Some of the other blog sites have talked about physics vs. chemistry. It seems this started with The experimental Error blog. Tom at Swans on Tea added a very excellent point to the discussion and the discussion continues at Uncertain Principles.
So, here is my take on the subject. Physics essentially deals with the fundamental stuff. You know, Maxwell's equations, the four forces, the particles, quantum mechanics. Chemistry is the study of substances and their interactions. First, let me attack chemistry. Here are some things I don't like:
- Photo electron. What is a photo electron? According to chemists, it is an electron released by interaction with light. We are in the department of chemistry AND physics, so many of the seminars I go to are chemistry oriented. Whenever they mention photoelectron, I lean over to a physicist and say "what's that?"
- Chemical potential. Ok, physicist use this also. The problem (in my book) is that chemical potential is just kind of a potential. Well, it's not directly due to a fundamental force.
- Van der Waals force. Again, not a fundamental force. Really, this is an electrostatic force.
- Pressure. What? Ok, wait. Let me explain. What is pressure? I think this is a great example. Pressure is due to interactions with a gas particle, really a whole bunch of gas particles. Really each particle has some type electrostatic interaction with other particles that creates a force and a pressure.
I just wanted to point out some aspects of chemistry that are really somewhat related to fundamental stuff. But here is the point. We need chemistry. Example - take a gas. Suppose you want to model this gas. A fundamental approach (with physics) would look at the gas as a whole bunch of particles. Each particle can have an electromagnetic interaction with other particles. Great, but if you have 1 mole of this stuff, that is not very easy to model. It's impossible. Even for a computer.
The chemist would say: "it's not impossible. We used to bulls-eye wamprats back home and they are not much bigger than 2 meters." The chemisty approach doesn't always look at each atom in a gas, but instead uses things like pressure and temperature to model it. Or take some complicated molecule. How would you find the vibrational energy levels of this? You could start with shrodinger's equation and solve this quantum mechanically, but good luck. Really, if it is not hydrogen, you can't do much without some tricks. So the chemistry way allows use to make up some non-fundamental stuff and use it in a useful way.
One day, there will be no difference between chemistry and physics. As computers become more powerful (but before they take over the world), maybe we will be able to model larger things with fundamental principles. But for now, that is not going to happen. The world needs chemists.
