616 reputation
1519
bio website andrewpro.me
location
age
visits member for 3 years, 6 months
seen 18 hours ago

Jun
29
comment Why do atomic clocks only use caesium?
@EmilioPisanty That's a nice question, but otherwise than "it's stable, it's ubiquitous, it's historical" I can't found any nice explanation on this.
Jun
22
comment Feynman Lectures: Why a non-reversible weight lifting machine cannot lift higher that a reversible one?
Just for reference link to a book for this chapter: Feynman Lectures.
Apr
18
comment Which one is colder? Zero temperature ice or zero temperature water?
Also, are you talking about temperature in some energy sense?
Apr
7
comment 2s orbital wavefunction has non-zero probability at $r=0$?
Why not? Especially the marked answer is a clear explanation that the probability isn't just a wavefunction at zero. You forget the volume, which a proportianal to $r^2$, so multiplying by zero is zero. And notice that the plot you added thave $4\pi r^2 R^2_{nl}$, and not just a wavefunction.
Apr
7
comment 2s orbital wavefunction has non-zero probability at $r=0$?
possible duplicate of Hydrogen radial wave function infinity at r=0
Apr
4
comment What is the significance of the “squared” in $E =mc^2$?
You forget some }s.
Apr
4
comment What is the significance of the “squared” in $E =mc^2$?
possible duplicate of Einstein's mass-energy equivalence
Mar
29
comment Why do lines in atomic spectra have thickness? (Bohr's Model)
Talking about Bohr model: I don't think it's explain it at all; in modern theories the thickness of absorption/emitting lines due to the uncertainty principle (the one about time-energy). And this was discovered far later than the Bohr model.
Nov
14
comment How would the representation of a circle in 4 dimensions?
Too short for answer: it's a hyper sphere! Or 3-sphere! Or glome! Also, the tags are mind-blowing.
Aug
21
comment Is there a quantity measured in kilogram seconds?
$\mathrm{kg}\cdot\mathrm{s}$ or $\frac{\mathrm{kg}}{\mathrm{s}}$? Anyway, it doesn't necessary to all combination have some interpretation.
Aug
9
comment Understanding the four fundamental forces of the standard model - are they magic
Clarke's Third Law: Any sufficiently advanced technology is indistinguishable from magic.
Jul
17
comment Can a web community write papers?
Yes, one of the most notable example I know: HoTT book. But it is underpopular now, as it should be.
Apr
16
comment Why do we see laser beams?
Thanks! There is also a Boom-Boom in Star Wars, so... the sci-fi isn't give much help in learning physics.
Apr
16
comment Why do we see laser beams?
So, in vacuum with a few particles in a unit of volume the laser beam would be almost invisible? (haven't found any photos of laser beam in space)
May
6
comment Why there are constant numbers in the universe?
I think this two questions on Math.SE would be interesting: Does π depends on the norm? and π in arbitrary metric spaces.
Feb
15
comment Usage of Schrödinger equation vs Madelung equations
And why do you think there are some superiority? I think they have same relation to Schrodinger as Euler equations to Newtons one.
Jan
26
comment Finding optimal angle for projectile, taking into account linear (Stokes) drag
Are you used Buckingham π theorem for making dimensionless coordinates?
Dec
8
comment Is there a small enough planet or asteroid you can orbit by jumping?
I want to see an answer!
Nov
23
comment Idea of precursors of the electro-magnetic waves
Yes, but I mean that for any wave frequency some of it would be observed much earlier.
Oct
29
comment Question about thermodynamic conjugate quantities
And what about $\langle X_i\cdot x_k\rangle = \delta_{ik}$? As I understood this implies only in the approximation of infinitesimal fluctuations. I'm right?