Particles Acting like Asses 2/?

Continuing our adventures in the realm of modern physics:

So, you have a photon. It hits an electron, and in the process, some of its energy is given to the electron. So far, so sensible.

But here's the thing. Apparently a photon cannot transfer all of its energy to an electron, even if it hits dead on. Most of the energy is transferred, but a small bit remains. If the math here is right, it means that no matter how many times a photon hits other stuff, it can't actually give up all of its energy.* The energy of a photon will thus asymptotically approach zero.

You guys! The Universe is full of old, worn-out photons everywhere**, meeting and greeting and exchanging (infinitesimal amounts of) energy, and generally getting it on. It's like massless brownian motion.

The next thing is that, during the collision, even though photons lack mass, they still have momentum and collide like classical masses. Let me explain.

There are these toys that executives have on their desks, with four chrome balls on strings. You life one of the ones on the end up, and when is drops, the to in the middle don't move but the one on the other end flies up. This is often used to demonstrate conservation of momentum.

Electrons have momentum. That's okay. Photons have momentum too, which is not. Momentum means "the mass of a moving object times its velocity," only photons don't have mass and they always move at the speed of light. So instead, there's some fancy and altogether unbelievable math that ends up with the photon's momentum dealing directly with its energy. Okay, whatever. We'll pretend like that makes sense.

A photon hits an electron. Momentum must be conserved. So the photon's momentum drops, which means its energy dropped. That makes sense; the photon transferred energy. And then the electron speeds up, or jumps to a higher orbital, or whatever. Fine. But momentum is also directional, and the electron responds like those little office desk toys or like pool balls, by moving off in a direction mostly determined by where the photon came from. So it's kind of like:

Electron: I have been hit.
Photon: [snickers]
Electron: [with hurt feelings] I must go off in this direction to sulk.

The photon still doesn't have any mass. I mean, srsly, whiskey tango foxtrot!

But the final thing is that, due to the wave-particle properties of light, the photon does not respond to losing energy by getting slower (it can't, its light, which moves at the speed of light regardless) or even less bright. Instead, they change color. There are equations that let you find out what color it changed to. In the visible ranges, the color change isn't really something that anyone who isn't a sensitive and very expensive piece of light detecting equipment can see, but in X-rays, the color change and backscatter allows you to see things like bones. While the person is still alive.

This is asinine. I don't need photons everywhere, especially crust old dries up spent ones. I don't need photons acting like they have mass, and shoving random electrons around. I especially don't need photons changing color at me all the time. Stop acting like assholes, you (massless) particles!

MW, the PLN, such as it is, has changed somewhat. I will return home for the voting process tomorrow, but I plan to stay for dinner, by virtue of the fact that school food is disgusting and we have a much better kichin in any case. So, y'know, I will halp with the cooking if you tell me what to grab and where and we make plns. Call me, but not while I am in class or during lunch hour, since there is a meeting.

*Although I didn't actually ask my prof about this, so this bit could be wrong entirely.

**Except the ones that spontaneously decide to be electrons.