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

Professor: Now when I mention the terms “boom and bust”, what is that going to mind?

Student: The dotcom crash of the ‘90s.

Professor: Ok. The boom in the late 1990s when all those new Internet companies sprung up and then sold for huge amounts of money. Then the bust around 2000…2001 when many of those same Internet companies went out of business. Of course, booms aren’t always followed by busts. We’ve certainly seen times when local economies expanded rapidly for a while and then went back to a normal pace of growth. But, there’s a type of rapid expansion, what might be called the hysterical or irrational boom that pretty much always leads to a bust. See, people often create and intensify a boom when they get carried away by some new industry that seems like it will make them lots of money fast. If you think that by the 90s, people would have learned from the past. If they did, well, look at tulips.

Student: Tulips? You mean like the flower?

Professor: Exactly. For instance, do you have any idea where tulips are from? Originally I mean.

Student: Well, the Netherlands, right?

Professor: That’s what most people think, but no. They are not native to the Netherlands, or even Europe. Tulips actually hail from an area that Chinese call the Celestial Mountains in Central Asia. A very remote mountainous region. It was Turkish nomads who first discovered tulips and spread them slowly westward.

Now, around the 16th century, Europeans were traveling to Istanbul and Turkey as merchants and diplomats. And the Turks often gave the Europeans tulip bulbs as gifts which they would carry home with them. For the Europeans, tulips were totally unheard of. Er…a great novelty. The first bulb to show up in the Netherlands, the merchant who received them roasted and ate them. He thought they were kind of onion. It turns out that the Netherlands was an ideal country for growing tulips. It had the right kind of sandy soil for one thing, but also, it was a wealthy nation with a growing economy, willing to spend lots of money on new exotic things. Plus, the Dutch had a history of gardening.

Wealthy people would compete, spending enormous amounts of money to buy the rarest flowers for their gardens. Soon tulips were beginning to show up in different colors as growers tried to breed them specifically for colors which would make them even more valuable. But they were never completely sure what they would get. Some of the most priced tulips were white with purple streaks, or red with yellow streaks on the petals, even a dark purple tulip that was very much priced. What happened then was a craze for these specialized tulips. We called that craze “tulip mania”.

So, here we’ve got all the conditions for an irrational boom: a prospering economy, so more people had more disposable income-money to spend on luxuries, but they weren’t experienced at investing their new wealth. Then along comes a thrilling commodity. Sure the first specimens were just played right in tulips, but they could be bred into some extraordinary variations, like that dark purple tulip. And finally, you have an unregulated market place, no government constrains, where price could explode. And explode they did, starting in the 1630s.

There was always much more demand for tulips than supply. Tulips didn’t bloom frequently like roses. Tulips bloomed once in the early spring. And that was it for the year. Eventually, specially-bred multicolored tulips became so valuable, well, according to records, one tulip bulb was worth 24 tons of wheat, or thousand pounds of cheese. One particular tulip bulb was sold and exchanged for a small sheep. In other words, tulips were literally worth their weight in gold. As demand grew, people began selling promissory notes guaranteeing the future delivery of priced tulip bulbs. The buyers of these pieces of paper would resell the notes and mark up prices. These promissory notes kept changing hands from buyer to buyer until the tulip was ready for delivery. But it was all pure speculation because as I said, there was no way to know if the bulb was really going to produce the variety, the color that was promised. But that didn’t matter to the owner of the note.

The owner only cared about having that piece of paper so it could be traded later at a profit. And people were borrowing, mortgaging their homes in many cases to obtain those bits of paper because they were sure they’d find an easy way to make money. So now, you’ve got all the ingredients for a huge bust. And bust it did, when one cold February morning in 1637, a group of bulb traders got together and discovered that suddenly there were no bidders. Nobody wanted to buy. Panic spread like wild fire and the tulip market collapsed totally.

, I have an interesting plant species to discuss with you today. Um…it’s a species of a very rare tree that grows in Australia, Eidothea hardeniana, but it’s better known as the Nightcap Oak. Now, it was discovered only very recently, just a few years ago. Um… it remained hidden for so long because it’s so rare. There are only about 200 of them in existence. They grow in a rain forest, in a mountain rage…range in the north part of New South Wales which is a…er… state in Australia. So just 200 individual trees in all. Now another interesting thing about the Nightcap Oak is that it is…it represents…er…a very old type…er…kind of tree that grew a hundred million years ago. Um, we found fossils that old that bear remarkable resemblance to the tree. So, it’s a primitive tree. A…a living fossil you might say. It’s relic from earlier times and it has survived all these years without much change. And it…it’s probably a kind of tree from which other trees that grow in Australia today evolved. Just to give you an idea of what we are talking about. Here’s a picture of the leaves of the tree and its flowers. I don’t know how well you can see the flowers. They’re those little clusters sitting at the base of the leaves. Okay, what have we tried to find out about the tree since we’ve discovered it? Hum…or how…why is…is it so rare? That’s one of the first questions. Um… how is it…um…how does it reproduce? This is another question. Um, maybe those two questions are actually related. Jim?

Student: Hum …I don’t know. But I can imagine that…for instance, seed disposal might be a factor. I mean if the…er…you know, if the seeds cannot really disperse in the wild area, then, you know, the tree may not colonize new areas. It can’t spread from the area where it’s growing.

Professor: Right. That’s…that’s actually a very good answer. Um, of course, you might think there might not be any areas where the tree could spread into, er…because…um…well, it’s very specialized in terms of the habitat. But, that’s not really the case here. Um…the suitable habitat, that is, the actual rainforest is much larger than the few hectares where the Nightcap Oak grows. Now this tree is a flowering tree as I showed you. Um…um…it produces a fruit, much like a plum. On the inci…inside there’s a seed with a hard shell. It…it appears that the shell has to crack open or break down somewhat to allow the seed to soak up water. You know, if the Nightcap Oak remains…if their seeds remain locked inside their shell, they will not germinate. Actually, the seeds…er…they don’t retain the power to germinate for very long, maybe two years. So there’s actually quite a short window of opportunity for the seed to germinate. So the shell somehow has to be broken down before this…um…germination ability expires. And…and then there’s a kind of rat that likes to feed on the seeds as well. So, given all these limitations, not many seeds that the tree produces will actually germinate. So this is a possible explanation for why the tree does not spread. It doesn’t necessarily explain how it became so rare, but it explains why it doesn’t increase. OK, so it seems to be the case that the species, this Nightcap Oak is not very good at spreading. However, it seems, though we can’t be sure, that it’s very good at persisting as a population. Um…we…there’s some indications to suggest that the population of the Nightcap Oak has not declined over the last. er…you know, many hundreds of years. So it’s stayed quite stable. It’s not a remnant of some huge population that is dwindled in last few hundred years for some reason. It’s not necessarily a species in retreat. Ok, so it cannot spread very well, but it’s good at maintaining itself. It’s rare, but it’s not disappearing. Ok, the next thing we might want to ask about the plant like that is what chances does it have to survive into the future. Let’s look at that.

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

Student: Professor Martin?

Professor: Uh, hi, Lisa, what can I do for you?

Student: Well, I’ve been thinking about, you know, what you were saying in class last week, about how we shouldn’t wait until the last minute to find an idea and get started working on our term paper.

Professor: Good, good, and have you come up with anything?

Student: Well, yeah, sort of. See, I’ve never had a linguistics class before, so I was sort of, I mean, I was looking over the course description and a lot of the stuff you described there, I just don’t know what it is talking about, you know, or what it means. But there was one thing that really did jump out at me.

Professor: Yes?

Student: The section on dialects, cause…like, that’s the kind of thing that’s always sort of intrigued me, you know?

Professor: Well, that’s certainly an interesting topic. But you may not realize, I mean, the scope…

Student: Well, especially now, cause I’ve got like one roommate who is from the south and another one from New York. And we all talk like totally different, you know

Professor: Yes, I understand. But…

Student: But then I was noticing, like, we don’t really get into this till the end of the semester, you know. So I…

Professor: So, you want some pointers where to go for information on the subject? Well, you could always start by reading the chapter in the book on social linguistics. That will give you a basic understanding of the key issues involved here.

Student: Yeah, that’s what I thought. So I started reading the chapter, you know, about how everyone speaks some dialect of a language. And I’m wondering like, well, how do we even manage to understand each other at all?

Professor: Ah, yes, an interesting question. You see…

Student: So then I read the part about dialect accommodation. You know, the idea that people tend to adapt their speaking to make it closer to the speech of whomever they’re talking to, and I’m thinking, yeah, I do that when I talk with my roommates, and without even thinking about it or anything, you know.

Professor: OK, all right. Dialect accommodation is a more manageable sort of topic.

Student: So I was thinking like, I wonder just how much other people do the same thing. I mean, there are students here from all over the place. Does everyone change the way they talk to some degree depending on whom they are talking to?

Professor: You’d be surprised.

Student: So, anyway, my question is, do you think it’d be OK if I did a project like that for my term paper? You know, find students from different parts of the country, record them talking to each other in different combinations, report on how they accommodate their speech or not, that kind of thing?

Professor: Tell you what, Lisa, write me up a short proposal for this project, how you’re going to carry out the experiment and everything, a design plan. And I think this’ll work out just fine.

Narrator: Listen to part of a lecture in a geology class.

Professor: Um, beginning in the late 1960s, geologists began to uncover some evidence of a rather surprising kind when they looked . . . um . . . at various places around the world. What they found out when they examined rocks from about a . . . the period from about 750 million years ago to about 580 million years ago, they found that . . . it seemed that glaciers covered the entire surface of the Earth-from pole to pole, including the tropics.

Um . . . how did they come to this astonishing conclusion? What was the evidence for this? Especially when glaciers today are found only at the poles . . . or in the mountains.

Well, uh . . . basically when glaciers grow and move they leave behind a distinctive deposit consisting of primarily . . . of, at least on the top level, of ground up little bits of rock . . . almost . . . they almost look like rocks that have been deposited by streams, if you’ve ever seen those. And that’s caused because, although the glacier is ice, it is actually flowing very slowly and as it moves it grinds the top layer of rock, it breaks off pieces and carries them away. So when you have glaciation you have a distinctive pattern of these pieces of rock which are called “erratics.”

Erratics are rocks . . . they’re the stones that are often carried long distances by glaciers.

So, in the 1960s and onward up through the 1990s, we keep finding evidence for glaciation, no matter what the latitude . . . even in tropical latitudes. Now, today there are glaciers in the tropics but only at very high elevations. But 750 million years ago, apparently there were glaciers even at sea level in the tropics.

How could this have happened?

Well. first . . . the growth of glaciers, uh, benefits, if you will, from a kind of a positive feedback loop called the “ice-albedo effect.”

With the ice-albedo effect, glaciers-’cause they’re white-reflect light and heat more . . . much more than does liquid water . . . or soil and rock, which are dark and absorb heat. So, the more glaciers there are, the more heat is reflected, so the climate gets cooler, and glaciers grow even more.

However . . . normally, on a global scale, there is a major process that functions to curb the growth of glaciers. And, that process involves carbon dioxide.

Now, we’re all familiar with the notion that carbon dioxide is what we call a “green-house gas.” The more carbon dioxide there is in the atmosphere, the more heat the atmosphere retains. That’s what a greenhouse gas does. So, the greenhouse-gas effect is kinda the opposite of the albedo effect.

Um . . . now as it happens . . . when silicate rocks, which is a very common class of rock, when they’re exposed to the air and to normal weathering, they erode. Carbon dioxide is attracted to these eroding rocks and binds to them, forming calcium carbonate.

Calcium carbonate is eventually washed into the ocean where it settles to the bottom. This process, this forming of calcium carbonate, has the effect of sucking the carbon dioxide out of the air and storing it at the bottom of the ocean.

Now, follow me here. The process that’s sucking carbon dioxide out of the air, keeping the greenhouse gas levels low, cannot happen if the rock is covered with ice.

So, while glaciers reflect light and heat . . . cooling the Earth, they at the same time cover rocks so there’s less calcium carbonate formed . . . which leaves more carbon dioxide in the atmosphere. Higher levels of carbon dioxide keep the atmosphere warm . . . which slows the growth of glaciers. So, it’s a balance, and the glacier growth remains pretty much under control.

Now, what happened 750 million years ago to upset that balance? It seems a relatively simple explanation actually . . 750 million years ago . . . all the major continents are rocky, bare, and pretty much lined up along the equator; they hadn’t yet moved to where they are today. So, what happened was, perhaps a slight cooling of . . . the very slight and temporary cooling of the Sun-which still happens from time to time-and the Earth starts to cool, the ice starts to spread on the oceans . . . starting at the poles.

Now, by the time the ice reaches about two-thirds of the way to the equator, it’s too late.

See . . . because the continents are the last things to be covered by glaciers, they continue weathering . . . the rocks keep eroding and the carbon dioxide levels keep falling . . . So, the ice-albedo effect from the glaciers is increasing in strength while the atmosphere continues to lose its ability to retain heat making glacier growth unstoppable. Now you have what’s called a “runaway freeze.” And for perhaps as long as 50 million years, possibly with some interludes, the Earth was frozen from pole to pole, like a giant snowball.

Narrator: Listen to part of a lecture in a creative writing class.

Professor: Alright everybody, the topic for today is, well, we’re gonna take a look at how to start creating the characters for the story you’re writing. One way of doing that is to come up with what’s called “a character sketch”, I don’t mean a sketch like a drawing, I guess that’s obvious. It’s um…it’s a…a sketch as a way of getting started on defining your characters’ personalities. To begin, how do we create fictional characters? We don’t just pull them from thin air, do we? I mean we don’t create them out of nothing.

We base them, consciously or unconsciously, we base them on real people, or we blend several people’s traits, their attributes into one character. But when people think fiction, they may assume the characters come from the author’s imagination. But the writer’s imagination is influenced by… by real people, could be anyone, so, pay attention to the people you meet, someone in class, at the gym, that guy who is always sitting in the corner of the coffee house, um… your cousin, who’s always getting into dangerous situations. We’re pulling from reality, gathering bits and pieces of real people.

You use these people, and the bits of behavior or characteristics as a starting point as you begin to sketch out your characters. Here is what you should think about doing first. When you begin to formulate a story, make a list of interesting people you know or have observed. Consider why they’re unique or annoying. Then make notes about their unusual or dominant attributes. As you create fictional characters, you’ll almost always combine characteristics from several different people on your list to form the identity and personality of just one character. Keeping this kind of character sketch can help you solidify your character’s personality, so that it remains consistent throughout your story. You need to define your characters, know their personalities so that you can have them acting in ways that are predictable, consistent with their personalities.

Get to know them like a friend, you know your friends well enough to know how they’ll act in certain situations, right? Say you have three friends, their car runs out of gas on the highway. John gets upset. Mary remains calm. Teresa takes charge of handling the situation. And let’s say, both John and Mary defer to her leadership. They call you to explain what happen. And when John tells you he got mad, you’re not surprised, because he always gets frustrated when things go wrong. Then he tells you how Teresa took charge, calmed him down, assigned tasks for each person and got them on their way. Again, you’re not surprised. It’s exactly what you’d expect. Well, you need to know your characters, like you know your friends. If you know a lot about a person’s character, it’s easy to predict how they’ll behave. So if your character’s personalities are well defined, it will be easy for you as the writer to portray them realistically…er… believably, in any given situation.

While writing character sketches, do think about details. Ask yourself questions, even if you don’t use the details in your story, um…what does each character like to eat, what setting does each prefer, the mountains, the city, what about educational background, their reactions to success or defeat, write it all down. But, here I need to warn you about a possible pitfall. Don’t make you character into a stereotype. Remember the reader needs to know how your character is different from other people who might fall in the same category. Maybe your character loves the mountains and has lived in a remote area for years.

To make sure he is not a stereotype; ask yourself how he sees life differently from other people who live in that kind of setting. Be careful not to make him into the cliché of the “ragged mountain dweller”. Okay, now, I’ll throw out a little terminology. It’s easy stuff. Major characters are sometimes called “round characters”. Minor characters are sometimes called, well, just the opposite, “flat”. A round character is fully developed; a flat character isn’t, character development is fairly limited. The flat character tends to serve mainly as a motivating factor. For instance, you introduce a flat character who has experienced some sort of defeat. And then your round, your main character who loves success and loves to show off, comes and boasts about succeeding and jokes about the flat character’s defeat in front of others, humiliates the other guy. The flat character is introduced solely for the purpose of allowing the round character to show off.

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

Professor: We’re really just now beginning to understand how quickly drastic climate change can take place. We can see past occurrences of climate change that took place over just a few hundred years. Take uh… the Sahara Desert in Northern Africa. The Sahara was really different 6,000 years ago. I mean, you wouldn’t call it a tropical paradise or anything, uh…or maybe you would if you think about how today in some parts of the Sahara it…it only rains about once a century. Um… but basically, you had granary and you had water. And what I find particularly interesting and amazing really, what really indicates how un desert-like the Sahara was thousands of years ago, was something painted on the rock, pre-historic art, hippopotamuses, as you know hippos need a lot of water and hence? Hence what?

Student:They need to live near a large source of water year round

Professor: That’s right.

Student: But how is that proved that the Sahara used to be a lot wetter? I mean the people who painted those hippos, well, couldn’t they have seen them on their travels?

Professor: Okay, in principal they could, Karl. But the rock paintings aren’t the only evidence. Beneath the Sahara are huge aquifers, basically a sea of fresh water, that’s perhaps a million years old filtered through rock layers. And…er…and then there is fossilized pollen, from low shrubs and grasses that once grew in the Sahara. In fact these plants still grow, er…but hundreds of miles away, in more vegetated areas. Anyway, it’s this fossilized pollen along with the aquifers and the rock paintings, these three things are all evidence that the Sahara was once much greener than it is today, that there were hippos and probably elephants and giraffes and so on. So what happened? How did it happen? Well, Now, we’re so used to hearing about how human activities are affecting the climate, right? But that takes the focus away from the natural variations in the earth climate, like the Ice Age, right? The planet was practically covered in ice just a few thousand years ago. Now as far as the Sahara goes, there is some recent literature that points to the migration of the monsoon in that area

Students: Huh?????

Professor: What do I mean? Okay, a monsoon is a seasonal wind that can bring in a large amount of rainfall. Now if the monsoon migrates, well, that means that the rains move to another area, right? So what caused the monsoon to migrate? Well, the answer is: the dynamics of earth’s motions, the same thing that caused the Ice Age by the way. The earth’s not always the same distance from the sun, and it’s not always tilting toward the sun at the same angle. There are slight variations in these two perimeters. They’re gradual variations but their effects can be pretty abrupt. And can cause the climate to change in just a few hundred years.

Student: That’s abrupt?

Professor: Well, yeah, considering that other climate shifts take thousands of years, this one is pretty abrupt. So these changes in the planet’s motions, they called it “the climate change”, but it was also compounded.

What the Sahara experienced was um…a sort of “runaway drying effect”. As I said the monsoon migrated itself, so there was less rain in the Sahara. The land started to get drier, which in turn caused huge decrease in the amount of vegetation, because vegetation doesn’t grow as well in dry soil, right? And then, less vegetation means the soil can’t hold water as well, the soil loses its ability to retain water when it does rain. So then you have less moisture to help clouds form, nothing to evaporate for cloud formation. And then the cycle continues, less rain, drier soil, less vegetation, fewer clouds, less rain etc. etc.

Student: But, what about the people who made the rock paintings?

Professor:  Good question. No one really knows. But there might be some connections to ancient Egypt. At about the same time that the Sahara was becoming a desert…

Student: Uh-huh

Professor: 5,000 years ago, Egypt really began to flourish out in the Nile River valley. And that’s not that far away. So it’s only logical to hypothesize that a lot of these people migrated to the Nile valley when they realized that this was more than a temporary drought. And some people take this a step further. And that’s okay, that’s science and they hypothesize that this migration actually provided an important impetus in the development of ancient Egypt. Well, we’ll stay tuned on that.

Narrator: Listen to a conversation between a student and an employee in the campus computer center.

Computer center employee: Hi, what can I help you with today?

Student: Hi, um, I wanted to-you see, the thing is, I don’t know much about computers, so I was wondering if, uh, if there’s a class or something . . . so I can learn how to use computers, like to write papers for my classes.

Computer center employee: Oh, I see . . . u m, we don’t really offer a course for beginners, since most students already have computing experience. But all the computers in our labs have a general tutorial installed on them. You could just go there and run it.

Student: And the tutorial explains everything? I mean, it might sound strange but I’ve never used a computer.

Computer center employee: Well, all the computer labs on campus are staffed with student assistants, and I’m sure that any one of them would be more than willing to get you started.

Student: Yeah? That sounds good. But is it expensive?

Computer center employee: No, in fact, it won’t cost anything; it’s one of the services of the computer center.

Student: That’s great. How do they-l mean, how do I get in touch with the student assistants? Should I just go to a computer lab and ask whoever’s there?

Computer center employee: Sure, you could do that, or I can let you have a list of names of the students who are assistants in the labs. You might know one of them.

Student: Actually, I think I’d prefer someone I don’t know, um, so I can ask dumb questions . . . Is there anyone you’d recommend?

Computer center employee: All of our student assistants are really knowledgeable about computers. I mean, they have to be, in order to work in the computer labs . . . It doesn’t mean that they’re necessarily good at teaching beginners . . . but you probably won’t be a beginner for very long.

Student: Hope not.

Computer center employee: And I just thought of something else. The bookstore has a lot of books on computers-there might be one for people like you. I mean, people who don’t have a lot of experience with computers. I actually bought one for my father so he could learn how to use e-mail, basic word processing, that sort of thing-and it worked pretty well for him.

Student: OK, I’II try that, too. And if the bookstore doesn’t have it, they can just order it for me?

Computer center employee: Right. Now is there anything else I can help you with today?

Student: Uh, just the list of names and the times they’re working. I’d like to get going on this as soon as possible.

Computer center employee: Right. Good luck.

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

Professor: When attempting to understand international trade, some things seem so obvious that they can hardly be controverted, and other points that are important are invisible unless you’ve thought about the subject carefully.

Consider the following: if there’s an increase in imports, let’s say, um, let’s say imports of furniture, and the domestic producers of furniture find this new competition very difficult and are cutting production and employment, then it seems obvious and easy to understand and many people conclude from this that increasing imports will cause generally greater unemployment at home.

What is not so obvious is that how much we import and how much we export … those are interdependent and you can’t understand the one without the other. But the exports that are generated are not easily discernable, so most people don’t see them. They see only the imports of furniture rising and employment in domestic furniture production falling.

So as a result, many people argue that we ought to protect jobs by limiting imports-either by tariffs, quotas, regulations, or whatever-without realizing that this also has the effect of reducing potential future exports to the rest of the world, things that we can produce very, very . . . cost effectively and therefore profitably.

The fundamental proposition in international economics is that it makes sense to import those things that we . . . that can be produced more economically abroad than at home and export things to the rest of the world that we can produce more cost effectively than produced elsewhere in the world. Therefore, if we limit imports, we put ourselves in danger of not being able to export.

The details of this relationship will take much longer to explain than I can fully go into now but the point of the matter is that gains-the benefits of gains-from international trade result from being able to get things cheaper by buying them abroad than you can make them at home. Now there’re some things that we can make at home that are . . . that we can do more economically than they can do abroad.

In the case of the United States, typically high-technology products, uh . . . are things that Americans have innovated in and started firms doing that sort of thing at which they do very well. Whereas goods that produce . . . that use a lot of relatively low skill labor, like furniture production, cotton production, sugar production . . . those are things that are frequently made more inexpensively in places where wage rates are low and the cost of using capital is very high.

However, in Florida they produce a lot of sugar, but the costs are so high, if we didn’t have extensive restrictions on imports of sugar, the output of sugar would decline dramatically. But the sugar industry in the U.S. doesn’t produce high-paying jobs, it uses resources in ineffective ways and it blocks the import of more cost-effectively produced sugar. It, it’s a very bad bargain for the people in the United

States to want to protect low-paying jobs thereby halting the growth of world trading and international . . . uh, more international specialization. It would be better to remove restrictions on imports and allow other countries in the world . . . countries that can produce them more cheaply . . . let them specialize in producing those products.

Now, I agree that people who are directly affected by imports, what they focus on . . . is, is that their prospects . . . their job prospects are being reduced, and their economic circumstances are getting worse. And that’s a relevant problem and an important problem; what isn’t so obvious is . . . that by retraining and relocating people to places and industries where jobs are expanding rather than contracting, we can make the whole economy function more effectively and productively than by trying to block imports.

Um, what is interesting to note is that, even if there were no international trade issues, like imports, any changes that occur in a country’s economy-any new technology, change in preferences, change in regulations or whatever-will lead to “adjustments” that lead some sectors of the economy to decline and others to expand.

And that’s what we have to figure out, and that’s a hard problem to deal with in detail, is how to facilitate people adjusting from sectors where their job prospects are not so good, and in particular where real wages aren’t so high, to acquire skills that will permit them to move into higher-paying jobs in other parts of the economy either by retraining or relocating. Helping pay for the relocation of these people would be very helpful, but trying to block the changes is really counterproductive. It makes people in our country poorer, and it makes people elsewhere in the world poorer as well.

Narrator: Listen to part of a lecture in a marine biology class.

Professor: I want to continue our discussion about whales. Specifically, today, um, I want to talk about whale migration-um, why whales head south for the winter. Or really why whales in the cold water of the Northern Hemisphere head south for the winter. Now, not all kinds of whales migrate, but most baleen whales do.

And interestingly enough, we still don’t really know why the baleen whales migrate. We do have several theories, however, which I’II discuss today. Uh, can anybody name one reason why baleen whales might migrate south, to the warm tropical water?

Male student: Uh, for food? You know, the whales move to warmer water in order to find a good area to feed.

Professor: Good guess. That should be an obvious reason-after all, most animals that migrate do so for the purpose of finding food. But, uh, that doesn’t seem to be the case with baleen whales. To understand why, you need to know something about water temperature. There are a lot of technical reasons that I’m not going to go into right now. But let’s just say that nutrients don’t rise to the surface of tropical water like they do in other kinds of water. Tropical water simply never gets cold enough. So . . . well, what this means, uh, is that tropical water doesn’t have much of the plankton that most whales feed on.

Male student: I don’t understand-if there’s no plankton, how do the whales survive through the winter?

Professor: Right. How do they survive? You see, they don’t have to eat anything, because they’ve stored up so much fat during the summer feeding season that they can just survive off of that. So if they don’t need to eat anything, we’re back to our original question. Why do baleen whales migrate? Any theories? No?

Well, there’s one idea out there that a lot of people believe. In fact, uh, you could say it’s the most popular theory we have about whale migration. Basically, the argument is that for baleen whales, migration is a kind of balancing act. Let me explain. On one hand, whales need to take advantage of the summer months by eating as much food as they can. And that’s what they can do best in the northern seas. This allows them to build up a lot of fat. But in the winter, food is scarce even in the north, so what the whales need to do is save energy. And that’s what migrating south can help them do . . . Amanda, you have a question?

Female student: Yes. Um, the balancing-act theory doesn’t make sense to me. Maybe whales might need to save energy during the winter, but wouldn’t moving all the way down to tropics make them lose energy?

Professor: That’s a good point, and it’s one reason why this isn’t a perfect theory. It does cost the whales energy to migrate, but it’s easier for whales to save energy in warm water than it is to save energy in cold water, so there might still be, you know, a good reason to move south for the winter. OK?

Now, before moving on to the next chapter, I want to briefly discuss how the baleen whale manages to navigate. It’s pretty remarkable, because the whales manage to return to the same places year after year, and have to travel over an enormous area of ocean in order to do it. I mean, it’s not like whales can just look at a map, right? So exactly how do they do it?

Well, a lot of experimental work still needs to be done, but we have been able to figure out at least three ways the baleen whale navigates without getting lost. The first is the ability to use Earth’s magnetic field like it was a map. That sounds strange, but we know that many birds use that method, use the magnetic field, and it’s possible that whales have the biological ability to do the same thing.

Another theory is that if they stay close to the coast, whales might be able to find familiar landmarks and use those as guides. But we don’t really know if a whale’s eye-sight is good enough to be able to do that, so that’s not a perfect theory.

And finally, we know that many whales make very loud sounds that can travel literally hundreds of miles underwater. Through a process called echolocation, it’s possible that these whales hear the sounds bounce off of islands or other pieces of land and use those echoes as clues to help them find their way.