Max Planck (Berlin-Grunewald)
Notes on the principle of action and reaction in general dynamics.
The Newtonian principle of equality of action and reaction is well known to consist mainly of the theorem of the constancy of momentum or impulse of motion; and I would therefore like to speak of such a principle only in the meaning of this theorem, especially in its importance for the general dynamics that not only covers mechanics in the narrower sense, but also electrodynamics and thermodynamics.
Many of us probably still remember the stir that was caused, when H.A. Lorentz in his construction of atomistic electrodynamics on the basis of a stationary aether, denied the universal validity of the third Newtonian axiom, and it was inevitable that this circumstance was considered (for example by H. Poincaré) as a serious objection to Lorentz's theory. A kind of stabilization only came back as it turned out, especially by the investigations of M. Abraham, that the reaction principle can still be saved in its full generality,
