Accepting Einstein’s photons…

Many colleagues in the physics community expressed scepticism towards Einstein’s notion of the photon when he first proposed the idea. This prompted Planck to defend his colleague in a somewhat lukewarm manner. In his nomination letter for Einstein’s membership of the Prussian Academy of Science in 1913, Planck wrote “that [Einstein] sometimes, as for instance in his hypothesis on light quanta, ... may have gone overboard in his speculations should not be held too much against him”.