Like I understand light is photons. But from whence the photons? How come if I’m in a dark room (by the way, why is the room dark? Why no photons in the room?) and I turn on a flashlight, suddenly there’s photons everywhere?
In: Physics
Photons are the *force carrier particle* for electromagnetism. What that means is, whenever a particle is affected by the electromagnetic force, something has to “tell” that particle to be affected. Any particle with *charge* like positive protons and negative electrons has to “feel” the force, which comes from photons. Photons represent the charged particles trading around energy.
What that really means is that the photon is giving the particle energy, which usually comes out as momentum. A proton is coming towards another proton, and since they’re both positively charged, they will repel each other. One proton spits out a photon and, as a result, loses momentum flies off in a direction. The other proton absorbs that photon, gains that momentum, and flies off in the other direction.
Photons also energize electrons into higher “orbits” around protons, which is what causes visible light. Proteins in our eyes absorb photons, which energizes an electron in the protein. That forces the protein to change shape, which triggers the nerve to fire and the photon is detected. If electrons absorb photons to go higher, you can probably guess that electrons *emit* photons when they drop into a lower “orbit”. Dropping down means the electron is losing energy, and that energy has to go somewhere. So, the electron spits it out as a photon. Another electron, somewhere, will absorb it.
How lights work depends on the light, but the short version is that through some method they’re pushing electrons into a higher orbit before they drop down and spit that energy out as photons.
Any time an electron absorbs energy, it’ll end up spitting it back out. But, because of entropy, a little less energy gets spit out. Eventually, the photons drop from the energy of the visible spectrum down to the invisible infrared and further down.
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