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I love amazing ideas. I recently encountered another amazing idea, one that may be an old story to some people, but it’s new to me, and I think it’s wonderful.
One of the many radioactive isotopes found naturally on Earth is an isotope of potassium called potassium 40. It decays into argon 40 with a half life of something over a billion years.
Now, potassium 40 is formed inside stars, and supernovas make lots and lots of it very quickly. Potassium 40 is very rare on Earth today, but that’s because so much of it has decayed. In the past it was much more common, which means that potassium incorporated into living things would have been much more radioactive in the past. A little radioactivity in your body isn’t such a big deal (you’ve got some now), but a lot of it could be a big problem.
One of the greatest mysteries of life on Earth is that it seems to have begun almost as soon as it could have, but remained only single-celled and simple for a very, very long time. The simplest conclusion to draw from these two facts is that the origin of life isn’t that difficult or unlikely, but the origin of complex life is much, much harder.
But what if potassium 40 has a role in this story? What if complex life couldn’t get going because every time a bunch of cells got together, the radioactivity of natural potassium was too much to handle?
If that were the case, it would put a sort of stellar stopwatch on the development of life. Life would have to wait some fairly set amount of time after the formation of a planet to get complex – that time depending on how recently the cloud from which the planet formed was seeded by a supernova.
It would also be yet another demonstration of the fact that the properties of radioactive decay are the same today as they were billions of years ago. Wonderful!
Take a look at more details here.
Episode Four of Cosmos is called Heaven and Hell. For me the two most memorable moments are when Sagan takes the Spaceship of the Imagination down to the surface of Venus and when he speaks so eloquently of the discoveries that let us explore that surface without even going there.
One of the incredible and thrilling things about science is that there’s a way we know everything we know. No divine revelation, no obvious truths, nothing but that which comes from rigorous logic and experimental evidence.
How do we know what stars and other bodies are made of? We can’t go there; most are much too far away. Even if we could, we couldn’t very well scoop up a bucketful of star and take it home to examine it. We need another way.
That other way is to look at the light from the stars. By sending that light through a diffraction grating we can spread the light out, and we find that the light of stars is made of all the colors of the rainbow. Amid all the rainbow colors are black lines. These are fingerprints, showing what atoms are present in the atmospheres of the stars. By examining the patterns of the black lines, we learn what the universe is made of.
This is one of the most profoundly beautiful and amazing findings of science. By examining closely a rainbow of starlight we discover the composition of the universe itself. And what do we find? We find that the universe is made of the same stuff as we are. We and the universe are one.
Not bad for a little stripe of colored light.
I like to write about the wonder of science. But in the spirit of Johannes Kepler and his discoveries that went against his own fondest wishes, I’m writing today about an unpleasant aspect of the theory of evolution. It’s an important aspect, though, because ignoring it can lead to some profound misconceptions about the nature of the world in which we live.
Human beings are odd and unique creatures in that some members of our species are able to digest lactose as adults. All mammals, of course, digest lactose as infants, but as most mammals grow and develop that lactose-digesting enzyme, called lactase gets turned off. In certain human populations, particularly those of Europe and parts of Africa, the enzyme keeps functioning during adulthood.
One can think of this as a genetic adaptation that swept through the population. But what does that mean, really? Once a child is born, that child either has lactose tolerance or does not. What it means is that those without lactose tolerance, in general, did not reproduce. Why? Because they did not thrive. For many, perhaps most, it means that they died in childhood before they could have children of their own.
Think of what that meant for these children. They were born into a society that was becoming more and more dependent on milk and its products. Yet these children couldn’t digest these products. They got sick. They probably got weak from lack of nutrition. Many probably died.
The lucky ones, those with the gene for making lactase into adulthood, did thrive, did survive, did reproduce and pass that gene on into the next generation. That’s natural selection.
Natural selection is a wasteful process. It’s main tool is death – or at least inability to reproduce. But let’s face it. Lactose intolerance, and even malnutrition, don’t result in healthy, happy adults who just happen to be infertile. It results in dead people. Dead children.
So when we say something like, “Lactose tolerance swept through the population because it greatly aided survival,” what we’re really saying is that those with the gene lived, those without it died. And they died not just a death, but an unhappy and miserable death in which their bodies rejected the very sustenance offered them by otherwise loving and caring parents.
This is a harsh lesson, but an important one. Sometimes well-meaning people try to bridge the gap between science and religion, between evolution and God, by saying, “Evolution is how God did it.” Fine, you can believe that if you wish. There is certainly no test for or against that idea that I could think to devise. But be aware of what you’re saying when you make such a claim. Beware of the attributes you’re giving God.
I’m a parent of two amazing girls. I can’t imagine a more horrible event than losing either of them. Yet evolution depends on this event, counts on it. Death makes evolution go.
It’s not pleasant, but it is real. Science can reveal breathtaking wonder and beautiful, deep, unexpected connections. But we must always examine it openly, without bias, because it doesn’t have to conform to our wishes or hopes. And often, as Kepler found, it won’t.
Episode three of Cosmos was on the menu for tonight. I have to say that though I love all 13 Cosmos episodes, three has never been one of my favorites. It’s a little dreary in places, particularly all the troubles surrounding Johannes Kepler, his boring teaching style, and his search for the “harmony of the worlds” (the name of the eposode).
But in the starkness there is still beauty, wonder, and truth. Sagan tells nothing less here than the birth of modern science. In his rejection of his most cherished beliefs in favor of observational truth, Kepler sets the stage for all the discoveries to come – a direct line can be drawn from Kepler to Newton, and from Newton to Maxwell, Einstein, Heisenberg and all the rest. By showing the world as it really is, absent the gods, angels, or crystal spheres, Kepler set the stage for the naturalistic description of the the world, the great triumph and achievement of science. We can understand the world. The world makes sense. We might not like the answer, but the answer is out there, and if we look hard enough, if we ask questions honestly enough, if we’re willing to embrace the answer no matter how uncomfortable, we can find it.
I’ve already written about the starfish story and how important it is to me. I’m faced with something of a dilemma as an educator and I want to write about it in terms of that story.
I identify with the young girl in the story, who visits the beach, picks up starfish, and throws them into the ocean. I feel that this act, of saving starfish one by one, is a metaphor for my work as an educator. Here’s the question.
Do I enjoy the act of throwing starfish back into the ocean, or do I enjoy the fact that starfish are thrown back in? If I knew that by never visiting the beach and never throwing in a starfish myself, that I could actually save ten, or a hundred, or a thousand times more starfish, would I do it? Or does my pleasure come from the actual act of lifting the starfish from the sand and throwing it into the waves with my own hands and arms?
I think that I do not need to be the thrower. If I can inspire others to become throwers, I believe that I can be just as happy. That’s not to say that I won’t do the occasional throwing myself; I think I still will. But if through my actions I can cause more starfish to be returned to the sea, I think I can be happy.
But what if I fail? I know I can reach down, throw a starfish, and have it hit the water. I know I can do that. What if I can’t inspire this action in others?
The starfish analogy is not really perfect for what I do. The interesting thing about what I do is that the starfish themselves can become star throwers. Through the act of being lifted from the sand and tossed back into the ocean, the starfish are given the chance to grow into beings that can walk along the beach, pick up starfish, and throw them back in.
Perhaps a better analogy is a chain reaction. By inspiring two star throwers, they each have the power to inspire two more, who can each in turn inspire two more. Now I start to see the power of inspiration. I teach others so that they may become teachers.
I just hope it works.
Episode Two of Cosmos, called One Voice in the Cosmic Fugue, is where Carl Sagan loses some folks. This episode is all about evolution, natural selection, and just how it is that we humans are cousins to trees.
Trees? Really? We don’t look like trees. We don’t act like trees. Isn’t it kind of insulting to compare me to something that seems so barely alive as a tree?
For me, Sagan lays out a convincing argument. We and trees are made of the same stuff. Our cells use the same systems, the same chemistry, the same code book. Any tree could read my dna sequence. When you look into the deep past, you find trilobite fossils, but no trees, and no people either. We’ve both evolved since those times. We had to come from somewhere. It only makes sense that we came from the life that was here before us. As we go back in time, those life forms we find in the fossil record converge to single-celled organisms. It makes sense that both we and trees, organisms made of many, many cells, would have evolved from single-celled organisms. And on and on.
But for some people the argument doesn’t work. Why? I wish I knew.
We are alive. Trees are alive. That itself is amazing, because there are so many more ways of being dead than alive. The fact that we share so much in common with trees, the fact that we’re both alive, is a big clue that we’re cousins. But what if “alive” were just a condition, like “acid” or “alkaline.” Couldn’t “alive” have happened again and again, and just look the same, just like all rust looks the same because it’s all the same chemical, or all protons in the universe have the same properties? What makes “alive” so different from “rust” or “proton?”
The answer is that life, our life on Earth, made certain choices. There are signatures, in places like the dna codebook, the particular proteins used for particular tasks, and on and on that show that all life on Earth is descended from a single instance, one particular day when something extraordinary happened.
In certain circles, it is considered important to argue about when life begins. If you learn the story that science tells, you discover that life, our life, had a single beginning on this planet, around four billion years ago. That realization renders the question meaningless. The cells in your body right now, wiggling about, taking in nutrients, burning oxygen, sending signals, are descendents of that first day, that single instance, that still unknown, but common, ancestor.
There’s an unbroken chain between then and now. There was never, never, a time when the cells that connect us to that time weren’t alive. Even the sperm cell and the egg cell that came together to form you were alive, before and after they joined. We are all, people and trees, turtles and butterflies, connected by a four billion year unbroken chain of life.
And that is a story worth knowing!
What does it mean to understand?
The essence of understanding in science is often, um, misunderstood.
The “scientifically literate” supposedly can rattle off lots of facts: the boiling point of water is 212 degrees F, hurricanes are caused by evaporation and condensation of ocean water, fog is a cloud on the ground, the cold you feel when you get out of the shower is caused by evaporation.
All facts, stated simply and separately. Any one might appear in question form on a standardized test, with the correct answer hidden among three “distractors.” If you get three of four, you’re literate. Only two, you fail the test. If you get all four, you’re a genius.
But the facts miss the important idea. If science is just a bunch of descriptive facts, then we haven’t learned a thing. Surely true understanding is about the connecting ideas between the facts. Yes, water boils at 212 degrees F, but even below this temperature there are bits of water (“molecules” if you want to get fancy) that enter the air as water vapor. Yes, fog is a cloud on the ground, caused by water vapor re-condensing when the temperature is too low for those molecules to stay in the gaseous state.
Hurricanes happen when water vapor condenses, releasing the very heat it took to evaporate it in the first place. That heat powers the hurricane, driving 100+ mph winds. You get cold when you step out of the shower for exactly the opposite reason. Evaporation is a cooling process. As the most energetic molecules escape from the water drops clinging to your skin, the average temperature of what remains drops lower. The powerful and deadly hurricane and your shivering reach for the bath towel have something deep and profound in common. And that is understanding.
Rock Dad (see the link to his blog on my page) recently reminded me of probably the most formative event of my life, the 13 glorious weeks in the fall of 1980 when Cosmos was broadcast by PBS. A few years ago my lovely wife bought me the 7 DVD boxed set (and I didn’t even ask for it; she is amazing!); I’ve probably watched it all the way through 4 or 5 times now.
I decided to start again Monday night.
First is the music. That sad, plaintive cry at the beginning with those gorgeous orange space scenes takes me right back to 1980, when a 12-year-old boy sat on the floor, inches from the TV, devouring every moment. Cosmos was probably the first time I really started to see science as art, science as humanity. To me, that song is the lone voice in the wilderness of a crazy, incoherent world, a voice that sayss, “And yet, it turns!”
“The Cosmos is all there is, or ever was, or ever will be.” Sagan right away gives us the scope of his subject – everything! His is a story of the universe, yes. But more, it is a story of us, of how we came to know the Cosmos, of how we came to recognize all those wonderful truths – we are all starstuff, a young species on an ancient world, a tiny planet lost in the immensity of a vast and mysterious. And then, perhaps the most important idea science has ever given us. “We are a way for the Cosmos to know itself.”
Sagan subtitled Cosmos “A Personal Voyage.” To me that means that the journey of discovery, from our first childhood questions to our last contemplative thoughts, is a journey open to all of us. Only Kepler could originate his laws of motion, but every one of us can revel in the regularities of the universe. Only Milton Hummason could make the images that proved that the universe is expanding, but we can all appreciate the solution to this puzzling and marvelous mystery. Only the scientists and engineers who built and operated the Voyager spacecraft could snap the first up-close pictures of Io, but we all can marvel at the bizarre wonders of that tortured world. The voyage of discovery is one every one of us can take, a truly personal voyage.
Next week, episode two!