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location Princeton, NJ
age 26
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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).

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


Jun
19
comment Do we know what event caused the Sun and Solar System to form?
@AcidJazz The densest nebulae rival the best laboratory vacuums on Earth. As for the shockwave, clearly some stars (if nothing else the first star in the universe) formed without a supernova trigger, so it's more a matter of whether or not something gives gravity a shove in the right direction.
Jun
15
comment Why is the Baryon Acoustic Oscillations (BAO) calculated like this?
Wow that's an awful wikipedia article. Just look at the formatting, the grammar, the unprofessional tone, not to mention the lack of capitalization of sentences. Probably better to delete the whole section than try to make sense of it.
Jun
15
comment Radioactive objects in a student's room
I guess as long as some sensible definition of "whole object" is understood it should be fine. Honestly, the answer is either "living tissue" or "the walls" if you include them depending on what the room is made of. To first order all living tissue is the same, the popular imagination's thoughts about bananas notwithstanding.
Jun
15
comment Radioactive objects in a student's room
I think the only thing wrong with this is using the metric "Bq/g" since then obviously the answer is a single stray atom of something highly unstable. Asking about dominant sources of radiation regardless of mass, however, is very important. As anyone who's ever worked in a radiation lab can tell you, the experimenter emits enough radiation to throw off numerous experiments.
Jun
13
comment How can we feel the effects of a Black Hole if all the mass is gone?
Nature, for all its fame, is the journal people in my field go to when they do shoddy work and can't get published in a real astrophysics journal. Also, we really do observe black holes: in fact we are on the verge of imaging them with angular resolution better than their size, which is more than can be said for all but a handful of stars.
Jun
12
comment Why does planetary spin affect the stability of orbits?
There's a good question here. Note though that there are two senses of "prograde" -- a moon orbiting a planet the same way the planet is spinning, and a moon orbiting a planet the same way the planet is orbiting the star. It's the second meaning that applies here. As it happens, though, most everything in the Solar System goes in the same direction, so the two definitions often coincide.
Jun
12
comment What happens if gravity of all objects in the universe disappears?
I'm actually voting to keep open, as I interpret this as "is gravity necessary for binding planet-sized objects?" This isn't "what would civilization do if gravity shut off?" or anything so subjective.
Jun
12
comment What's the difference between cosmic time and conformal time?
See also Relation between comoving distance and conformal time?
Jun
11
comment How close to the surface of the Sun would one have to be to determine an 'upright' position relative to it's surface?
How far away do you think this distance is from Earth? If you're thinking the astronauts in the space station are far enough away, then there is a more serious misunderstanding here.
Jun
10
comment What is the heaviest stable element in the center of the sun due to Photodisintegration?
An excellent question. I don't have time to write up a good answer now, but the last part of chapter 5 of Clayton would be a good place to start if anyone else wants to answer. If no one does I'll be sure to get back to this.
Jun
9
comment How did Newton figure out the law of gravity?
possible duplicate of How did Newton discover the universal law of gravitation?
May
27
comment Black Body Golf Balls
"I don't think that the sides of the dimples will re-absorb radiated heat in any significant amount as long as the dimples are not too deep" -- but if the dimples weren't deep, there would be no change in surface area either. Both effects vanish in the limit of infinitesimal dimples.
May
27
comment Resolving General relativity and Newtonian mechanics to a computer
Planets flying off? System falling apart? Sounds like a problem with your numerical algorithm (or just a bug), not an issue of physics per se. See for example What is the correct way of integrating in astronomy simulations?
May
26
comment Perfect fluid and Cauchy momentum equation
I'm pretty sure $\nabla_\mu(\rho u^\mu) = 0$ is the correct continuity equation. It holds in arbitrary spacetimes for any perfect fluid with conserved rest mass density $\rho$.
May
25
comment Confusion about two forms of connection coefficients
While you could use the same dummy index in multiple locations (e.g. $g_{\alpha\beta} g^{\beta\gamma} + \Gamma_{\alpha\beta}^\gamma X^\beta$), this is a bit risky, and might lead to mistakes later on.
May
24
comment Confusion about two forms of connection coefficients
Yes, you can always replace all occurrences of an index with another one that is not already in use.
May
23
comment Confusion about two forms of connection coefficients
Hi Sayan Datta, and welcome to Physics Stackexchange! Note that we support LaTeX-style MathJax for math formatting. You can click "edit" to see how I formatted your equations if you're not familiar with the syntax.
May
22
comment What speeds are “fast” enough for one to need the relativistic velocity addition formula?
I've heard the centimeter-level precision claim too, though I can't fathom how they deal with the varying light travel time though a dynamical atmosphere to the point where GR becomes relevant.
May
21
comment Number of significant figures
Nitpick: In a digital instrument where there is no doubt the displayed digits are correct, the discretization error is $1/\sqrt{12}$ times the scale step, not $1/2$, if you're going for the standard deviation.
May
20
comment What would happen to the human body if we went almost at the speed of light?
possible duplicate of Would travelling at relativistic speeds have any impact on human biology? and What happens to body chemistry at the speed of light?