1
vote
1answer
107 views

Can someone prove that the $\tilde{E}$ and $\tilde{H}$ fields in a waveguide looks as pictured?

Hi, I'm trying to use the solution to the wave's equation in a rectangular waveguide for $\tilde{E}$ and $\tilde{H}$ to show how I can get the above picture. For example, why is the magnetic field ...
1
vote
1answer
75 views

Is there uncertainity of position of the perfectly homogenous radiating body?

I heard the standard interpretation of Heisenberg Uncertainty Principle: Just the measurement affects the position of the body because always you want to see a body (=to measure the position), you ...
0
votes
0answers
16 views

Higgs field with pinwheel singularities

The Higgs field is a scalar complex field and the "only thing that matters" is the magnitude of the field. The field is at the lowest energy configuration at 246 GeV: If someone (somehow) created a ...
6
votes
4answers
1k views

Are atoms made of protons, electrons and neutrinos?

If neutrons decay into proton, electron and (anti)neutrino of electron type, then is it safe to say that atoms are protons, electrons and neutrinos?
3
votes
1answer
282 views

Least Action Principle (Classical and Quantum Theory)

I) My first question would be "why should classical systems obey the principle of least action ?" When we find out the propagator in quantum physics, we find the amplitude to be equal to the sum over ...
0
votes
0answers
40 views

What does the Equation $E_s = -dF$ mean in terms of a Rydberg Atoms Dipole Moment and its Energy?

Could someone explain what the equation $E_s = -d$•$F$: Where, '$d$' is the Rydberg Atoms Dipole Moment, '$F$' is The Electric Field Strength and '$E_s$' is the Energy of the Rydberg Atom. In terms ...
2
votes
1answer
88 views

Why are laser pulses Sech Squared in temporal shape?

Ultrashort pulses from mode-locked lasers often have a temporal shape which can be described with a squared hyperbolic secant ($\mathrm{sech}^2$) function: $$ P(t)=P_0 \mathrm{sech}^2 \left( ...
0
votes
5answers
130 views

About the perception of the flowing of time

The user John Rennie suggested I ask the following as a new question: If time is continuous why would the perception of time being continuous or flowing be an illusion?
0
votes
2answers
50 views

Power transmission loss in a large circuit

This is a followup question to this question Consider a large circuit like the german electric power transmission network. You have a lot of of people consuming power and a lot of power stations ...
-1
votes
1answer
60 views

If you are not given a metric, which one is more fundamental: a vector or a covector? [closed]

If we do not have the metric $g_{\mu\nu}$ for a given spacetime, are vectors $x^\mu$ more fundamental than covectors $x_\mu$ or vice versa? Why? (if the metric were given we could just raise/lower ...
1
vote
0answers
173 views

Calculate Helmholtz Free Energy with Entropy, Work given [closed]

it's my first time here and I hope the post complies with the general rules. My problem originates here: I'm doing a statistical physics task which unfortunately leaves me clueless atm. I keep my ...
2
votes
1answer
131 views

Why is the Carnot engine the most efficient?

It seems that the only condition used in proving that the Carnot engine is the most efficient is that it is reversible. More specifically, the Carnot engine can be run in reverse as a refrigerator. ...
4
votes
5answers
420 views

Confusion about Length Contraction (ex in Muon decay)

I am a bit confused about the implications of length contractions; For example, in the muon decay problem, we assume that the distance between the muon and the earth is contracted only in the frame ...
2
votes
0answers
34 views

Ray tracing a three-way intersection

I've been studying ray tracing in media with linear velocity-depth functions. One of the key concepts I've come across is the ray parameter, and in particular the idea that the ray parameter is ...
1
vote
4answers
212 views

Where do Newton's Laws not work? [closed]

I'm working on high school level project about Newton's Laws and I picked topic that describes situations, where they dont work. Can you name any practical cases where they do not work? Why do they ...
1
vote
1answer
45 views

The Higgs field and spacetime intervals

The Higgs field imparts a rest mass to certain fundamental particles, but it also seems to do something more interesting. Particles that don't couple to the Higgs field, i.e. the rest-massless, are ...
0
votes
2answers
76 views

Kirchoff's loop law

Can any one provide me with mathematical proof of kirchoff's loop law? I am not able to understand from where to start.
0
votes
3answers
71 views

Power transmission in a circuit

lets say you have a battery and a resistance which form a circuit. The electrons flow through the resistance. How can you visualize the flow of energy? How do you visualize the energy field? I ...
0
votes
1answer
36 views

Why is energy of emitted particles negative?

recently I had one problem here, and in comments I got interesting thing written by user Sofia. Unfortunetly, the topic is in hold now and I can't ask her more. Here is the comment: Radio-activity ...
4
votes
0answers
108 views

Strong CP Problem

So, as far as I know, the Strong CP Problem in QCD results from the theta angle term in the action: $i\theta\int_X F_\nabla\wedge F_\nabla$ where $\nabla$ is the gauge connection and $X$ is a manifold ...
0
votes
2answers
104 views

How can we show that pressure is exerted sideways too?

We can show that pressure upward and downward in a fluid is caused by weight of fluid column or volume. A simple derivation of this: ...
0
votes
1answer
36 views

Thomson problem vs. maximizing sum of distance

Given $N$ equally charged points lying on the unit sphere ("electrons"), the Thomson problem consists of finding the configuration of these points such that the electrostatic potential energy $$ ...
0
votes
0answers
94 views

Gaze tracking with the pupil-glint response how does the geometry work?

I am struggling to understand the geometry behind the pupil glint response (see above) (With only one light source). I understand that you use the glint to find the corneal centre (Centre of corneal ...
1
vote
2answers
63 views

How come milk pours smoothly from a bag?

I have seen the commercial about the new beer can where it is vented by puncturing a whole on the can (air behind water). If you just pour normally with normal cans it will get bottle necked and the ...
0
votes
2answers
40 views

How velocity dispersion changes with change of inertial frame

I'm analysing a bunch of simulated galaxies, and one of the properties I'm looking at is their velocity dispersion (which is the same thing as the standard deviation of their speeds as far as I know). ...
5
votes
0answers
82 views

SciFi Stasis Field and the Quantum Zeno Effect

The Quantum Zeno Effect concerns the use of repeated measurement of a particle to prevent the time evolution of the wave function, and hence "freeze" it in the observed state. A Stasis Field is a ...
0
votes
1answer
56 views

How did the Huygens probe use EM waves to measure wind speeds on Titan?

In the Wikipedia's article on Huygens spacecraft, it was mentioned that one of the experiments was to measure the wind speeds on Titan by Doppler wind experiment. To quote the exact lines, it was ...
2
votes
0answers
61 views

What does it look when we travel at the speed of light? [closed]

Suppose we're in a spaceship or in a car which runs at the speed of light. We are watching the light which is coming towards eyes at the speed of the light. What would it look like when the driver ...
0
votes
3answers
117 views

Do electrons get accelerated or decelerated by the atoms of the anode during X-rays production?

The electrons striking the anode get deflected by the heavy nucleus. Though the speed may or may not change, the direction of motion changes which leads to acceleration. The charged particles emit ...
0
votes
1answer
52 views

Electron-positron annihilation to neutrinos

I was wondering, even though the electron-positron annihilation prefers to give us photons, it can turn into neutrinos as well - as far as I understand. My question is, since the equations I have seen ...
1
vote
0answers
41 views

Will the usage of Exo-Skeleton Gear actually weaken the human body over time? [closed]

As we all know, Exo Skeletons as they exist now are just a series of Force multiplying apparatuses working together, also the human body changes to accommodate environment specific factors in order to ...
2
votes
0answers
53 views

Estimate of the second shallowest bound state?

Suppose we have a 1D potential $V(x)$ of finite range, i.e., $$ V(x) ~=~0 $$ for $|x| > b $. The potential is assume to support at least two bound states, but might have more, say $n\geq 2$. ...
2
votes
1answer
184 views

Photon polarization sum prescription in $e^-e^+\to{}2\gamma$

In calculating the amplitude for the process $e^-\gamma\to{}e^-\gamma$ the substitution $\sum\epsilon_{\mu}\epsilon^*_{\nu}\to-\eta_{\mu\nu}$ is useful to sum over photon polarizations. If we ...
0
votes
0answers
16 views

Is uncertainty in velocity via HUP reference frame dependent? [duplicate]

Simply put HUP involves position and momentum, further more consider a mass of 1kg. as momentum is mass X velocity = 1X velocity = velocity for calculation purposes. now for a stationary observer the ...
0
votes
3answers
157 views

Was Aristotle Actually Correct About Gravitation? [duplicate]

Apparently, Aristotle reasoned (without experimentation) that heavier objects must fall to Earth faster than lighter objects. For example, a 1,000 kg ball of iron would fall faster than a 1 kg ball ...
3
votes
3answers
295 views

How would you define electrostatics and magnetostatics starting from Maxwell's equations?

I'm reading Griffith's text, and he starts by defining Electrostatics as requiring the source charges don't move. I've seen a few slightly different definitions of electrostatics and magnetostatics. ...
1
vote
0answers
178 views

Help understanding Fizeau's calculation of speed of light

While searching for different methods of calculating Speed of light, I came across one of the methods that Fizeau discussed below which I cannot fully understand. In short, in Fizeau’s apparatus, a ...
0
votes
1answer
35 views

energy in a current induced magnetic field

a mass of metal is near a current carrying wire, say a DC current. the metal feels a magnetic force of attraction and moves toward the wire overcoming some kinetic friction. the work done by the field ...
0
votes
0answers
47 views

How can I determine the convergence of self energy in Green's function

I want to solve for the Green's function (in the context of many body theory) but I have a question. After the determination of the retarded Green's function and the lesser Green's function we ...
1
vote
2answers
71 views

Gravitational force of several massive bodies, from the viewpoint of general relativity

According to Wald's GR, "absolute gravitation force has no meaning". The text goes on to describe two cases: one where a gravitational force can be defined, and one in which it cannot. I'd like to ...
0
votes
1answer
144 views

Did the derivation of self inductance equation overcalculate winding number? [duplicate]

Let $L , I , \phi$ are self inductance , current and magnetic flux (created by each loop) of a solenoid with $n$ turns . $r$ is the radius of those loops . We have , $LI=n \phi = nAB $ [$A=\pi r^2$] ...
0
votes
2answers
246 views

Net work done for rubber bands

I know that work is done on a rubber band to extend it, and then the rubber band does work to contract. However, then what is the net work done? If it returns to its original length, is the area ...
1
vote
0answers
28 views

Do three spacelike separated events on the same lightcone satisfy the triangle inequality?

If three events are (pairwise) spacelike related to each other then their interval ratios do not necessarily satisfy the triangle inequality. (For example, consider the case that two of the three ...
2
votes
0answers
23 views

Has the formation of a new quark pair as we separate two quarks been observed or is it only a prediction? [duplicate]

Because of quark confinement we know that as we try to separate quarks appart the energy required will increase, but if the force is strong enough (I do not know if possible in the lab, but at least ...
0
votes
1answer
182 views

Can Hooke's law go along with Newton's 3rd law & how is momentum conserved in case of spring?

Let there be a spring in its relaxed state- that is neither compressed nor extended. One end is fixed on the left and other end is free in the right. Now, I stretch the spring by pulling the free-end ...
0
votes
1answer
169 views

References for experimental results of the double-slit experiment

Every other popular science book and intro level text on QM starts with the double slit experiment. It is always just stated as a fact that experiments have been done, actual data is never presented ...
0
votes
0answers
23 views

Kármán Line Definition from “Aeronautical Flight” (Mass, Area, and Lift)

This question asks something very similar, and the single following answer says, in part, that the balance is achieved when: $$ \frac{2m}{\rho(r) A C_L r} = 1 $$ [...] I note that the mass ...
0
votes
3answers
105 views

How can the bodies attain same velocities during the max. deformation during collision?

My book writes: Collision between two bodies is almost similar to the case where there is a spring between the two colliding bodies. At the instant they come into contact , the rear ball has a ...
0
votes
2answers
101 views

Do there exist functions $\phi$ and $A$ such that $\vec E$ satisfies the Helmholtz Theorem $\vec E = -\nabla \phi + \nabla \times \vec A$?

Helmholtz Decomposition theorem stats: "Let $\vec F$ be a vector field on a bounded domain $V$ in $\mathbb R^3$, which is twice continuously differentiable, and let $S$ be the surface that encloses ...
2
votes
2answers
97 views

Derivation of velocities in the Coriolis force

In Fitzpatrick's Newtonian Dynamics book on the Coriolis force, he states \begin{align} v_{x'}&\simeq V_0\cos\theta-2\Omega t V_0\sin\lambda~\sin\theta \tag{433}\\ ...

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