Thomas Young's experiment

Wave theory of light
In Young's own judgment, of his many achievements the most important was to establish the wave theory of light.

To do so, he had to overcome the century-old view, expressed in the venerable Isaac Newton's "Optics", that light is a particle. Nevertheless, in the early 1800s Young put forth a number of theoretical reasons supporting the wave theory of light, and he developed two enduring demonstrations to support this viewpoint. With the ripple tank he demonstrated the idea of interference in the context of water waves. With the two-slit, or double-slit experiment, he demonstrated interference in the context of light as a wave. He used reflection off thin films of soap and oil.

The picture ( which was an animation before I uploaded it ) shows a double slit source in front. If the particle theory alone was correct, what would be seen would be only two bright light lines on the screen. But what is seen actually are many bright( and dark) fringes which meant the 2 light sources had been diffracted and then experienced interference. which meant light was also a wave and not just a particle.

An earlier posting on my blog about the giant soap bubble showed colourful fringes in the soap bubbles which were a result of interference from two sources of light, one source from the upper skin of the bubble and the 2nd source - one reflected off the lower thin skin of the soap bubble

Never be afraid to think differently from the venerable authorithies eg Newton! You could prove them wrong. And thinking differently is innovation!