6 8 D O C . 1 3 D I A L O G U E A B O U T R E L A T I V I T Y T H E O R Y
Rel.: Your last assertion is, of course, incontestable. But the entire line of rea-
soning is not legitimate because, according to the special theory of relativity, the
coordinate systems and are not at all equivalent systems. As a matter of
fact, this theory claims only the equivalence of all Galilean (nonaccelerated) sys-
tems, i.e., coordinate systems relative to which sufficiently isolated material
points move uniformly in straight lines. The coordinate system is indeed such
a system, but not the intermittently accelerated system . Consequently, no con-
tradictions in the foundations of the theory can be construed from the fact that
is late against after the to and fro movement.
Krit.: I see, you have defused my objection, but I must tell you, your argument
leaves me more convicted than really convinced. Besides, my objection is imme-
diately resurrected from the dead if one accepts the general theory of relativity.
Because according to that theory, coordinate systems of arbitrary states of motion
are equivalent, and I can describe the previous process as well with respect to
(permanently linked to ) as I can with respect to .
Rel.: It is certainly correct that in the general theory of relativity we can use
the coordinate system as well as the coordinate system . But it is easily seen
that the systems and are by no means equivalent when it comes to the pro-
cess under consideration. Although the process, when seen from system is to
be interpreted in the manner outlined above, when viewed from the process is
something completely different, as shall be demonstrated in the juxtaposition as
shown below and in the figure.
System of reference is System of reference is
K K′
K
K′
U2
U1
K′
U2
K
K′ K
K K′
K,
K′
K (at rest)
z’ z
y
U2
x’ x
U1
K’ (moving to and fro)
z’
y
A
U1
U2
B
z
y’ y’
K’ (at rest) K (moving to and fro)
K K′
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