604 reputation
38
bio website jacobi.luc.edu
location Chicago, IL
age
visits member for 3 years, 2 months
seen 2 days ago

I'm an assistant professor of physics at a university in Chicago.


Feb
2
awarded  Yearling
Nov
19
answered Symmetry transformation in AdS space
Nov
4
awarded  Nice Answer
Nov
1
answered How does the full string theory potential look?
Jun
30
comment What experiment would disprove string theory?
Downvote for not answering the question.
Apr
14
awarded  Quorum
Feb
2
awarded  Yearling
Jan
21
answered What exactly are we doing when we set $c=1$?
Nov
22
answered What does Friedrichs mean by “Myriotic fields”?
Nov
13
comment Cubic term in gauge theories
I'm not sure why you'd do that. Do you know of some way of building a sensible F^3 theory?
Nov
12
awarded  Commentator
Nov
12
comment Cubic term in gauge theories
Adding F^3 to the standard YM Lagrangian gives a non-renormalizable theory; you should only consider it as part of a low-dimensional effective theory. F^3 is the "least irrelevant" gauge-invariant operator for pure YM. So the low-energy expansion of some theory that holds at higher energies might have F^2 as the leading term and F^3 term as the first "correction".
Nov
9
answered Cubic term in gauge theories
Nov
7
awarded  Yearling
Nov
7
answered Einstein tensor in Friedmann equations : where is the missing $c^2$?
Sep
3
answered How do I calculate the induced metric in the Gibbons–Hawking–York boundary term?
Aug
12
awarded  Citizen Patrol
May
28
awarded  Critic
Aug
12
comment Does the lack of modular nuclearity in string theory mean anything?
You don't even need quantum gravity to see that extensivity breaks down when gravity is important. Solve the Tolman-Oppenheimer-Volkov equation for a self-gravitating perfect fluid with equation of state $p=\kappa\rho$. This gives an energy density $\rho \sim r^{-2}$. Cut off the solution at some radial size $R$ and join it on to a solution that goes to zero at a finite distance. Relate the entropy density to the energy density using the EOS, integrate, and you get entropy $\sim R^{\frac{1+3\kappa}{1+\kappa}}$. The entropy of the self-gravitating object never grows faster than the area.
Aug
2
comment Cheat sheet of elementary particles
Here is a handy Eightfold Way reference chart from an undergrad class I taught on particle physics: cl.ly/8yhy . Of course, it will only be useful if you understand what it represents! There is a good review in "Introduction to Elementary Particles" by Griffiths.