D O C U M E N T 4 7 9 F E B R U A R Y 1 9 2 7 4 7 3 479. To Hendrik A. Lorentz Berlin, 16 February 1927 Dear and esteemed Mr. Lorentz, It would surely be of great profit to the Solvay conference if we could persuade Millikan to attend.[1] I personally would naturally also be very pleased if he came I am very much in favor of his being invited. Quantum theory is completely Schrödingerized and has much practical success as a result.[2] But this surely cannot be the description of the real process. It is a mystery. It turns out that the unification of gravitation and Maxwell’s theory is completely satisfactorily achieved by 5-dimensional theory (Kaluza-Klein- Fock).[3] I am curious what you will say to this. Warm regards to you and your wife, your A. Einstein