*taking*my second quarter of Particle Physics, 9 years later, I find it even more humorous looking back upon.

Here is a typical problem that might have been given on a homework in Georgia Tech's "Particle Dynamics" class:

A baseball is thrown with an initial speed of 10m/s at an angle of inclination of 30 degrees. Neglecting air resistance, how long does it take to hit the ground? How far from the feet of the thrower does the ball fall?

And here's a question off of my current homework assignment, which is

*actual*particle physics:

Consider a theory of three scalar fields with an SO(3) internal symmetry, under which they transform as a 3-vector. Write down the most general Lagrangian with at most two derivatives invariant under this symmetry. Keeping only the terms of two lowest order polynomials in the fields, find the condition on the parameters such that the classical minimum breaks the symmetry. Is there an unbroken subgroup? What is it? How many Nambu-Goldstone bosons are there? Answer the same questions for SO(n). Answer the same questions for SU(2) with scalars transforming in the complex doublet representation (isospin 1/2). Prove that in this last case the Lagrangian actually has an SO(4) symmetry (introduce real and imaginary parts of the two component complex doublet to get 4 real fields).

They might as well have named their Newtonian mechanics class "Knitting and Crochet", it would have been no less relevant to the subject matter. Although they did rename it just to "Physics I" in recent years, it still gives me a chuckle.

- Current Mood: complacent
- Current Music:L7 - Andres

## Comments

kaolinfireI recognize some of the words in your current homework assignment, but not well enough to do anything with them. ;)

spinemasherspoonlessspoonlessEither it's something like that, or the question is screwy. Or maybe it's something about being locally isomorphic but not isomorphic? But I don't believe that, because it doesn't even have the right number of degrees of freedom.

spinemasherReal dimensions. But what is "it"? The "it" is the spatial symmetry of the fields. But an internal symmetry is a totally different space altogether. It can be whatever it wants with the exception that if it is a spin like internal symmetry its invariant inner product will hence be an inner product of aComplex space. But invariantComplex n dimensions are invariant Real 2n dimensions. So they want the derivative to be invariant under the SU(2) symmetry or at least thats what I gather from the question. This is different because derivatives act on the physical coordinate space typically. In physics we often protect our internal symmetries by modifying the spatial derivatives with connection coefficients of the requested internal symmetry space.Hope this makes sense as well as helps.