0
votes
0answers
10 views

Can the question of a gravitationally accelerated charge radiation be tested experimentally?

I know that the question of radiation from a gravitationally accelerated charge has been discussed extensively at Does a charged particle accelerating in a gravitational field radiate?. Yet the ...
0
votes
1answer
8 views

Which experiments of harmonic generation at low frequency are preceeding Franken SHG?

In "The principles of Nonlinear Optics" by Shen, he says that that generation of harmonics at low frequencies were long known before Franken did SHG in optical range. "Franken's idea was simple. ...
0
votes
0answers
7 views

what is the reaction force of electromagnetic force created on a conductor in a magnetic field?

If a force is created on a conductor carrying a current in a magnetic field, what does the reaction of this force act on?
0
votes
1answer
8 views

Why , under constant light intensity and constant frequency, do electrons emitted from a metal surface travel at different speeds?

I was playing around with this PheT simulation: https://phet.colorado.edu/en/simulation/photoelectric Under a certain threshold wavelength and an intensity at 20%, the electrons were being emitted ...
2
votes
1answer
15 views

Does 'real' photon electromagnetically interact with matter?

Consider the standard description of Compton scattering - radiation is constituted of stream of photons (these are supposed to 'real' as contrasted to 'virutal' photons of the QED). One of these ...
1
vote
1answer
10 views

Systematic+Random Uncertainty for velocity measurement

I have a question regarding systematic and random uncertainties. I have to measure the mean value of a velocity measurement in flow field at a point. I've recorded say 1000 samples in time, which I ...
-2
votes
0answers
12 views

pendulum acceleration vector

I'll make this quick, I want the acceleration vector for a pendulum WITHOUT using angle acceleration and angle velocity, just using the tension and gravity forces.
0
votes
0answers
9 views

Flame composition types

Can anyone define the atomic structure of a carbon fuelled flame. I have studied variations of flame patterns but this type seems to stand out.
1
vote
1answer
17 views

What is a good book to self-teach optics?

I'm interested in camera lenses and how things like barrel distortion and lens flare happens, but know that one cannot just start there. I'm a math major and I've worked out of Strauss PDE book so I ...
10
votes
1answer
36 views

Why are LIGO's beam tubes so wide?

Gravitational wave detectors and particle accelerators have at least one thing in common -- they require long vacuum tubes through which a narrow beam is fired (a laser in the gravitational wave case, ...
1
vote
0answers
8 views

Optical bandpass filter at focal point of lens

Optical bandpass filters are designed for a particular angle of incidence (AOI), e.g. see Fig 4 here. However that is for the ray picture of light. Imagine I have a thin bandpass filter positioned ...
-2
votes
0answers
27 views

A Take on Dark Energy [on hold]

Extreme over-simplification alert (the full proof is hundreds of pages long and it’s quite unfinished as of yet). Okay, I have a simple (enough) explanation of what dark energy is, but I am not sure ...
0
votes
0answers
6 views

How is zonal flow defined and computed?

The transition to turbulence in pipe flow was recently observed to be in the same universality class as directed percolation. This was done by reinterpreting the turbulence and laminar flow in terms ...
-2
votes
1answer
27 views

Which one of these energy formulas is correct?

Which one of the following formulas is correct? What do they mean/represent? How are they used? $E=mc^2$ $E^2=m^2c^4+p^2c^2$ $E=\frac{mc^2}{\sqrt{1-\frac{v^2}{c^2}}}$
1
vote
1answer
22 views

Why cannot a fundamental string couple to the R-R gauge field $C_{\mu\nu}$?

People usually say that D-branes can carry R-R charges, or can couple to R-R sector gauge fields. But why a fundamental string cannot couple to a 2-form R-R sector gauge field? What's the essential ...
-3
votes
0answers
24 views

Is using nonlinear crystals considered nonlinear optics according to you?

Ok let me rephrase would you consider interaction of nonlinear crystals with light that does not have enough intensity to induce nonlinear polarization ?
-3
votes
1answer
30 views

Why can´t we call the energy released after the annihilation of a particle and its antiparticle `pure` energy?

As a particle and its antiparticle annihilate each other a huge amount of energy is released, and no mass is left. This energy always comes in the form of force mediating particles (photons, gluons). ...
0
votes
0answers
12 views

Partial trace with unitary

We know that $\mathrm{Tr}_B(\rho(t))\neq\rho _{S}(t)$ in general. But why if we include the unitary in the partial trace: \begin{eqnarray} \mathrm{Tr}_B( U_B^\dagger (t)\rho(t) U_B(t)) &=& ...
-1
votes
0answers
16 views

Will this approach to gauge-gravity duality work?

This is a question on whether quantum gravity has an internal symmetry structure given by gauge fields. I set up the basics of the idea first. Let us consider the complex 3-dim space $E^3$ with the ...
0
votes
0answers
12 views

How thin lens model work when there are two images with different distances from the lens?

I am trying to understand how thin lens camera work. From what I understand of thins lens model, the image is formed on image plane that obey the equation $$\frac1S_1 + \frac1S_2 = \frac1f$$ So ...
0
votes
0answers
20 views

What are Superstring Theory's equations which provide the successful unification between general relativity and quantum mechanics? [duplicate]

This is NOT a duplicate question. The thrust of this question is "What are Superstring Theory's equations which provide this successful unification between general relativity and quantum mechanics?" ...
0
votes
0answers
18 views

Laplacian equations and transformation invariance and homogeneous functions

Functions whose Laplacian is zero are said to be harmonic. 1) Do harmonic functions always imply a conservation law and transformation invariance of some kind? 2) Homogeneous functions do not admit ...
0
votes
0answers
35 views

QFT Weinberg scattering thoery

I have a question about beginning of chapter 3 (scattering) of QFT.vol.1 by Weinberg i think (am i wrong?) $\Psi_\alpha$ means a collection of particles each whit a definite $p^\mu$ specially $p^0$ ...
-1
votes
0answers
28 views

Wave speed derivation using x^2, x^3, etc

The derivation below uses a circle approximation of the curve. How would you do it with a parabolic, cubic, or higher order approximation(x^4, x^5, etc.)? I've heard one would just approximate the ...
-4
votes
3answers
36 views

Can we bring the distribution of the landing places of falling leaves from a tree bring in connection with a Lorenz attractor?

I have already asked a few weeks ago if the motion of a falling leave is chaotic. Wich it is. But if we consider the collection of the trajectories of all the falling leaves, a pattern emerges on the ...
-3
votes
0answers
22 views

How can the concept of locality be used for feature engineering the concept of spacetime?

Can spacetime be described in terms of (some sort of) evolution of locality (being able to observe the local things only)?
1
vote
0answers
29 views

A lot of high power microscopes have 2500x magnification, why that specific number?

I've been shopping around for a microscope, and I've noticed something I didn't really expect. Across different brands, across different times (look at some "vintage stuff"), many many microscopes ...
2
votes
0answers
31 views

Does changing a closed surface in the manner outlined contradict Gauss' Law?

As I understand it, Gauss' Law states that the electric flux on any arbitrary closed surface is equivalent to the sum of all charges enclosed within the surface times a constant. Mathematically, this ...
0
votes
0answers
13 views

Topological insulators and high symmetry points

I've been reading about topological insulators (topological systems in general) and one signature (or the defining signature?) is that an odd number of surface states cross the Fermi energy between ...
-1
votes
0answers
9 views

At which points Normal reaction acts on a moving object is more , if possible give an image for this , A,B,C,E . Thanks For Answering [on hold]

At which points Normal reaction acts on a moving object is more , if possible give an image for this , A,B,C,E . Thanks For Answering.
0
votes
0answers
22 views

Are general coordinate transformations and diffeomorphisms the same? [duplicate]

Infinitesimal diffeomorphisms $x{}^\mu \rightarrow x{}^\mu + \xi{}^\mu$ (with $\xi{}^\mu \ll 1$) change geometric objects by means of the Lie derivative, that is, $X \rightarrow X + \mathcal{L}_\xi \, ...
-3
votes
0answers
32 views

Work done in less than a circle

For a horizontal uniform circular motion, involving conservative centripetal force, (much like in case of satellite) Work done in a full circle is zero. But what about half circle or any other ...
0
votes
0answers
37 views

Could a photon also be a fermion? [duplicate]

Some phycisits have found photons that has a spin of 1,5. Now fermions has always a half spin and bosons like photons always with a whole spin. But if those photons really exists are they than ...
1
vote
1answer
28 views

The relativity of all motion

From a basic text on special and general relativity, I've gleaned that accelerated motion provided Einstein a headache initially because it seemed like his principle of relativity- that all motion ...
-3
votes
0answers
37 views

Virtual particles and space inflation [on hold]

Could virtual particles be separated by fast inflation of space between them while they were created.
2
votes
3answers
32 views

Gas pressure within containers [on hold]

If, hypothetically, a gas had no inner pressure, and it was made to fill up a container. If, then, the pressure within the container was increased by filling it up with yet more gas, until high ...
-4
votes
0answers
56 views

Is the “time remnant” theory (explained in The Flash Tv Series) a real theory? [on hold]

I don't know if someone of you does follow the Tv Series: THE FLASH, but since sometimes some fascinating physical theory jumps out, I thought that would have been the rightest place in which to ask ...
-1
votes
0answers
11 views

Calcite Seed Generation

What is known about calcite seed generation with respect to water treatment? I have proved the efficacy of using this method to change the behaviour of inorganic content.
1
vote
2answers
38 views

Work done according to Newton's Principia

Actually I was going through the principia, reading Newton's derivations of the properties of ellipses. Suddenly I had this question which got stuck in my mind - Throughout Principia Newton uses the ...
0
votes
0answers
17 views

What is Hastatic order?

I've looked around for a proper definition and defining terms for this property. Can anyone explain Hastatic order? Is there a proper theory as to why it occurs? (Also, I don't have points to create a ...
1
vote
2answers
42 views

How do I find the linear components of acceleration in a pendulum?

I have managed to derive the equation of motion of a simple pendulum under the influence of gravity using the Lagrangian, but since that only tells me what the angular acceleration is, I now want to ...
0
votes
1answer
17 views

Parity conservation in second harmonic generation?

The second harmonic arises from susceptibility of third rank tensor $X^{(2)}$ which have (-1) parity. page 28 Let say two photons are absorbed and one is emitted, so the total change in parity is ...
1
vote
0answers
17 views

Coordinate time difference between emiting and detecting a photon in bent spacetime

Consider an arbitrary non-trivial metric $g_{ij}$ - like the Schwarzschild metric. Now, consider two observers $A$ and $B$, staying at fixed radii $R_A$ and $R_B$, respectively, with $R_A > R_B$. ...
3
votes
1answer
38 views

What, exactly, is a “delta function p-form” as used in the theory of branes?

In string theory, when dealing with branes, the following happens: We rewrite a worldvolume action $S = \int_{\Sigma_{p+1}} \omega^{(p+1)}$ of a $D_p$-brane as an integral over the whole ...
1
vote
0answers
29 views

Sudakov double logarithm

I have calculated a few NLO corrections in QED and in the final result the Sudakov double logarithms have always canceled. So I thought that they have no physical meaning. On the other hand I have ...
2
votes
0answers
25 views

Non-abelian current commutators

There many articles, in which non-abelian current commutators are computed. The general result is that quantum corrections lead to additional term in commutator $$[J^a_\mu (x), J^b_\nu (y)] \delta ...
3
votes
1answer
420 views

Can we use radiation pressure to push human

I want to know, at least in theory, are there any safe em wavelength that could affect human body as net force and do no harm To put it bluntly I want to know is it possible for levitate human on ...
3
votes
1answer
62 views

Photons are self-conjugate but neutrinos may or may not: why is that?

Caution: This may be a very naive question but I find it confusing. Moreover, I believe this question is based on potential misconception. I would like it to be clarified. Although the neutrinos are ...
6
votes
2answers
61 views

Will accelerated observer see radiation from the charge that is at rest in observers's frame?

So I had a huge debate about this with my friends. Imagine that you are in a non-inertial frame of reference. For simplicity, assume that frame is accelerated along x-axis. You have held a charge in ...
0
votes
2answers
33 views

When a tram brakes there is a huge volume of air getting inside the vehicle, if the windows are open. Why?

I have noticed this weird phenomenon. When a tram brakes with the windows open, there is a huge volume of air entering the vehicle. Much, much more air gets in when it brakes than when it accelerates ...

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