2 6 0 D O C U M E N T 2 4 7 A P R I L 1 9 2 6 With regard to the persons involved, we are going to invite the following phys- icists (the members of the scientific committee are not mentioned here): Bohr, Kramers, Planck, two of the three physicists Born, Heisenberg, Pauli [You and Ehrenfest may advise me on the selection of these two],[9] Fowler (Cambridge, England), W. L. Bragg, L. Brillouin, L. de Broglie, A. H. Compton, Debye, Ehren- fest, Schrödinger, C. T. R. Wilson, and Deslandres.[10] We have another list of sub- stitutes, but I do not need to speak about that now. As always, of late, the three professors of physics in Brussels will also be receiv- ing an invitation. Now, if you say “yes” to the request to succeed Onnes on the committee, that would please me most particularly. With kind regards, yours truly, H. A. Lorentz 247. From Pascual Jordan [Göttingen, after 6 April 1926][1] Dear Professor Einstein, Thank you very much for your kind card![2] My opinion of the formula is as follows: The question of how probable a certain spatial energy distribution is, given a particular quantum state, cannot be formulated directly by the theory of matrices. Classically, there is a function that is a number and that indicates how much energy is in v while the system is in a specific state. That is why the question: How large is the probability that becomes = the total en- ergy? is legitimate. But theoretically, there is no such number it would be completely wrong to want to say, for instance, that one should simply augment with the zero-point energy in order to find an quantum-theoretical ! That is because the quantum-theoretical energy in v is not a diagonal matrix, hence it is not assigned to particular numbers of states (rather to “transition” numbers).[3] Physically, it certainly does make sense to ask with what probability one would encounter the whole energy in V, under the assumption of a particular state. But if one wants to relate this probability to quantities defined by matrix theory, then (at the present state of the theory) only the following procedure exists: If is the W V V0¹ -----· - © § E hν ------ = f t) ( f t) ( Matrix- quantum- f t) ( f t) ( E t) (