PRIDE CHEKERAand incident on the opposite plate.
It was observed that the photons, instead of making two strips
separated by distance ‘a’ as per common sense, they formed a
diffraction pattern of bright and dark fringes due to interference,
as the ones formed by water waves in a ripple tank.
The same experiment was repeated with electrons and they were
found to do the same behavior, being diffracted. Light and
electrons which were thought to be particles all this time were
now behaving strangely.
The photoelectric effect conspicuously showed that light is
particulate but Young's double slit experiment showed that light
is wave in nature.
But, even more stranger, when a single photon or electron was
emitted, and passed through the slit to incident on an opposite
plate it appeared to hit a certain point. How a wave hit a point?!!
What was happening? Was it due to fault in instruments used
(systematic errors) or something else unnoticed? This was
actually strange. The whole of the physics society was
distracted. Was light wave or particulate in nature? No one knew
the right answer at that moment.