Conversation1
Narrator
Listen to a conversation between a student and a professor.
Professor Excuse me, can I help you? You look a little lost.
Student Yeah, I am. This is my first day on campus, and I don’t know where anything is.
Professor Can’t find your orientation session?
Student Uh-huh. What a way to begin! Lost going to orientation
Professor Well, my guess is in the auditorium, that’s where they usually are.
Student You’re right, the general ones. I went to one of those sessions ealier today. But now I need the one for my major, engineering. My schedule says the meeting room is in ... Johnson Hall? In the engineering department, which should be right here in front of us, according to the map. But this building is called the Morgan Hall.
Professor Well, your map reading skills are fine actually. This used to be Johnson Hall, all right. Trouble is they changed the name to Morgan Hall last spring. So they sent you a map with an old name? I am surprised.
Student Well, this was actually mailed out month and month ago. I got a second pack in the mail more recently with another one of these maps in it. I guess they must have the updated name. I left that one in my dorm room.
Professor Well, things change fast around here. This building was renamed after one of our professors. She retired a few months ago. She is very well-known in the world of physics. Too bad for Johnson, I guess.
Student Who is Johnson anyway?
Professor Oh, one of the early professors here. Unfortunately, I thinks his ideas are going out of style. Science kept marching forward.
Student I’ll say it does. That’s why I transferred to this university. I was really impressed with all the research equipment you guys have at the laboratories. You are really on the forefront.
Professor Um... so do you know what kind of engineering you want to specialize in?
Student Yeah, aerospace engineering.
Professor Well, the aerospace engineering department here is excellent! Eh... do you know that this university was the first one in the country to offer a program in aerospace engineering?
Student Yeah, I know. And a couple of students who graduated from here became astronauts and orbited the Earth.
Professor Right. The department has many prominent alumni. Well, you might end up taking some of your advanced math course with me. I get a lot of students from the engineering department because I teach the required applied mathematics courses.
Student Oh, cool. Actually, I want to get a minor in math.
Professor Excellent. Hmm... A major in aerospace engineering with a minor in math, you’ll go far with that degree. More of our students should do that. There are so many more opportunities available in the field when you have a strong math background.
Student I’m glad to hear you say that.
TPO 21 Lecture 1 Astronomy(Geocentric&Heliocentric theory)
Narrator Listen to part of a lecture in a history of science class. Aristarchus-Heliocentric Theory
Professor Ok, we have been talking about how throughout history, it was often difficult for people to give up ideas which have long been taken for granted as scientific truth, even if those ideas were false. In Astronomy, for example, the distinction between the solar system and the universe wasn’t clear until modern times. The ancient Greeks believed that what we called the solar system was in fact the entire universe, and that the universe was geocentric. Geocentric means Earth-centered, so the geocentric view holds that the Sun, the planets, and the stars, all revolve around the Earth, which is stationary. Of course, we now know that the planets, including Earth, revolve around the Sun, and that the solar system is only a tiny part of the universe.
So, why did the ancient Greeks believe that the Earth was the center of the universe? Well, it made sense to them. Observations of the sky make it appear as if the Sun, the moon, and the stars all revolve around the Earth everyday, while the Earth itself stayed in one place. And this view is also supported by their philosophical and religious beliefs about the origin and structure of the universe. It was presented in the works of well-known Greek philosophers as early as the fourth century B.C.E., and the geocentric theory continue to prevail in Western thought for almost 2,000 years, until the 17th century.
Now, what’s especially interesting is that when astronomical observations were made that seemed to be inconsistent with the geocentric view, the ancient Greeks did not really consider alternative theories. It was so intuitive, so sensible that the Earth was the center of the universe that astronomers found ways to explain those seemingly inconsistent phenomena within the geocentric view.
For example, Greek astronomers made excellent, very accurate observations of the movements of the planets, but the observations revealed a bit of a problem. The geocentric theory said, that the planets would move around the Earth in one direction. However, astronomers noticed that at times, several planets seem to stop moving in one direction and start moving backward in their orbits around the Earth, and they came up with a theory that these planets themselves moved in smaller circles called epicycles as they travelled around the Earth. Here’s a picture of what they imagined. You see how this epicycle theory could account for the seemingly backward motion of the planet. Of course, today we know that this appearance of backward motion is caused by the fact that Earth, as well as other planets, all move in their own orbits around the Sun, and the relative movements of the planets with respect to each other can get quite complex.
However, there were a few astronomers in Greece and other places who didn’t agree with the geocentric view, for example, a Greek astronomer who lived in the third century B.C.E. He proposed the theory that our planetary system might be heliocentric, his name was Aristarchus. Heliocentric means Sun-centered, that the Earth revolves around the Sun. Aristarchus recognized from his calculations that the Sun was much larger than the Earth and other planets. It was probably this discovery that led him to conclude that the universe is heliocentric. I mean, isn’t it more sensible to think that a smaller heavenly body would orbit a larger one, rather than the opposite?
However, his proposition was rejected largely based on other scientific beliefs held at the time, which all made sense in a way even if they were incorrect. Let me mention two objections Greeks made to Aristarchus’s theory. First, they believe that everything that moves creates its own wind, so to speak, everyone has this experience when you are running, right? So, they thought that if the Earth itself was moving, there would have to be a constant wind blowing, sweeping them off their feet, and of course there wasn’t. And second, the idea of an Earth that moved didn’t fit in with the ancient Greeks’ understanding of gravity. They thought that gravity was basically a natural tendency of all things to move towards the center of the universe, which was the Earth, or the center of the Earth, so that explains why apples and other falling objects were falling straight down. If the Sun was at the center of the universe, things would fall toward the Sun and away from the Earth, which of course they didn’t. So these were some of the reasons they rejected the heliocentric theory.
TPO21 Lecture 2 Computer Science(Software Development)
Narrator Listen to part of a lecture in a Computer Science class. The professor is discussing software engineering.
Professor We’ve been talking about the software development cycle, and today I’d like to move on to the next stage of that cycle-testing, and why finding bugs during testing is actually a great thing. Eh...eh... the quality of the software product often relies heavily on how well it’s been tested. Liz?
Student Um... just a quick thing. Bugs is the word for problems in the program code, right?
Professor
Yeah, in code or in a computer itself. There is a bit of a story behind that term. Um... back in the 1940s, when the computer industry was just starting, a group of computer scientists was working late one night, and there was a problem in one of the computers’ circuits1. When they examined it, they found a five-centimeter long moth caught in there. Once they debugged the computer, it worked just fine. And ever since then, all kinds of computer problems have been known as bugs.
Anyway, you want to find bugs while the software is still in the development and testing phases. Finding them when the software product has already been put on the market can be quite embarrassing. Generally speaking, every software development project has a group of testers and a group of developers. Jack?
Student And they are different people?
Professor They are generally completely different group of people. My personal opinion is that they have to be different groups of people because developers often have a bias for their own work, and it blinds them to certain problems that might be obvious to somebody else. So it is always good to have a different set of eyes to go in there and make sure that everything is tested properly.
Ok, now, here’s the key. Developers and testers have different mentalities. The mentality of the software developer is construtive, creative, they are spending long hours working together to create and build something new. A software tester, on the other hand, their entire goal is to look at this product and find problems with it, to improve it. Now, this difference between the testers and the developers can lead to an environment where there is a bit of friction. And that friction sometimes makes it difficult for the two teams to work together.
There are two projects that I worked on a couple of years ago. One, which I’ll call Project Split, well, the testing and development teams did not work well together. And the other, I’ll call Project Unity, during which both teams worked very well together. Now, during Project Split, we had defect meetings where the developers and the testers met together, eh... eh... to discuss various problems and how they should be fixed. And you could sense the conflict just by walking into the room. Literally, the testers and the developers sat on opposite sides on the table. Um... and ... and the developers were very defensive about the feedback.
Student Well, if bugs are being pointed out they wouldn’t be too happy since its their work.
Professor Exactly. Now, ‘cause the two teams weren’t working well together, the fixes were coming very very slowly. And you know, a lot of times when you fix bugs you introduce new bugs, or you discover bugs and other areas that only come to light because something has been changed, so fixing all those new additional bugs was also being delayed. Um... the test process went on much longer than expected and we ended up having to put the product on the market with known bugs in it, which was obviously not ideal.
Student Ok, and what about Project Unity? How was it different?
Professor
Um... this was different because two teams worked closely together during the defect meetings, instead of put up walls. Um... we didn’t even talked about, you know, who should fix this, who is at fault2. We all acknowledge what needed to be fixed. So if we had ten bugs, we said, ‘Hey, you know what? Let’s do this one first ‘cause this would expose another whole bunch of defects that we haven’t even seen yet.’ So we were being proactive3 and effective. And because we were so much more effective with our time, we were actually able to do more than just fix the bugs, we even put in some improvements that we hadn’t planned.
TPO21 Conversation 2
Narrator Listen to a conversation between a student and her public relations professor.
Student Hi, professor Gordin. I really learned a lot from your lecture, the one about analyzing all those different segments of the population. Oh, the official term is audience, right? I never imagine that one company could have over thirty audiences to communicate with.
Professor Yeah, a lot of students are taken aback by this, and some public relations consultants don’t figure it out until they’ve worked in the field a while.
Student Everyone thinks, public relations, eh, PR is easy, but there’s a lot to it. You really got to know what you are doing.
Professor Absolutely. So, Stacy, your email implied that you needed my advice about graduate school?
Student No, since my undergraduate degree will be in public relations, I’ve already decided to get a master’s degree in marketing. Sorry, I wasn’t clear. My issue is, I have got two require courses and two electives. I am trying to figure out which elective course is to take. My advisor suggested economics and accounting, but I am not really sure.
Professor About?
Student Well, I endured accounting and economics in high school and barely stayed awake, they were so ...
Professor Ok, Ok. I hear you. Eh... you say you wanted a master’s in marketing, you have got one more semester till graduation. Have you taken any marketing courses yet?
Student No, I figured I’ve got the marketing basis already since I have take every PR in communication courses offered here.
Professor Well, there’s some overlap between PR and marketing, but there are important differences too. Marketing focuses on selling your product or service, eh, you know, attracting customers through advertising, and also buiding relationships with customers. That’s what a marketing department does. PR is all about, it involves relationships too, that’s why I am saying the two fields overlap. But in PR, you are developing relationships with a wider range of audience.
Student Right. Like employees, suppliers, the media. I do understand this in theory, but aren’t you still selling your product, just in a different way?
Professor Not necessarily. Ok, do you remember that PR strategy I alluded to the other day? The one our university uses, a strategy that doesn’t overlap its marketing strategy?
Student You mean how the university invites local residents to attend certain lectures and classes for free?
Professor Yeah, this cultivates a sense of good will and helps the university avoid becoming isolated from the larger community. Bringing neighbours into our classrooms is good PR, but it is not marketing since our neighbours aren’t our customers, for the most part.
Student That’s why I want to focus on marketing in graduate school. Wouldn’t having expertise in PR and marketing giving me more career options?
Professor Yeah, but you’ll also want to enjoy your work. So for you electives, why don’t you take advertising principles and intro to marketing, which I teach. This way, you’ll find out if marketing is something you really want to pursue. Graduate School tuition is expensive, and these courses will give you a good overview of the field before committing yourself.
Student I wish my advisor had suggested those courses.
Professor Well, I am someone who has worked in both marketing and PR, so I can offer a different perspective than someone who only teaches ...
TPO21 Lecture3 Biology(Snake Evolution)
Narrator Listen to part of a lecture in a biology class.
Professor Probably back in some previous biology course you learned that snakes evolved from lizards, and that the first snakes weren’t venomous and then along came more advanced snakes, the venomous snakes. Ok, venomous snakes are the ones that secrete poisonous substances or venom, like the snakes of the viper family or cobras. Then there is non-venomous snakes like constrictors and pythons. Another family of snakes, the colubrids, don’t really fit neatly into either category though. Colubrids, and you probably learned this too, although they are often classified as venomous snakes, they are actually generally non-venomous. They are classified as venomous snakes because they resemble them, their advanced features more than the other non-venomous snakes.
Now, what if I told you that there is a good chance that most everything I just said is wrong? Well, everything except the part about snakes evolving from lizards. See, the basic theory about snake evolution has been challenged by a recent study that revealed a whole new understanding of evolutionary relationship for reptiles, you know, which reptiles descended from which ancestors. The researchers study the proteins in the venom genes of various species of colubrids. Emm... snake venom is a mixture of proteins, some toxic, poisonous, and some not. By analyzing the DNA, the genetic material of the proteins, the researchers could focus on the toxic genes and use them to trace the evolution of snake venom, and from this, the evolution of snakes.
Traditionally, to understanding evolutionary relationships, we looked at various easily observed physical characteristics of animals, their skeleton, the size of their brain, and... and then classify them based on similarities and differences. The problem with this method is that characteristics that appear similar may actually have developed in quite different ways. For example, some venoms are chemical-based, and others are bacteria-based, so they clearly had to have developed along different routes and may not be as closely related as we thought.
Now, and not everyone will agree about this. The classification based on DNA seems to be much more reliable. Ok, back to the research. The researchers found that venom evolved before snakes even existed, about a hundred million years before. Now, a couple of venomous lizards were included in this study. And the researchers found some of the same DNA in their venom as in the snakes’ venom. This suggested that the common ancestor of all snakes was actually venomous lizard, which means that actually, according to this research, anyway, in terms of the snakes’ ancestry, there is no such thing as a non-venomous snake, not even colubrids. What separates colubrids from other snakes we have been classifying is venomous, is not the lack of venom, but the lack of an effective way to deliver the venom into its prey. In most venomous snakes, like vipers and cobras, the venom is used to catch and inmoblize the prey; but in colubrids, venom drips onto the prey only after the prey is in the snake’s mouth. So for colubrids, the venom must serve some other purpose, maybe linked to digesting prey. As the different families of venomous snakes evolved, the teeth moved forward, becoming larger, and the venom becoming stronger, so the evolution of the obvious venomous snakes, like cobras and vipers, is about the evolution of an efficient delivery system, not so much the evolution of the venom itself.
So, if there are no truly non-venomous snakes, were the so-called non-venomous snakes, like constrictors and pythons, were they venomous at some point in their evolution? Well, that’s not clear at this point. Constrictors have evolved to kill their prey by crushing, but perhaps they once were venomous, and then at some point their venom-producing apparatus4 wasn’t needed anymore, so it gradually disappeared. There’s one species of snake, the brown tree snake, that uses both constriction and venom, depending on its prey. So, well, it is possible.
So, we have these new concepts of snakes’ evolution and a new DNA database, all these information on the genetic makeup of snake venom. And what we have learned from this has led researchers to believe that venom proteins may have some exciting applications in the field of medical research. You see, venom alters biological functions in the same way certain drugs do, and the big benefit of drugs made from snakes venom would be that they target only certain cells, so maybe that’ll create fewer side effects. Now, it sounds far-fetched5, venom is the basis for human drugs. So far, only one protein has been targeted for study as a potential drug, but who knows, maybe someday.
TPO21 Lecture 4 Art History(Alice Neel)
Narrator Listen to part of a lecture in an Art History class.
Professor
All right, so today we are moving on to Alice Neel, N-E-E-L. Um... Alice Neel painted portraits, she was born in Pennsylvania, and she lived from 1900 to 1984. And I guess you might say, she experienced difficulties as an artist. She was in her 70s, before she had her first major solo exhibition. Um, and this is due at least in part to eh... or... because of photography. After photography became regarded as an art form, portrait painting became less prestigious6, less respected as an art form. And, well, art photography kind of took its place, so you can imagine that a portrait artist, would have had a hard time finding acceptance.
Eh, but the real reason I want to look at Neel, is that I really find her style ... eh, she had interesting ways of portraying people. She combined some elements of realism. What’s realism, Alison?
Student It’s like painting something exactly how it is, so an artist would try to make it as accurate, um... and objective as possible. Painting stuff just how it appears on the surface.
Professor Ok, good. So Neel combined realism with, well, actually, with expressionism. And that is? We, we just covered this.
Student Um... It’s into emotion, like artists are trying to, well, express themselves through the painting, right?
Professor
Yep. The artist is depicting subjective emotions, showing the inner reality as interpreted by the artist rather than the outward form. So the image itself might be distorted or exaggerated in some way. The expression overrides7 objective representation. Ok, so, Alice Neel combined these two styles ... Yes?
Student Em... How is that even possible? How can your portray something exactly as it is and at the same time distort it with emotions? I don’t get it.
Professor
All right, good question. It is actually a good lead-in8 to some of the techniques that Neel used, that she employed to bridge that contradiction. In a minute, I’ll show you some of her portraits, and I’ll want you to notice a few things about them.
First, Neel’s use of bold color. All right? You’ll see she uses color to convey emtion and feeling, like the subjects’ clothing for instance, it appears brighter than it really is. And the subjects, the people being portrayed, Neel paid special attention to faces. The way she paints the eyes and how the faces are portrayed, these are quite realistic, like the realists’ work. But another thing Neel did was use elongated, sort of stretchy figures.
Student But didn’t a lot of expressionist painters do that? So really your are saying that Neel’s techniques were similar to what other artists were doing. What was it that she did, that was like all her own?
Professor Ok, well, I think it has to do partly with the way she combined these techniques. So, for example, those realistic faces and eyes, but bright, distorted figures. It is a mix. You’ll see that her portraits do reflect reality, the people that were actually sitting there. Realism was important in the sense that she wanted to show people as they really were, much like a photographer would. But Neel wasn’t satisfied with photo-like realism, she went beyond that. And this is where expressionism comes in.
She believed in capturing the whole person, not just what was on the surface, that’s where the expressionists’ distortion is important, in an attempt to reveal the subjects’ character or personality.
But Neel’s paintings are distinctive for her time in part because they are portraits. Remember I said that photography and art photography had largely taken the place of portraiture, to the extent that some critics had declared the genre of portraiture to be dead. But Neel felt that painting should reflect reality, a real realist’s stance9 you could say. And to her, individuals, people best reflect the reality of their time, of the age that they lived in, so she painted portraits. And if you look at her work, we are talking in the vicinity of10 three thousand paintings. If your looked at them, it is like this gallery of the whole century, an enomous range of subjects: families, women, children, artists, people in poverty--these paintings really span class, age and gender. It is like she transformed the genre, it is not just formal depictions of presidents and ancestors any more.
But keep in mind that she was doing this when abstract art dominated the art scene. Representations of people weren’t fashionable in the art world. And it wasn’t until fairly late in the century that critics recognized the power of what she did.
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Conversation 1 (Faculty Advisor)
Narrator: Listen to a conversation between a student and a faculty advisor for the university newspaper.
Student: Hi, I am sorry to bother you, but…
Faculty advisor: Yes?
Student: This is about the newspaper.
Faculty Advisor: Oh, Ok. Well. I am only the advisor; the newspaper office is off campus on Pine Street. Eh…what was it? Did you want to work for the paper? We are always looking for writers.
Student: Well, my problem was with the writing actually, with an article that was published in yesterday’s newspaper.
Faculty Advisor: Oh? Which one?
Student: The one about the student government and its president Sally Smith.
Faculty Advisor: Is this something to do with what the editor wrote about the statue? Eh, the statue at the main entrance of the university?
Student: Well, that’s part of it. But you know, the editor used the situation to say some really unfair things, about the student government, and the president Sally Smith in particular. I think the paper should publish a retraction, or at the very least an apology to Sally.
Faculty Advisor: Ok. Um… if I remember correctly, what you are referring to wasn’t a news story, but an editorial, right? Eh, it was on the opinion page, it was signed by one of the editors, and was clearly labeled as commentary.
Student: Well, yes. But the thing about the statue, Sally made this simple comment that was in really bad condition and should be replaced. And, well, the tone in the editorial was demeaning. It accused her of not respecting the past and it had some personal stuff that seemed unnecessary.
Faculty Advisor: Wait a minute. Remind me.
Student: Well, you know, it implied that Sally doesn’t know much about the university’s history and it called her a big city politician because she’s from Boston. It’s just mean-spirited, isn’t it?
Faculty Advisor: Haven’t you heard the saying “all publicity is good publicity”?
Student: Well…
Faculty Advisor: I’d say the article is bringing attention to the student government organization, which is pretty invisible. Eh, you rarely hear about what the student government is doing.
Student: But this article…
Faculty Advisor: And the piece, well, yeah, it had a bit of an exaggerated tone. It was satirical, or at least it was meant to be. It wasn’t just poking fun at Sally, but the whole idea that our school is sort of rural, and you know, not cosmopolitan.
Student: Well, none of us thought it was very funny.
Faculty Advisor: Well, sometimes it’s best just to roll with it. It is just a cliché; everybody knows it is not true.
Student: But I thought we could expect better than that here.
Faculty Advisor: Well, I am certainly in favor of getting a variety of viewpoints. [so why don’t you go talk to the editor, Jennifer Hamilton, and tell her you want equal time? You or Sally could write a response.]
Student: [Really? She would let us do that? ] Didn’t she write it?
Faculty Advisor: I’ll let Jennifer know you are coming, she feels the same way I do. She is journalism major. She would be happy to publish another point of view.
TPO22 Lecture 1 (Anthropology)
Narrator: Listen to part of a lecture in an anthropology class.
Professor: One of the big questions when we look at prehistory is why did the earliest states form?
Well, to begin we’d better define exactly what we mean when we talk about states. The human groups that are the smallest and have the least social and political complexity, we call bands. The groups that are the largest and most socially and politically complex, we call states. So, the level of complexity here refers to the organization of people into large, diverse groups, and densely populated communities. And there are four levels in total: bands, tribes, chiefdoms and states.
But, but back to my original question. Why did early states form? Why not just continue to live in small groups? Why become more complex?
One theory called the environmental approach hypothesizes that the main force behind state formation was population growth. It assumes that centralized management was critical to dealing with issues caused by sudden population surges, like a strain on limited food supplies.
At the least complex end of the spectrum, the few families living in bands are able to meet their own basic needs. They usually hunt together and forage whatever foods are available to them, instead of domesticating animals and planting crops. In order to efficiently take advantage of the wild foods available, bands are often nomadic and move around following herds of animals. This strategy is feasible when you have a small population.
But when you have a large population, well, the whole population can’t just get up and move to follow a wild herd of animals. So you need sophisticated technologies to produce enough food for everyone. And there is an increase need to resolve social problems that arise as people begin to compete for resources. To manage intensified food production, to collect, store and distribute food, you need centralized decision-making, centralized decision-makers.
It’s the same thing when it comes to maintaining social order. You need to create and efficiently enforce a formal legal code. It makes sense to have a centralized authority in charge of that, right? So a hierarchy forms. By definition, states had at least three social levels. Usually, an upper class of rulers, a middleclass comprised of managers and merchants, and a lower class of crop producers and agricultural laborers.
The environmental approach hypothesizes that states appear in certain environmental settings, settings which have a severe population problem or a shortage of agricultural land. But not everyone agrees with the theory. It definitely has some weaknesses. For example, states have developed in places like the mild lowlands of Mesoamerica and in Egypt’s Nile River Valley. Both places had vast areas of fertile farmland, no shortage of agricultural land. And what about population increase? Well, there were some early states that formed where there wasn’t any sudden population increase. So it seems that these are valid criticisms of the environmental approach.
TPO22 Lecture 2 (Astronomy)
Narrator: Listen to part of a lecture in an astronomy class.
Professor: Today, I want to talk about a paradox the ties in with the topic we discuss last time. We were discussing the geological evidence of water, liquid water on Earth and Mars three to four billion years ago. So, what evidence of a liquid water environment did we find in rock samples taking from the oldest rocks on Earth?
Student: Eh… Like pebbles, fossilized algae?
Professor: Right. And on Mars?
Student: Dry channels?
Professor: Good. All evidence of water in liquid form, large quantities of it. Now, remember when we talked about star formation, we said that as a star ages, it becomes brighter, right? Hydrogen turns into Helium, which releases energy. So our standard model of star formation suggests that the Sun wasn’t nearly as bright three to four billion years ago as it is today, which means the temperatures on Earth and Mars would have been lower, which in turn suggests…
Student: There would have been ice on Earth or Mars?
Professor: Correct. If the young Sun was much fainter and cooler than the Sun today, liquid water couldn’t have existed on either planet.
Now, this apparent contradiction between geologic evidence and the stellar evolution model became known as the faint young Sun paradox.
Now, there have been several attempts to solve this paradox.
First, there was the greenhouse-gas solution. Well, you are probably familiar with the greenhouse gas effect, so I won’t go into details now. The idea was that trapped greenhouse gases in the atmospheres of Earth and Mars might have caused temperatures to raise enough to compensate for the low heat the young Sun provided. And so it would have been warm enough on these planets for liquid water to exist. So, what gas do you think was the first suspect in causing the greenhouse effect?
Student: Um…carbon dioxide, I guess. Like today?
Professor: In fact, studies indicate that four billion years ago, carbon dioxide levels in the atmosphere were much higher than today’s levels. But the studies also indicate that they weren’t high enough to do the job—make up for a faint Sun.
Then some astronomers came up with the idea that atmospheric ammonia might have acted as a greenhouse gas. But ammonia would have been destroyed by the ultra-violet light coming from the Sun and it had to be ruled out too.
Another solution, which is proposed much later, was that perhaps the young Sun wasn’t faint at all, perhaps it was bright. So it is called the bright-young-Sun solution, according to which the Sun would have provided enough heat for the water on Earth and Mars to be liquid. But how could the early Sun be brighter and hotter than predicted by the standard model? Well, the answer is mass.
Student: You mean the Sun had more mass when it was young?
Professor: Well, if the young Sun was more massive than today’s, it would have been hotter and brighter than the model predicts. But this would mean that it had lost mass over the course of four billion years.
Student: Is that possible?
Professor: Actually, the Sun is constantly losing mass through the solar wind, a stream of charged particles constantly blowing off the Sun. we know the Sun’s current rate of mass loss, but if we assume that this rate has been steady over the last four billion years, the young Sun wouldn’t have been massive enough to have warmed Earth, let alone Mars, not enough to have caused liquid water.
Student: Maybe the solar wind was stronger then?
Professor: There is evidence that the solar wind was more intense in the past. But we don’t know for sure how much mass our Sun’s lost over the last four billion years. Astronomers tried to estimate what solar mass could produce the required luminosity to explain liquid water on these planets. They also took into account that with a more massive young Sun, the planets would be closer to the Sun than they are today. And they found that about seven percent more mass would be required.
Student: So the young Sun had seven percent more mass than our Sun?
Professor: Well, we don’t know. According to observations of young Sun like stars, our Sun may have lost as much as six percent of its initial mass, which doesn’t quite make it. On the other hand, this estimate is based on a small sample. And the bright-young-Sun solution is appealing. We simply need more data to determine the mass loss rate of stars. So there’s reason to believe that we will get an answer to that piece of the puzzle one day.
TPO22 Conversation 2 (Professor)
Narrator: Listen to part of a conversation between a student and his music history professor.
Student: So, I was wondering what I could do to improve my paper before the final draft is due.
Professor: Well, Michael, I have no problem with your writing style. It’s graceful and clear. Eh, and it’s interesting that you are writing about your grandmother’s piano concert.
Student: Yeah, when you said we had to attend a concert and write about it, I immediately thought of her. I have been to lots of her concerts. So I am really familiar with her music.
Professor: That’s not necessarily an advantage. Familiarity sometimes makes it hard to see things objectively.
Student: So I shouldn’t write about my grandmother?
Professor: No, no, no. I am just talking in general. But as I mentioned in my comments, I’d like you to place your grandmother’s concert in… in a broader context.
Student: Yeah, I saw that, but I wasn’t sure what you meant. I mean, I mentioned my grandmother’s childhood, how much her parents love music, how she played the piano at all our family gatherings.
Professor: Ok. I see what happened now. By broader context, I mean how the concert relates to some period in music history.
Student: I see. Ok. Um… I have an idea.
Professor: Ok.
Student: Well, as you read in my paper, my grandmother performs classical music.
Professor: Yes.
Student: That’s her true love. But for most of her career, she performed jazz. She originally studied to be a classical pianist. But jazz was in its heyday back then, and when she got out of the conservatory, she was invited to join a jazz orchestra. And the opportunity was just too good to turn down.
Professor: Really. Well, that’s fascinating. Because she probably had to reinvent her whole musical style.
Student: She did. But jazz was where the money was at that time, at least for her.
Professor: But she eventually went back to classical?
Student: Right. But only recently.
Professor: Ok.
Student: So if I can show how her choices relate to what was happening in the world of music at the time…?
Professor: I think that might work very nicely.
Student: And if I do that, I guess I’ll have to like, interview her.
Professor: Right.
Student: And I guess that would mean…
Professor: You’ll have to rewrite most of your paper.
Student: Ouch!
Professor: Yeah. Would an extra week ease the pain?
Student: Definitely.
Professor: Ok. So are there other musicians in your family?
Student: Yeah. My mother plays piano, too. Not as well as my grandmother, but…
Professor: And you?
Student: I don’t play any instruments, but I sing in the university choir. In fact, we are performing next week, and I have a solo.
Professor: That’s great! Could I tell the class about your concert?
Student: Um…sure. But…about my paper… what question should I be asking my grandmother?
Professor: You know what, I have a meeting now. Why don’t you come to class a few minutes early tomorrow?
Student: Will do.
TPO22 Lecture 3 (Zoology)
Narrator: Listen to part of a lecture in a zoology class.
Professor: A mass extinction as when numerous species become extinct over a very short time period, short, geologically speaking that is, like when the dinosaurs died out 65 million years ago. And the fossil record, it indicates that in all the time that animals have inhabited Earth, there have been five great mass extinctions, dinosaurs being the most recent. In each of the others up to half of all land animals and up to 95 percent of marine species disappeared.
Well, today we are witnessing a sixth mass extinction, but unlike the others, the current loss of bio-diversity can be traced to human to human activity. Since the Stone Age, humans have been eliminating species and altering ecosystems with astounding speed. Countless species have disappeared due to over-hunting, habitat destruction and habitat fragmentation, pollution and other unnatural human causes.
So, as a way of repairing some of that damage, a group of conservation biologists has proposed an ambitious, or some might say, a radical plan, involving large vertebrates, or , megafauna. Megafauna include elephants, wild horses, big cats, camels, large animals. Eh, actually, the proposal focuses on a particular subset of megafauna, the kind that lived during the Pleistocene epoch.
Ok. The Pleistocene epoch, most commonly known as the Ice Age, stretched from 1.8 million to 11,500 years ago. In the Americas, many megafauna began disappearing by the end of the Pleistocene.
So here’s the biologists’ idea. Take a select group of animals, megafauna from places like Africa and Asia, and introduce them into other ecosystems similar to their current homes, beginning in the United States. They call their plan Pleistocene rewilding.
Now, the advocates of Pleistocene rewilding cite two main goals. One is to help prevent the extinction of some endangered megafauna by providing new refuges, new habitats for them. The other is to restore some of the evolutionary and ecological potential that has been lost in North America. What do I mean by restore evolutionary potential? Well as you know the evolution of any species is largely influenced by its interactions with other species.
So during the Pleistocene epoch… let’s take the now extinct American cheetah, for instance. We believe it played a pivotal role in the evolution of the pronghorn antelope, the antelope’s amazing speed, to be exact, because natural selection would favor those antelope that could outrun a cheetah. When the American cheetahs disappeared, their influence on the evolution of pronghorn and presumably on other prey animals stopped. So it is conceivable that the pronghorn antelope would have continued to evolve, get faster maybe, if the cheetahs were still around. That’s what’s meant by evolutionary potential. Importing African cheetahs to the western United States could, in theory, put the pronghorn back onto its… uh, natural evolutionary trajectory according to these biologists.
Another example is the interaction of megafauna with local flora, in particular, plants that rely on animals to disperse their seeds. Like Pleistocene rewilding could spark the re-emergence of large seeded American plants, such as the maclura tree. Many types of maclura used to grow in North American, buy today, just one variety remains and it is found in only two states. In the distant past, large herbivores like mastodons dispersed maclura seeds, each the size of an orange in their droppings. Well, there aren’t any mastodons left, but there are elephants, which descended from mastodons. Introduce elephants into that ecosystem and they might disperse those large maclura seeds, like their ancestors did.
Get the idea? Restoring some of the former balance to the ecosystem? But as I alluded to earlier, Pleistocene rewilding is extremely controversial. A big worry is that these transplanted megafauna might devastate plants and animals that are native to the western United States. In the years since the Pleistocene epoch, native species have adapted to the changing environmental there, plants, smaller animals, they have been evolving without megafauna for millennia. Also, animal species that went extinct 11,000 years ago, uh, some are quite different genetically from their modern-day counterparts, like elephants don’t have thick coasts like their mastodon ancestors do when they graze the prairies of the America West during the Ice Age. Granted, the climate today is not as cold as it was in the Pleistocene. But winters on the prairie can still get pretty harsh today. And there are many more considerations. Well, you see how complex this is. If you think about it though, the core problem with this sixth mass extinction is human interference. Pleistocene rewilding is based on good intentions, but you know, it probably would just be more of the same thing.
TPO22 Lecture 4 (Music History)
Narrator: Listen to part of a lecture in a music history class.
Professor: So, uh, if you are a musician in the United States in the early twentieth century, where could you work?
Student: Same as now, I suppose. In an orchestra, mainly.
Professor: Ok. And where would the orchestra be playing?
Student: Uh, in a concert hall or a dance hall?
Professor: That’s right. And smaller groups of musicians were needed in theaters as accompaniment to visual entertainment, like cabarets and variety shows. But the largest employer for musicians back then was the film industry, especially during the silent-film era.
Student: Really? You mean being a piano player or something? I thought movie theaters would have used recorded music.
Professor: Well, no. Not during the silent-film era. We are talking a period of maybe thirty years where working in movie theaters was the best job for musicians. It was very well-paid. The rapid growth of the film industry meant movie theaters were popping up everywhere. So suddenly there was this huge demand for musicians. In fact, over 20,000 jobs for musicians were gone, disappeared at the end of the silent-film era, 20,000. Ok. So from the beginning, music was a big part of film, even at the first…
Student: Excuse me, professor. I think I read somewhere that they used music to drown out the sound of the film projectors?
Professor: Yeah. That’s good story, isn’t it? Too bad it keeps getting printed as if it were the only reason music was used. Well, think about it. Even if that were the case, noisy projectors were separated from the main house pretty quickly, yet music continued to accompany film. So, as I was saying, even the very first public projection of a film had piano accompaniment. So music was pretty much always there.
What’s strange to me though, is that at first film music didn’t necessarily correspond to what was on the screen. You know, eh, a fast number for a chase, deep bass notes for danger, something light and humorous for comedy. And that’s instantly recognizable now, even expected. But in the very early days of film, any music was played. A theater owner would just buy a pile of sheet music and musicians will play it, no matter what it was. Pretty quickly though, thankfully, everybody realized the music should suit the film. So eventually, film makers tried to get more control over the musical accompaniment of their films., and specify what type of music to use and how fast or slow to play it.
Student: Are you saying there was no music written specifically for a particular movie?
Professor: Yeah. Original scores weren’t common then. Rarely a filmmaker might send along an original score composed especially for a film, but usually a compilation of music that already existed would be used. Yeah, that was a good time for a lot of musicians. But that all changed with the introduction of sound on film technology. Actually, even before that, organs could mimic a number of instruments and also do some sound effects. So they were starting to replace live orchestras in some movie theaters, and it only takes one person to play an organ.
Student: Ok. But even after that someone still had to play the music for the sound for the sound recordings, the soundtracks.
Professor: Yeah. But think of all the movie theaters there were, most employing about six to eight musicians, some even had full orchestras. But in the early 1930s, most theater owners installed new sound systems. So suddenly a lot of musicians were looking for work. Once recording technology took off, studio jobs working exclusively for one film company, eh, studio jobs did become available. But the thing is, each major movie company pretty much had only one orchestra for all their productions, a set number of regular musicians. So if you could get it, studio musician was a good job. If you were cut out for it, musicians had to be able to read music very well, since the producers were very conscious of how much money they were spending. They didn’t want to waste any time. So a musician was expected to play complicated pieces of music pretty much without any preparation. If one couldn’t do it, there were plenty of others waiting to try. So there was a lot of pressure to do well.