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A few days ago I wrote about the approach of Darwin Day and used turtles as an example of creatures with the visible “scars” of evolution (their lungs). Just today I read about a new turtle fossil that, perhaps, shows even my simple statements might be wrong.
This turtle looks like a classic transitional form. It has half a shell – the bottom half. The idea is that perhaps the bottom shell evolved first, in a water-living creature. The plastron might protect the bottom of the animal as it swam near the surface.
What this would mean is that turtles themselves evolved in the water. Now of course their ancestors are still certainly land-living creatures. That doesn’t change. Some creature lived on the land, laid eggs on land, breathed air. Then it returned to the water. While there, it and its descendants evolved the turtle’s shell, starting with the plastron (lower shell) and finishing, sometime later, with the carapace (upper shell).
I’m not sure I buy it. First of all, it just seems like such an unlikely creature. Why only one shell? It doesn’t seem like much protection, particularly from big-jawed creatures that might bite top and bottom at the same time. I wonder if we’re missing something?
More importantly, though, is the lesson that evolution is rarely a straight line. We know very few fossil turtles; there are probably lots of twists and turns in turtle evolution that we just don’t know yet – maybe we never will. Something else I read about today reminded me of that.
One of the most amazing developments (maybe the amazing development) of life on Earth was photosynthesis. The ability to make food from just sunlight and common materials would seem like a pretty fantastic development, not one that any organism would ever want to give up. And yet there are plants (including the mistletoe) that have at least partially given up photosynthesis. Others, like the Indian pipe or ghost plant,
have completely lost their chlorophyll and taken up a parasitic lifestyle. This sort of development shows, without any doubt, that evolution has no direction. If plants can lose the ability to make their own food, then we shouldn’t be surprised at the loss of anything, including a turtle’s shell.
Is this turtle really a transitional form, or is it simply an early turtle that has, for whatever reason, lost its top shell? Until we get more information, i think both ideas have to be possible. Evolution is not a straight line, but a complex bush. We still have much to learn about turtles.
In Episode Eight, Carl Sagan takes us into the impossibly weird world of Einstein’s relativity. Special relativity is one of the most beautiful ideas I’ve ever encountered. Unlike most deep theories, the math is straightforward, at least at its most basic level. It is something that everyone can grasp, and once you understand it, you’ll never forget it again. Ready?
Special relativity comes from a simple idea. If you jump on an interstellar spaceship and go to use your electric toothbrush, it still works. Why? Because there is no difference in traveling at 99% the speed of light and standing perfectly stock still. No difference at all. The laws of nature are exactly the same.
If I throw a baseball to you in our interstellar spaceship, it obeys the same laws of motion as it would were the spaceship lazily drifting through the solar system at some pedestrian speed well below the speed of light. The same, Einstein realized, must be true for all other physical phenomena.
Electric toothbrushes use electric motors, and electric motors work because of the way moving electrons affect other moving electrons. How do they do that? By sending out light of very long wavelengths. That long wavelength light (that’s what makes your AM radio buzz when you hold your electric toothbrush near – try it!) is still light – even though we can’t see it, we can pick up this invisible light perfectly well on our instruments (like AM radios).
That invisible light coming from your electric toothbrush moves at (you guessed it!) the speed of light; if it didn’t, your electric toothbrush wouldn’t work. If it works here on Earth, Einstein said, then it must also work in your interstellar spacecraft. And if it works in an interstellar spacecraft, then even when traveling at 99% the speed of light, your electric toothbrush makes light that travels at – the speed of light!
Einstein said that for the world to be consistent, for motion and non-motion to really be equivalent, the speed of light has to be the same for you no matter how fast you’re moving. The speed of light is the same for all observers. And electric toothbrushes remain on the list of approved devices for interstellar flights.
But here’s the thing. Moving light can be used for lots of different things, including creating clocks. Suppose we create two clocks – call them light clocks. They use a single piece of light and two mirrors. The light bounces up and down inside the clocks.
If both the clocks remain still relative to each other, then they stay perfectly in sync. When one piece of light bounces off the top mirror, so does the other. But what if we put one of these clocks on the interstellar spacecraft. To you, riding along with the clock, the clock behaves just as it had back on Earth, the light going up and down, up and down. But to someone watching back on Earth, the light in the moving clock takes a diagonal path from mirror to mirror.
But (as every student of Pythagoras knows) that diagonal path has to be longer than the straight line path taken by the clock still back on Earth. Since the piece of light always moves at the same speed, and it’s traveling a longer distance, it must take a longer time to move from mirror to mirror.
But time is exactly what the clock is measuring! So to you back on Earth, the moving clock seems to run slow. In fact, if the spacecraft reaches its destination, circles back, and splashes down on Earth, you’ll find that the astronauts on board have experienced less time passing than you have. Aboard the moving spacecraft, time itself slows down! In essence, those aboard the spacecraft live in a different time than those back on Earth. By moving near the speed of light, they’ve remade their universe.
All this from such a simple observation: the speed of light is always the same. Einstein’s ideas changed our view of reality forever. And the best part is this: you can take this same journey, riding along on a light clock, discovering for yourself how an electric toothbrush on a speeding spacecraft remakes your own personal universe.
I’m reading the Michael Freyn play Copenhagen, and there is something in there that is so brilliant I have to write about it.
(OK, truthfully, it gives me an excuse to try a new way of teaching something, and that’s really why I’m writing about it. But I do think it’s brilliant. Really.)
A couple years ago, I convinced my wife Julie to go and see the play Copenhagen with me. OK, actually we made a deal. She would go see Copenhagen with me, and I would go to the Rick Springfield concert with her. We’re an interesting pair, we are.
I LOVED it (no, sorry, pop culture fans. I loved Copenhagen. Rick Springfield . . . well, I love Julie).
Why did I love it? Because that’s just the insufferable know-it-all science geek that I really am at heart. I loved seeing a play about two people I knew a lot about, but probably many in the audience didn’t. I loved laughing out loud when the physics was funny, and having the rest of the audience look at me like, “what’s he laughing at, the insufferable know-it-all?” I loved being indignant when in the play Hahn and Strassmann are credited with the discovery of fission, when I knew it was Lise Meitner who made the all-important, but historically neglected, cognitive leap. I loved watching the passion and the excitement for science that I’ve felt myself and seen (on a much grander scale) in real working physicists portrayed so honestly and so well by two actors on stage. I’m that kind of insufferable know-it-all science geek.
For my birthday somebody gave me a Barnes and Noble gift card and I used it to buy Copenhagen the play and Copenhagen the PBS movie. Yes, I do know how to party, thank you very much. In case you don’t know, the play is about German physicist Werner Heisenberg’s visit to Danish (and half-Jewish) physicist Niels Bohr in occupied Denmark in 1941. That real-life meeting is the stuff of legend and controversy. It resulted in an argument that kept the teacher (Bohr) and the student (Heisenberg) apart for the rest of their lives. Heisenberg was head of the German atomic bomb effort. Bohr was the world’s expert on fission. What had Heisenberg said that had so angered his mentor that they never spoke civilly again? Why had Heisenberg come to Copenhagen? What had he hoped to accomplish?
That’s the subject of the play, and it’s a beautiful (if probably non-historical) piece of theater, with a moment that literally made me jump out of my skin, I was so enraptured.
But that’s not what I want to write about.
Reading and watching the play again, I’ve come across an idea that flew by too quickly in the live play, but that now has fully caught my attention and utterly thrilled me.
Heisenberg of course (he says in his insufferable know-it-all science geek way) is known for the Uncertainty Principle, and his first description of it is described in the play. Imagine Margrethe Bohr (Niels’ wife) as the nucleus of an atom. Imagine Niels as an electron in orbit. We can’t see electrons, we can’t measure them in any way, so we have no idea where Niels is. On this scale, Niels could be anywhere in Copenhagen, so much larger is the atom than its nucleus.
But Heisenberg, playing the part of a photon, collides with Niels, detecting him. Photons have energy, and this act of collision knocks Niels from his orbit. We know where Niels was, but now we don’t know where he is, because the act of measuring has altered him forever. That, says Heisenberg, is uncertainty.
Not so fast, says Bohr. It is true that the collision has affected me. But, my dear Heisenberg, the collision has also affected you. If we simply measure you before and after, we can know exactly what happened to me. We can still know where the electron is and where it is going. The problem, Heisenberg, is that we can’t measure YOU.
This is exactly the discussion Bohr and Heisenberg had when Heisenberg first introduced the uncertainty principle. Heisenberg wanted to define it entirely in terms of measurement messing up our ability to know everything. Bohr recognized the fallacy. Uncertainty isn’t an emergent property, happening only when two particles interact. Instead, uncertainty is inherent, the result of the fact that both interacting particles themselves possess an intrinsic uncertainty.
Huh? OK, here’s my try at teaching the Uncertainty Principle in a different way, as best I understand it, anyway. I’ve been wanting to do this for a long time, so bear with me.
Einstein showed that light is lumpy. It comes in waves, but also particles called photons. Depending on what it’s doing, light can be wave-like or particle-like. De Broglie suggested that not just light, but matter, too, has this duality. An electron, in other words, can behave like a wave.
OK, imagine an electron as a wave. It is what we call a wave pulse. In most locations the amplitude (up and down disturbance) of the wave is zero. In a particular location the amplitude gets large. That’s the electron!
Ignore the “time” caption. It’s really spread in space, not time, but that’s the best image I could find. What’s waving? Wait for it . . . it’s a probability wave. The peaks show a high probability, the zeros show a low probability that the electron is there.
Where the peaks are big, there’s a better chance of finding the electron. Where the peaks are small, there’s less chance of finding it.
Now here’s the thing. To really know the electron, we have to know where it is (its position) and what it’s doing (its momentum). Momentum is related to the wavelength of the electron, the number De Broglie said all electrons have. Now if we know its position exactly, that means at one spot in space the peak is “1” and everyplace else it’s zero. So what’s the wavelength? We can’t know! We have no information on wavelength (and therefore on momentum) if we know its position exactly.
What if we know the wavelength exactly? Well, it turns out that for a wave pulse, to know the wavelength exactly you have to have an infinite number of crests and troughs – who’s to say it won’t change somewhere along the line, after all? If we have an infinite number of crests and troughs, then our wave pulse has become an ordinary infinite sine (or cosine) wave, like this:
So now we know the wavelength exactly. We have no information whatsoever on the position!
For anything in-between, we know something about the position (but not exactly) and something about the wavelength (but not exactly). We can never know both exactly at the same time. And that is the Uncertainty Principle. Notice that there’s nothing weirdly quantum mechanical in here at all, except for the notion that matter has a wavelength. Once we let that idea into physics, uncertainty just pops right out.
I owe this explanation to my quantum mechanics prof at Ohio State, Bill Reay. When he first presented it to me as a sophomore back in 1987 (yes, really), I remember thinking this must be really important, but I didn’t really get it. Since then I’ve gone back to it again and again, and I think I’ve got enough of it now to make it a deep part of how I understand and look at quantum mechanics. I hope I’ve taught it successfully.
OK, if you’re still with me after all that, either you’re an insufferable know-it-all science geek like me, or else you really have nothing to do. So what about Copenhagen? The brilliant part, I think, is that Freyn takes this very esoteric argument about the nature of uncertainty, an argument that Bohr and Heisenberg really had, and turns it into a literary device that reveals the whole point of his play. Where does uncertainty come from? Not from our interactions, that’s just a side effect. Uncertainty comes from each of us. Why don’t we know what really happened in that fateful meeting? Because Bohr didn’t know himself. Because Heisenberg didn’t know himself. There is intrinsic uncertainty within all of us.
Bohr: But Heisenberg! Heisenberg! You also have been deflected! If people can see what’s happened to you, to their piece of light, then they can work out what must have happened to me! The trouble is knowing what’s happened to you!
Though it happens on p 69 of a 94-page play, that for me is the climax, the critical moment when it all comes clear – or, ironically, intrinsically unclear. God, how I wish I had written something a tenth as brilliant as that analogy.
On February 12, we celebrate Darwin Day, the 200th birthday of Charles Darwin. As the milestone approaches, I’m reminded of something I learned recently.
Never rise above.
I was listening to an NPR series on science and faith, and the topic of the episode was Evolution and God. A filmmaker named Randy Olson, the producer of a film called “A Flock of Dodos” was being interviewed. He said something that really caught me. In the film, Olson shows the leaders of the intelligent design movement, and also a group of biology professors. He found that the biology professors came off to the audience as smug and arrogant. Why? Because they ignored the cardinal rule of filmmaking. Never rise above.
When you rise above in any scene, whether in a movie, on TV, in live theater, what have you, you create sympathy for the “other side.” This makes a lot of sense to me, and it occurs to me that we teachers usually obey this rule everywhere – except when discussing evolution.
Here’s the thing: evolution is hard. It is no wonder that many people today don’t get it. Evolution seems unbelievable, which of course is part of what makes it so wonderful. If you disagree that it seems unbelievable, consider that for thousands and thousands of years no one got it. Not Isaac Newton, not Aristotle, not Gauss, not Descartes, not Galileo, not any of these minds we think of as the best minds that ever were. If they didn’t get it, then what chance do we have?
We have an advantage, of course. We live after Darwin, Alfred Russell Wallace, Ernst Mayr, Theodosius Dobzhansky, George Gaylord Simpson, JBS Haldane, and dozens of others. We live after Rosalind Franklin, Watson and Crick, and Thomas Hunt Morgan. And we live in the time of Richard Dawkins and Stephen Jay Gould, the great teachers of evolution in our time.
Still, if you’re not immersed in these ideas, you are in the same situation as Aristotle, Newton, and the rest. And they didn’t get it. So it should not be surprising that so many very smart people don’t get evolution. It’s hard.
When we teach the uncertainty principle, special relativity, electromagnetism, even Newton’s laws, we are gentle. We are understanding of setbacks and misconceptions. We use humor. We use bad jokes. We help our learners. We teach gently.
When we teach evolution, why are we seen as smug and arrogant? Why do we lose our temper? Why do we “debate”, ridicule, condescend?
Well, we know why. There are people who lie. There are people who aren’t interested in the truth, but instead are focused on scoring rhetorical points. They say, “Why have you never seen a fish turn into a frog?” knowing full well that this isn’t how evolution works. Fish don’t turn into frogs. If they did, evolution would be in a mess, because such an event would show that genomes are so fragile as to make such concepts as “species” utterly meaningless. These people know they’re setting up straw men. The arguments sound good, particularly if you’ve only heard the comic book version of evolution. But they’re not good science, they are rhetoric. And that makes one angry.
It’s so important, though, not to get angry. Don’t rise above. Teach gently.
There are clues, if we know where to look. Sea turtles are my favorite animals. They live in the ocean, often floating above miles of mostly frigid ocean water. Yet they breathe air. They must lay their eggs on land. What a ridiculous place for an air-breathing, egg-laying animal to find itself! It is as if an elephant must spend half its life in the clouds, trying not to fall. What are turtles doing in this crazy place?
Evolution tells us. Millions of years ago, the first turtles, or at least their ancestors, lived on land. They (like many land creatures) lived close to water, because water meant food. Water meant protection. Water meant life. Some turtles found it easier to stay hidden in water, hunt in water, stay cool in water. Those that were (accidentally) better adapted to this watery life survived better. Perhaps there were dangerous predators on land, or perhaps the food they sought was further out in the water.
This happened many, times, with many species of turtles. We see some turtles – like box turtles – that only occasionally return to the water. We see others – like sliders and painted turtles – that live mostly in the water, but can still move about well on land. Some even can climb trees! Still others, such as the fly river turtle, live in fresh water, but have developed paddles instead of front legs. And then there are the sea turtles, creatures that live in the sea nearly their entire lives, returning to land only to lay their eggs.
And yet all these turtles still breathe air, still lay hard-shelled eggs. None have lost these land adaptations. We never find a turtle with gills.
Similarly, we never find a whale with gills, or a snake, or a crocodile, or any of the other many species that have returned to the water. They carry with them the signs that their ancestors once lived on land.
This is not proof, of course, but that’s not what we’re after, any more than we’re after proof when we move a magnet through a coil of wire to make electricity. We’re building a case, we’re presenting evidence, ideas, thoughts that might grow. We light a fire. We are gentle guides, not demogogues trying to win a debate.
So as this 200th Darwin Day approaches, remember that evolution is hard. Teach gently.
Episode Seven of Cosmos is another of my very favorites. Sagan starts with a question I remember asking as a boy: what are the stars?
He goes to his old elementary school and shares his sense of wonder with a group of ten-year-olds. He hands out photographs from the Voyager probes to Jupiter. He answers their questions with depth and passion and gentleness. He really is a teacher in these scenes. I don’t know how much these teaching moments meant to me back in 1980, when I was an enraptured 12-year-old, but they certainly mean a lot to me now.
We are each on a personal journey. We start in a place – “What are the stars? Where did the world come from? Is there any such thing as a piece of water, or a piece of air?” – and the answers we find lead us along new paths. That’s why I’m not so interested in teaching cutting edge science. All science is cutting edge for someone. It’s all a journey. It’s all going from one place to another, and every discovery, when you make it yourself for the first time, is wondrous. I’m after that moment.
I’m still listening to Joseph Campbell, and I have to say I’m very confused. At times he seems to be saying, life is great, everything is great, find and follow your bliss and you will be happy. At other times he says if you want to know what happens when a culture loses its mythology, read the New York Times. He talks about people in ancient times or in recent but non-Western cultures who willingly, with joy, accepted ritual sacrificial torture and death as true heroes. Then he says that the death and destruction wrought by our own society shows that we’ve lost our way. I think there’s a bit of false nostalgia in what he says, because it’s my contention that all those societies were violent, wasteful, unwise with resources, cruel, misogynistic, and a real mess. Read The Third Chimpanzee if you don’t believe me. Look at the record of macrofaunal extinction. Look at how the Native Americans systematically destroyed the environment, killed one another, changed the world, despite their beautiful later philosophy.
I don’t know. Maybe I’m just not getting the full picture yet, or maybe Campbell really is just contradictory. “Do I contradict myself?” Whitman said, “Very well, then, I contradict myself ,I am large, I contain multitudes.”
When questions such as these, of meaning and interpretation, of journeys and destinations, come up, I think of a young baseball player. He is ten years old. His team trails by 2 runs and it is the bottom of the final inning. There are 2 outs and one runner stands on second base. The ballplayer squeezes the bat handle, then swings. The ball connects and flies away. The joy and poetry of movement and effort are alive in his motion. He is alive, as alive as he’s ever been, alive in this moment of bat connecting with ball. The ball soars over second base and lands squarely in centerfield. The baserunner streaks around third and heads home. The centerfielder scoops and throws toward home plate and our batter, now rounding first base, sees his chance and dashes for second. But it’s a trap; an alert infielder cuts off the throw, throws behind our hero, and he is trapped. Trapped between first and second, with the game on the line.
Our batter, now abecome a runner, heads for second base, knowing the ball, the final out, the death of all opportunity, lay behind him. He knows what is coming, too. The ball flies past his ear and lands in the glove of the shortstop. Our hero reverses ground, heads back to first, but the ball is there first, and he must reverse yet again. Back and forth he goes, his game, his very life, the very life of his team, on the line.
We, of course, are in the stands. We see the journey. We know that the outcome of a game between two teams of ten-year-olds matters not at all. Perhaps, we think, we shouldn’t even keep score. It is about building skills, ethic, character. The destination doesn’t matter. Not to us.
But to our hero, destination is everything. The journey is thrilling, yes, the joy of hitting the ball, the satisfaction of seeing it land untouched in center. The terror of being picked off first and the desperation of reversing, again and again, between the bases.
Were he a Buddhist, our hero might stop, allow himself to be tagged out. It wasn’t meant to be. For after all, only by giving up the struggle can we find true bliss. But if he did so, willingly, then the game would be over. Literally and forever over, for who would play the game if all understood that the destination is no different from the place we are right now, at this very moment? And yet the game is beautiful, a beautiful thing that is beautiful only because the participants realize only dimly, if at all, that they are dying men playing a game only to hide for a while the pain of dying. They play not for the journey but for the destination, and so it must be, or else the game stops. Rage, rage against the dying of the light!
Finally our hero slips, turning too quickly or not quickly enough. He is tagged out, and the game ends. While the opponents celebrate, our hero bursts into tears, right there between 1st and 2nd. His joy turned to pain, his loss so real, so solid, that it weighs on him. Why play the game at all if it leads only to pain? Because it is all we can do. Because tomorrow is another game. Tomorrow is another chance to reach 2nd.
James Trefil wrote a book called “Why Science?” I was disappointed by it. Trefil focused on the idea of scientific literacy, the idea that you have to know a little about Darwin, a little about Einstein, etc. to be a socially literate person. Fine. All well and good. Also not very inspiring. I was left uninspired.
Joseph Campbell (again) gave me so much better an answer. Of course he wasn’t talking directly about science. Instead he was talking about his subject, mythology. In so doing, he caught me by my soul – quite a trick for an atheist, I think.
In “The Power of Myth,” Bill Moyers asks Campbell:
“Why myths? Why should we care about myths? What do they have to do with my life?”
It’s the question I’ve heard a thousand times, whether spoken or not. It’s always there, waiting to jump out and show its ugly face. This is all well and good, what you’re showing me, but of what use is it? How can it make me richer, prettier, more popular? What good is it?
And Campbell blows it out of the water. Here’s what he says. Savor the words.
“Well, my first answer would be, well, go on, live your life, it’s a good life, you don’t need this. I don’t believe in being interested in subjects because they’re said to be important and interesting. I believe in being caught by it . . .”
How marvelous! How exactly what I wish I had said, what I always wanted to say, what I always meant to say. Then he goes on.
“But you may find, with a proper introduction, this subject will catch you.”
This is teaching.
Joseph Campbell’s “proper introduction” is what I want to do with my own living myth, the story revealed by science. It’s caught me. I want to help others be caught by it, too. Or even if they’re not, it matters little. I have to do what I do, I have to tell the tale, precisely because it has caught me. When you’re in love, you want to tell the world.
It would be silly to deny the usefulness of science in the world today. We are very much like the passengers on the Titanic. Without science we cannot survive on this tiny planet – most of us, anyway. Were science to disappear tomorrow the suffering and carnage that would befall the human race would dwarf even the most bloody and vile of the “holy” books’ worst descriptions.
Yet, like the overcrowded occupants of that tiny boat, ignorance of science can be deadly. Hitting an iceberg is bad. Having watertight compartments dependent upon the idea that you won’t sideswipe an iceberg is worse, particularly if your rudder turns you too slowly to avoid such an event. If we don’t get the message science gives us, we’re in cold water with no rescue in sight.
All that is well and true. It also will never work. Most people will go on living their lives not knowing what’s under the hood, how carbon dioxide heats the Earth, or how misuse of antibiotics leads to unfortunate microbial evolution. The world is a mess and it always has been, and people will keep living and dying surrounded by, and creating, the mess of the world. You don’t have to know anything about science to participate in the mess. Death is not much of a motivator – it’s just too common a thing.
But if you can get caught by science, it can change your life – yes, in all the material and practical ways, but also, mysteriously, in a deeply spiritual sense. You are a way for the universe to know itself. You are the consciousness of the planet. You speak for Earth. Your body is the result of billions of years of evolution, and your deepest ancestors as different from you as they are from a mushroom. You and the mushroom, in fact, are cousins, separated by a common ancestor only (at most) a couple billion years in the past.
We live on a tiny bit of rock circling a thermonuclear reaction almost a hundred million miles away. Below our feet the simmering remains of ancient stars keep the center of our planet so hot that to go only a few miles into this molten cauldron would bring certain death. Only a few miles above the surface the air becomes too thin to breathe and the pounding radiation from that faraway star would fry us in seconds. Yet within this thin envelope we have evolved, overcome enormous odds, and finally become aware enough to understand our perilous condition.
Yet in this thin envelope we are surrounded by life. The trees in the forests from which we came are marvelous machines for collecting sunlight and changing air into wood, for one reason and one reason only. The wood provides a protective scaffold allowing the trees to climb high above their neighbors, collect more sunlight, and, finally, send their own DNA code into a tiny seed that – if it is very, very lucky – will grow into yet another wood-making machine.
And all this activity, all this significance, plays out on the canvas of the universe, as much an event as a place. We think we know how it started, but we don’t really understand what started that start. We think we understand the laws of nature, but we don’t know why they are what they are, if they might ever change, or even if such a question has meaning.
We know that stars make carbon, and that the knife-edged process that creates carbon in stars seems utterly unlikely, and yet (given the laws of nature) completely inevitable. Did it have to be so? We don’t know, but we’d like to find out.
We are a young species on an ancient planet in an even more ancient Cosmos. We don’t know why we’re here, we don’t know where we are going, we don’t know even if such questions can have a meaning. But we, the collective consciousness of the planet, are trying to find out. That’s science. Did it catch you?
One of the great things about the history of science is the discovery of a great but hidden story. Unlike art, or writing, or other things that make us human, most of the amazing discoveries of science are hidden from view. Instead, we get a “smoothed out” version taught in school and in various popular accounts.
How do we know what stars are made of? To answer that question, I could write about Fraunhofer lines, spectrographs, maybe even mention the discovery of the expansion of the universe. But there’s a hidden story here, the story of a scientist named Cecilia Payne.
Astronomy was one of the few fields in which women were early on encouraged to participate. Of course, “participate” is a relative thing. Mostly women were used as “computers,” performing long and complex calculations so that the male astronomers could theorize, get published, and earn tenure. But a few women overcame the barriers and found their own way.
Cecilia Payne was from England, but came to Harvard University to study the spectra of stars – mostly because Cambridge University in England did not award degrees to women. Unbelievably, this was less than 100 years ago, In 1923, Payne began her studies at Harvard.
At the time, most scientists believed, based on what they saw in the spectra of stars, that stars were made mostly of iron. Payne had another idea. Despite what everyone else thought, Payne analyzed the spectra of stars and thought she saw the overwhelming signature of hydrogen and helium, the two simplest and lightest elements in the universe.
Payne’s advisor, the famous astronomer Henry Norris Russell (of the Hertzsprung-Russell diagram) , convinced Payne to remove her most spectacular finding – the abundance of hydrogen and helium – from her Ph.D. thesis. It was simply too controversial, and Payne acquiesced.
A few years later, Russell recognized his mistake. Payne had seen what no one else had. Stars were mostly made of the universe’s very simplest ingredients.
Why was this so important? Simply this – stars are the places where all the complex elements of the universe are formed. Everything around us – carbon in our toast, oxygen in our air, silicon in our computers – was formed long ago and far away inside giant stars. There are other wonderful hidden stories behind these discoveries, too. But our awakening to this amazing fact started with Cecilia Payne, a woman scientists who overcame the obstacles to see where no one else had seen before. She looked inside the rainbows of the stars, and discovered there one of the best-hidden secrets of the universe.
I began reviewing each episode of Cosmos, but was sidetracked by a multitude of other things. Much delayed, I finally found the time to watch episode six, “Travelers’ Tales.”
Strange that I waited so long for this one, because this is the episode I remember most from my youth as the reason to make science my way of life. “The world is my country,” Sagan quotes Christiaan Huygens in this episode, “Science my religion.”
In particular, the final sequence, a journey through the rings of Saturn and to the surface of the cloudy moon Titan, struck me as the sorts of wonder promised by science. When Cosmos was first shown, we were in the midst of the greatest voyages of discovery in history, those of the Viking, Mariner, and finally the Voyager spacecraft. What would we find in these faraway worlds? Wonder . . .
Sagan mentioned that he couldn’t wait for the Cassini probe to reach Saturn and send a lander to Titan. Sagan, of course, didn’t survive long enough to see this mission succeed, but succeed it did. Now we can know so much more about Titan than Sagan was ever able to know himself. Now we can know just what’s down there.
Let’s take a real visit, aboard the Huygens spacecraft, launched by Cassini to the surface of Titan.
I am the Huygens spacecraft, named for a human from 17th century Earth, the first human to view through a telescope my own final destination, the Saturnian moon called Titan. On Christmas Day, 2004, I left the only home I had ever known, the Cassini spacecraft, and began my short journey toward the cloud-covered world larger than Mercury, with an atmosphere thicker than Earth’s.
On January 14, in the year 2005, I enter this atmosphere, taste its composition, measure its thickness, and begin my descent. As I fall, I deploy a parachute that captures the thick nitrogen and methane sky and slows my rapid descent. I open my eyes and look around.
What wonders I see! Below me are rivers that flow, not with water, but with liquid methane. Far to the north, beyond the reach of my own cameras, Cassini will spot entire lakes of liquid hydrocarbon. This place is a pyrotechnician’s dream. Were there free oxygen here and a single random spark, the entire frozen world would go up in flames.
For two and a half hours I drift toward the landscape below. I land, finally, near a plateau called Xanadu, after the mythical pleasure dome sanctuary imagined by the human poet so long ago. Around me are rocks, made not of silicate, but of water ice, frozen so solid as to behave like solid stone. Chips of these stones, a sand of water ice, surround me everywhere. On Earth, sand grains are washed and worn by the action of liquid water. On this world, the “sand” is water, and is worn by liquid methane, which rains from the sky and rolls across the surface. Titan is the first world besides Earth where we have seen standing bodies of any liquid. Truly an amazing sight.
More wonders abound. Here there are ice volcanoes, driven by the tidal forces of giant Saturn. The volcanoes spew out not molten lava, but liquid methane and ammonia, and may be the source of the atmosphere blanketing the planet. The pressure of the atmosphere here at the surface is about what one would feel at the bottom of a swimming pool on Earth – were you to visit me here, you would literally swim through a sea of nitrogen and methane.
In this bizarre, very cold, but very active landscape, could anything be alive? Though I have taught you much you never knew before, there are many questions I cannot answer. My time is short here. My batteries grow weak, and I become weary. After barely an hour in this world of amazement, I am silent. You must come here again. When you come, find me, won’t you? Find this place, the place where, for the first time, living beings from Earth landed a probe on the moon of another world. I . . . will wait.
Recently, in relation to a question about educational impact, someone made the claim that everything is measurable. In response, I said that while educational goals are good and important, I didn’t believe the really important ones were measurable. Instead, I said, you just got to have faith.
What in the world does a professed atheist mean by such a statement? Isn’t faith the enemy of reason? Well, maybe. If the scientific endeavor teaches us anything, I think it teaches us humility in the face of a universe that is a complex, glorious, beautiful mess.
In 1896 Henri Becquerel discovered that photographic film left near uranium salts was exposed by those salts. Marie and Pierre Curie, Ernest Rutherford, and others went to work to find out what was happening and why. They discovered something amazing. The uranium atoms were exploding, shooting off pieces of themselves and in the process changing into something else.
Marie Curie named the process radioactivity. Rutherford found that he could predict, with great accuracy, exactly how many explosions would happen in a given period of time, and found that the activity of a sample went down over time, and more and more radioactive atoms transformed themselves into stable atoms.
But the fundamental question remained. Consider a single uranium atom. Sit it on a table and watch it. It might explode in a second. It might explode in a year. It might explode in a billion years or more. Why? No one knows. Every uranium atom (of the same isotope, that is) is exactly like every other uranium atom. Why should one explode now and another not for billions of years? No one knows. Not only that, but through rigorous study and logic, the next generation of scientists discovered that there is no possibility of an answer. The probabilities are as deep as the reality goes, as far as we can tell. Yet somehow this atom explodes and that one doesn’t.
In the face of this sort of mystery, I choose humility. There’s so much we don’t know, so much mystery left to explore. When I say I am an atheist, does that mean I’m certain what I say is correct? Not even close.
The universe is hard. I’m still learning. In the process, I have faith, faith that the direction I’ve chosen, sight unseen, will get me somewhere interesting.