Forgetting Non-GR Physics: How Specialists Can Stay Sharp

[TomServo]

TL;DR

If you’re working on a PhD and haven’t done a QM problem for several years is it bad if you forgot most of it?

I’m worried I’m going to get my PhD knowing GR but having a less-than-undergrad grasp on the other core topics like stat mech and QM. I feel like “forgetting” most of core physics makes me a bad physicist.

Or is this normal when you specialize?

How do y’all stay sharp on these topics?

 

[Dale]

How do y’all stay sharp on these topics?

Answer questions on PF!

 

[hutchphd]

Summary: If you’re working on a PhD and haven’t done a QM problem for several years is it bad if you forgot most of it?

I’m worried I’m going to get my PhD knowing GR but having a less-than-undergrad grasp on the other core topics like stat mech and QM. I feel like “forgetting” most of core physics makes me a bad physicist.

Or is this normal when you specialize?

How do y’all stay sharp on these topics?

Dale has it right.
I managed to teach most of the undergrad and some graduate curriculum before being lured into the fast and lucrative realm of engineering R & D. To my delight when asked to resurrect things I hadn't thought about for decades the stuff I had taught was still pretty much all there. (We shall see how much longer that continues7...)
So if you can teach it you will keep it. I find it very surprising and satisfying.

 

[vanhees71]

Don't worry. In Wigner-Weisskopf approximation any perturbed state decays exponentially, and that's also the case with the "active knowledge" in our brains. What you don't use regularly you tend to forget quite quickly. That makes sense, because the brain needs the resources for the tasks at hand. Usually, however, when looking at a problem again one remembers something from previous studies, and you understand it quicker than when looking at it at the first time.

Concerning PhD work, it's normal to specialize on a subject. Doing new research is impossible these days without specializing. The only problem is, not to get too narrow, but there's always the problem to find the right balance between concentrating on your PhD work (or later on your research work) and staying up-to-date with both standard-curriculum physics (here teaching is great, because nobody in the classroom learns more than the teacher teaching the subject) and recent results on "new physics" outside your field of expertise. I think that's even important for your specialized research work. You never know whether there might be concepts and methods of other fields that can be useful for your own research, if not looking from time to time to what other communities do in their research.

As @Dale in #2 said, also to read and post here at PF is a great opportunity to keep your interests broad.

 

[TomServo]

Thanks for your answers everybody. I either have imposter syndrome or am not as knowledgeable as I should be and it causes a lot of anxiety.

 

[romsofia]

Yes, it's normal to "forget" i.e i might not be able to solve problems off the top of my head without a textbook, but the general concepts should be there.

Ways to combat it: Sit in on classes, spend an hour a night typing up your old notes/HW into LaTex, try to TA certain classes, engage in content here on PF, and my favorite: Spend time inside a textbook! Just because you have no classes anymore doesn't mean you can't pick up new textbooks. I have 4 different textbooks on GR alone! Different perspectives can help you realize how physics is connected.