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location Princeton, NJ
age 25
visits member for 1 year, 11 months
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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).


Jul
19
comment What is the probability density function over time for a 1-D random walk on a line with boundaries?
General word of advice: "closed form" isn't terribly well defined. What people generally mean is "in terms of nice functions that I like and understand" but this is clearly subjective. There are many solutions to physically-inspired math problems are perfectly well-behaved and analytic, but that no one has bothered assigning abbreviations to like $\mathrm{e}$, $\sin$ or $J_0$. These functions are still manipulable and easily calculable to arbitrary precision.
Jul
19
comment Is it possible for a planet to be made entirely of water (even it's core)?
@lonewookie The title of your question certainly duplicates that linked post. On the other hand, that post is more concerned with boiling at the surface than with the properties of the core. As-is this is likely to be closed, but if you edit it to ask specifics not addressed in that other post, it would make for a good question.
Jul
19
comment What stabilizes neutorns against beta decay in a neutron star?
@Slaviks I don't want you to go away with the impression that neutrons are unchanging in neutron stars. In fact, neutrons are transforming all the time via the (direct and modified) Urca process (see also here), and the subsequent release of neutrinos is one of the main channels for neutron stars to cool off. The neutron/proton ratio is very much set by thermodynamics, not kinetics.
Jul
19
comment What stabilizes neutorns against beta decay in a neutron star?
I agree this doesn't fully explain the value of the equilibrium concentration, but +1 for emphasizing the equilibrium nature of neutron stars. There is nothing magic preventing them from decaying, and indeed they will go back and forth between neutron and proton states.
Jul
18
comment What can be the lightest possible moon launch vehicle?
space.stackexchange.com is now in (private) beta. I suggest either obtaining an invite from someone on the inside (or simply waiting a few days) and then reposting there, where the expertise is more aligned with the question. If you do repost, this post can be deleted.
Jul
18
comment What does “clockwise” mean, exactly?
This question appears to be off-topic because it is about English terminology having nothing to do with physics.
Jul
18
comment What routine tasks have to be performed on the outside of spaceships/stations?
This is not a physics question. It would however be suitable for space.stackexchange.com
Jul
18
comment decay time for a blast wave
More on overpressure of blast waves: Bulk transport of an aerosol by a blast wave
Jul
17
comment Hydrogen cloud at the universe's beginning?
You may be interested to learn that the vast majority of the hydrogen in the universe still hasn't collapsed into stars. Just as steam cannot condense into water droplets above the boiling point, hot gas cannot clump into a star without cooling sufficiently.
Jul
17
comment What is the physical property of metal nanoparticles?
The second part of the question makes sense (though it may be more at home on chemistry.stackexchange.com), but the first part needs more detail to be answerable. What physical properties are you interested in? Density may be much the same as in the bulk case, but electrical conductivity and hydrodynamic forces depend more sensitively on the size.
Jul
17
comment Biological Themodynamics - What does an endpoint saturated signal mean. How does it relate to equillibrium constant
Where biology and physics meet, there is chemistry.stackexchange.com to consider. At the very least, most physicists are not on a day-to-day familiarity with assays, so the definitions of absorbance and $K_d$ might be needed.
Jul
17
comment Qubit (Qdit) equivalence with bits/bytes/Kbytes/
...as seen in our faq and this meta post
Jul
17
comment How do human ears distinguish the frequencies in sound?
In general we discourage link-only answers (see the faq and this meta post). Could you summarize some of what is mentioned at those links?
Jul
17
comment How do human ears distinguish the frequencies in sound?
In general you shouldn't put any weight on formulas, as they are merely human inventions for describing nature, not laws that nature has to look up and obey. Your ears no more understand Fourier transforms than the Earth understands Kepler's laws for planetary motion.
Jul
16
comment Optimal telescope size?
@BenCrowell Indeed, my non-AO-assisted amateur astrophotography experience is usually that - throw out the bad; stack the good. But for deep-sky imaging of diffuse objects not much brighter than sky background, long exposures are unavoidable. It would be interesting to see if a larger aperture helps in that case, beyond just intrinsically reducing the needed exposure time.
Jul
16
comment Maxwell equations and Fourier decomposition
I'm inclined to let this stay - it is not purely math. @Amzocks For the record (and I know no one told you this) we discourage cross-posting. A better alternative if you learn the question is better at another site is to flag it and request that the moderators migrate it to that site.
Jul
16
comment Why does lightning emit light?
I don't know whether or not this is right, but I do know that none of the other answers have demonstrated that thermal emission is the dominant cause, so +1 for bringing up this possibility.
Jul
16
comment Saturation of the Cauchy-Schwarz Inequality
As for addressing the question, this is just a passing thought: I don't have the text, and I'm not entirely familiar with what's going on, but should $\max_{y_2\neq0}$ be replaced with $\sup_{y_2\neq0}$? As in, is it possible that no $y_2$ actually saturates, but that there always exists a sequence that converges as needed? Of course this question is moot if the underlying space is nice and compact or something, but again I also don't really know what I'm talking about...
Jul
16
comment Saturation of the Cauchy-Schwarz Inequality
Wow - much more detailed than the early version :) I think you could get a good answer either here or on math - and I'm personally not against leaving the question here.
Jul
16
comment Are quantum effects significant in lens design?
@PhilipKendall Welcome to Physics, by the way! Feel free to come by with any more physics questions arising in photography.