EINSTEIN'S LECTURE

NOTES

5

includes

numerous

applications

as

well

as

historical references

and discussions of

conceptual issues. Many years

earlier

this textbook had

proved helpful

to

Einstein

when

he

was

preparing

for the

entrance

examination

at

the

ETH.[12]

In

addition,

however,

Einstein's

notes

show the

influence

of other

texts

that

played

a

role

in his

own

earlier

study

of mechanics. The

introductory part,

which

begins

with

a

careful

exposition

of the fundamental

concepts

of

classical

mechanics,

includes

an

introduc-

tion of the

concept

of

mass

that

is

modeled after Ernst Mach's

treatment

in his

historical

exposition

of

the

principles

of mechanics

(Mach

1897).[13]

Its

emphasis

on

conceptual

issues

constitutes the main

difference

between the intro-

ductory

part

of Einstein's

notes

and

contemporary

textbooks.

Following

the intro-

duction,

the

course moves on

to

more

standard

topics,

such

as

equations

of

motion,

conservation

laws,

and the motion of

planets. Occasionally,

Einstein

seems

to

have

consulted

Kirchhoff 1897,

a

book

that

he had read

as a

student.[14]

The

course

ends

with

a

detailed

treatment

of rotation of

rigid

bodies

that

is

very

similar

to

the

one

given

in

Klein,

F. and

Sommerfeld

1897-1910.[15]

In

general,

Einstein's choice of

topics

and their

treatment

in the second

part

of the

course

is

standard

and conforms

to

books

that

were common

at

the

time,

such

as

Helmholtz 1898 and

Voigt

1901.[16]

But when

he

treated such

subjects as graphical

statics,

Einstein also

drew from his

knowledge

of technical mechanics

acquired

in Albin

Herzog's

courses

at

the

ETH[17]

and

probably

also from

August

Föppl's Vorlesungen

über

technische

Mechanik.[18]

Two

aspects

of Einstein's

notes

merit further

comment. First, it is

remarkable

that

almost nowhere do his lectures touch

upon

relativistic

issues.

Apart

from

very cau-

tious

remarks

on

the

equivalence

of

gravitational

and inertial

mass

and

a

passing

reference to

light

pressure

and the

mass

of

energy,

there

is

no

explicit

discussion of

any

modifications

that

should be made in

mechanics

as a

consequence

of

special

relativity.

Second,

the

use

of

vectors

was

not

yet

common

in

physics

at

the

time, although

some

textbooks

employed

them.[19]

At

first

it

seems

that

Einstein

will

adopt

vector

notation

in his

course:

at

its

beginning

he

introduces the

vector

character of

velocity

and

[12]See

the

biographical

sketch

by

Maja

Winteler-Einstein

in Vol.

1, p.

lxiv.

A copy

of

Violle

1892 is in

Einstein's

personal library.

[13]Einstein read this book

during

his

student

years;

see, e.g.,

Einstein

to

Mileva

Maric,

10

September

1899

(Vol. 1,

Doc.

54).

In

a

later letter

to

Mach,

Einstein referred

to

Mach

1897 when

he wrote "your

inspired

studies

on

the foundations of mechanics"

("Ihre genialen

Untersu-

chungen

über die

Grundlagen

der

Mechanik").

Einstein

to

Ernst

Mach, 25

June

1913.

[14]See Einstein

to

Mileva

Maric,

1

August 1900

(Vol.

1,

Doc.

69).

[15]The last

part

of this

four-part

work is in Einstein's

personal library.

[16]Books

related

to

mechanics

in

Einstein's

personal library

that

he

may

have consulted

as

well

are

Dühring

1887

and the second and third volumes of

Appell

1902-1909.

[17]See

Vol.

1,

Appendix E,

"ETH,

Einstein's

Curriculum,"

pp.

364-365.

[18]Föppl

1897-1900,

which

was

first

published

in

four volumes

between 1897 and

1900

and

went

through many

later

revised

and

expanded

editions.

[19]An

example

is

Föppl

1897-1900.

Föppl

had

already

made extensive

use

of

vectors in

Föppl

1894.

For

more

details

on

the earlier

history,

see

Crowe

1967;

for

a

discussion of the

adoption

of the vector calculus

in

early twentieth-century

physics,

see

Jungnickel and

McCormmach

1986,

pp. 341ff.