Atom: Conversation with Lawrence Krauss
|"Atom" and "The Physics of Star Trek", by L.M. Krauss.|
Lawrence Krauss, the department chair of physics at Case Western Reserve University , is the author of a half-dozen books, ranging from The Physics of Star Trek, to his most recent astrobiology book, Atom, which takes up the classic challenge to see the universe in an atom–and vice versa.
Stephen Hawking wrote that "Lawrence Krauss has Carl Sagan’s knack of expanding the imagination and explaining the mysteries of the universe in simple terms." Unique to his authoritative writing, Krauss draws on his experience and judgements as an active research cosmologist with over 180 scientific publications and numerous popular articles discussing issues related to physics, science, and society. In 2003, his recent astrophysical research article was the January 3rd cover for the prestigious Science magazine [The Age of Globular Clusters in the Milky Way: Constraints on Cosmology].
Astrobiology Magazine (AM): How did the idea of following the oxygen atom from the small to the large and back again first come to you as a narrative for describing the relationship between the big bang and life on earth?
Lawrence Krauss (LK): Well, for some time, I had always felt that one of the most poetic aspects of all of science is the fact that we are all star children, literally, as each and every atom in our bodies was once inside of a star, perhaps several stars, and the very elements that make us up were forged inside fiery stellar furnaces. I was not prepared when I began, however, for the truly remarkable journey I ultimately wrote about.
One of the joys, and trials, of writing is the experience of learning how much one hadn’t known about various subjects in advance. I knew when I decided to take up the challenge of the "Atom" that the experience would be qualitatively different from anything I had done before. The prospect of using the lives of an atom to present a literary view of the history of the universe, including the romances of our own human drama, became more seductive the more I thought about it. It was also clear that this story would involve not merely physics and astrophysics, but at the very least geophysics, geology, astronomy, biology and paleontology. Frankly, initially this challenge was also an attraction.
AM: The concept of moving from the infinitesimal to the infinite has the classic visualization, called "Powers of Ten" which is attributed to a variety of illustrators but typically begins at the sub-atomic and zooms out to great distances in factors of ten. A 1950’s European version covered around 40 powers, and a 1970’s version with Phillip Morrison narrating covered another 5 to 10 orders more. The 1990’s version probably is most famous in the opening sequence to the movie "Contact" where a twist is given to the zooming, because the viewer is travelling with an electromagnetic wave, and thus involves not only spatial zoom, but time travel. Can you comment on this, particularly is this journey by powers of ten in scale useful as a tutorial or heuristic?
LK: I think it provides a very useful tutorial about scales in the Universe… perhaps the only problem with it is that it turns out, in fact, that if I draw a line from the Earth to the limits light has travelled since the Big Bang, this line has only a 1 in 1000 chance of intersecting a galaxy. The odds of finding a needle in a haystack are not much worse. So one problem with the zoom to infinity as depicted in these is they show not enough black, empty space in between.
AM: Are we any closer to understanding this trip from the atom to the Big Bang, only if the element of "time" is involved?
LK: It turns out that we are forever shielded from direct visual observation of the initial Big Bang because as we look farther and farther out, we are guaranteed to hit a wall. The likelihood that our light ray will be scattered by a proton or an electron before it could reach us approaches 100 percent, so that the primordial soup is opaque, more like tomato soup than consomme. We cannot see into it, we can see only its surface.
AM: On the cover art, the background illustration for "Atom" shows particle tracks spiralling with opposite polarities. In choosing to follow an oxygen atom as the tracer for life on earth, does that bias the journey towards animal evolution, since oxygen gas is more a waste or poison for the earliest life here? Or is the atom’s odyssey all the various combinations, from carbon dioxide, water, oxygen and ozone that comprise the ‘staff of life’ chemically?
|Tree of life, divided between three major cell types, those with and without a nucleus (Bacterial Prokaryotes and Animal Eukaryotes), preceded by the root of the tree, Archea.|
LK: I actually picked oxygen at the beginning without fully understanding the remarkable relationship between oxygen and life. The more I learned, however, the more perfect it seemed, because I wanted to trace the changes that took place in an oxygen atom’s ‘life-cycle’ on earth as it began as part of a geological cycle, then became a part of life as a waste product, and then became an integral part of animal life through respiration. All phases are equally important, I think.
Thus, your question assumes that oxygen as a plant waste product is less important to life than in animal respiration, which I don’t think is the case. It does stand to reason, however, that present-day life evolved out of bacteria that thrived without oxygen, perhaps without light and only in hot water. In the first place, in the early Earth, there was no free oxygen. Next, in the absence of oxygen, there was no ozone layer to protect life against the extreme ultraviolet radiation coming from the sun. While there is little doubt that life can survive such conditions, this may nevertheless have inhibited its growth on the surface of the oceans and on land.
AM: Most attempts to detect spectral properties from planetary atmospheres have a kind of rank order of the importance given to these chemical combinations, with oxygen as ozone near the top. This ranking often is higher than water itself, at least for remote sensing in the atmosphere. The appearance of ozone on earth was more about radiation protection from UV than a classic nutrient or waste balance in what is required as biological prerequisites. Could a dead rocky planet get ozone or keep it without the action of some form of biology?
LK: I doubt it. But also remember that many forms of life do not need oxygen.
|X-ray jet from the center of Centaurus A, the closest active galaxy to Earth, at 10 million light-years away. The mystery of why all matter can’t escape from the center of this giant elliptical galaxy (if a black-hole is present), but a fine jet is blasted out is perplexing Credit: NASA Chandra/NOAA/NSF|
Biochemical arguments suggest that sulfur-eating bacteria, or methane-producing fermenters, are likely to have predated more sophisticated photosynthetic bacteria. In fact, before photosynthesis there was quite likely chemosynthesis. Here primordial life forms would have lived without oxygen and in the dark. They would not have been powered, as plants are, by the sun, but rather by the heat of the Earth.
AM: Why did life on Earth flourish, while the surface of Mars is a wasteland?
LK: Probably because our sister planet was just a little too small.
AM: It is often said that the three key findings for astrobiology were: extremophiles, extrasolar planets and a sense that water may be more ubiquitous even in our own solar neighborhood (in meteors like the Mars’ Lafayette, Europa, and the ice frost on polar Mars). In some cases, this picture has evolved quite suddenly, for instance, with 100-plus extrasolar planets found in just the last decade (and none known before around 1995). In your work, do you find one prong of this triad to be most compelling scientifically: life living in extremes, lots of candidate planets, or water?
LK: I find the existence of extremophiles the most compelling new development.
The first cells were probably more accustomed to the darkness and the putrid smell of sulfur assicatied with hydrothermal vents. Every year one reads of new forms of life discovered in places ranging from the relatively benign hydrothermal vents to the acidic, toxic, sweaty regions at the bottom of deep oil wells. Most compelling of all, perhaps, is the recent discovery that the tree of life has merely three branches, not five [plants, animals, fungi, bacteria and protists (sophisticated single-celled animals)], and that the one closest to the root involves bacteria that live in hot environments, the hyperthermophiles. Hyperthermophiles defy all conventional wisdom. These forms of life not only can thrive in environments that normalize sterilize materials, in excess of the normal boiling temperature of water at sea level, 100 degrees Celsius, they require such temperatures. These arguments suggest that all life on Earth today descended from species that liked it hot.
AM: "Atom" has a poetic parallel to William Blake’s famous ‘the world in a grain of sand’, but in this case even a more radical step from what must necessarily be inanimate for oxygen but presumably even Blake’s grain of sand is not completely sterile or devoid of life in a microbial sense. You comment in the book that "Remember that the motor that drives life is simply based on the movement of electrons, " and go on to compare oxygen as an electron acceptor combined with hydrogen, an electron donor.
Do you consider the fundamental unit that might bridge biology and physics is now just on the cusp of what we call ‘inanimate’, such as the biomolecules (RNA, DNA, oxygen, water), or is it more of a process like metabolism (electron transfers) or photosynthesis? In other words, is life a product or a process?
LK: That is the million dollar question, of course.. and I don’t have the answer!. As a physicist, I guess I tend to concentrate on processes more than objects, and thus I find metabolism fascinating, and to me the most compelling characteristic of life.
|Porphyrins are a ubiquitous class of naturally occurring compounds with many important biological representatives including hemes, chlorophylls, and several others.|
AM: One key chemical structure shared by both chlorophyll and hemoglobin is the porphyrin ring which is itself devoid of oxygen, but the larger molecule makes carbohydrates. Did your theme of one atom’s odyssey ever flirt with following carbon atoms or carbon-based life, rather than oxygen, as its tracer?
LK: I originally thought of carbon, but in retrospect that would have been a poorer candidate, I believe.. The transformations that oxygen is a part of are more fascinating, I think.
Carbon can bond in a hugely diverse set of combinations, with bonds of different types for different purposes. Oxygen however will occupy a very special role. For as far as we know, only oxygen atoms can combine to form molecules with the ability to power a civilization. So one might say, life is powered by oxygen, and fed by carbon.
As for porphyrin, eventually microbes hit upon this ringlike molecule. At the center of a its ring of carbon atoms, a single iron atom can be located, in which case this is called a heme group. The particular structure of this group allows electrons to flow easily within it. In this way, they can be accepted from outside, move to the middle during transport, and then be redeposited elsewhere. The development of these structures and of the associated energy transfer and production processes they mediate is of crucial importance to our oxygen atom on Earth. For it makes way for the two most profound developments in the history of life: photosynthesis and, later, respiration.
By these two processes, not only would life be forever changed but so would the Earth.
AM: In the last part of the book, you quoted Yogi Berra "The future ain’t what it used to be" and discuss various scenarios for the mortality of life such as global catastrophes. The magazine did an excerpt of many scientists’ reflections on "A Perfect World" and immediately the theme emerged that population growth was the greatest near-term catastrophe, while life prolongation or extension was the greatest near-term biological hope. There was necessarily some tension between those two outcomes.
|Star Trek’s "V-ger", as Spock investigates ancient probe. V-ger, as it called itself (pronounced vee-jer) was an ancient mechanical space probe that was on a mission to explore and discover and report back its findings–based on the NASA mission, Voyager.
From the point of view of a physicist seeing the changes in biology, do you have a best candidate for the near-term risks and also how the planet might recover?
LK: I think the near-term risks involve social problems having to do with scarce resources related to energy production and usage. Global warming is going to happen, and produce disasters, but I also see destroying the ocean ecosystems as a possible disaster. Perhaps the recovery will involve developing sentient life-forms that use less energy. For example, I see no obstructions to the creation of intelligent, self-aware, self-programmable, computing machines.
If this occurs, these machines will have have a tremendous evolutionary advantage over purely biological machinery. We will, I believe, soon be able to manipulate living systems on scales currently unthinkable. It seems to me that this combination of technologies has one logical outcome. Humans if they are to compete with the machines of their own invention, will inevitably be forced to do what will ultimately become possible to do, namely, integrate their biology with computer technology.
If it is possible, it will happen, as I expect cloning, genetically selective reproduction, and a host of other practices that have not yet begun to give ethicists nightmares will also happen.
Of course this is the optimistic outlook, from my perspective. Alternatively, as I have alluded, there is the possibility that scarce resources on a hot, polluted planet, mixed with a possible victory of superstition and myth over logic and rationality, will result in numerous devastating wars, and perhaps the establishment of theocracies that suppress scientific thought, well before technological progress reaches the stage I desribed. Human civilization then takes a giant step backward.
|Planetary dangers, resource use, and civilization|
AM: You also authored the book, "The Physics of Star Trek", prior to undertaking, "Atom". Do you personally find the vision of Star Trek, as many species who journey into space, to be forward-looking to a certain stage of evolution or just wishful thinking scientifically?
LK: Star Trek is primarily wishful thinking!…. but of course wishful thinking is also a part of science.. and sometimes it pays off.
AM: The epilogue’s closing lines are ‘Sisyphus was smiling’. Would you conclude that Sisyphus is smiling because of his own cyclical journey, or because he doesn’t see an alternative to pushing up his rock on the same hill and thus as a kind of comic acceptance?
LK: I believe Sisyphus is smiling because the struggle is what makes life worth living.. the voyage is often far more enlightening than reaching the destination.
Lawrence M. Krauss is Ambrose Swasey Professor of Physics, Professor of Astronomy, and Chair of the Physics Department at Case Western Reserve University. His research has focused primarily on the interface between elementary particle physics and cosmology, where his studies include the early universe, dark matter, general relativity and quantum gravity, stellar evolution, and neutrino astrophysics. Previous awards for his research include the Gravity Research Foundation First Prize Award (1984), and the Presidential Investigator Award (1986). He is also a Fellow of the American Physical Society. He received his B.Sc. in Mathematics and Physics from Carleton University in Ottawa, his Ph.D. in Physics from the Massachusetts Institute of Technology in 1982 then joined the Harvard Society of Fellows. In 1985 he joined the faculty of Physics at Yale University, and moved to take his current appointment in 1993. Prof. Krauss is the author of 6 books, over 180 scientific publications, numerous popular articles, and appears frequently on radio and television discussing issues related to physics, science, and society.