Newton's Discovery of the Refraction of Light

Episode Eleven – Newton’s Achievements

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Newton’s experiments show that this is not the case and that colour is a result of the interaction of entities with light.

Red apples are red because their nature is such that when light interacts with it, the wavelengths of light that get reflected or transmitted are the wavelengths from the red spectrum of visible light. The sky is blue because of the way light interacts with the particles in the sky. Not because the apple has the property of “being red” or because the sky has the property of “being blue”.

Redness is not “in the apple”, nor is blueness “in the sky”. Colors are not properties of the object. They are a result of the way the object interacts with light.

All these discoveries about light, served as the basis for our understanding of how light interacts with objects and what color is. As well as what light is, at least for a time. But what did he think light is?

He argued that light is composed of particles or “corpuscles” which were refracted by accelerating into a denser medium . This was dominant for about 100 years, but was eventually superseded by a wave theory of light.

However, light currently occupies a weird limbo state. It sometimes seems to behave like a particle and sometimes like a wave. It cannot be both, so there must be some explanation which would explain this apparent contradiction.

Newton’s particle theory of light may yet prove to have some truth to it.

There is of course more to the concept of colour since we have not discussed the role of sense perceptions yet. But let’s not steal the light from Newton, we will cover this in another blog post in the future.

For instance, if redness is not in the apple, is it in the light? While we can separate white light into different colors using a prism, does this mean that those different colors are intrinsic properties of light?

reflecting telescope

The first reflecting telescope, as built by Newton himself.

Reflecting Telescopes

Newton built the first practical reflecting telescope, also known as the Newtonian telescope or the Newtonian reflector.

Although it was not the first telescope, it was the first practical telescope to work on the principles of reflection of light. Previous telescopes, such as those Galileo built in 1609, were refracting telescopes.

Refracting telescopes work by using lenses bending light rays and causing them to converge at a focal point, thus producing a magnified image.

However, reflecting telescopes work differently. They use a combination of curved mirrors to reflect light and form a magnified image.

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