I understand that it’s impossible to bring a photon to a state of rest, therefore impossible to collect them into a cup to weigh them and calculate their mass. A guy in a pub explained to me, quite smugly, that photons are just expressions of energy and that’s that. From my understanding solar sails would be just large surface areas being hit by photons, pushing the spacecraft in a desired direction, just like normal ship sails are being pushed by wind. But air particles do have mass. How could photons push the spacecraft if they don’t weigh anything?
In: Physics
Other posters have explained the science of photons, but I just wanted to mention this “physical proof” that photons can move things: look up videos of “radiometers”. They’re mostly in the context of a desk toy (I had one we a kid) and you can shine a flashlight on one and it’ll start to spin purely from the light hitting it.
Latest Answers