17 October 2012
It is ironic, though not particularly paradoxical, that the earth sciences as we known them today only came into being as the result of the emergence of space science, and space science was a consequence of the advent of the Space Age. We had to leave the Earth and travel into space in order to see the Earth for what it is. Why was this the case, and what do I mean by this?
It has often been commented that we had to go into space in order to discover the earth, which is to say, to understand that the earth is a blue oasis in the blackness of space. The early images of the space program had a profound effect on human self-understanding. Photographs (as much or more than any theory) provided the theoretical context that allowed us to have a unified perspective on the Earth as part of a system of worlds in space. Once we saw the Earth for what it was, What Carl Sagan called a “pale blue dot” in the blackness of space, drove home a new perspective on the human condition that could not be forgotten once it had been glimpsed.
To learn that our sun was a star among stars, and that the stars were suns in their own right, that the Earth is a planet among planets, and perhaps other planets are other Earths, has been a long epistemic struggle for humanity. That the Milky Way is a galaxy among galaxies, a point that has been particularly driven home by recent observational cosmology as with the Hubble Ultra-Deep Field (UDF) image (and now the Hubble eXtreme-Deep Field (XDF) image), is an idea that we still today struggle to comprehend. The planethood of the Earth, the stellarhood of the sun, the galaxyhood of the Milky Way are all exercises in contextualizing our place in the universe, and therefore an exercise in Copernicanism.
But I am getting ahead of myself. I wanted to discuss the earth sciences, and to try to understand what they are and how they have become what they are. What are the Earth sciences? The Biology Online website has this brief and concise definition of the earth sciences:
The Earth Sciences, investigating the way our planet works and the mechanisms of nature that drive it.
Earth Science is the study of the Earth and its neighbors in space… Many different sciences are used to learn about the earth, however, the four basic areas of Earth science study are: geology, meteorology, oceanography and astronomy.
For a more detailed overview of the earth sciences, the Earth Science Literacy Initiative (ESLI), funded by the National Science Foundation, has formulated nine “big ideas” of earth science that it has published in its pamphlet Earth Science Literacy Principles. Here are the nine big ideas taken from their pamphlet:
1. Earth scientists use repeatable observations and testable ideas to understand and explain our planet.
2. Earth is 4.6 billion years old.
3. Earth is a complex system of interacting rock, water, air, and life.
4. Earth is continuously changing.
5. Earth is the water planet.
6. Life evolves on a dynamic Earth and continuously modifies Earth.
7. Humans depend on Earth for resources.
8. Natural hazards pose risks to humans.
9. Humans significantly alter the Earth.
Each of these “big ideas” is further elaborated in subheadings that frequently bring out the planethood of the Earth. For example, section 2.2 reads:
Our Solar System formed from a vast cloud of gas and dust 4.6 billion years ago. Some of this gas and dust was the remains of the supernova explosion of a previous star; our bodies are therefore made of “stardust.” This age of 4.6 billion years is well established from the decay rates of radioactive elements found in meteorites and rocks from the Moon.
Intuitively, we would say that the earth sciences are those sciences that study the Earth and its natural processes, but the rapid expansion of scientific knowledge has made us realize that the Earth is not a closed system that can be studied in isolation. The Earth is part of a system — the solar system, and beyond that a galactic system, etc. — and must be studied as part of this system. But we didn’t always know this, and this comprehensive conception of earth science is still in the process of formulation.
The realization that the processes of the Earth and the sciences that study these processes must ultimately be placed in a cosmological context means that contemporary earth science is now, like astrobiology, which seeks to place biology in a cosmological context, a fully Copernican science, though not perhaps quite as explicitly as in the case of astrobiology. The very idea of Earth science as it is understood today, like planetary science and space science, is essentially Copernican; Copernicanism is now the telos of all the sciences. Copernican civilization needs Copernican sciences. As I said in my presentation to this year’s 100YSS symposium, the scope of an industrial-technological civilization corresponds to the scope of the science that enables this civilization.
What this means is that the sciences that generations of Earth-bound scientists have labored to create in order to describe the planet upon which they have lived, which was the only planet that they could know prior to the advent of space science, are all planetary sciences in embryo — all potentially Copernican sciences that can be extended beyond the Earth that was their inspiration and origin. Before space science, all science was geocentric and therefore essentially Ptolemaic. Space science changed that, and now all the sciences are gradually becoming Copernican.
In the case of earth science, this is a powerful scientific model because the earth sciences have been, by definition, geocentric. That even geocentric sciences can become Copernican is a powerful lesson and provides a model for other sciences to follow. I have often quoted Foucault as saying that “A real science recognizes and accepts its own history without feeling attacked.” I think it can be honestly said that the geosciences recognize and accept their history as geocentric sciences and this in no way inhibits their ability to transcend their geocentric origins and become Copernican sciences no longer exclusively tied to the Earth. I find this rather hopeful for the future of science.
Another way to conceptualize earth science is to think of the earth sciences as those sciences that have come to recognize the planethood of the Earth. This places the Earth in its planetary context among other planets of our solar system, and it also places these planets (as well as the growing roster of exoplanets) in the context of planetary history that we have learned first-hand from the Earth.
To a certain extent, earth science and planetary science (or planetology) are convertible: each is increasingly formulated and refined in reference to the other. What is planetary science? Here is the Wikipedia definition of planetary science:
Planetary science (rarely planetology) is the scientific study of planets (including Earth), moons, and planetary systems, in particular those of the Solar System and the processes that form them. It studies objects ranging in size from micrometeoroids to gas giants, aiming to determine their composition, dynamics, formation, interrelations and history. It is a strongly interdisciplinary field, originally growing from astronomy and earth science, but which now incorporates many disciplines, including planetary astronomy, planetary geology (together with geochemistry and geophysics), atmospheric science, oceanography, hydrology, theoretical planetary science, glaciology, and the study of extrasolar planets. Allied disciplines include space physics, when concerned with the effects of the Sun on the bodies of the Solar System, and astrobiology.
The Division for Planetary Sciences of the American Astronomical Society doesn’t give us the convenience of a definition for planetary science, but in its offerings on A Planet Orbiting Two Suns, A Thousand New Planets, Buried Mars Carbonates, The Lunar Core, Propeller Moons of Saturn, A Six-Planet System, Carbon Dioxide Gullies on Mars, and many others, give us concrete examples of planetary science which examples may, in certain ways, be more helpful than an explicit definition.
The “aims and scope” of the journal Earth and Planetary Science Letters also give something of a sense of what planetary science is:
Earth and Planetary Science Letters (EPSL) is the journal for researchers, policymakers and practitioners from the broad Earth and planetary sciences community. It publishes concise, highly cited articles (“Letters”) focusing on physical, chemical and mechanical processes as well as general properties of the Earth and planets — from their deep interiors to their atmospheres. Extensive data sets are included as electronic supplements and contribute to the short publication times. EPSL also includes a Frontiers section, featuring high-profile synthesis articles by leading experts to bring cutting-edge topics to the broader community.
A recent (2006) controversy over the status of Pluto as a planet led to an attempt by The International Astronomical Union (IAU) to formulate a more precise definition of what a planet is. The definition upon which they settled demoted Pluto from being a planet to being a dwarf planet. While this decision does not have complete unanimity, it is gaining ground in the literature. Here is the IAU of planets, dwarf planets, and small solar system bodies:
(1) A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.
(2) A “dwarf planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
(3) All other objects, except satellites, orbiting the Sun shall be referred to collectively as “Small Solar System Bodies.”
With this greater precision of definition than had previously been the case in regard to planets, we could easily define planetary science as the study of celestial bodies that (a) are in orbit around the Sun, (b) have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (nearly round) shape, and (c) have cleared the neighbourhood around their orbits. Of course, this ultimately won’t do, because a comprehensive planetary science will want to study all three classes of celestial bodies detailed above, and will especially want to study the mechanisms of planet formation, dwarf planet formation, and small object formation for the light that each shines on the other. Like the Earth, that is part of a larger system, all the planets are also part of a larger system, and how they relate to that system will have much to teach us about solar system formation.
This more comprehensive perspective brings us to the space sciences. What is space science? The Wikipedia entry on space sciences characterizes them in this way:
The term space science may mean:
●The study of issues specifically related to space travel and space exploration, including space medicine.
●Science performed in outer space (see space research).
●The study of everything in outer space; this is sometimes called astronomy, but more recently astronomy can also be regarded as a division of broader space science, which has grown to include other related fields.
It is interesting that this definition of space science does not mention cosmology, which is more and more coming to assume the role of the master category of the sciences, since it is ultimately cosmology that is the context for everything else, but we could easily modify that last of the above three stipulations to read “cosmology” in place of “astronomy.” As the definition notes, the space sciences have grown to include other related fields, and in the future it may well be that the space sciences become the most comprehensive scientific category, providing the conceptual infrastructure in which all other scientific enterprises must be contextualized.
Since the Earth is a planet, and planets are to be found in space, one might readily assume that the Earth sciences, planetary sciences, and space sciences might be arranged in a nested hierarchy as follows:
Conceptually this is correct, but genetically, i.e., in terms of historical descent, it is obvious that the sciences that we have created to study our home planet are the sciences that, when generalized and applied beyond the surface of the Earth, are the sciences that become planetary science and space science.
Before space science and planetary science, there were of course the familiar sciences of geology (later geomorphology), atmospheric science or meteorology (later climatology), oceanography, paleontology, and so forth, but it was only when the emergence of space science and planetary science placed these terrestrial sciences into a cosmological context that we came to see that our sciences that study the planet that we call our home together constitute the Earth sciences in contrast to, and really in the context of, space science and planetary science. Great strides have been made in this direction, but further work remains to be done.
We know that the Earth and its solar system is about 4.6 billion years old, and most recent estimates for the age of the known universe put it at about 13.7 billion years. This means that the Earth has been around for almost exactly a third of age of the entire universe, which is not an inconsiderable length of time. Our sun and its solar system stands in relation to other stars of a similar age, and these stars and solar systems with significant traces of heavier elements stand in certain relationships to earlier populations of stars. The whole history of the universe is present in the rocks of the Earth, and we have to keep this in mind in the expanding knowledge base of the earth sciences.
While geological time scales are essentially geocentric, it would be possible to formulate an astrogeography and an astrogeographical time scale, extrapolating earth science to planetary science and thence to space science, that not only placed Earth’s geological history into cosmological context but also placed all planetary bodies and planetary systems and their geology in a cosmological context. For such an undertaking the generations of stars and planetary formation would be of central concern, and we could expect to see patterns across stars and solar systems of the same generations, and across planets within a given solar system.
This work has already begun, as can be seen in the above table laying out the geological histories of the Earth, the Moon, and Mars in parallel. Since one of the major theories for the formation of the Moon is that most of its substance was ripped out of the Earth by an enormous collision, the geological histories of the Earth and the Moon may ultimately be shown to coincide.
Stars and planets formed from the same dust and debris clouds filled with the remnants of the nucleosynthesis of earlier poulations of stars. This is now familiar to everyone. Galaxies, in turn, formed from stars, and thus also reflect a generational index reflecting a galaxy’s position in the natural history of the universe.
Since we now also believe that all or almost all spiral galaxies (and perhaps also other non-spiral or irregular galaxies) have a supermassive black hole at their centers, I have lately come of think of entire galaxies as the vast “solar systems” of supermassive black holes. In other words, a supermassive black hole is to a galaxy as a star is to a solar system. As planetary systems formed around newly born stars, galaxies formed around newly born black holes (if their gravity was sufficiently strong to form such a system). This way of thinking about galaxies introduces another parallelism between the microcosm of the solar system and the macrocosm of the universe at large, the structure of which is defined by galaxies, clusters of galaxies, and super clusters.
All of this falls within a single natural history of which we are a part.
Our history and the history of the universe are one and the same.
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19 March 2012
This post has been superseded by Eo-, Eso-, Exo-, Astro-, which both corrects and extends what I wrote below.
The Philosophical Significance of Astrobiology as a
Cosmological Extrapolation of Terrestrial Biology
In yesterdays’ Commensurable Perspectives I finished with this observation:
Ecology is the master world-narrative that unifies the sub-narratives employed by individual species in virtue of their perceptual and cognitive architecture. Ultimately, astrobiology would constitute the universal narrative that would unify the ecological narratives of distinct worlds.
The naturalistic narrative has the power to unify even across species and across worlds. This power may not be particularly evident at present, but in the long term future of our species (if our species does in fact have a long term future) this power will prove to be crucial.
If indeed astrobiology is the universal narrative of life, that gives astrobiology a privileged position among the sciences. That is a tall order. But what is astrobiology? At one time I had heard both the terms “exobiology” and “astrobiology” and I was not quite clear about the exact difference between the two, or how each was defined. Thereby hangs a tale. The distinction between the two is in fact a very interesting story, and it is a story to which an entire book has been devoted, The Living Universe: NASA and the Development of Astrobiology, by Steven J. Dick and James E. Strick.
I urge the reader to get this book and peruse it for yourself for the detailed version of the emergence of astrobiology as a scientific discipline. I will give only the bare bones of that story here, which will be only enough to grasp the crucial concepts involved. And our interest is in the concepts, not the personalities.
Exobiology is the older term, introduced by Joshua Lederberg (first used in a public lecture in 1960), and contrasted by him to eobiology. Exobiology has some currency in the public mind, but I didn’t know about eobiology until I read about the history of the discipline. However, the contrast between the two terms is conceptually important. Exobiology is concerned with biology off the surface of the earth, while eobiology is biology on the surface of the earth. (cf. p. 29) In other words, all biological science prior to human spaceflight was eobiology, even if we didn’t know that it was eobiology. Another way to formulate this distinction is to say that eobiology is the biology of the terrestrial biosphere, while exobiology is the biology of everything else.
In the book The Living Universe: NASA and the Development of Astrobiology the authors give a lot of background on the internal politics and budgeting of NASA and how this affected the emergence of astrobiology. It is an interesting story, but I will not go into it here, as our interest at present is exclusively with the conceptual infrastructure of the discipline. Suffice it to say that in 1996 the first attempts were made to define astrobiology (cf. p. 202), and within a couple of years there was a virtual Astrobiology Institute.
“Astrobiology is the study of the origin, evolution, distribution, and future of life in the universe. This multidisciplinary field encompasses the search for habitable environments in our Solar System and habitable planets outside our Solar System, the search for evidence of prebiotic chemistry and life on Mars and other bodies in our Solar System, laboratory and field research into the origins and early evolution of life on Earth, and studies of the potential for life to adapt to challenges on Earth and in space.”
“The study of the living universe. This field provides a scientific foundation for a multidisciplinary study of (1) the origin and distribution of life in the universe, (2) an understanding of the role of gravity in living systems, and (3) the study of the Earth’s atmospheres and ecosystems.”
The important lesson to take away from this is that astrobiology is the more comprehensive concept, and that in fact we can consider astrobiology the union of eobiology and exobiology. This sounds simple enough (and it is), but it is important to understand the conceptual leap that has been taken here.
From the perspective of astrobiology, earth sciences are only fragments of far larger and more comprehensive sciences. Just as all biology was once eobiology, the same observation can be made in regard to the other earth sciences, and the same tripartite conceptual distinction can be brought to the other earth sciences. We can formulate eogeology and exogeology unified in astrogeology; we can formulate eohydrology and exohydrology unified in astrohydrology; we can formulate eovulcanology and exovulcanology unified in astrovulcanology; we can formulate eoclimatology and exoclimatology unified in astroclimatology. All of these are cosmological extrapolations of earth sciences. One suspects that, in the future, the prefixes will be dropped and we will return to climatology simpliciter, e.g., but while the conceptual revolution is underway it is important to retain the prefixes as a reminder that science is no longer defined by the boundaries of the earth.
I assert that this is a conceptual leap of the first importance because what we have with astrobiology is the formulation of the first truly Copernican science; astrobiology includes eobiology but it is not exhausted by eobiology; it is supplemented by exobiology. The earth, for obvious reasons, remains important to us, but it no longer dictates the center of our science. All mature sciences will eventually need to take this Copernican turn and dethrone the earth from the center of its concern.
We can take a further step beyond this conceptual formulation of Copernican sciences by observing that traditional earth sciences began as local enterprises, and it has only been in recent decades that truly global sciences have emerged. These global sciences have culminated in objects of scientific study that take the world entire as their object. Thus biology has converged upon study of the biosphere; hydrology has converged on study of the hydrosphere; glaciology has culminated in the study of the cryosphere. Copernican sciences based on the model of astrobiology can go one better than this, transcending earth-defined “-spheres” in favor of more comprehensive concepts.
When I spoke last year on “The Moral Imperative of Human Spaceflight” at the NASA/DARPA 100 Year Starship Study symposium it was my intention to spend some time on the emergence of Copernican sciences, but I didn’t have enough time to elaborate. I cut most of that material out and still was rushed. The point that I wanted to make there was that the concepts of the biosphere, the lithosphere, the geosphere, hydrosphere, cryosphere, atmosphere, anthrosphere, sociosphere, noösphere, and technosphere are essentially Ptolemaic concepts. (If the proceedings of the symposium are published, and if my paper is included, this contains my first sketch of Copernican sciences as transcending these earth-defined “-spheres.”) The Copernican Revolution entails the formulation of Copernican concepts to supersede Ptolemaic concepts, and this work is as yet unfinished. In some spheres of human thought, it has scarcely begun.
One way to transcend our Ptolemaic concepts and to replace them with Copernican concepts, and thus to extend the ongoing shift to a truly Copernican perspective, is to substitute for the earth-defined “-spheres” a conception of the object of the sciences not dependent upon the earth, and this can be done by defining, respectfully, biospace (in place of the biosphere), lithospace, geospace, hydrospace, cryospace, atmospace, anthrospace, sociospace, noöspace, and technospace. In so far as we can facilitate the emergence of Copernican sciences, we can contribute to the ongoing Copernican Revolution, which will someday culminate in a Copernican civilization (if we do not first destroy ourselves).
We can pass beyond the earth sciences and the natural sciences and similarly extend our conceptions of a the social and political sciences. Although concepts from the social sciences are not usually expressed in geocentric terms — except for the above-mentioned anthrosphere, sociosphere, noösphere, and technosphere (which are not employed very often) — our social and political thought is usually even more tied to planetary prejudices than the concepts of the natural sciences. Thus we can extend our conception of politics by distinguishing between eopolitics and exopolitics, both of which are subsumed under astropolitics. Similarly, we can formulate eoeconomics and exoeconomics, subsumed by astroeconomics, eostrategy and exostrategy, subsumed by astrostrategy, and so forth.
As a final note, it is ironic that the breakthrough to a Copernican science should occur first with biology, because biology was among the latest of the sciences to actually attain a scientific status. Prior to Darwin, biological theories were essentially theological theories with but a few exceptions. Darwin put biology on a firm biological footing and created the discipline in its modern scientific form. Thus biology was among the last of the sciences to attain a modern scientific form, though it was the first to attain to a Copernican form.
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This post has been superseded by Eo-, Eso-, Exo-, Astro-.
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