Narrator: Listen to part of a conversation between a student and a university employee.

Employee: Oh, hello … can I help you?

Student: Um … yeah … I’m looking for Professor Kirk; is she here? I mean is this her office?

Employee: Yes, you’re in the right place—Professor Kirk’s office is right behind me—but no … she’s not here right now.

Student: Um, do you know when she’ll be back?

Employee: Well, she’s teaching all morning. She won’t be back until … let me check … hmm, she won’t be back until … after lunch. That’s when she has her office hours. Perhaps you could come back then?

Student: Oh, unfortunately no. I have class this afternoon. And I was really hoping to talk to her today. Hey, um, do you know if … she’s accepting any more students into her Introduction to Biology class?

Employee: You wanna know if you can take the class?

Student: Yes, if she’s letting any more students sign up, I’d like, I’d like to join the class.

Employee: Introduction to Biology is a very popular class, especially when she teaches it. A lot of students take it.

Student: Yeah, that’s why the registrar said it was full. I’ve got the form the registrar gave me, um, to get her permission to take the class. It’s all filled out except for her signature. I’m hoping she’ll let me in even though the class is full. You, see, I’m a senior this year, and, uh … this’ll be my last semester, so it’s my last chance …

Employee: Oh, wow, really. I mean most students fulfill their science requirement the first year.

Student: Well, I mean, um … to be honest, I kept putting it off. I’m not really a big fan of science classes in general, and with the labs and everything, I’ve never quite found the time.

Employee: Your advisor didn’t say anything?

Student: Well, to tell you the truth, she’s been after me to take a class like this for a while, but I’m double-majoring in art and journalism and so my schedule’s been really tight with all the classes I gotta take, so somehow I never …

Employee: [politely cutting in] Well, perhaps you could leave the form with me and I’ll see if she’ll sign it for you.

Student: You know, I appreciate that, but maybe I should explain the problem to her in person … I didn’t want to do it, but I guess I’ll have to send her an email.

Employee: Hmm. You know, not all professors check their emails regularly—I … I’m not sure if Professor Kirk does it or not. Here’s an idea … why don’t you stick a note explaining your situation under her door and ask her to call you if she needs more information?

Student: Hey, that’s a good idea, and then I can leave the form with you—if you still don’t mind.

Narrator: Why does the man say this to the woman:

Student: You know, I appreciate that, but maybe I should explain the problem to her in person …

Narrator: Listen to part of a lecture in an astronomy class.

Professor: I’m sure y’all have been following the news about Mars. A lot of spacecraft have been visiting the planet recently—some have gone into orbit around it, while others have landed on it. And, they’ve sent back a … an abundance of data that’s reshaping our knowledge … our vision of the planet in a lot of ways. Is there anything that you’ve been particularly struck by in all the news reports?

Female Student: Well, they seem to mention water a lot, which kinda surprised me, as I have this picture in my head that Mars is dry … sort a dry and dead.

Professor: You’re not the only one. You know, for centuries, most of our knowledge of the planet came from what we saw through telescopes, so, obviously, it was pretty limited—and our views of the planet were formed as much by writers … as they were by serious scientists. When the first science-fiction stories came out, Mars was described as being a lot like Earth except [pauses to let students finish his sentence]

Male Student: I know: the planet was red and, uh, the people were green. I’ve seen some of those old movies. [half laughing, half sarcastic] What were they thinking? I mean really … they …

Professor: [interrupting] Well, it seems silly to us now, but those ideas were quite imaginative and, occasionally, scary in their time. Anyway, we began to rethink our image of Mars when the first spacecraft flew by the planet in 1965 and sent pictures back to Earth. Those pictures showed a planet that looked a lot more like our Moon than Earth—lots of craters and not much else. It was bitterly cold, it had a very thin atmosphere, and that atmosphere was mostly carbon dioxide. So the view of Mars after this first flyby mission was that dry, dead planet that Lisa mentioned.

But, then there were more visits to the planet in the 1970s—and this time the spacecraft didn’t just fly by; they orbited … or landed. This allowed us to receive much more detailed images of the planet, and it turned out to be a pretty interesting place. Mars had … has a lot more than craters—it has giant volcanoes and deep canyons. It also showed signs of dried-up riverbeds and plains that had been formed by massive floods. So we concluded that there must have been water on the planet at one time—billions of years ago. Now, what does it take for water to exist?

Male Student: You need to have a warm-enough temperature so that it doesn’t freeze.

Professor: That’s one thing—and the other is that you need enough atmospheric pressure, thick-enough air so that the water doesn’t instantly vaporize. The Mars we see today doesn’t have either of those conditions—it is too cold and the air is too thin—but a long time ago, there may have been a thicker atmosphere that created a greenhouse effect that raised temperatures—and maybe that combination produced water on the surface of the planet. So maybe Mars wasn’t just a dead, boring rock; maybe, it was, uh, a fascinating fossil that was once alive and dynamic—worthy of exploration. [pause] Now let’s jump forward a few decades to the beginning of this century, and a new generation of orbiters and landers that have been sent to Mars. Of course, the scientific instruments now surveying Mars are far more sophisticated than the instruments of the ′70s, so we’re getting all kinds of new data for analysis. And, not surprisingly, that data is challenging our notions of what Mars is like. Lisa, you mentioned that a lot of the news reports talked about water—do you remember any of the details?

Female Student: Well, they were showing these pictures of these long, uh, cuts in the ground, which would be gullies here; I mean on Earth.

They say that since, uh, gullies are usually formed by water, it seems like they might be evidence that water still exists on Mars, but I didn’t get how that worked.

Professor: I’m not surprised. There’re a lot of theories … a lot of speculation … and some argue the formations aren’t caused by water at all. But there’re some ingenious theories that assume that there’s a lot of water right under the planet’s surface that somehow is causing the gullies to form. If we could only get a lander there … but the gullies aren’t in places where we can send landers yet. Anyway, if there is some kind of water activity, it may change our view of the planet once again … to something that’s not dead, not even a fossil, but rather a planet like Earth that undergoes cycles—think of our ice ages—over long periods of time. Maybe Mars could sustain water again at some distant date.

Narrator: Listen to part of a lecture in an art history class. The professor has been talking about colossal statues.

Professor: We’ve been looking at colossal statues—works of exceptionally huge size—and their essentially public role, in commemorating a political or religious figure. We’ve seen how some of these statues date back thousands of years … like the statues of the pharaohs of ancient Egypt—which you can still visit today—and how others, though surviving only in legend, have fired the imagination of writers and artists right up to our own time, such as the Colossus of Rhodes, that 110 foot statue of the Greek god Helios [HEE-lee-us]. Remember, this same word, colossus—which means a giant or largerthan-life-size statue—is what today’s term colossal derives from.

Now, it was one thing to build such statues, at an equally colossal cost, when the funds were being allocated by ancient kings and pharaohs. But if we’re going to think about modern-day colossal statues, we need to reexamine more closely their role as social and political symbols, in order to understand why a society today—a society of free, taxpaying citizens— would agree to allocate so much of its resources to erecting them. A good example to start out with would be Mount Rushmore.

Now, many of you have probably seen pictures of Mount Rushmore; perhaps you’ve actually visited the place. Mount

Rushmore, in South Dakota, is a colossal representation of the faces of four U.S. Presidents: George Washington, Thomas Jefferson, Theodore Roosevelt, and Abraham Lincoln, carved directly into a mountain. Imagine: each of those faces in the rock is over 60 feet high! Now, carving their faces took over six and a half years, and cost almost a million dollars. And this was in the 1930s, during the worst economic depression in U.S. history! Does that strike any of you as odd?

Well, I personally think that the Great Depression of the 1930s actually makes this more understandable, not less so. Often it’s the case that, precisely at times of hardship—when the very fabric of society seems to be unraveling and confidence is eroding—uh, that people clamor for some public expression of strength and optimism, perhaps as a way of symbolizing its endurance in the face of difficulty.

So with that in mind, let’s go back to Mount Rushmore. Actually, the original motivation for a colossal monument in South Dakota had very little to do with all this symbolism … and everything to do with money: you see, it was first

conceived of basically as a tourist attraction, and it was supposed to feature the images of legendary figures of the American West, like the explorers Lewis and Clark. The government of South Dakota thought it would bring lots of money into the state.

It was only later on that the sculptor—the artist who designed and oversaw the project, a man named Gutzon Borglum— decided the project should be a monument honoring four of the most-respected Presidents in U.S. history; much more than a tourist attraction … its very prominence and permanence became perceived as a symbol of the endurance of U.S. ideals and the greatness of the country’s early leaders. So, you see, what began as a tourist attraction became something far loftier.

Let’s look at another example of this phenomenon.

The Statue of Liberty is another colossal statue—[indicating by his tone of voice that his assumption is a near

certainty] one that I assume a number of you are familiar with. But, umm, I would guess that—like many people today—you don’t realize that, when it was designed, over a century ago—by a French sculptor—it was intended to symbolize the long friendship between the people of France and the people of the United States—one which dated back to France’s support of the American colonies’ war for independence from the British.

But the shift in the statue’s meaning started soon after it was built. Back in 1883, Emma Lazarus wrote that famous poem

—you know, the one that goes: “Give me your tired, your poor…” [pause] and so on and so forth. That poem describes the Statue of Liberty as a beacon of welcome for the entire world. Well, in the early 1900s, it was put on a plaque on the pedestal that the Statue of Liberty stands on.

From that point on, the Statue of Liberty was no longer perceived as just a gift between friendly republics. It now became a tribute to the United States’ history of immigration and openness.

This association was strengthened in the imagination of the general public just a few decades after the statue’s completion, with the immigration waves of the early twentieth century … especially since the statue happened to be the first sign of America seen by those immigrants sailing into the port of New York. So, as with Mount Rushmore, the original motivation for this colossal statue was forgotten, and the statue is now valued for more important reasons.

Narrator: Listen to a conversation between a student and a receptionist at the registrar’s office on the first day of the semester.

Female Student: Excuse me, uh, I’m supposed to be having my physics class in the science building, but no one’s in the classroom … Could you tell me where the class is? Physics 403? Has it been moved?

Receptionist: Well, there’s a room assignment sheet on the bulletin board outside this office …

Female Student: Yeah, I know, but my class isn’t listed there. There must be some kinda mistake or something. Could you look it up, please?

Receptionist: Mm, okay, let me check on the computer. It’s physics, right? Wait, did you say Physics 403? 

Female Student: Yeah.

Receptionist: Well, I’m sorry, but … it says here that it was canceled … You should’ve gotten a letter from the registrar’s office about this

Female Student: What? I never got it.

Receptionist: Are you sure? ’Cause it says on the computer that the letter was sent out to students a week ago.

Female Student: Really? I should a gotten it by now … I wonder if I threw it away with all the junk mail by mistake …

Receptionist: Well, it does happen … Um, let me check something. What’s your name?

Female Student: Woodhouse. Laura Woodhouse.

Receptionist: OK, ummm, Woodhouse … let me see … ah, it says here we sent it to your apartment on … uh … Center Street.

Female Student: Oh, that’s my old apartment … I moved out of there a little while ago …

Receptionist: Well … and I suppose you haven’t changed your mailing address at the administration office. Well, that would explain it.

Female Student: Yeah, I guess that’s it. But, how can they cancel a class after offering it? If I’d known this was gonna happen, I’d’ve taken it last semester.

Receptionist: I know, it’s really inconvenient for you; I understand that, but, um … if we don’t have enough students signed up for the course, the college can’t offer it. You know, it’s, um, a practical issue, like, we can’t have an instructor when there’re only a few students in the class. You see what I mean?

Female Student: I guess, but now I don’t know what course I should take instead.

Receptionist: Okay, let’s see … do you have any courses you were gonna take next semester? If you do, you might wanna take ’em now and sign up for Physics 403 next semester.

Female Student: Yeah, I guess I could do that. I just hope it won’t be canceled again. Do you know how many people have to be enrolled in order to keep a class from being canceled?

Receptionist: Well, it depends on the class, but for that class, you have to have … um … let’s see … usually it’d be at least 10 people, but since it was canceled this semester, they might even do it with less. But you know what you should do? Give the physics department a call a coupla weeks before the semester starts. They’ll be able to tell you if they’re planning to go through with it … It’s their decision, actually.

Female Student: Oh, OK, I’ll do that. Thanks for the info.

Receptionist: No problem. Sorry about the class … Oh, why don’t you go change your mailing address now; it’ll only take a minute.

Female Student: Oh, oh, sure, I’ll do that right away.

Narrator: Listen to part of a lecture in an environmental science class.

Professor: Now, we’ve been talking about the loss of animal habitat from housing developments, um, growing cities … small habitat losses. But today I want to begin talking about what happens when habitat is reduced across a large area. There are, of course, animal species that require large areas of habitat … and, um, some migrate over very long distances. So what’s the impact of habitat loss on those animals? Animals that need large areas of habitat?

Well, I’ll use the hummingbirds as an example. Now, you know a hummingbird is amazingly small. But even though it’s really tiny, it migrates over very long distances … travels up and down the Western Hemisphere … the Americas … back and forth between where it breeds in the summer and the warmer climates where it spends the winter. So we would say that this whole area over which it migrates is its habitat, because on this long-distance journey, it needs to come down to feed and sleep every so often, right?

Well, the hummingbird beats its wings—get this—about 3,000 times per minute. So you think, wow, it must need a lot of energy, a lot of food, right? Well, it does—it drinks a lot of nectar from flowers and feeds on some insects—but it’s energyefficient, too. You can’t say it isn’t. I mean as it flies all the way across the Gulf of Mexico, it uses up almost none of its body fat. But that doesn’t mean it doesn’t need to eat! So hummingbirds have to rely on plants in their natural habitat. And it goes without saying, but … well, the opposite is true as well. Plants depend on hummingbirds too. There are some flowers that can only be pollinated by the hummingbird. Without it stopping to feed and spreading pollen from flower to flower, these plants would cease to exist!

But the problem, well … as natural habitat along these migration routes is developed by humans for housing or agriculture, or, um, cleared for raising cattle, for instance … there’s less food available for migrating hummingbirds. Their nesting sites are affected, too … the same … by the same sorts of human activities. And all of these activities pose a real threat to the hummingbird population.

So, to help them survive, we need to preserve their habitats … And one of the concrete ways people have been doing this is by cleaning up polluted habitat areas … and then replanting flowers, uh, replanting native flowers that hummingbirds feed on. Promoting ecological tourism is another way to help save their habitat. As the number of visitors—ecotourists who come to hummingbird habitats to watch the birds—the more the number of visitors grows, the more local businesses profit. So ecological tourism can bring financial rewards. All the more reason to value these beautiful little creatures and their habitat, right?

But to understand more about how to protect and support hummingbirds the best we can, we’ve gotta learn more about their breeding … nesting … sites and, uh, migration routes—and also about the natural habitats we find there. That should help us determine how to prevent further decline in the population.

A good research method … a good way to learn more … is by, um, running a banding study. Banding the birds allows us to track them over their lifetime. It’s a practice that’s been used by researchers for years. In fact, most of what we know about hummingbirds comes from banding studies … where we, uh, capture a hummingbird and make sure all the information about it—like … its weight and, um, age and length—are all recorded … put into international … an international

information database. And, then we place an extremely lightweight band around one of its legs … well, what looks like a leg

—although, technically it’s considered part of the bird’s foot. Anyway, these bands are perfectly safe. And some hummingbirds have worn them for years with no evidence of any problems. The band is labeled with a tracking number … oh, and there’s a phone number on the band for people to call, for free, to report a banded bird they’ve found or recaptured. So when a banded bird is recaptured and reported, we learn about its migration route, its growth … and how long it’s been alive … its life span. One recaptured bird had been banded almost 12 years earlier! She’s one of the oldest hummingbirds on record.

Another interesting thing we’ve learned is … that some hummingbirds, uh, they no longer use a certain route; they travel by a different route to reach their destination. And findings like these have been of interest to biologists and environmental scientists in a number of countries, who are trying to understand the complexities of how changes in a habitat … affect the species in it—species like the humming birds.

Narrator: Listen to part of a lecture in a film history class.

Professor: Okay, we’ve been discussing film in the 1920s and ’30s, and, ah, how back then, film categories as we know them today had not yet been established. We, ah, said that, by today’s standards, many of the films of the ’20s and ’30s would be considered “hybrids”; that is, a mixture of styles that wouldn’t exactly fit into any of today’s categories. And in that context, today we’re going to talk about a, a filmmaker who began making very unique films in the late 1920s. He was French, and his name was Jean Painlevé.

Jean Painlevé was born in 1902. He made his first film in 1928. Now, in a way, Painlevé’s films conform to norms of the ’20s and ’30s; that is, they don’t fit very neatly into the categories we use to classify films today. That said, even by the standards of the ’20s and ’30s, Painlevé’s films were a unique hybrid of styles. He had a special way of fusing—or, or some people might say confusing—science and fiction; his films begin with facts, but then they become more and more fictional— they gradually add more and more fictional elements. In fact, Painlevé was known for saying that “science is fiction.”

Painlevé was a, a pioneer in underwater filmmaking, and a lot of his short films focus on the aquatic animal world. He liked to show small underwater creatures displaying what seemed like familiar human characteristics—what we think of as unique to humans. He might take a, a clip of a mollusk going up and down in the water and set it to music—you know, to make it look as if the mollusk were dancing to the music like a human being. That sort of thing. But then he’d suddenly change the image or narration to remind us how different the animals are, how unlike humans. He confused his audience in the way he portrayed the animals he filmed, mixing up our notions of the categories “human” and “animal.” The films make us a little uncomfortable at times because we’re uncertain about what we’re seeing. It gives his films an uncanny feature … the familiar made unfamiliar, the normal made suspicious. He liked twists; he liked the unusual. In fact, one of his favorite sea animals was the sea horse because with sea horses, it’s the male that gets pregnant, it’s the male that carries the babies.

And he thought that was great. His first and most celebrated underwater film is about the sea horse. Susan? You have a question?

Female Student: But underwater film making wasn’t that unusual, was it? I mean weren’t there other people making movies underwater?

Professor: Well, actually it was pretty rare at that time. I mean we’re talking the early 1930s here.

Female Student: But what about Jacques Cousteau? Wasn’t he, like, an innovator, you know, with underwater photography, too?

Professor: Ah, Jacques Cousteau. Well, Painlevé and Cousteau did both film underwater, and they were both innovators, so you’re right in that sense, but that’s pretty much where the similarities end. First of all, Painlevé was about 20 years ahead of Cousteau … Um, and Cousteau’s adventures were high-tech, with lots of fancy equipment, whereas Painlevé kind of patched equipment together as he needed it … Uh, Cousteau usually filmed large animals, usually in the open sea, whereas Painlevé generally filmed smaller animals, and, and he liked to film in shallow water … Uh, what else? Well, the main difference was that Cousteau simply investigated and presented the facts; he, he didn’t mix in fiction. He was a strict documentarist; he set the standard, really, for the nature documentary. Painlevé, on the other hand, as we said before, mixed in elements of fiction, and his films are much more artistic, incorporating music as an important element. John, you have a question?

Male Student: Well, maybe I shouldn’t be asking this … Uh, but if Painlevé’s films are so special, so good, why haven’t we ever heard of them? I mean everyone’s heard of Jacques Cousteau …

Professor: Well, that’s a fair question. Uh, the short answer is that Painlevé’s style just never caught on with the general public. I mean it probably goes back, at least in part, to what we mentioned earlier, that, that people didn’t know what to make of his films, that they were confused by them. Whereas Cousteau’s documentaries were very straightforward, uh, met people’s expectations more than Painlevé’s films did. But your true film-history buffs know about him, and Painlevé’s still highly respected in many circles.

Narrator: Listen to a conversation between a student and a professor.

Male Student: Hi, Professor Archer. You know how in class last week you said that you were looking for students who were interested in volunteering for your archaeology project?

Professor: Of course. Are you volunteering?

Male Student: Yes, I am. It sounds really interesting. But, ummm, do I need to have any experience with these kinds of projects?

Professor: No, not really. I assume that most students taking the introductory-level class will have little or no experience with archaeological research, but that’s OK.

Male Student: Well, as you know, we’re studying the history of the campus this semester. This used to be an agricultural area, and we already know that where the main lecture hall now stands there once were a farmhouse and barn that were erected in the late 1700s. We’re excavating near the lecture hall to see what types of artifacts we find—you know, things people used in the past that got buried when the campus was constructed. We’ve already begun to find some very interesting items like, um, old bottles, buttons, pieces of clay pottery …

Professor: Oh, good—that’s a relief. Actually, that’s why I’m volunteering for the project—to get experience. What kind of work is it?

Male Student: Buttons and clay pottery? Did the old owners leave in such a hurry that they left their clothes and dishes behind?

Professor: That’s just one of the questions we hope to answer with this project.

Male Student: Wow—and it’s all right here on campus …

Professor: That’s right, no traveling involved. I wouldn’t expect volunteers to travel to a site, especially in the middle of the semester. We expect to find many more things, but we do need more people to help.

Male Student: So … how many student volunteers are you looking for?

Professor: I’m hoping to get five or six. I’ve asked for volunteers in all the classes I teach, but no one’s responded. You’re the first person to express interest.

Male Student: Uh … sounds like it could be a lot of work. Is there … umm … is there any way I can use the experience to get some extra credit in class? I mean can I write a paper about it?

Professor: I think it’ll depend on what type of work you do in the excavation, but I imagine we can arrange something. Well, actually, I’ve been considering offering extra credit for class because I’ve been having a tough time getting volunteers … Extra credit is always a good incentive for students.

Male Student: And … how often would you want the volunteers to work?

Professor: We’re asking for three or four hours per week, depending on your schedule. A senior researcher—I think you know John Franklin, my assistant—is on-site every day.

Male Student: Sure, I know John. By the way, will there be some sort of training?

Professor: Yes, uh, I wanna wait till Friday to see how many students volunteer. And then I’ll schedule a training class next week at a time that’s convenient for everyone.

Male Student: OK, I’ll wait to hear from you. Thanks a lot for accepting me!

Narrator: Listen to part of a lecture in an art history class. The professor has been discussing the origins of art.

Professor: Some of the world’s oldest preserved art is the cave art of Europe, most of it in Spain and France. And, uh, the earliest cave paintings found to date are those of the Chauvet cave in France, discovered in 1994.

And, you know, I remember when I heard about the results of the dating of the Chauvet paintings. I said to my wife, “Can you believe these paintings are over 30,000 years old?” and my three-year-old daughter piped up and said, “Is that older than my great-grandmother?” That was the oldest age she knew. And, you know, come to think of it, it’s pretty hard for me to really understand how long 30,000 years is too. I mean, we tend to think the people who lived at that time must have been pretty primitive … but I’m gonna show you some slides in a few minutes, and I think you’ll agree with me that this art is anything but primitive—they’re masterpieces. And they look so real, so alive, that it’s very hard to imagine that they’re so very old.

Now, not everyone agrees on exactly how old. A number of the Chauvet paintings have been dated—by a lab—to 30,000 or more years ago. That would make them not just older than any other cave art, but about twice as old as the art in the caves at Altamira or Lascaux, which you may have heard of.

Some people find it hard to believe Chauvet is so much older than Altamira and Lascaux, and they noted that only one lab did the dating for Chauvet, without independent confirmation from any other lab.

But be that as it may, whatever the exact date, whether it’s 15,000, 20,000, or 30,000 years ago, the Chauvet paintings are from the dawn of art, so they’re a good place to start our discussion of cave painting.

Now, one thing you’ve gotta remember is the context of these paintings. Paleolithic humans—that’s the period we’re talking about here, the Paleolithic, the early Stone Age, not too long after humans first arrived in Europe. The climate was significantly colder then, and so rock shelters—shallow caves—were valued as homes protected from the wind and rain. And in some cases at least, artists drew on the walls of their homes. But many of the truly great cave art sites—like Chauvet —were never inhabited. These paintings were made deep inside a dark cave, where no natural light can penetrate. There’s no evidence of people ever living here—cave bears, yes, but not humans.

You would have had to make a special trip into the cave to make the paintings, and a special trip to go see it, and each time you’d have to bring along torches to light your way. And people did go see the art—there’s charcoal marks from their torches on the cave walls, clearly dating from thousands of years after the paintings were made—so we can tell people went there. They came, but they didn’t stay. Deep inside a cave like that is not really a place you’d want to stay, so, uh, why? What inspired the Paleolithic artists to make such beautiful art in such inaccessible places? We’ll never really know, of course, though it’s interesting to speculate.

But, uh … getting to the paintings themselves. Virtually all Paleolithic cave art represents animals, and Chauvet is no exception. The artists were highly skilled at using—or even enhancing—the natural shape of the cave walls to give depth and perspective to their drawings. The sense of motion and vitality in these animals—well, wait till I show you the slides. Anyway, most Paleolithic cave art depicts large herbivores. Horses are most common overall, with deer and bison pretty common too. Probably animals they hunted. But earlier, at Chauvet, there’s a significant interest in large, dangerous animals. Lots of rhinoceroses, lions, mammoths, bears … remember that the ranges of many animal species were different back then, so all these animals actually lived in the region at that time—but, uh, the Chauvet artists didn’t paint people. There’s a halfman, half-bison creature, and there’s outlines of human hands, but no depiction of a full human.

So why these precise animals? Why not birds … fish … snakes? Was it for their religion? Magic? Or sheer beauty? We don’t know, but whatever it was, it was worth it to them to spend hours deep inside a cave, with just a torch between them and utter darkness. So, on that note, let’s dim the lights so we can see these slides and actually look at the techniques they used.

Narrator: Listen to part of a lecture in an astronomy class.

Professor: Now, astronomy didn’t really, uh, balloon into the science it is today until the development of spectroscopy. Spectroscopy is basically the study of spectra and spectral lines of light, and specifically for us, the light from stars. It makes it possible to analyze the light emitted from stars. When you analyze this light, you can figure out their distance from the Earth and identify what they’re made of—determine their chemical composition.

Before we get into that, though, it’s probably a good thing to back up a bit. You all know how when you take a crystal prism and pass a beam of sunlight through it, you get a spectrum which looks like a continuous band of rainbow colors. The light that we see with our human eyes as a band of rainbow color falls in the range of what’s called visible light. And visible light spectroscopy is probably the most important kind of spectroscopy.

Anyone wanna take a stab at the scientific term for visible light? … And I’m sure all of you know this because you all did the reading for today …

Female Student: Optical radiation. But I thought being exposed to radiation’s dangerous.

Professor: Yes and no. If you’re talking about radiation like in the element uranium, yeah, that’s dangerous, but radiation as a general term actually refers to anything that spreads away from its source, so optical radiation is just visible light energy spreading out.

OK, so we’ve got a spectrum of a beam of sunlight and it looks like the colors bleed into each other; uh, there’re no interruptions, just a band flowing from violet to green to yellow to … you get the idea. Well, what happens if the sunlight spectrum is magnified? Maybe you all didn’t do the reading. Well, here’s what you’d see:

I want you to notice that this spectrum is interrupted by dark lines, called spectral lines. If you really magnified the spectrum of the sunlight, you could identify more than a hundred thousand of ’em. They may look kinda randomly placed, but they actually form many distinct patterns. And if you were looking at the spectrum of some other star, the colors would be the same, but the spectral lines would break it up at different places, making different patterns. Each pattern stands for a distinct chemical element, and so different sets or patterns of spectral lines mean that the star has a different chemical composition.

Female Student: So how do we know which spectral patterns match up with which elements?

Professor: Well, a kind of spectroscopic library of elements was compiled using flame tests. A known element—uh, say a piece of iron, for example—is heated in a pure gas flame. The iron eventually heats to the point that it radiates light. This light is passed through a prism, which breaks it up into a spectrum, and a unique pattern, kind of like a chemical fingerprint, of spectral lines for that element appears. This process was repeated over and over again for many different elements. So we can figure out the chemical makeup of another star by comparing the spectral pattern it has to the pattern of the elements in the library.

Oh! An interesting story about how one of the elements was discovered through spectroscopy. There was a pretty extensive library of spectral line patterns of elements even by the 1860s. A British astronomer was analyzing a spectrograph of sunlight and he noticed a particular pattern of spectral lines that didn’t match anything in the library. So he put two and two together and decided there was an element in the Sun that hadn’t been discovered here on the Earth yet. Any guesses about what that element is? It’s actually turned out to be pretty common, and I’m sure all of you know it. OK. Let’s try something else. Any of you happen to be familiar with the Greek word for Sun, by chance?

Male Student: Something like helios or something like that? … Oh! It must be helium. So you’re sayin’ that helium was discovered on the Sun first?

Professor: Yes. And this is a good example of how important spectroscopy is in astronomy.