32,592 reputation
23694
bio website joshphysics.com
location Los Angeles
age 28
visits member for 2 years, 4 months
seen 1 hour ago

New project: phermi.com

Let me know if you know of any hard physics problems with clever solutions. (email listed to the left)

Personal website: joshphysics.com

Currently a lecturer at the UCLA Department of Physics and Astronomy.

Ph.D. theoretical high energy physics, UCLA.

BA/BS in physics/math, UC Berkeley.


May
17
revised Origins of Moment of Inertia
deleted 145 characters in body
May
16
comment Best method for building balsa-wood bridge
@AnubianNoob Changed to truss given that apparently, Warren truss is un-arched by definition. Is that what you were getting at?
May
16
revised Best method for building balsa-wood bridge
deleted 7 characters in body
May
12
comment Why do we say that irreducible representation of Poincare group represents the one-particle state?
@SRS That is a separate mathematical question -- I think it would be best addressed as its own new question.
May
9
awarded  Nice Answer
May
3
comment Normalising Generators of a Lie Algebra
@Joe The definition above gives an inner product on any real or complex vector space of square matrices. It is commonly called the Frobenius or Hilbert-Schmidt inner product. Naturalness comes from thinking of matrices as rearranged column vectors and then applying the standard inner product on $\mathbb C^{n^2}$. See en.wikipedia.org/wiki/Matrix_multiplication#Frobenius_product . Note that I wrote norm-squared $1/2$.
May
1
answered Normalising Generators of a Lie Algebra
Apr
30
comment Drag on a spinning ball in fluid
@niceman Link removed.
Apr
30
revised Drag on a spinning ball in fluid
deleted 31 characters in body
Apr
26
reviewed Edit Why is the harmonic oscillator so important?
Apr
26
revised Why is the harmonic oscillator so important?
few spelling mistakes
Apr
24
revised Trace of an operator matrix (Quantum computation and quantum information)
added 13 characters in body
Apr
23
comment Is Archimedes' principle valid with moving objects?
@ManuelJesus I'm not entirely sure what you mean by "perfect" and "ideal" with respect to the fluid, but there will also be effects from Bernoulli's Principle even if there is no drag but the water is moving around the object.
Apr
22
answered Is Archimedes' principle valid with moving objects?
Apr
11
awarded  Popular Question
Apr
8
comment When to use Hamiltonian vs Lagrangian?
Related: (read all answers) physics.stackexchange.com/questions/89035/…
Apr
5
awarded  Favorite Question
Apr
5
awarded  Good Question
Apr
4
awarded  Popular Question
Apr
2
comment Tensor Operators
Thanks for pointing that out.