Well, because he looked around himself and he saw all these fabulous physicists that created quantum mechanics and modern physics, and they were all in their 20s and early 30s when they did so.
Nos azért, mert körülnézett, és látta azt a rengeteg nagyszerű fizikust, akik akkor fektették le a modern fizika és a kvantummechanika alapjait, mikor huszonévesek voltak, de legfeljebb épp csak harmincasok.