Questions Without Answer

Daddy,' she says, 'which came first, the chicken or the egg?' Steadfastly, even desperately, we have been refusing to commit ourselves. But our questioner is insistent. The truth alone will satisfy her. Nothing less. At long last we gather up courage and issue our solemn pronouncement on the subject: 'Yes!' So it is here. 'Daddy, is it a wave or a particle?' 'Yes.' 'Daddy, is the electron here or is it there?' 'Yes.' 'Daddy, do scientists really know what they are talking about?' 'Yes!'

 Wave-Particle Duality

It did not cause anxiety that Maxwell's equations did not apply to gravitation, since nobody expected to find any link between electricity and gravitation at that particular level. But now physics was faced with an entirely new situation. The same entity, light, was at once a wave and a particle. How could one possibly imagine its proper size and shape? To produce interference it must be spread out, but to bounce off electrons it must be minutely localized. This was a fundamental dilemma, and...