Reputation
1,925
Next privilege 2,000 Rep.
Edit questions and answers
Badges
2 18 53
Impact
~367k people reached

Jan
29
comment Proving that Planck's Law is dimensionally homogeneous
Why is it called dimensionally "homogeneous" if the opposite would just be "wrong"?
Jan
9
comment Startups for astrophysics
You can surely also find information if you search "introduction to..." here in the search bar.
Oct
6
comment How do Hubble Units work?
Found this Wikipedia reference.
Oct
1
comment Yang and Mills' (and others') justification for local gauge invariance
@ACuriousMind: Maybe that's the answer for him, then.
Oct
1
comment Yang and Mills' (and others') justification for local gauge invariance
I'm certain OP is aware of the first point and is just asking if a global-only field theories must be ruled out for describing physics if locality principles are assumed.
Sep
13
comment Harmonic Oscillator propagator
I'd say the second equation with the derivative is not so evident, is it?
Sep
13
comment Harmonic Oscillator propagator
From one perspective, you just ask how $\frac{∂}{∂t}\langle x|e^{At}|y\rangle=\langle x|Ae^{At}|y\rangle=A\langle x|e^{At}|y\rangle$ should be made sense of. Is the case without the term $\frac{p^2}{2m}$ clear?
Sep
9
comment Intuition for spin 1/2 and 1 propagators
$\frac{1}{p^2-m^2}$ is $(\Box+m^2)^{-1}$ in Fourier space, in that it solves $(\Box+m^2)\,\phi=j$ for $\phi$. The spin 1/2 case $\frac{\gamma\,p+m}{N}$ solves $(\gamma\,\partial-m)\,\psi=j$, and so on.
Aug
19
comment Kinetic energy as $\pi k_B T$
@LubošMotl: The question is if it matters as long as you keep on using a temperature-unit that's formally distinct from an energy unit. Sure, you may take the reductionist approach and fix all factors using the deeper theory, but "I haven't seen what the energy (...) is converted into" and so if all quantities in the theories account for this strange $\pi$, it may end up not ruining any results. I agree that it's odd that a particle should carry an irrational energy-quantity - I'm not advocating it. But apparently people have used this quantity for some time and it worked for their use.
Aug
19
comment Kinetic energy as $\pi k_B T$
@LubošMotl: You don't need to violate any exact entropy expressions or the absolute temperature scale. Just consider $k_B^*\equiv \pi\,k_B$ the auxiliary constant. Some like $k_B=1$ and electron volts, and some might find $\approx 10^{-23}J/K$ and kelvins or "pi-kelvins" useful. That's why I said I don't know what would be the merit of adopting another $3.14$ to get energy out of temperature. I showed OP where $\sqrt{\pi}$ pops up. In expectation values, it will pop out anyway, because the density $\rho\propto{\mathrm e}^{-H\,/\,k_BT}$ gets normalized.
Aug
17
comment Isothermal versus Isometric/Isochoric
You can make a big delta $\Delta$ via backslash Delta. Also, are you sure it "literally means zero temperature change"? 'zero' in Latin would be a word starting with 'n'.
Aug
17
comment Third principle of Nernst
@Qmechanic: The duplicate has been deleted.
Aug
16
comment How to compute this change of Gibbs energy for a Van der Waals gas?
@Gert: I'm not sure which aspect of your question isn't answered by the first sentence.
Aug
10
comment Why $C_{abcd}C^{abcd}$ in de Sitter–Schwarzschild metric doesn't depend on $\Lambda$
@user34669: I'm not sure if this is intended as a response to what I propose, is it?
Aug
10
comment Why $C_{abcd}C^{abcd}$ in de Sitter–Schwarzschild metric doesn't depend on $\Lambda$
It would be interesting take $-f(r)\,\mathrm dt^2+\frac{1}{f(r)}\mathrm d r^2+r^2\mathrm d\theta+r^2\sin^2\theta\,\mathrm d\theta \mathrm \,d\phi$, compute the scalar, set it to $c\,r^n$ and solve the ODE. Challenge accepted?
Aug
2
comment What are the technical obstructions that prevent scale relativity from being a viable theory of quantum-gravity?
I have the feeling that hardly anybody knows of the theory (which in part is an answer to the question too). Like with Fractional anything, if no big solution to an old problem through it is being made popular and/or if the author isn't popular, getting ideas known is very hard. Nobody's who isn't payed for it is gonna invest the time to look into it in the first place - to take the time must presuppose a suspicion you can get something out of it. There are also tools like Gyrovector spaces nobody uses for SRT, and so on and so on.
Jul
8
comment How does one determine an inertial frame?
Seems so. And I see no paradoxes, let alone inconsistencies. Might be because at least the latter has a precise formal meaning that I inevitably read if one uses the word. Newtons system is just lacking and we find that not pretty. And even if, I'm a tolerant person :)
Jul
8
comment How does one determine an inertial frame?
That wasn't supposed to be my only point though. The "you need X" just jumped my eye. It's like if someone says you need to unlock the keys to your bike before you cross the road. No I don't, it's merely an action plan that leads to some particular outcome. You said "It's not possible to know the inertial reference fame. This is why you need GR." I need it for what? I guess you're saying to be in a framework where the problem wouldn't arise in the first place. That's a suggestion leading far away from the question. The merit is only in the education that in GR things are different.
Jul
8
comment How does one determine an inertial frame?
I like this related list.
Jul
8
comment How does one determine an inertial frame?
Yes, that's right. But it doesn't follow that one needs general relativity, just because the latter is a theory that doesn't exhibit this unnice circularity. One needs that particular alternative IF what? Maybe you mean if you want to describe gravity without inertial frames? You could just drop the obligation and state that the research relevant theory of general relativity doesn't make use of those frames.