358

DOC.

18

DISCUSSION OF DOC.

17

Prof.

Einstein:

The

main

thing

now

is

to set

up

the

most exact

experiments

possible

in

order

to test

the foundation. In the

meantime,

all this

brooding is

not

going

to

take

us

far.

Only

those

consequences can

be of interest that lead

to

results that

are,

in

principle,

accessible to

observation.

Prof.

Meissner:

You

have

brooded

over

this,

and discovered

the

magnificent

time

concept.

You found that

it

is not

independent.

This

must

be

investigated

for other

concepts

as

well.

You

have shown

that

mass

depends

on

the

energy

content,

and

you

have

made the

concept

of

mass more

precise.

You

did not

carry

out

any

physical

investigations

in

the

laboratory-you

were

brooding

instead.

Prof.

Einstein:

The observations

we

made created

an

embarrassing predicament

for

us.

Prof.

Meissner:

Just think of non-Euclidean

geometry.

People

thought they

knew

what

an angle was,

but

they

did not.

Dr. Lämmel:

Regarding

these

speculations,

the

question is

whether

we

are

dealing

with

mathematical

or physical

considerations.

Purely

mathematical considerations

cannot

produce

anything

but

premises,

while

physical

considerations

can open new

paths.

Hence

I

understand the

statements

made earlier

by

Prof.

Einstein.