system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If light is made of photons and if photons are particles, how can it pass through glass or any medium??
gpt
Although particles (sort of), photons are *massless*, so the only thing that really prevents them from passing through solid objects is if they get absorbed by an electron along the way. Electrons can only absorb specific amounts (called *quanta*) of energy, so they only absorb photons that contain that same amount. For transparent objects like glass, the specific quanta that their electrons absorb are outside the range of visible light; therefore any visible light passes straight through.

The amount of energy a photon contains is related to its *wavelength* (because photons are also waves, for... reasons). Visible light photons have wavelengths between 400 and 700 nanometers.