Richard Feynman Messenger Lectures

Ladies and gentleman,

it's my privilege to introduce the Messenger lecturer,

Professor Richard P. Feynman of the California Institute

of Technology.

Professor Feynman is a distinguished theoretical

physicist, and he's done much to bring order out

of the confusion which has marked much

of the spectacular development in physics

during the postwar period.

Among his honors and awards, I will mention only the Albert

Einstein Award in 1954.

This is an award which is made every third year

and which includes a gold medal and a substantial sum of money.

Professor Feynman did his undergraduate work

at MIT and his graduate work at Princeton.

He worked on the Manhattan Project at Princeton and later

at Los Alamos.

He was appointed an assistant professor here at Cornell

in 1944, although he did not assume residence

until the end of the war.

I thought it might be interesting to see

what was said about him when he was appointed at Cornell.

So I searched the minutes of our board of trustees.

And there's absolutely no record of his appointment.

There are, however, some 20 references

to leaves of absence, salary, and promotions.

One reference interested me especially.

On July 31, 1945, the chairman of the physics department

wrote the dean of the arts college stating

that "Dr. Feynman is an outstanding teacher

and investigator, the equal of whom develops infrequently."

The--

The chairman suggested that an annual salary of $3,000

was a bit too low for a distinguished faculty member

and recommended that professor Feynman's salary be increased

$900.

The dean, in an act of unusual generosity

and with complete disregard for the solvency of the university,

crossed out the $900 and made it an even $1,000.

You can see that we thought highly of Professor Feynman

even then.

Feynman took up residence here at the end of 1945

and spent five highly productive years on our faculty.

He left Cornell in 1950 and went to Caltech,

where he has been ever since.

Before I let him talk, I want to tell you just a little bit more

about him.

Three or four years ago, he started teaching a beginning

physics course at Caltech.

And the result has added a new dimension to his fame.

His lectures are now published in two volumes,

and they represent a refreshing approach to the subject.

In the preface of the published lectures,

there's a picture of Feynman performing happily

on the bongo drums.

My Caltech friends tell me that he sometimes

drops in on the Los Angeles night spots

and takes over the work of the drummer.

But professor Feynman tells me that that's not so.

Another of his specialties is safe-cracking.

One legend says that he once opened

a locked safe in a secret establishment,

removed a secret document, and left a note saying, guess who?

I could tell you about the time that he learned Spanish before

he went to give a series of lectures in Brazil,

but I won't.

This gives you enough background, I think.

So let me say that I'm delighted to welcome Professor

Feynman back to Cornell.

His general topic is the nature of physical law.

And his topic for tonight is the law of gravitation,

an example of physical law.

Professor Feynman.

It's odd, but in the infrequent occasions

when I've been called upon in a formal place

to play the bongo drums, the introducer never

seems to find it necessary to mention that I also

do theoretical physics.

I believe that's probably that we respect the arts more

than the sciences.

The artists of the Renaissance said that man's main concern

should be for man.

And yet, there are some other things

of interest in the world.

Even the artists appreciate sunsets and the ocean waves

and the march of the stars across the heavens.

And there is some reason, then, to talk of other things

sometimes.

As we look into these things, do we

get an ascetic pleasure from them directly on observation.

But there's also a rhythm and a pattern between the phenomena

of nature which isn't apparent to the eye,

but only to the eye of analysis.

And it's these rhythms and patterns

which we call physical laws.

What I want to talk about in this series of lectures

is the general characteristics of these physical laws.

That's even another level, if you will,

of higher generality over the laws themselves.

And it's-- really all I am talking about is nature as seen

as a result of detailed analysis.

But only the most overall general qualities of nature

is what I mainly wish to speak about.

Now, such a topic has a tendency to become too philosophical

because it becomes so general that a person talks

in such generalities that everybody can understand him.

And it's considered to be some deep philosophy

if you-- however, I would like to be very rather more special.

And I would like to be understood in an honest way

rather than in a vague way, to some extent.

And so if you don't mind, I'm going

to try to give, instead of only the generalities,

in this first lecture an example of physical law

so that you have at least one example

of the things about which I am speaking generally.

In this way, I can use this example again and again

to give an instance to make a reality out of something which

will otherwise be too abstract.

Now, I've chosen for my special example of physical law

to tell you about the theory of gravitation

or the phenomena of gravity.

Why I chose gravity I don't know.

I had-- whatever I chose, you would

have asked the same question.

Actually, it was one of the first great laws

to be discovered.

And it has an interesting history.

You might say, yes, but then it's old hat.

I would like to hear something about science, more

modern science.

More recent perhaps, but not more modern.

Modern science is exactly in the same tradition

as the discoveries of the law of gravitation.

It is only more recent discoveries

that we would be talking about.

And so I do not feel at all bad about telling you

of the law of gravitation because I

am, in describing its history and the methods,

the character of its discovery and its quality,

talking about modern science, completely modern.

This law has been called the greatest generalization

achieved by the human mind.

And you can get already from my introduction,

I'm more interested not so much in the human mind

as in the model of nature who can

obey such an elegant and simple law as this law of gravitation.

So our main concentration will not

be on how clever we are to have found it

all out but on how clever she is to pay attention to it.

Now, what is this law of gravitation

that we're going to talk about?

The law is that two bodies-- or bodies

exert a force upon each other, which

is inversely as the square of the distance between them

and varies directly as the product of their masses.

And mathematically, we can write that great law down

in a formula-- some kind of a constant times

the product of the two masses divided

by the square of the distance.

Now, if I add the remark that a body reacts

to a force by accelerating or by changing its velocity

every second to an extent inversely as its mass.

It changes velocity more if the mass is lower and so on,

inversely as the mass.

Then I answer everything about the law of gravitation

that needs to be said.

Everything else is a consequence,

a mathematical consequence of those two things that I said.

That's a remarkable enough phenomenon in itself

that the next lecture will consider this in more detail.

Now I know you're not all here-- I know some of you are,

but you're not all mathematicians.

And so you cannot all immediately see all

of the consequences of these two remarks.

And so what I would like to do in this lecture is to briefly

tell you the story of the discovery,

tell you what some of the consequences are,

what the effect of this discovery

had on the history of science, what kinds of mysteries

such a law entails, something about the refinements

made by Einstein, and possibly the relation

to other laws of physics.

The history of the thing, briefly,

is this-- that the ancients first

observed the way the planets seemed to move about in the sky

and concluded that they all, along with the Earth,

went around the sun.

This discovery was later made independently by Copernicus,

after people had forgotten that it had already been made.

Now, the next big question that came up to study

was exactly how do they go around the sun?

That is, exactly what kind of motion?

Do they go with the sun at the center of a circle?

Or do they go in some other kind of a curve?

How fast do they move?

And so on.

And this discovery took longer to make.

The times after Copernicus were times

in which there were great debates

about whether the planets, in fact, went around the sun along