Why does laser light appear as a beam?

Answer: Particles scatter coherent light

Particles scatter coherent light ✓ — Correct! You can't see light traveling sideways—only light entering your eyes. Laser beams are visible because particles (dust, water droplets, air molecules) scatter some laser photons toward you. Laser light is coherent (same wavelength, phase), making scattered light visible. In a perfect vacuum, you wouldn't see a laser beam passing by!

Laser creates a physical beam — Wrong. Lasers emit photons, not physical beams. You see the beam because airborne particles scatter light toward your eyes.

Eyes see laser wavelengths better — Wrong. Wavelength doesn't make beams visible. Laser beams appear because particles scatter the coherent light, directing some photons to your eyes.