Laser
Electricity and Magnetism
Level
2
If a laser is shone through a vacuum, could one see it from the side?
Yes
No
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1 solution
The reason we are able to see lasers in air is due to either a dusty environment or Rayleigh scattering. For red light, which does not experience significant Rayleigh scattering, the photons scatter off large particles (eg dust) in the air. For green to blue light, Rayleigh scattering occurs alongside the scattering off large particles (again eg dust).
In a vacuum, neither of these two phenomena may take place. Therefore, lasers cannot be seen from the side in a vacuum.