Nyx Notions

In this article, we will cover:

• What is light?
• What it is made of?
• Speed of light
• Why is the sky blue?
• Mysteries
• Resources

“We begin with light.[..] Light is like raindrops, each drop is called a photon and all the raindrops are of the same size. When we say light, we mean all aspects of light.”

QED – the Strange Theory of Light and Matter, Richard Feynman

What is light?

Light is more than just light. [..]

It turns out that visible light is just a part of a long scale. The scale of light can be described by numbers, called the frequency. And when the frequency gets higher, the light goes from red to blue to violet all way to ultraviolet. If we go higher in frequency, can see red, infrared (heat) waves, television waves, radio waves – all of this is light, just different number. And it’s made of particles.” – QED – the Strange Theory of Light and Matter, Richard Feynman

What is light made of?

Light is made of extremely small particles called photons which are the smallest quantity of energy that can be transported. Photons have no mass, and they are the carriers for electromagnetism (one of the four natural forces of the Universe). They also have no charge, but they are exchanged between charged particles, such as electrons and protons, whenever they interact. Photons behave like a particle and a wavelength.

Speed of light

Light travels at a speed of 299, 792, 458 m /s. It is the fastest known particle, and according to Special Theory of Relativity, nothing travels faster than the speed of light. Light always travels at a constant speed. To quote John D. Barrow in The Constants of Nature: Some of the numbers that define our Universe is the Cosmological Constant.

Why is the sky blue?

The sky is blue because blue lights is scattered more easily around the sky than red light. Light from the Sun contains all the colours of the rainbow, with red at the end. Red light has a longer wavelength than blue light, which means it doesn’t scatter as easily.

Some phenomenas of light

• Light reflects off a mirror
• Light bends from air to water
• Light goes in straight lines
• Light can be focused be a lens
• Light is diffracted by a shadow

Light Facts

• Light always travels at a straight line and it always takes the quickest route.
• Photons cannot come to rest, they can only transform.
• Photons can act sometimes as particles, and sometimes as wavelengths.
• Newton discovered that sunlight can be split into colours and named 7 colours (ROYGBIV).
• Rainbow is formed by sunlight refracting through individual drops of rain. 
• Redshift is caused by the Universe stretching which stretches the light.

Mysteries

• Why do photons travel at the speed limit? 
• We understand that in space, nothing can travel faster than the speed of light. But the universe is expanding faster than light travels. Why can’t we see the edge of the Universe? Is there an edge?
• Light interacts with ordinary matter, but does not interact with dark matter.

Resources

• A New Map of Wonders, Caspar Henderson
• Black Holes and Baby Universes, Stephen Hawking
• The Constants of Nature. John D. Barrow
• QED – the Strange Theory of Light and Matter, Richard Feynman

Thank you, I hope you enoyed the article. Please note, I carefully research the topic before publishing, however some facts could have changed since publishing this article, so I appreciate your understanding. All articles published are thoroughly researched and inspired by published books. The list of resources are published in every article. Please be kind, and have a nice day.