, but it is faith based on a combination of courses and hands-on experience, as well as the sheer mass of incontrovertible, reproducible evidence from spectrometers around the world. Abstractions were made, these models became scientific knowledge, NMR machines were built, and now I rely on varying degrees of faith to use this knowledge and operate on a day-to-day basis. A large part of the foundation of this faith is evidence. But what if the evidence is confusing or not forthcoming? Puzzles are part and parcel of research, but usually a quick question-and-answer session with a co-worker will resolve the issue of contradictory evidence. After all, the coworker was there. Right there! So I can use a conversation to tease apart what happened to a sample and hopefully solve the puzzle at hand. It may also require the familiarity with the science and the laboratory that comes from being a (lightly) seasoned investigator, but such a puzzle can usually be solved. Then there is the situation where the data is, by its very nature, scant. We’ve all been there as researchers; we simply turn to an alternative technique or protocol to gain more data. NMR spectroscopy experiments are not providing the requisite structural information? Get an X-ray structure! In the meantime, we need a bit of faith in what we know. As chemists we seldom actually say that. Instead we say that “our best available evidence suggests that…” or, “current understanding is…”, but those are just prosaic ways of saying that we’re sort of on thin ice right now (we’re dealing with an abstraction) but that we hope as we gain more information the ice will thicken (bedrock knowledge). We have faith. But in the case of the Curiosity rover there are no experiences or familiar territory to rely on. And this doesn’t really need stating, but there’s no co-worker standing over the instrument that can be interrogated after the fact. Furthermore, the evidence gathered so far is relatively thin on the ground, but we can’t just turn to another technique to corroborate what we know or suspect. Faith is alive and well in chemistry,
but it really does need to be alive and well in extraterrestrial chemistry. The second thought that arose after reading those three aforementioned papers is that it could potentially be the case that accepted knowledge — as well as current and future chemical abstractions — could engage with the idea of extraterrestrial life. We do not yet know what these might be: A model of the reactivity of carbenes with certain functional groups, a picture of ion accumulation or depletion from the air/water interface, an abstraction that doesn’t exist yet? Whatever is already in place (or ultimately will be in place) is (will be) ideally positioned for the search for extraterrestrial life. Why? Because moving from the current, nascent, state of affairs to even the minimalist, manned, exploration of Mars is going to take a long time. Furthermore, when they get there it seems unlikely that they’re going to quickly stumble across a fossil of something as complex and indisputable as a trilobite. Nor is it likely that a Martian insect is going to land on one of their cameras whist filming (this isn’t Hollywood you know). Instead it’s likely to be a long slow process to identify extraterrestrial life; even assuming we know what we ought to be looking for. Think spotting life is straightforward? Try talking to those involved in the debate6 about the existence of a shadow biosphere on Earth (the idea that alternative, perhaps non-carbonbased life-forms thrive right under our very noses). Whether our species is exploring Mars, Titan, Europa or wherever, progress in the search for extraterrestrial life will probably be — like all forms of research — incremental. And key to this process will be increasingly sophisticated chemical instrumentation being sent yonder. Chemistry is therefore going to get every chance to engage its knowledge and abstractions with the major philosophical question of the existence of extraterrestrial life. Move over metaphysics, metachemistry is coming. Sounds like fun! ❐ Bruce C. Gibb is in the Department of Chemistry at Tulane University, New Orleans, Louisiana 70118, USA. e-mail: [email protected] References 1. Dean, C. Scientific savvy? In US, not much. The New York Times (30 August 2005). 2. Tully, R. B., Courtois, H., Hoffman, Y. & Pomarede, D. Nature 513, 71–73 (2014). 3. Francois, P. et al. in Eighth Int. Conf. on Mars Abstract 1201 (California, 2014). 4. Glavin, D. et al. in 45th Lunar and Planetary Sci. Conf. Abstract 1157 (Texas, 2014). 5. Sarewitz, D. Nature 488, 431 (2012). 6. Cleland, C. E. & Copley, S. D. Int. J. Astrobiol. 4, 165–173 (2006).
NATURE CHEMISTRY | VOL 6 | NOVEMBER 2014 | www.nature.com/naturechemistry
© 2014 Macmillan Publishers Limited. All rights reserved
Faith, chemistry and extraterrestrial life NASA/JPL-CALTECH/MALIN SPACE SCIENCE SYSTEMS
Bruce Gibb wonders whether our faith in chemistry — and what it can teach us about the Universe beyond our Earthly bounds — will have a role to play in the search for alien life.
Scientists and religious leaders have argued about the importance of, and relationship between, science and religion since time immemorial. Against this backdrop, both science and religion have changed as the body of human knowledge has increased. For example, thanks to the likes of Nicolaus Copernicus most religions no longer accept the Ptolemaic model of the cosmos in which Earth is the centre of the Universe (although between 10–20% of people polled in the US do believe this1), and courtesy of Albert Einstein, our scientific view of the Universe has changed considerably since the days of Isaac Newton. What drives these changes? In science, of course, it is the perpetual feedback cycle between new thoughts and new technologies. New thoughts lead to new abstractions (models) that allow us to define and build new technologies that lead to new thoughts and abstractions… And over time these abstractions become accepted scientific knowledge; consider for example the simple atomistic view of matter put forth by the Greeks and how our understanding of the structure of the atom fits into the current bedrock of knowledge. (I’ll leave the thought of how an abstraction transforms into bedrock knowledge to the epistemologically inclined readers.) Some of the new abstractions rub off onto religion, which in turn contributes to the slower — but analogous — change that it experiences. Correspondingly of course, these changes to scientific and religious
understanding open up new areas in which scientists and theologians can engage with one another; it was the case when Eratosthenes used maps and gnomons to demonstrate that Earth was round rather than flat, and it is the case today with the likes of the Large Hadron Collider. The latter example has provided ample opportunity for scientific abstractions to clash with theological ones; you’re kind of asking for it if you label the Higgs boson the ‘God particle’ (the origin of which is Nobel Laureate Leon Lederman’s 1993 book The God Particle: If the Universe is the Answer, What is the Question?). Scientists who lie within the central science — that’s us chemists of course — are somewhat insulated from this sort of thought. Between us and the meaning of the Universe are the physicists, between us and the meaning of life are the biochemists and molecular biologists, and between us and the contemplation of the existence of the soul are the neuroscientists. So chemists don’t have to spend much of their job contemplating how their abstractions and models clash with religious doctrine, faith and why we and the rest of the Universe actually exist. Compare and contrast, for example, the abstractions/knowledge of an organic chemist (atomic orbitals, molecular orbitals, valence-shell electron-pair repulsion, induction, resonance and so on) with the God particle. There really is no comparison; most people don’t care about the former, whereas the latter is for the philosopher in everyone. Chemistry still influences
NATURE CHEMISTRY | VOL 6 | NOVEMBER 2014 | www.nature.com/naturechemistry
© 2014 Macmillan Publishers Limited. All rights reserved
almost everyone on the planet, and there can be plenty of philosophical discussions around diverse topics such as health care and pharmaceutics, the cornucopia of materials around us, greenhouse gases and global warming… the list goes on. But it’s hard to imagine contemporary abstractions from chemistry engaging with something as metaphysically heavy as the meaning of life in the same way as alchemy did with religions that arose in China and India (and to a lesser extent those of the West). That is not to say that there aren’t any future possibilities. Now, my crystal ball is as murky as the next person’s, but a couple of recent — and at first glance disparate — events made me think of one possibility where chemical abstractions and knowledge might intertwine with weighty philosophical thoughts. The first of these was a map; not a map of the world, but a map of where our galaxy fits into the greater scheme of things2. For those of you who missed the article, your complete address is now something like: 59 Smith Street, Indianapolis, Indiana, USA, Planet Earth, The Solar System, Milky Way, Laniakea, The Universe. Mentioning this to my younger daughter led to a look of youthful wonderment quite impossible to encapsulate in words. ‘Ineffable’ — a word that represents the greatest linguistic opt-out possible — is what comes to mind. The second event was when I stumbled across two related conference abstracts3,4; no, not from the American Chemical Society, but 943
thesis from the International Conference on Mars and the 45th Lunar and Planetary Science Conference. (Don’t these conferences sound much more fun than your average ACS meeting?) On one level, to an organic chemist the topics of these papers are fairly mundane: the detection of chlorobenzene and, assuming this data to be true, the source of this simple aromatic compound. But as the titles of the conferences suggest, the real tricky part to these questions is the location of the sensor that collected the data; the sensor is on the Curiosity rover on Mars.
Chemists don’t have to spend much of their job contemplating how their abstractions clash with religious doctrine, faith and why we exist. One component of the rover is the Sample Analysis at Mars (SAM) instrument designed to determine which organic and inorganic volatiles thermally evolve from collected solid samples. Of primary note are an evolved-gas analysis system and a pyrolysis gas-chromatography mass spectrometer. Using these tools, the rover seems to have discovered chlorobenzene on Mars. And so, many questions emerge: Does it arise from the reaction of Martian oxidants with the polymer in the hydrocarbon trap of the instrument or with known terrestrial organics in the instrument such as the silylating agent N-methyl-N(t-butyldimethylsilyl)trifluoroacetamide? Perhaps it is derived from Martian organics or simply from thermal desorption of chlorobenzene directly from the samples? So far it has been established that it doesn’t arise from the instrument in the rover, although polymers may be responsible for a small fraction of the observed signal. Although the source of chlorobenzene remains unclear, it seems to be present either in Martian soil samples or formed by other organics in the famous red sand that react with Martian oxidants during pyrolysis. In either case, it’s natural to wonder what the precursor to this extraterrestrial chlorobenzene is. The confluence of these events stirred two thoughts. First, faith is alive and well in chemistry. Now when I say ‘faith’, I should note that I’m not a believer in digital faith (it’s either on or off, you either have it or you don’t) but on the fine balance between faith and trust from theoretical and evidence-based underpinnings. Take NMR spectroscopy for example. This is 944
a technique that our research team uses routinely. However, I must admit to being a bit rusty regarding the finer mathematical details of the subject. To be honest, I would probably fail — if I took it right now — a graduate-level exam on NMR theory. I don’t really have much choice; apart from the NMR experts, to function in this world we all take the theoretical nitty-gritty of NMR for granted. Some have argued that in this situation, where I don’t know the subject down to the subtlest mathematical minutia, I am acting on faith5. That may be so, but it is faith based on a combination of courses and hands-on experience, as well as the sheer mass of incontrovertible, reproducible evidence from spectrometers around the world. Abstractions were made, these models became scientific knowledge, NMR machines were built, and now I rely on varying degrees of faith to use this knowledge and operate on a day-to-day basis. A large part of the foundation of this faith is evidence. But what if the evidence is confusing or not forthcoming? Puzzles are part and parcel of research, but usually a quick question-and-answer session with a co-worker will resolve the issue of contradictory evidence. After all, the coworker was there. Right there! So I can use a conversation to tease apart what happened to a sample and hopefully solve the puzzle at hand. It may also require the familiarity with the science and the laboratory that comes from being a (lightly) seasoned investigator, but such a puzzle can usually be solved. Then there is the situation where the data is, by its very nature, scant. We’ve all been there as researchers; we simply turn to an alternative technique or protocol to gain more data. NMR spectroscopy experiments are not providing the requisite structural information? Get an X-ray structure! In the meantime, we need a bit of faith in what we know. As chemists we seldom actually say that. Instead we say that “our best available evidence suggests that…” or, “current understanding is…”, but those are just prosaic ways of saying that we’re sort of on thin ice right now (we’re dealing with an abstraction) but that we hope as we gain more information the ice will thicken (bedrock knowledge). We have faith. But in the case of the Curiosity rover there are no experiences or familiar territory to rely on. And this doesn’t really need stating, but there’s no co-worker standing over the instrument that can be interrogated after the fact. Furthermore, the evidence gathered so far is relatively thin on the ground, but we can’t just turn to another technique to corroborate what we know or suspect. Faith is alive and well in chemistry,
but it really does need to be alive and well in extraterrestrial chemistry. The second thought that arose after reading those three aforementioned papers is that it could potentially be the case that accepted knowledge — as well as current and future chemical abstractions — could engage with the idea of extraterrestrial life. We do not yet know what these might be: A model of the reactivity of carbenes with certain functional groups, a picture of ion accumulation or depletion from the air/water interface, an abstraction that doesn’t exist yet? Whatever is already in place (or ultimately will be in place) is (will be) ideally positioned for the search for extraterrestrial life. Why? Because moving from the current, nascent, state of affairs to even the minimalist, manned, exploration of Mars is going to take a long time. Furthermore, when they get there it seems unlikely that they’re going to quickly stumble across a fossil of something as complex and indisputable as a trilobite. Nor is it likely that a Martian insect is going to land on one of their cameras whist filming (this isn’t Hollywood you know). Instead it’s likely to be a long slow process to identify extraterrestrial life; even assuming we know what we ought to be looking for. Think spotting life is straightforward? Try talking to those involved in the debate6 about the existence of a shadow biosphere on Earth (the idea that alternative, perhaps non-carbonbased life-forms thrive right under our very noses). Whether our species is exploring Mars, Titan, Europa or wherever, progress in the search for extraterrestrial life will probably be — like all forms of research — incremental. And key to this process will be increasingly sophisticated chemical instrumentation being sent yonder. Chemistry is therefore going to get every chance to engage its knowledge and abstractions with the major philosophical question of the existence of extraterrestrial life. Move over metaphysics, metachemistry is coming. Sounds like fun! ❐ Bruce C. Gibb is in the Department of Chemistry at Tulane University, New Orleans, Louisiana 70118, USA. e-mail: [email protected] References 1. Dean, C. Scientific savvy? In US, not much. The New York Times (30 August 2005). 2. Tully, R. B., Courtois, H., Hoffman, Y. & Pomarede, D. Nature 513, 71–73 (2014). 3. Francois, P. et al. in Eighth Int. Conf. on Mars Abstract 1201 (California, 2014). 4. Glavin, D. et al. in 45th Lunar and Planetary Sci. Conf. Abstract 1157 (Texas, 2014). 5. Sarewitz, D. Nature 488, 431 (2012). 6. Cleland, C. E. & Copley, S. D. Int. J. Astrobiol. 4, 165–173 (2006).
NATURE CHEMISTRY | VOL 6 | NOVEMBER 2014 | www.nature.com/naturechemistry
© 2014 Macmillan Publishers Limited. All rights reserved
