27,748 reputation
459104
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location Princeton, NJ
age 26
visits member for 2 years, 11 months
seen 3 hours ago

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

My primary interest is in general relativistic magnetohydrodynamics simulations of black hole accretion.


Mar
15
comment Space is expanding so what is time doing?
This seems to be an unpopular answer, but I besides brevity I'm not sure there's anything wrong with it. It highlights the fact that having time itself change over time... doesn't even make sense.
Mar
14
comment If I bend a rod, will its moment of inertia change?
@Sean I think Floris is using the in-screen vertical axis. Of course, the question is rather unclear on this point.
Mar
13
comment Immortality within the multiple worlds interpretation of quantum mechanics
Similar things have been considered, but I strongly suggest not trying the experiment yourself.
Mar
13
comment Effective aperture of an isotropic antenna; question on polarisation
While this could have been asked in a comment, I don't think it's necessarily bad to ask as a standalone question.
Mar
12
comment Kerr metric Christoffel symbols
Schwarzschild is easy; Kerr less so. Even changing the metric in Mathematica, one would need to manually specify substitutions in order for it to return anything remotely reasonable (i.e. not expanding the traditional $\Delta$ and $\rho^2$ abbreviations).
Mar
12
comment Is gravity instantaneous?
possible duplicate of Time taken for gravity of a distant object to interact with a newly created particle?
Mar
12
comment What is the mass of a sphere?
The relativistic mass does increase, and I don't think this is a relativistic mass vs. rest mass confusion. It's more subtle, having to do with the difference between stationary and static mass distributions.
Mar
12
comment Where can I find actual data for the hysteresis of a magnetic material?
I think looking up physically relevant parameters is an important part of physics. Even better, this is asking where to look up parameters, which amounts to asking for a tool that can be used for all sorts of physics.
Mar
12
comment What spacelike, timelike and lightlike really mean?
I might add to the last sentence something like "without bouncing off a mirror" since timelike separated events can also be connected by a piecewise null path. Either that or just define lightlike as the boundary case between timelike and spacelike.
Mar
4
comment Why doesn't $ds^2 = 0$ imply two distinct points $p$ and $p'$ on a manifold are the same point?
@Void You're quite right. I just forgot the square root.
Mar
3
comment The Frequency of a Trill
This might be more appropriate for music.stackexchange.com. In particular, as a physicist who doesn't play string instruments, I don't really know if trilling alters the pitch/timbre of the note (it generally will if and only if the period of the trill is shorter than about the duration of the attack, when the vibrations are reaching steady state). It's also a pure question of music, not physics, as to what trills should sound like.
Mar
2
comment Relation between Vector space $V$ and its dual $V^{*}$
The relevant cross-post: math.stackexchange.com/q/1172022 I know a user there told you you should post here, but cross-posting is generally discouraged, especially if you're well on your way to an answer on the other site.
Mar
2
comment Variation of infinite grid of ideal one-ohm resistors: what would be the equivalent resistance between 2 points in a 3D lattice?
Yes, the formulas hold for any points (one taken to be the origin). The knight's move case is $(l_1,l_2,l_3) = (0,1,2)$ in any order.
Mar
2
comment Difference between Gunn Peterson trough and the Lyman Alpha Forest? Cosmological implications?
Don't worry -- IGM and HI are standard enough terms in astronomy that anyone in the field would know them :)
Mar
1
comment Why is space (almost) flat? Is it because masses are approximately homogeneously distributed?
possible duplicate of Difference between horizon and flatness problems & how inflation solves flatness (w/out math)
Feb
28
comment Could Hyper-Massive Black Holes be due to Dark Matter in the Early Universe?
Good point, but at 1 Gyr old the average density of the universe was less than 1000 times what it is now -- not enough to save the argument. And I took a value of $\rho$ that was a few hundred thousand times the average density of DM in the universe (and DM agglomerations were not as relatively dense back then as they are now).
Feb
26
comment Experimental Data for Mass Distribution of a Galaxy
I guess the $\rho \propto r^{-1}$ comes from taking the mass in the annulus that is the intersection of the galactic disk with a spherical shell and distributing that matter over the shell. That is, if the shell theorem did apply, it would be the right density model for a uniform density disk.
Feb
26
comment Units inside a logarithm
@AlfredCentauri Um, shouldn't the limits of integration match the units of the differential, not the whole integrand?
Feb
26
comment What is the reasoning behind the idea that light cannot escape from a black hole?
@SeñorO No, I'm sorry, Jim is right. A Newtonian black hole would be qualitatively different from a GR one. In particular, you could escape from inside a Newtonian black hole without ever going faster than light, just as you can escape from Earth without ever reaching escape velocity. And light emitted from inside a Newtonian black hole would leave, go a long distance away, and eventually turn around and come back.
Feb
26
comment Is there a limit as to how fast a black hole can grow?
Good answer. I would just note that "speculative" means that we aren't sure which details are right, not that we have no good ideas. Overcoming Eddington is easy in principle -- just break spherical symmetry, letting matter flow inward in some places and radiation flow outward elsewhere. It's not like accretion disks are spherically symmetric anyway.