Light is a Particle [and a Wave]

Author's Note: This piece is about light and it explains how light is both a particle and a wave.  I used examples, comparisons, and retold how Einstein made the discovery of light being a particle.  The pictures and diagrams are a visual aid of the concepts that I am trying to explain.

Many believed as recently as the turn of the last century that light was just a wave, but in 1905 Einstein discovered that it was also an object, a particle.  Objects can be affected by gravity, but waves cannot.  On the other hand, waves cannot be touched or felt, but particles can.  This is where most people would stop here and conclude that light is a wave, but what they don't know is that light can actually move due to gravity. 

In some ways light is a wave.  If you compare light and sound, they both have some similarities.  They both radiate and can amplify by diffracting and reflecting off of other objects.  Changing with the number of different waves is also something that occurs in both light and sound waves.  The wavelengths can change color and pitch, and the amplitude can change the brightness and volume.  Although in many other ways they are completely different.  When someone far away from you talk the amplitude of the wave stretches out making it harder to hear and the sound will fade, but if you are far away from the sun you can still see it because the waves are consistent.  Light waves are smaller and faster than sound waves.  That's why sometimes you can hear what you can't see.

 

Light has some qualities of a particle that a wave would not have.  For example, if a light is shining at a screen with a hole through it, light will stop and hit the screen like a particle, but it will also go through the hole and end up on the other side.  That example demonstrates one way of how light can be both a particle and wave.  All Einstein needed to do was corroborate that light was a particle. 

To substantiate this, he conducted a little experiment.  He waited for a day where there would be an eclipse.  The gravitational impact would help prove his hypothesis.  With the research that he did, he hypothesized that even though the eclipse's corona is very bright, the stars should still be seen around the moon due to gravitational force.  Stars are always constant, so they should always be seen in the same spot.  If the light of the stars are seen around the corona, then he'll know that the position and light of the stars was moved and bent by gravity, therefore making it a particle.

When he saw the star's light around the moon he provided evidence to his point.  The placement of stars is constant, and even though the stars were blocked by the eclipse, the corona curved the light so it could still be seen.  His theory was proven, because gravity shifted the light giving showing that it had properties of a particle.  That's also why they call it Einstein gravity.  The theory of relativity as he called it is now one of his most famous experiments.