Notable Quotes from Prof. Mohapatra
from quantum field theory class (Physics 624)
University of Maryland, College Park, fall 1994.
If we hadn't studied the simple harmonic oscillator before field theory, I don't know what we'd be doing.
Do you know Casimir? He's much too old for me: he's dead. So you don't know him.
If you want to do serious physics, sometime you just have to learn it.
Quantum field theory is a constant thinking process for a whole semester. No parties this semester.
Somebody should write a book: the Joy of the Dirac Equation.
When you use the same things, everything looks similar.
Zitterbewegung: what happens when you take too much coffee.
Dirac became quite a legend for taking the best square root in town.
Lagrange must have invented the Lagrangian, because that's his name.
That's too sophisticated. We'll do simple field theory, where everything I say is correct.
Many people find physics difficult. It must be momentum.
I will especially use the fact that it is meaningless. When something has no meaning, you can do whatever you want.
A derivation is not something you look forward to on Friday. Hopefully time will run out so I won't have to do it.
Mandl and Shaw has a rather mysterious derivation.
Light travels with the velocity of light. That's a nice sentence.
The best thing in physics when you're in trouble is to sit down and calculate. It's always refreshing and healthy.
When you have a whole mess, it's safe to assume that it doesn't vanish.
The role of the propagator is to propagate.
You can't take this to an experimentalist. He'll throw you out of the room.
We'll make sure you're thoroughly bored with this material.
It's like unshooting your anti-grandmother... well, I don't want to get sued by the anti-grandmothers association.
You say I'm right. I think I'm wrong.
I'm writing very fast... it's a question of how fast you can work your hand.
If I knew the Lagrangian of the whole world, I wouldn't be here.
You can check at the end in a simpler way. But this is field theory; I want to do it the field theory way.
The midterm is easy.
When you see some trouble, just drop it and see what happens.
One is just one, always.
Maybe it will work, maybe it will not, but it did, so they are famous.
I don't have enough space to write an infinite number of states.
This is just the tip of the iceberg. I will, of course, not go beyond that.
It's a matter of how long you live, rather than how much you understand when you are alive.
This is how physics works, as long as you're doing good physics.
That's not part of the American constitution. You can devise your own rules.
Time ordering is a more powerful person than normal ordering.
Lots of calculations. I've locked the door so you can't get out.
This is the normalization. You can do nothing to erase it, unless you make a mistake.
If you don't feel it inside, it won't stay, it won't stick. It will just evaporate.
Don't write this down and sue me later for mental agony.
So you understand everything... except those minor vacuum fluctuations.
Put a sign on the back of your car: learning 624 -- watch out!
You work on renormalization theory for years and years, and then you decide: I'd better work on something else.
I don't want to write too many things. It makes my hand tired.
There's a lot more to renormalization theory which can be summarized in one sentence: It's not terribly complicated.
I know you didn't understand anything I said in the last two minutes.
You don't want any self-respecting vacuum to break gauge invariance.
If you keep thinking about it, ultimately it will make you feel bad.
Let's compromise. Let's do it my way.
...then all hell breaks loose, or whatever the appropriate sentence for the season is.
