|
“
...
That light requires the same time to traverse the path A→M as for
the path B→M
is in reality
neither a supposition
nor a
hypothesis
about the physical nature of light, but a stipulation which
I
can make of my own free will in order to arrive at a definition of
simultaneity. " |
|
Albert
Einstein, “Relativity ...”, chapter
8,
“On the
idea of time in physics”, 1916
|
"
A
mathematical friend of mine said to me the other day half in jest:
“The mathematician can do a lot of things, but never what you
happen to want him to do just at the moment.” Much the same often
applies to the theoretical physicist when the experimental physicist
calls him in. What is the reason for this peculiar lack of
adaptability? ... " |
|
Albert
Einstein, "Principles
of theoretical physics", 1914
|
"
The
supreme task of the physicist is to arrive at those universal
elementary laws from which the cosmos can be built up by pure
deduction. There is no logical path to these laws; only intuition,
resting on sympathetic understanding of experience, can reach them. " |
|
Albert
Einstein, "Principles
of research", 1918
|
"
... I must
observe that the theory of relativity resembles a building consisting
of two separate stories, the special theory and the general theory.
The special theory, on which the general theory rests, applies to all
physical phenomena with the exception of gravitation; the general
theory provides the law of gravitation and its relations to the other
forces of nature. " |
|
Albert
Einstein,
"What is the theory of relativity?",
1919
|
"
... In my
opinion the answer to this question is, briefly, this: as far as the
propositions of mathematics refer to reality, they are not certain;
and as far as they are certain, they do not refer to reality. ... " |
|
Albert
Einstein,
"Geometry
and Experience", 1921
|
"
... I must
emphasize that Newton himself was better aware of the weaknesses
inherent in his intellectual edifice than the generations of learned
scientists which followed him. This fact has always aroused my deep
admiration ... " |
|
Albert
Einstein,
"The mechanics of Newton and their influence on the
development of
theoretical physics", 1927
|
"
As regards the final aim, intermediary layers are only of temporary
nature. They must eventually disappear as irrelevant. We have to deal,
however, with the science of today, in which these strata represent
problematic partial successes which support one another but which also
threaten one another, because today's systems of concepts contain deep
seated incongruities ...
There is no inductive method which could lead to the fundamental
concepts of physics. Failure to understand this fact constituted the
basic philosophical error of so many investigators of the nineteenth
century. ... " |
|
Albert
Einstein, "Physics and
reality", 1936
|
"
For the
time being, we have to admit that we do not possess any general
theoretical basis for physics, which can be regarded as its logical
foundation. The field theory, so far, has failed in the molecular
sphere. It is agreed on all hands that the only principle which could
serve as the basis of quantum theory would be one that constituted a
translation of the field theory into the scheme of quantum
statistics. Whether this will actually come about in a satisfactory
manner, nobody can say. " |
|
Albert
Einstein,
Science, 1940
|
"
Only at
this further development where frequent use is made of so-called
abstract concepts, language becomes an instrument of reasoning in the
true sense of the word. But it is also this development which turns
language into a dangerous source of error and deception. Everything
depends on the degree to which words and word-combinations correspond
to the world of impression. " |
|
Albert Einstein,
“The common language of science”, 1941
|
"
The name “theory of relativity” is connected with the fact that motion
from the point of view of possible experience always appears as the
relative motion of one object with respect to another ... Motion is
never observable as “motion with respect to space” or, as it has been
expressed, “absolute motion” " |
|
Albert
Einstein, “The theory of relativity” 1949
|
"
The general theory of relativity is as yet incomplete insofar as it has
been able to apply the general principle of relativity satisfactorily
only to gravitational fields, but not to the total field. We do not yet
know with certainty, by what mathematical mechanism the total field in
space is to be described and what the general invariant laws are to
which this total field is subject. One thing, however, seems certain:
namely, that the general principle of relativity will prove a necessary
and effective tool for the solution of the problem of the total field.
" |
|
Albert
Einstein, “The theory of
relativity” 1949
|
"
According
to general relativity, the concept of space detached from any
physical content does not exist. ...
... all
attempts to obtain a deeper knowledge of the foundations of physics
seem doomed to me unless the basic concepts are in accordance with
general relativity from the beginning. This ... forces
us to apply free speculation to a much greater extent than is
presently assumed by most physicists. "
|
|
Albert Einstein,
“On the generalized theory of gravitation” April
1950
|
"
...
We are now in a position to see how far the transition to the general
theory of relativity modifies the concept of space. In accordance
with classical mechanics and according to the special theory of
relativity, space (space-time) has an existence independent of matter
or field. ...
...
On the basis of the general theory of relativity, on the other hand,
space as opposed to “what fills space” ... has no separate
existence. ... If we imagine the gravitational field ... to be
removed, there does not remain a space of the type (1), but
absolutely nothing, and also no “topological
space”. "
|
|
Albert
Einstein,
“Relativity ...”
Appendix 5, “Relativity
and the
problem of space” 1952
|
"
Physical
objects are not in space, but these objects are spatially
extended. In this way the concept “empty space” loses its
meaning. "
|
|
Albert Einstein,
“Relativity ...”,
Notes to
the Fifteenth Edition
|
"
It is the essential achievement of the general theory of relativity
that it has freed physics from the necessity of introducing the
"inertial system" (or inertial systems). This concept is unsatisfactory
for the following reason: without deeper foundation it singles out
certain coordinate systems among all conceivable ones. It is then
assumed that the laws of physics hold only
for such inertial systems (e.g. the law of inertia and the law of the
constancy of the velocity of light. Thereby, space as such is assigned
a role in the system of physics that distinguishes it from all other
elements in the physical description. It plays a determining role in
all processes, without in its turn being influenced by them.
Though such a theory is logically possible, it is on the other hand
rather unsatisfactory. "
|
|
Albert Einstein,
“The Meaning of Relativity”, Appendix II
(1950/1955)
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