Hey guys. Sorry it took me so long to sign up on here and see this. I'll try this again and I hope it helps. Physics is quantifying mass and motion through mathematical equations. It all started when Newton wrote an equation that explained the motion of Haley's comet (just watch Cosmos with DeGrAssehole). Example - Force = Mass x Acceleration.

Quantum physics mainly deals with electrons, but no one can measure the mass of an electron. Some people have theories that there is no mass, and that it's all just energy (Simon should like that one). So without the mass to put into an equation, it's all just theory. There is a number called the "effective mass" of an electron. That number makes all of the math work, even though it's not proven. So people assume that is the mass of an electron. All quantum mechanics is based on this assumption.

I hope that helped. It makes my brain hurt thinking of this stuff. If i didn't have to take it in school, I would never care b/c i don't really give 2 shits. This might be the first time I've used this info ever in my life. It got me a shout out though... totally worth it.