Skip to content

Comment on Is The Speed of Light Everywhere the Same?parent

Comments

Yes. Refraction takes place because photons are slowed down through interactions with matter. If a photon is absorbed briefly and re-emitted, this can be taken to represent a reduction in velocity, even though the photon travels at c when between atoms.

In a convex lens, photons take longer to pass through the thickest part, which creates a concave wavefront that naturally converges on a focal point:

http://arachnoid.com/example/index.html#Lens_Example

Photons don't need to have mass for this to happen, because they aren't being deflected like billiard balls, they're being slowed by their interaction with atoms.

AboutSource Built by g1lg1l

Hackerly is an independent reader for Hacker News, built on the public HN API. Not affiliated with Y Combinator.