Mention the main difficulty in establishing the wave theory of light.

(N/A) The main difficulty in establishing the wave theory of light was the assumption that light waves are mechanical in nature.
According to the classical physics of that time,mechanical waves require a material medium for propagation.
Since light travels through the vacuum of space (e.g.,from the Sun to the Earth),it was difficult to explain how light could propagate without a medium.
This led to the hypothetical concept of the 'luminiferous ether',a pervasive,massless,and transparent medium,which was later disproven by the Michelson-Morley experiment.