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location Princeton, NJ
age 25
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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).


Aug
24
comment geodesic conjugate points
Huh - every source I've ever read would call that an instance of the Raychaudhuri equation, and google returns scarce few hits for RNP equation outside of finance. So who would tack on an N and a P to R? Ah, Penrose himself apparently.
Aug
24
comment The Thermodynamic Limit of Quantum Statistical Mechanics & Interpretation of Quantum Field Theory
"is way too mathematically advanced for 99% of philosophers to understand" - A fair number of the philosophers I've learned from had graduate degrees in pure mathematics. And honestly, 99% of professional physicists don't know what a C*-algebra is, nor have they ever touched non-commutative geometry. Don't be so quick to assume a whole group of people is entirely stupid or incompetent.
Aug
24
comment How powerful would a series of rail guns or bombs need to be to destabilize a hurricane?
What does it mean to destabilize a hurricane? Storms are driven by gradients (in temperature or humidity or better yet entropy) between different altitudes and/or latitudes. When the gradients are steep enough, the atmosphere becomes unstable in that small flows build on themselves. Getting rid of storms amounts to either engineering a planet-wide method of calm equilibration (giant metal pipes everywhere?), or just doing away with the gradient altogether (permanently melt the ice caps perhaps?).
Aug
24
comment A Sphere of Black Holes
@Blackbody The actual definition of "event horizon" is the boundary you cannot cross to get to the rest of the universe, ever. And it has no effect other than this - you can't know you are crossing an event horizon from any local experiment, even in principle. Thus in a very real sense there is only ever an "outer" event horizon. The "inner" ones you're picturing don't demarcate anything of importance, and in fact wouldn't exist according to the definition by the time the outer one formed.
Aug
24
comment How and under what principle are measurements made at quantum level?
This really is a bit broad and non-specific. What kind of measurements are you talking about? What does "quantum level" mean? At some level quantum mechanics is everywhere, and we observe predictions of quantum theory the same way we observe any other experiments - with instruments designed to aid our senses. For example, a Stern–Gerlach apparatus is at its heart just a beam of silver atoms and a magnet. Classical physics predicts one pattern on the detector, quantum mechanics predicts another.
Aug
23
comment Presence of planets in Milky Way and other galaxies
Well, it's not like we can see M-dwarfs very well in the Magellanic clouds (or even in most of our own galaxy). And certainly we can't see fainter things like white dwarfs.
Aug
22
comment Why doesn't the light from galaxies appear stretched?
This is a good question, but the big bang/inflation aspect is something of a confusing tangent. Galaxies had not formed by the time of recombination, and in fact most images of galaxies are from at most a few billion light years away.
Aug
20
comment Alcubierre drive and inertia.
Realize that you are asking for details regarding a physically impossible device. If you allow for the existence of a warp bubble, you may as well import anything else you desire from science fiction to help alter its properties.
Aug
15
comment How did Fizeau make his famous speed-of-light experiment?
Hopefully the laser came with some specs. Not just power output (btw you were lucky to get an actual high power one from amazon - most of the lasers online are many times worse than advertised) but also "beam divergence" or something similar. That could at least help in diagnosing why your particular setup didn't work.
Aug
15
comment How accurate are constants in cgs units?
I would think that for most major solar system bodies, $GM$ is known far better than $G$ or $M$, and this isn't going to change any time soon. The only non-$GM$ ways of getting mass I can think of are compositional inference and shoving the thing with a known force.
Aug
14
comment Wouldn't the presence of dark matter slow the expansion of the universe?
@allanemery be careful about jumping to hypotheses like that. The "dark" in both is a complete coincidence of naming. And moreover the ratio of dark matter to dark energy changes with the scale of the universe.
Aug
14
comment Why are cgs units the norm in astrophysics?
And this is why the IAU is a worthless organization. The audacity of professional bureaucrats to go up to scientists and say "these are the units you should be using." There may be reasons to prefer one unit system over another, but "we should go along with some long-dead French engineers because completely different fields do so" is definitely not one of them.
Aug
14
comment What is the physical meaning of commutators in quantum mechanics?
Maybe I'm underthinking this (certainly compared to the given answers), but exactly is wrong with "this expresses how much applying A then B is different from applying B then A"? Commutators of operators are important whenever operators don't commute. I suppose I realized this better when I learned about the commutator of covariant derivatives in GR (better known as the Riemann tensor of course).
Aug
13
comment Does extreme cold make **everything** extremely brittle?
Note that most things you see shattered in movies have lots of water in them, and we all know that ice tends to shatter. So, at least in principle, most movies can be sort of right even if other objects aren't so affected. In fact, answers should distinguish between "shattering because it turned into ice" and "shattering because it was a solid that became brittle."
Aug
13
comment Thermal superconductivity
In light of your characterization, would it be fair to say superconductivity is the prevention of gradients from building up, rather than the prevention of losses in flows? That is, it is only coincidental that nonzero electrical gradients imply nonzero ohmic losses?
Aug
13
comment What's the biggest cube you could have before gravity rounded it?
The easy observational way, no first principles required: larger than oddly shaped asteroids, smaller than round moons.
Aug
13
comment Is our universe an emulation?
@CountIblis That's a good thing to turn into an answer.
Aug
11
comment Why are objects opaque?
@NikosM. Sorry, but I can't let this slip unchallenged, off-topic though it may be. The existence of black holes is as well accepted in astrophysics as is the existence of other galaxies, or of planets around other stars, or of the asteroid belt. For just one of a multitude of solid pieces of evidence, see the dynamics of S2 around our own galaxy's central black hole.
Aug
11
comment Is interstellar flight possible in near future in a way that would keep our civilization alive?
@HostileFork That comment displays a remarkable lack of understanding of physics. FTL travel to a physicist is as nonsensical as "a positive integer less than 0" to a mathematician. There is not a single practicing physicist who believes FTL is possible.
Aug
11
comment Is 'amp' a technically invalid term?
@baharini It's entirely up to you (no pressure), but alemi's answer is now far more official and complete than mine so you may consider changing the accepted answer.