Physics GRE Discussion Forums

Can anyone clarify what exactly is the difference between experimental and theory? Such as, what does one do as an experimentalist that they don't as a theorist and vice versa.

Are you serious?

Experimentalists do experiments. Theorists make theories. Kinda self-explanatory.

It's not quite that simple. That said, the question usually comes from people who aren't thinking of becoming physicists (e.g. I had an economist ask me what the difference is since all physicists obviously need to know theory). If you're a physics undergrad you should be able to pick up the distinction along the way.

I'd make the distinction this way: theorists do not do physical experiments.

In fact, theorists are best kept far away from experiments.

odin wrote:Can anyone clarify what exactly is the difference between experimental and theory? Such as, what does one do as an experimentalist that they don't as a theorist and vice versa.

Yeah it's really not a dumb question. One difference obviously is that theorists don't do lab work, measure stuff, build things etc..., but conversely, I do not understand how an experimentalist could get by without needing to know (and possibly expand) the theory behind what they're doing. I was sortof shocked the first time I heard that physicists are strictly divided into two disjoint classes. I thought the whole philosophy of science was based on the interplay of "formulating hypothesis" and "testing" them... The fact that a physicist can only do one or the other was very surprising. I haven't had enough exposure to discern what experimentalists and theorists do in real life, but if all an experimentalist is supposed to do is run tests of the theories and measure stuff, that sounds kindof boring.

Theorists do model building.

Experimentalists test models.

Each has its own unique set of skills.

Experimentalists don't necessarily have to test models.

Models are an explanation of what's going on; for example one model of gravity assumes that massive bodies attract one another with a force proportional to the product of their masses and the inverse square of their distance. Another model of gravity posits that a magical invisible unicorn pulls the sun around the earth because otherwise we'd get cold and die. Now, one role of experiment is to verify that the first assumptions are okay, but this could be a happy coincidence imposed by the magical unicorns to keep their existence hidden (they're tricky beasts, they). The other role of experiment is to be completely agnostic to theory and make actual observations of nature which sweep under the rug the infinitely many competing ridiculous explanations.

That's why I get confused when people say that experimentalists have to know theory. The "theory" in theoretical physics isn't a thing; it's a technique. Of course everyone involved has to know theories, but that doesn't make someone a theorist.

Theorists have been known to test models (through computer simulation).

Experimentalists have been known to make models to explain or motivate experiments.

But computer simulation of models is just part of the process of model-building. It helps make predictions when the models are hard to solve analytically, but it doesn't tell us anything about the universe; just something about the model.

When experimentalists build models to explain their experiments, they are practicing theory.

And suddenly the shades of gray appear!!

I think it is just the matter of how you approach the problem in Physics. Both theorists and experimentalist must know the 'theory' behind physical phenomena. Theorists advance their understanding by using analytic methods, while experimentalists go about the same problem by actually performing the experiment in the lab to see what exactly is going on. Often times it happens that theorists take a lead on this race of understanding, and therefore they sort of 'guide' experimentalists and help them where to look at. This obviously does not mean that experimentalist are fool or something, but it is due to the fact that theorists enjoy the convenience of working the model out in a piece of paper or on the computer.


EDIT: oh man, ''Pauli effect'' is really funny( see dlenmn's link)

Ahhh.....thank you all for your input.

The Pauli effect is hilarious.

dlenmn did it again, posting a relevant and hilarious link.