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I am a graduate student studying astrophysics at Princeton. I received my bachelor's in physics and mathematics from Caltech (2011).


Feb
24
comment How far would I have to go to see a fully rounded Earth?
@Johannes is explaining what Neil deGrasse Tyson claimed without proof: twitter.com/neiltyson/status/431554750119550976
Feb
24
comment Maximum Weight Sustained by wire / Breaking limit of wire
Isn't this a repost of physics.stackexchange.com/questions/99738/… and physics.stackexchange.com/questions/99973/…?
Feb
24
comment Why does the bathroom become hot after a bath?
Other facts that might be relevant: Where does the water come from (cistern on the roof, or underground pipes)? What time of day does this happen? Is the area outside the bathroom de-humidified in some way? How small is the bathroom, and how long is the person in there, and what kind of lighting does it have?
Feb
24
comment What are functions of a complex variable used for in physics?
Just found this very closely related question: physics.stackexchange.com/q/89072
Feb
23
comment Is any time-dependent hydrogen atom Schrödinger equation solvable analytically?
What do you mean by "analytically"? You probably don't mean the math definition, which is that the function converges to its Taylor series. If you mean "involving simple functions" the you should know there's no qualitative difference between numerical integration and special functions. In fact many common special functions are evaluated by your computer via the differential equation they satisfy.
Feb
23
comment Relativistic Doppler effect on gamma rays
If you understand the answer you should write it as a proper answer rather than leave it as an addendum to the question. No need to show all the details either - just the concepts will do.
Feb
23
comment Difference between horizon and flatness problems & how inflation solves flatness (w/out math)
I'd argue that flatness is only particularly meaningful if there is some scale larger than which everything is uniform (as is the case in our universe). As for how inflation achieves this: You can treat the curvature term in the equations exactly the same as another substance (matter, radiation, dark energy, and curvature simply have different scalings with time), and going through the math you see the relative contribution of the curvature term compared to the others goes to 0.
Feb
23
comment Shortcut to find $\hat{p}^2$ expectation value
This is a bit broad. Certainly there's no general way to just ignore the action of taking an expectation. On the other hand, anything you might be asked to compute for a harmonic oscillator is easy and shouldn't require integrals.
Feb
23
comment Humour: Noble Gases, Music, Feynman diagrams
This question is not about physics.
Feb
22
comment Gravitational compression in the atmosphere
Are you asking if the air near the surface is kept warm by gravity? Because virial heating from gravity is a one-time thing - once the contraction stops, no further heating occurs.
Feb
22
comment Does strong magnetic field cause time dilation?
Note that people who like to play with Maxwell's equations with a magnetic monopole term inserted will tell you that magnetic monopoles have the exact same effect on this metric (in CGS-like units, of course) - they add a $Q_\mathrm{mag}^2/r^2$ term.
Feb
22
comment expectation of momentum in the bound state
@user26143 Why not turn that into an answer?
Feb
22
comment The physics of sound boards
Another possibility (not necessarily incompatible with yours): the soundboard serves to match impedances, like the bell of a brass instrument.
Feb
22
comment If Black Hole never forms, how important will be to study Black Hole paradoxes?
What exactly do you count as a paradox? Are you referring to the information paradox? (My understanding is that is not so trivially solved, as the amount of information on/near the horizon does not scale the same as the amount of Hawking particles yet to be emitted.) Or something like "what happens when I cross inside the ring singularity in a Kerr BH?" Or something else?
Feb
21
comment Good Source to Understand Angular Momentum
This question appears to be off-topic in that it does not specify enough objective criteria, as per our policy.
Feb
21
comment Can walking provide electrical energy?
@Vishwa Iyer there are many ways of turning the kinetic energy of jostled objects into electricity, such as with piezoelectric crystals or electromagnetic induction (magnets near coils). The trick is to make sure the system only pumps the battery rather than discharges it, for which the use of diodes is key. The details of particular designs could probably be hashed out on electronics.stackexchange.com
Feb
20
comment Energy-momentum tensor for dust
Not that this answers your question, but the easy way to get $T^{\alpha\beta}$ for dust is to slip into the frame comoving with the fluid; note that $\vec{v}\to(-1,0,0,0)$, note that there is no momentum flux, pressure, or shear but only energy density $\rho_0$, and say $T^{\alpha\beta} = \rho_0 v^\alpha v^\beta$. As you have a true tensor equation, it must hold in all frames. QED.
Feb
20
comment Meaning of Eigenvalues/Eigenvectors of a linear system of equations
As it stands, though, it sounds like you just have each quantity expressed in terms of the other 40, without reference to inputs and outputs. What is the difference between the column vector being multiplied by $M$ and the result of that multiplication? Perhaps I'm just misreading things, as I'm also not sure where time comes into play.
Feb
20
comment Meaning of Eigenvalues/Eigenvectors of a linear system of equations
Usually such matrices represent a transformation of sorts. You have a black box that takes input $x$ and gives output $y$. You test it with different inputs. The $y$ that corresponds to an $x$ of $(1,0,0,\ldots)$ becomes the first column of $M$, etc. Once you've done this 41 times, you have the full $M$ such that (output) = M * (input). Then there are many directions to go, e.g. (1) fix an output and ask what then input must have been, (2) ask what inputs remain constant modulo scaling when acted upon, (3) ask what those scaling are...
Feb
19
comment Meaning of Eigenvalues/Eigenvectors of a linear system of equations
You have 41 equations, but it's unclear what form they have. If you were to write them out in matrix notation, it looks like $M (B_1, \ldots, B_{41})^T = (B_1, \ldots, B_{41})^T$, where $M$ is 41 by 41 and has zeros on the main diagonal? Is this right?