David H
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 Jun 1 comment Measuring the nearest order of magnitude What rob said. Moreover, that's the entire purpose of questions like these. The question intentionally forgets to tell you how big $d$ is, forcing you resort to a guess and deal with the uncertainty that unavoidably enters into your result. This is the difference between an actual physics problem as opposed to mere applied math problems. May 26 comment Icecube experiment at the North pole instead of the South? The biggest reason is probably because the North Pole is in the middle of the Arctic Ocean. The IceCube laboratory was able to be installed 1 kilometer below the surface of the Antarctic ice sheet because the depth of the ice sheet goes down almost 3 kilometers, and below that is solid land. At the North Pole, the ice is a mere 10 feet thick in most places before you hit liquid water, and even that 10 feet might melt altogether come summertime. May 21 comment time dependent current/ magnetic field You could in principle use Jefimenko's equations, but I imagine that's a bit overkill here. May 4 comment “Periodic Table” of Particles of the Standard Model? @Geremia The inner circle is the set of particles that interact with gluons (strong force), the middle circle is the set of particles that interact with photons (electromagnetic force), and the outer circle is set of particles that interact with W's and Z's (weak force). We know some of the particles the Higgs interacts with but we're not sure if there are more or not so no circle as of yet. May 3 comment “Periodic Table” of Particles of the Standard Model? @Geremia Your table is out of date. It has 17 particles now. upload.wikimedia.org/wikipedia/commons/0/00/… May 2 comment Why is the Coulomb taken as the unit positve test charge, though $1 C$ charge is a high value? And note that 1 ampere of current (~ 1 light bulb) is neither an extremely large nor extremely small amount of current. In fact it's a very ordinary amount. Apr 26 comment Weak interaction and Neutrino You heard wrong. All known fermions interact through the weak interaction. That includes all leptons and all quarks. Apr 21 comment Schroedinger equation. Mass. Charge You could say the same thing about $F=ma$. Apr 21 comment Gauss' law and an external charge @user37433 I'm not quite sure what you're asking. What are you trying to do with this cubic Gaussian surface?. Apr 19 comment Is cosmic background radiation absolute It most definitely does. See the link in my comment above for more info on microwave radiation. Apr 19 comment Is cosmic background radiation absolute Two key words: microwave radiation. Since it is light, it's speed is...? (and no, it's certainly not stationary!) Apr 19 comment Will it ever be possible to observe the cosmic neutrino background? The IceCube South Pole Neutrino Observatory already reported the first observations of cosmic neutrinos last Noveember. In fact, it was deemed the biggest breakthrough of 2013. Apr 18 comment double of temperature The Celsius temperature scale is a difference scale, not a ratio scale. Try doubling $0^\circ$ C. Apr 17 comment Why uncertainty principle is not like this? Because the fundamental equation of quantum mechanics is $[\hat A,\hat B]=i\hbar \hat I$, for conjugate variables $\hat A$ and $\hat B$. Apr 12 comment De Broglie Wavelengths See wiki for info on wavenumber and wave vector. Apr 12 comment About the speed of light Apr 11 comment Is there any general position function $x(t)$ that gives the solution to $x''(t) = k/x(t)^2$, where k is a constant? Try multiplying by x' and integrating Apr 6 comment Gauss' Law for Magnetism Derivative Form: With or without volume integral? They're equivalent alright. This is exactly how you go between the integral and differential formulations of Maxwell's laws. Apr 6 comment Hamiltonian Operator Interpretation of Quantum Anomaly A quick google search turned up this article: link.springer.com/article/10.1007%2FBF01466595. Sadly, only a preview is freely available, which is a shame since it appears exactly what you're looking for. Apr 6 answered What prevents an orbiting object from getting a speed which is greater than $c$?