68

DOC.

7

RELATIVITY LECTURE NOTES

[19]See

also

Vol.

4,

Doc.

1,

§§9,

10,

for

a more

detailed derivation of the Lorentz transfor-

mation.

[20]This approach

was

first

taken

by

Sommerfeld

(see Sommerfeld 1909).

[21]The

abbreviation

w

for the

quantity

2

V

2

C

already

occurs

in

Einstein's lectures

on

electricity

and

magnetism

in

winter

semester

1913/1914

(see

note

2 above).

[22]On

the

right-hand

side "t" and "x" should be

interchanged.

[23]"w'2"

should

be

"w"2."

[24]See

note 20.

[25]See

also the discussion of four-dimensional vector calculus

in Vol. 4,

Doc.

1,

[pp.

43-

54].

[26]In

the

expression

below, T

is

a

stress-energy tensor

and X is

the

x-component

of

an ex-

ternal force.

[27]Dual

six-vectors

are

denoted

by an

asterisk. See

also

Vol.

4,

Doc.

1, [pp.

55-56],

for

a

discussion of their

use

in

covariant

electrodynamics.

[28]The sign

of

"5-

"

should be minus.

(7^2

[29]The

signs

of the

components

in

the fourth

row

of the

array

should be minus.

[30]See

also the

analogous

discussion of the inertia of

energy

in Vol.

4,

Doc.

1,

§21.

[31]The

four

integrals

above

are

written

as

AI etc.,

with I

momentum

and E

energy.

[32]The

four

expressions to

the

right

of the vertical line

are

written

in

pencil.

30,