Interaction Definition and 653 Threads

Both the strong and weak interactions are short range forces of approximately 1 fm. Two protons are separated by this distance. Which equation should i use for these two question? i) The strength of the electrical and gravitational interactions that influence each of these protons. ii)...

Hi, I'm reading ad article of Lal et al (junction of several weakly interaction quantum wires: a renormalization group study). It's quite cleare but there are some row I'm not good to understand. Could someone help me to understand how obtain equation (6) from equation (4)? I don't know how to...

I was reading a description of the many-worlds interpretation and it stated that the separate universes cannot interact with each other. But in the double slit experiment isn't the interference pattern that is seen when both slits are open, specifically caused by this interference? How can...

I guess it does not produce any field in 2nd coil because there's no change in current in coil right?So there won't be any emf .. but coil 2 has magnetic field passing through it which results in current in coil(by forcing movement of electrons of coil 2 SINCE ELECTRONS ARE ALREADY IN MOTION...

Hi, It never occurred to me before, but when you derive the spin-orbit Hamiltonian as a perturbation to the hydrogen Hamiltonian, you imagine your electron orbiting around the nucleus, and of course that's not the correct picture because of the electromagnetic radiation that leaks out. So I...

Question about this "interaction" in QFT Hi, I started two months ago my course in QFT, and since I heard about the fact that the bare mass appearing in the Lagrangian of a theory isn't the physical mass of a particle (due to self interaction, I guess), I tried to find an example explicitly...

I'm currently doing a project on how the solar wind interacts with the Earth's magnetic field, but I'm having a hard time grasping the concept of the plasma emitted by the Sun and how it shapes the Earth's magnetic field. I read somewhere about a simple mirror dipole approximation (I'm guessing...

Well, I would like to know the interaction process of an x-ray photon with ice? Thanks in advance.

[SIZE="3"]First of all, I've already had and scheduled SEVERAL appointments with a psychiatrist, and I'm not asking for self-diagnosing advice - I'm simply wondering what I should look forward to after all the checking is done.So let me begin with a list of symptoms that I'm experiencing, or...

2 questions on symmetries: "conserved in interaction => eigenstate in interaction"? Hello, I'm currently taking an introductory course in elementary particles (level: Griffiths) and I have 2 questions that are severely bothering me; all help is appreciated! They are related to Griffiths'...

I need to report about the Van der Waals interaction in our Quantum Mechanics class. Can someone please help me sort things out about Van der Waals interaction? How do go think should I go about it? In our book, the only thing discussed is the Van der Waals interaction between two hydrogen atom...

; Can someone explain to me (in layman's terms,) how it might be possible to associate the interactions of the up/down quarks in the strong nuclear force as analogous to the way electrons and photons interact in quantum electrodynamics ?

Hi Say I want to describe the interaction between a free atom atom and a classical EM field. The full Hamiltonian for the problem must be H = (H_0 + p^2/2m) + (H_V + H_E) + H_D where H0 denotes the internal levels of the atom, HV the vacuum field, HE the energy density of the classical...

What kind of force mediates the reaction: K- + alpha(ppnn) -> pi- + "hypernucleus"(ppn lambda) s(u) + (uud + uud + udd + udd) -> d(u) + (uud + uud + udd + uds) (u) is anti u We need to explain which force mediates this reaction. I am pretty sure it does not involve the weak force...

This is a follow-up of the following thread on refraction: https://www.physicsforums.com/showthread.php?t=576212&highlight=photon In a nutshell, an optical photon that traverses a solid dielectric extends over many atoms. While the photon traverses the dielectric, it continuously transmits...

There is given two neutral parallel plates, distance between them is d. Between them is putted insulating plate with a thikness of d. After that one of two plates was charged positively. How can I find electrostatic interaction force?

Hi all, While the articles I have been reading are about a year old (which can be considered relatively outdated in terms of particle physics) I have been looking at the possibility of Neutrinos being able to travel at FTL (Experiments conducted by CERN and OPERA). I understand in the articles...

Hi When looking at the interaction between an EM-wave/field E with an isolated atom, we know that they interact via the time-dependent dipole interaction V = dE. This can be derived by looking at an electron bound to an atom, and it is used in systems, where the atom can be rightfully...

Hello, as far I understand wavefunction collapse (or decoherence or whatever stops particles from acting as waves) is initiated through something referred to as a measurement. These measurements are thought of as interactions. Now the question I have is, why are some interactions measurements...

I am currently reading E=Mc^2 and have a quick question regarding some of the nuclear fusion they describe that takes place in stars: When proton fusion occurs, one of the protons decays into a neutron + positron + neutrino – due to the weak interaction. And the proton and neutron , acted...

Please teach me this: Why is CP symmetry violated in electro-weak interaction? Is it correct that because of the mass of neutrino is zero(so that the left and righ neutrinos do not mix with each other)? Thank you very much in advance.

According to the mathematics of sub-atomic particles, unless your force parameters on them, their wave function extends indefinitely through space, so why is it that interactions only happen at certain distances? Is there some kind of critical boson exchange rate?

Hi all, I am doing a masters in SSSI and I am a mechanical engineer so a lot of this stuff is all new to me (manly civil engineering based masters) so I have a question for the pros. (I will also do some analysis on SSI (soil-structure interaction) What is a good software to use to analyse...

Homework Statement A person weighing 800 lbf climbs a flight of stairs that extends a vertical distance of 300ft. Calculate the work and power required for this process if it requires 3 min, 5 min, and 10 min. Homework Equations W=integral(Fds) Power=FV The Attempt at a Solution...

Homework Statement Denver's Mile High football stadium incorporates a system by which a section of stands can be moved to accommodate different sports on the field. The grandstand, which has a mass of 4x10^6 kg, can be moved a distance of 45 m on a thin film of water. The movable grandstand...

As time is considered the 4th dimension can we say the 3-d world to be floating(advancing forward in time) in the 4D. If so is every inertial frame has is own velocity rate(moving in the time dimension) in the 4-D. When you have 3-D world if you want to bring 2 objects in contact you can bring...

Hey, I've simulated a solid metal cluster of gold fcc100 And a surface Platinum in fcc111 using a classical mechanical approach. Do you think i could get the surface free energies(the ones to use in determining the Wulff shape) from periodic boundary conditions and if so how? I am really...

Hello there, I'm studying thermodynamics right now, and a question popped into my mind for which I haven't found a decent and detailed explanation so far. Say that we have a container filled with any kind of gas, and we can control the temperature of the wall of the container. If we increase...

I read this week in Schutz's description of Pound-Rebka experiment, which demonstrate that a photon also interacts with gravity, i.e measuring its redshift. My question, is more from particle physics, I mean a photon is the interaction carrier of EM, its chargeless and massles, so how can it...

Greetings In order to make a mathematical model of the forces that act on a mechanism, I need to use the formula for the force between two magnetic dipoles. It would have to be a complete formula, that should take into consideration, aside magnetic moment and environment permeability...

Homework Statement Which of the following reactions are forbidden and why? \pi^{0}\rightarrow\gammaHomework Equations None? The Attempt at a Solution I'm pretty sure that the decay doesn't occur (it's forbidden) but I don't know why. I know that it decays most of the time into two gammas...

Homework Statement I am trying to follow a derivation in Jackson - Classical ElectrodynamicsHomework Equations In equation 1.58 (2nd/3rd edition) of Jackson - Classical Electrodynamics he says that by using the fact that \mathbf{\rho} \cdot (\mathbf{\rho} +\mathbf{n})/ | \mathbf{\rho +n|}^{3}...

A textbook gives the following interaction Hamiltonian describing the interaction of an atom (having transition dipole moment \mu) with a photon whose polarization can be \epsilon_{1} or \epsilon_{2}): H = g \Sigma^{2}_{s=1}\mu\bullet\epsilons\sigma^{-}a^{+}_{s} + h.c. where \sigma^{-} is...

Richard Feynman writes, on page 97 of his primer of quantum electrodynamics, QED: The Strange Theory of Light and Matter, about the interaction of a photon and an electron. He writes: "One way this event can happen is: a photon is absorbed by an electron, the electron continues on a bit, and a...

Homework Statement Consider the Hamiltonian H=\alpha L \cdot S Where L denotes an angular momentum with quantum number l and S a spin with quantum number s. Work out L \cdot S |(ls)jj_{z}> direction. Hint: expand (L+S)2 and go from there. 2. The attempt at a solution I'm highly...

Is it "Information" or "Interaction" that "Observes"? First off, I know there are many questions on this forum in regards to "does consciousness collapse the wavefunction" and I admit that this is roughly the same question in a different way. I wanted to approach this in a new topic though...

How does the 'particle' view of the electron for example interact with the lattice of matter when matter is also a wave function? coming from the view that the wave function is a probability field for the particle, so if that is used wouldn't the same need to be done for all possible...

Do photons experience time? If they move at the speed of light then special relativity states that they do not, but then does that mean they do not move forward in time which means the distance they travel is instantaneous (thus it is infinitely fast), which we know is not true (as they move at...

I am trying to understand the behavior of blackbodies in interaction with each other. Conditions as follows. 1) There are two blackbodies, say B_1 and B_2, with corresponding temperature T_1 and T_2. 2) Initially T_1>T_2. 3) B_1 and B_2 have thermal contact only through radiation...

At what distance do 2 hydrogen atoms (not ions) begin to attract each other? No, this is not a homework question. I am 58.

i want to know how neutrinos interact with strong beam of laser , if laser beam is going in opp direction along a neutrino beam?

Do we already know enough about the Higgs to be certain that we cannot interact with it(i.e. exert any type of control over it, like we can with electrons) or is there room for discovery there? I was just pondering some implications of such an ability, and realized that I don't know if the...

Hi, a few lines below equation (3.1.5) Weinberg writes: "The transformation rule (3.1.1) is only possible for particles that for one reason or another are not interacting." I thought a lot about it, but don't see any possible reason. Can you help please? After a few lines he defines...

Sorry for a naive question. In EM textbook and QM path integral textbook, the action and Lagrangian in electromagnetic interaction are S = L dt = e(\phi – A v) dt ---equ.(1) But in QFT textbook, the action and Lagrangian density are S = L d^4x = A J d^4x ---equ.(2) As I...

In order to explain the relativistic nature of magnetism, a book shows an example of linear procession of charges: positive charges in one direction and negative charges in the opposite one. It says that this is equivalent in the reality to a not charged current carrying wire. In a metallic wire...

Homework Statement In different (scientific) sites I find different values for MF of H-1 ranging from 0.3 to 0.6 Tesla. Isn't there a generally acknowledged value? what about H-2 and H-3 ? The Attempt at a Solution using the general formula I get 1/ 8 tesla, that formula it not valid...

Dear All, I have a question that is afflicting me and I would be glad if you can give me an answer. I have a dipole in vacuum put at a certain distance from the surface of a dielectric material. I know the entity of the dipole, I know the distance from the surface and I know the interaction...

In the free case,we decomposite the free Hamiltonian into the creation and annihilation operators, i just wonder why this ad hoc method can not be used to the interaction theory?

Hi I would like to ask that what makes a transparent medium transparent ? What happens when a photons of light passes through our atmosphere ? I suppose that visible spectrum of light passes through atmosphere without causing excitation of electrons of gases' molecules, but what happens when...

So this concept of H = H_o + H_int has been extremely confusing to me. Wikipedia offers the best explanation, but there a couple things that still confuses me http://en.wikipedia.org/wiki/Interaction_picture Why is the state vector in the Interacting picture defined as |\psi_{I}(t)> = e^{i...