892 reputation
114
bio website joshphysics.com
location Los Angeles
age 28
visits member for 1 year, 9 months
seen 8 hours 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.


1d
revised Big O notation for complex-valued functions of a real variable
edited body
1d
comment What is the dimension of the vector space of functions $f:\mathbb R\to\mathbb R$?
Wonderful! Thanks Asaf.
1d
accepted What is the dimension of the vector space of functions $f:\mathbb R\to\mathbb R$?
1d
comment What is the dimension of the vector space of functions $f:\mathbb R\to\mathbb R$?
Wow ok $2^{2^{\aleph_0}}$ it is then. Pretty monstrous (to a non-set-theory aficionado at least). That's a very nice last equation you wrote. Does it have a special name? Where in standard books would I find such wonderful gems?
1d
asked What is the dimension of the vector space of functions $f:\mathbb R\to\mathbb R$?
Sep
27
comment How are eigenvectors/eigenvalues and differential equations connected?
Great answer btw. Would you happen to know of any good references that treat ODEs heavily using linear-algebraic language as in this answer? In particular, a text which discusses Jordan normal form in this context as you allude to would be useful. I'll be teaching a math methods for physics class, and I'd find such a reference very useful.
Sep
23
comment How are eigenvectors/eigenvalues and differential equations connected?
Shouldn't $e^{\lambda y}$ read something like $e^{\lambda t}$ instead?
Sep
10
awarded  Revival
Sep
4
comment How to calculate this functional derivative?
@Trimok Thanks; edited.
Sep
4
answered How to calculate this functional derivative?
Aug
3
comment What is the probability of being in a “run” of length $k$?
Thanks. This agrees with the expression I wrote it seems since $\sum_j j 2^{-j} = 2$.
Aug
3
accepted What is the probability of being in a “run” of length $k$?
Aug
2
asked What is the probability of being in a “run” of length $k$?
Jul
18
accepted Limit of a sequence of determinants.
Jul
2
awarded  Curious
Jun
29
revised Special conformal killing fields - solving for integral curves.
deleted 28 characters in body
Jun
28
revised Special conformal killing fields - solving for integral curves.
deleted 11 characters in body
Jun
28
revised Special conformal killing fields - solving for integral curves.
added 322 characters in body
Jun
28
comment Special conformal killing fields - solving for integral curves.
@HansLundmark Very slick; thanks.
Jun
28
comment Special conformal killing fields - solving for integral curves.
@Kirill I found where I went wrong; I hadn't originally simply directly computed $\dot y$, so I had obtained the identity $y\cdot(\dot y + b)$ which is of course still true but not what we want. I hope you don't mind if I post my own answer as well and perhaps accept it since it's a bit simpler? Thanks so much for your help!