Hubert Reeves talks about light



Hubert Reeves talks about light.

ASTROLab/Mont-Mégantic National Park

© ASTROLab/Mont-Mégantic National Park


Transcript

Light is about seeing things. When I see you, it’s because there is light. I cannot see light itself, but thanks to the light you emit, I can see you. If we discuss light in physics terms, we have known since Maxwell’s time that light is a wave, an electromagnetic wave. In other words, light represents variations in a magnetic field. To this, quantum physics has added the notion of a photon: light is also particles, tiny particles that leave a source and move towards you. The question of how light can be both a wave and particles at the same time is answered by quantum physics, but I won’t give you the answer right now because we would be here for a very long time! What we usually tell people (and I quite like this way of putting it) is that light behaves as particles when you’re looking at it, and as a wave when you’re not!


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