TPO-21 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.
