277 reputation
14
bio website
location Williston, Florida
age 34
visits member for 2 years, 6 months
seen Apr 4 at 6:17

Mar
22
awarded  Yearling
Dec
4
answered Quantum uncertainty of particle falling in black hole
Jun
26
comment In what sense is SUSY a spacetime symmetry?
It's not necessarily true that the exponential of a susy generator terminates at the first term; it depends on how many components of the susy generator there are. In 4d with N=1 susy, the series terminates at fourth order. Also, in the comment above, acting with the exponential of a susy generator doesn't merely shift theta, it also changes x. See Chapter 4 of Wess and Bagger. The susy generators contain a theta derivative and a P term.
Jun
12
comment Direct observations of a black hole?
Just a note: The even horizon doesn't necessarily have a strong gravitational field, so we can apply GR without having to extrapolate to regimes where new physics are required.
Jun
6
awarded  Revival
Apr
15
answered What is currently incomplete in M-theory?
Apr
14
comment Fluid Mechanics from a variational principle
A nice lagrangian treatment is available for incompressible potential flows with hydrostatic pressure, or for flows allowing one component of vorticity. Also, for a general Hamiltonian description one may resort to Clebsch variables, and then define the resultant lagrangian from these. One can check out some of Zakharov's reviews on the subject.
Apr
8
answered Is dark matter really matter?
Apr
8
answered Is existence of cosmic dark energy falsifiable yet?
Apr
6
answered Is acceleration relative?
Apr
5
revised A simple pendulum moving at a relativistic speed - how does the period change?
Made some corrections in light of the the detailed calculation of the other answer.
Apr
5
answered Why can't we know the speed, $\vec{v}(t)$, and position, $\vec{r}(t)$, of an electron (the two) at the same time $t$?
Apr
4
answered Microwave oven + water: dielectric heating or ion drag?
Apr
4
answered Are we inside a black hole?
Apr
4
awarded  Supporter
Apr
4
comment A simple pendulum moving at a relativistic speed - how does the period change?
Okay, I concur with Alexey's answer below. You really can't get the pendulum's period just by considering the change in the density, this was just laziness. A full calculation seems necessary, verbal hand waving won't suffice.
Apr
4
answered Can dark matter and energy be formulated as local perturbations of the metric
Apr
4
answered Why doesn't dark energy vary with time?
Apr
4
awarded  Editor
Apr
4
revised A simple pendulum moving at a relativistic speed - how does the period change?
Addressed question 2.