EINSTEIN'S RESPONSE TO THE NEW DYNAMICS 447Bohr's drawing of Einstein's clock-in-the-box experiment [B6]. (Reproduced with the
kind permission of Professor A. Schilpp.)and Bohr trotting near him, very excited.... The next morning came Bohr's
triumph' [Rl].
Bohr later illustrated his arguments [B6] with the help of the experimental
arrangement reproduced above. The initial weighing is performed by recording
the position of the pointer attached to the box relative to the scale attached to the
fixed frame. The loss of weight resulting from the escape of the photon is com-
pensated by a load (hung underneath the box) that returns the pointer to its initial
position with a latitude Aq. Correspondingly, the weight measurement has an
uncertainty Am. The added load imparts to the box a momentum which we can
measure with an accuracy Ap delimited by ApAq « h. Obviously A/> < tgAm,