naturally does not exist for this observer. He must fasten himself with
strings to the floor, otherwise the slightest impact against the floor
will cause him to rise slowly towards the ceiling of the room.
To the middle of the lid of the chest is fixed externally a hook with
rope attached, and now a being (what kind of a being is immaterial to
us) begins pulling at this with a constant force. The chest together
with the observer then begin to move upwards with a uniformly
accelerated motion. In course of time their velocity will reach
unheard-of values provided that we are viewing all this from another
reference-body which is not being pulled with a rope.
But how does the man in the chest regard the Process? The acceleration
of the chest will be transmitted to him by the reaction of the floor of
the chest. He must therefore take up this pressure by means of his legs
if he does not wish to be laid out full length on the floor. He is then
standing in the chest in exactly the same way as anyone stands in a
room of a home on our earth. If he releases a body which he previously
had in his land, the accelertion of the chest will no longer be
transmitted to this body, and for this reason the body will approach
the floor of the chest with an accelerated relative motion. The
observer will further convince himself _that the acceleration of the
body towards the floor of the chest is always of the same magnitude,
whatever kind of body he may happen to use for the experiment._
Relying on his knowledge of the gravitational field (as it was
discussed in the preceding section), the man in the chest will thus
come to the conclusion that he and the chest are in a gravitational
field which is constant with regard to time. Of course he will be
puzzled for a moment as to why the chest does not fall in this
gravitational field. just then, however, he discovers the hook in the
middle of the lid of the chest and the rope which is attached to it,
and he consequently comes to the conclusion that the chest is suspended
at rest in the gravitational field.
Ought we to smile at the man and say that he errs in his conclusion? I
do not believe we ought to if we wish to remain consistent; we must
rather admit that his mode of grasping the situation violates neither
reason nor known mechanical laws. Even though it is being accelerated
with respect to the Galileian space first considered, we can
48