2 8 0 D O C . 3 3 4 F E B R U A R Y 1 9 2 0 At the same time, represents the Euclidean portion of space that lies of M. For each M, such a Euclidean interior and exterior is at least con- ceivable, and we have certain justification in assuming so. If we do assume so, then our relativity is valid in M and inside of M, as outside, there will be—shall we say—an “absolute” Euclidean space. If M is, as you would like, the whole universe, our assumption is consequently not necessary. If, however, M is merely a part of the universe, and more specifically, a self-contained one, independent of others, then we must imagine many M’s that are separated by Euclidean space-time from one another, and in each of these your relativity is completely valid. Each has its own constant .[6] The answer given by Mr. Hamel was: “Those are simply other worlds and they don’t concern us at all.” That does not satisfy me for the following reasons: 1. Beyond our Milky Way galaxy S there are stellar nebulae so very far away that the field strength of at S can be regarded as zero or approximately zero. Your theory encompasses both but doesn’t it include the possibility that, since S can be regarded as a closed system with respect to , S and each have their own relativity physics, with the maximum velocities and ?[7] 2. Whatever applies to these large distances also applies to ultramicroscopic dis- tances of the tiniest of particles, such as we denoted as atoms, for ex. Atoms were regarded as much tinier than the distances separating them from one another hence, mutually “closed systems.” Therefore, every crystal, every volume of water would consist of minuscule closed systems where each had its own “relativity.”[8] 3. What ought to be understood by “closed system” in this sense, you, Professor, will be able to specify completely more easily than I.[9] Consequently, it could be that my interpretation needs correction. Nevertheless, this would not overturn my above considerations. Helmholtz stated his energy conservation law only for closed systems, i.e., for those into which no energy enters from outside, and none exits. The internal energy store is then constant. However, we can interpret a closed system more broadly as well, namely, that the incoming and outgoing energy balances out. Then the eigen-energy also remains constant. Thus a warm-blooded animal, which maintains metabolic equi- librium, is in a certain sense a closed system. If one understands this concept approximately in this way, then the whole uni- verse is composed of discrete closed systems of the most diverse orders of magni- f xi) ( 0 inside outside ⎭ ⎬ ⎫ Mλ cλ S′ S′ S′ S′ cS cS′