What Is A Photon?

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A photon is the basic unit of light and is the smallest discrete amount (quantum) of electromagnetic radiation. Photons are always in motion, have zero mass, and in empty space move at the speed of light.

Because they can move at the speed of light, time has no effect upon them. A photon takes 8 minutes to travel from the sun to the Earth. Eight minutes passes for us on Earth but no time passes for the photon!

Even more amazing the light of stars has taken billion of years from our perspective to reach the Earth but “the photon itself experiences none of what we know as time: it simply is emitted and then instantaneously is absorbed, experiencing the entirety of its travels through space in literally no time”

EPFL’s ultrafast energy-filtered transmission electron microscope (one of only two in the world) captured the photo below (the first of its kind) showing light as both a particle and a wave.


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