What is Interaction: Definition and 711 Discussions

Interaction is a kind of action that occurs as two or more objects have an effect upon one another. The idea of a two-way effect is essential in the concept of interaction, as opposed to a one-way causal effect. Closely related terms are interactivity and interconnectivity, of which the latter deals with the interactions of interactions within systems: combinations of many simple interactions can lead to surprising emergent phenomena. Interaction has different tailored meanings in various sciences.

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  1. Q

    A problem in deriving the interaction field equation for photons

    Well, I was doing a problem the other day, inserting the complete interaction QED Lagrangian into the Euler-Lagrange equations, in order to obtain the field equation governing the interacting electromagnetic field, with the Dirac field. The problem is that, by doing so, I got the equation, but...
  2. M

    Stress-energy tensor for electromagnetic field with interaction term

    First of all, I'm not sure if this thread belongs here or at the "Special & General Relativity" sub-forum, if I posted at the wrong place please move it. Homework Statement I encountered this problem working in my master's degree. I need to find the stress-energy tensor of the following...
  3. P

    Understanding Charge Attraction: Theories and Explanations

    Charge attraction Hi I googled why different charges attrack each other and I found severel answer but I guess this answers are not true because there is no info about in wikipedia or there is no mathematicaal explanation.I want to know these theories are true or not or this theory is just...
  4. T

    External Magnetic Field & Electron Spin Interaction

    In my lecture notes, there is a slide about an external field interacting with a system of electron spins. In this situation can we assume that B=B_0 ( or in other words that μ_0*M =0)? I would think so, but does a system of electron spins imply that these electrons belong to some matter...
  5. A

    Interaction with plane waves

    Hi all, While I am reading interaction of atoms with radiation the following doubt came to me...While solving Maxwell equations in a charge and current free region, we get solutions for Vector potential,Electric field and so on which are plane wave solutions...However, when we study the...
  6. P

    Two positively charged plates : interaction force

    Hello, I am facing a paradox, well it seems like one, resolving the interaction force between two equally charged plates each bearing a positive charge. Let us assume this as Q, and plates having area A. On one hand , we can claim the force = Q^2/2Ae0 where e0 is the vacuum permittivity...
  7. A

    Van del waals interaction in qm

    Hello I read the follow paper about van del waals interaction in quantum mechanics http://www.damtp.cam.ac.uk/user/gold/pdfs/teaching/van_der_waals.pdf In this paper the potential V= e^2/R + e^2/(R+y)+e^2/(R-x)+ e^2/(R+y-x) is aproximated to V \approx -2 e^2/R^3 xy with R>>|x|,|y| why...
  8. J

    Angular momentum in particle interaction

    Imagine that two electrons interact by exchanging a virtual photon. Electron A gains momentum ##-\vec{p}## and electron B gains momentum ##\vec{p}##. If the two momentum vectors are not collinear then there will be extra angular momentum left over from the interaction. In a simple Coulomb...
  9. H

    Do Leptons and Quarks Interact Electromagnetically?

    Hi people, I have one question, leptons and quarks are electromagnetically charged particles. Is there an electromagnetic interaction between them? Thank you for the help!
  10. E

    Interaction between current and magnetic field

    According to Fleming's left hand rule, if the direction of a current that is running through a wire is perpendicular to the direction of the magnetic field that it is in, a force is acted on a wire that moves it in a direction that is both perpendicular to the wire and the field. Why does the...
  11. S

    Interaction between wavefunction of two particles

    What I am trying to find out is: whether the superposition of a singe photon (across the all the paths --that the photon can possibly take) interfere/interact with the superposition of another single photon... assuming that the superimposed paths of both the photons are close enough to...
  12. B

    Asymmetric photon interaction with gravity?

    Assumptions: 1] I'm an observer at inertial rest 2] Light is going c 3] Gravitational interaction can't exceed c I'm going to use "photon" and "graviton" as shorthand to pose the questions initially. Maybe correcting the form or assumptions of the questions will provide the answer...
  13. S

    Expressing the interaction energy between two spheres?

    Homework Statement Two identical spheres with radius R have uniform charge Q throughout their volume and separated d>2R apart Homework Equations https://www.physicsforums.com/attachment.php?attachmentid=63061&d=1382054852 is the general potential energy equation this should be my...
  14. F

    Electromagnetism - interaction between the electron and the quarks

    electromagnetism -- interaction between the electron and the quarks Which theory explains the electromagnetic interaction between the electron and the quarks within a hydrogen atom ? Is it QED or should I look at Standard Model ?
  15. P

    Functional Derivative of Long Range Dipole Interaction Energy

    Homework Statement Dear all, Good day. I am currently working on the phase field modeling of ferroelectrics. For this reason, I need to find functional derivative of an expression as presented in attached picture 1. Then in picture 2, it shows the final form of equation that I am...
  16. C

    Interaction of radiation with matter

    1. Problem statement i am trying to calculate the momentum and energy of the products in the reaction 7Be4 + e -----> 7Li3 + neutrino 2. Relavant equations p = mv mass of 7Be = 7.016929 u mass of 7Li = 7.016004 u 3. The attempt at a solution i know that after the electron capture, the...
  17. Crazymechanic

    How Do Charged Particles and Electric Fields Interact?

    Ok so I have few question and would be happy if someone could answer them or reassure me of the way I think is right, thank you. First of all do electrons that have higher energy levels can attract two ions closer than electron with lower energy? Or is it a fundamental property that has to...
  18. L

    Which interaction does the Higgs field rely on?

    Dear Physics Forum, can anyone tell me which of the fundamental interactions is involved in the Higgs Field? Or is it a new and unique type of interaction apart from the fundamental 4?
  19. Crazymechanic

    Ball lightning atmosphere interaction

    There are numerous threads here about ball lightning but I am not exactly sure have any of those addressed this issue? Now a ball lightning even though haven't been duplicated in the lab is most likely a some sort of sphere or form of a plasma or ionized gas that has to do with charges and...
  20. A

    About c being constant and interaction at c.

    Hi.. I was reading about the special theory of relativity, and was thinking about interactions and speed of source retained by the body getting ejected from the body. As per the classical idea, imagine an airplane dropping something on the ground, then the dropped object acquires the speed of...
  21. M

    What is the meaning of interaction in science?

    when we say two masses or charges or particles interacts with each other, we have used the word interacts, what does that mean, does that mean a physical contact or something of that kind?
  22. M

    Doubt in Law of mutual interaction

    Book: Classical mechanics (textbook) by Douglas Gregory (cambridge publications) Law of mutual interaction states that when two particle (let it be P1 and P2) interacts, the particle (P1) induces an instantaneous acceleration (a21) on particle P2 and the particle P2 induces an instantaneous...
  23. A

    Interaction Hamiltonian of Scalar QED

    Homework Statement Problem 7.15 from Aitchison and Hey, Volume I, 3rd Edition. Verify the forum (7.139) of the interaction Hamiltonian \mathcal{H_{S}^{'}}, in charged spin-0 electrodynamics. Equation 7.139 is \mathcal{H_{S}^{'}}= - \mathcal{L}_{int} - q^2 (A^0)^2 \phi^{\dagger} \phi...
  24. F

    Spin interaction with B field

    Homework Statement The problem is stated on page 10 and it is number 9. http://panda.unm.edu/pandaweb/graduate/prelims/QM_F11.pdfHomework Equations I know how to write Sy in the z basis for either spin up or down and I have all the spinors.The Attempt at a Solution I tried solving for |ψ(t)> by...
  25. T

    Interaction of two wavefunctions

    Hi, I've been thinking about the following scheme: let's say I have an incoming photon ray with wavefunction ψ1 that finds a bloch electron with wavefunction ψ2. Is there any way to compute the optical coefficients (transmitivity, reflectivity etc) of the material knowing only this two ψ and...
  26. shounakbhatta

    Strong interaction and unified field theory

    Hello All, I am quiet new to the subject, so if anybody can help me. The four fundamental forces of nature, gravity, strong, weak,electromagnetism. Through weak force, all the electrons, protons and neutrons interact with each other. An attempt was made late in the 20th.century to unify...
  27. O

    Interaction of Photon with water

    Dear all respected expert/collegues, I'm setting out a photoelectrochemical cell. I'm facing problem to regulate temperature in my photoreactor durng reaction. Can i just dip the photoreactor inside a big water jacket? But i wondering incoming photon or light supplied by my Xenon arc lamp...
  28. G

    Interaction of e.m radiation: from classical to quantum behavior

    (I am not sure what is the best subforum for this doubt, please move the thread if necessary) When we study the interaction of the electromagnetic waves with a charged particle (let's say an electron) we can find two totally different approaches in the literature. If we are talking about light...
  29. I

    Contact interaction in Lagrangians

    Hi all, If I take an action involving two point particles coupled together by a delta function contact interaction is it possible to carry out the variation with respect to the fields? For e.g. S = \int dt \frac{1}{2} \dot{x}^{2} + \int \int dt \dot{x}(t) \delta^{D}\left(x(t) - y(t')\right)...
  30. lfqm

    QED Interaction Lagrangian with two different fermions

    Let say I want to study electron-proton scattering (without considering proton's quarks, i.e. no QCD), which is the Lagrangian? I've seen two different answers to this question :confused: First one: L=\bar{ψ}e(i∂-me)ψe+\bar{ψ}p(i∂-mp)ψp-\frac{1}{4}Fμ\nuFμ\nu-e\bar{ψ}eγμψeAμ+e\bar{ψ}pγμψpAμ...
  31. Psinter

    Mathematical model for interaction force between magnetic fields?

    I wanted to know if there is a mathematical model to know the force with which a source of a magnetic field attracts or repels another source of magnetic field. For example, the mathematical model for the electrostatic force a charged particle exerts over another charged particle is: F =...
  32. W

    Particle with spin 1 in a non perturtuvative interaction

    Hi, i have been trying to figure how to solve this problem, i just don't know how to proceed Homework Statement A particle with spin s=1 has due to rotational invariance all three states |s_z\rangle=1, |s_z\rangle=0 and |s_z\rangle=-1 degenated with energy E_0>0. Then its introduced an...
  33. D

    ANSYS Workbench tire/pavement interaction

    I am trying to run a simulation (transient analysis) in ANSYS Workbench of a rolling tire on a flexible pavement surface. The tire is a truck tire with pressure of 0.7 MPa. I defined various outputs at consequential small time steps, and I can see the tire gradually inflating until (what...
  34. T

    Particle-photon interaction to create new particle

    Homework Statement A particle with known rest mass energy, m_{p} c^{2} pass through a cloud of monoenergetic photons with energy E_{\gamma}. The particle collides with a photon and a particle A, with mass m_A is created. Show that the minimum energy of the particle required for the interaction...
  35. C

    Parton model and quark interaction in DIS.

    I'm currently reading about the parton model and deep inelastic scattering. As I've understood it was observed that when protons collided at high energy very little transverse momentum transfer was observed, while when electrons were collided with protons transverse momentum transfer was...
  36. M

    Archived Strong interaction and strangeness

    Homework Statement Homework Equations This one has confused me, I know that Baryon number has to be conserved so X has to be a baryon. I can see how charge is conserved The Attempt at a Solution I know this is the strong interaction. Is it a collision? Is that where the...
  37. J

    Interaction of electromagnetic waves with a plane mirror

    I was reading about how a plane mirror reflects light and would like confirmation I have the right theory. It says that the metal coating of a mirror is a conductor in electrostatic equilibrium which means the electric field is zero. As the electromagnetic wave hits the mirror the electrons...
  38. S

    Why does the model interaction for Cooper pairs make sense?

    Hi All, I am trying to understand why Cooper pairs form. The textbook proof that I am reading (Grosso & Parravicini) starts out as follows: Imagine a 'passive' electron gas filled out to some Fermi sphere kF. Add two 'extra' electrons that interact via a potential U(x-x'). Transform to...
  39. xortdsc

    Interaction between Neutrons/Neutrinos

    Hello, I was wondering if there is any evidence on how (free/not within nucleus) neutron/neutron interactions work. I know there is QCD which states they attract (but maybe only in a nucleus?), but that's theory - has this been experimentally proven at all ? I'm only interested in the free...
  40. R

    Solar and geomagnetic field interaction with or without solar wind

    The usual story is that after a solar flair (coronal mass ejection) towards the Earth the Earth's magnetic field gets strongly deformed. It usually takes a few days from the solar event to when the Earth is impacted. But I wonder if there is also a direct interaction: If there is drastic...
  41. R

    Alpha and beta radiation interaction

    Before I sound stupid I am only at GCSE level (high school in America) so understanding is little. But theoretically could an alpha particle (helium nucleus) gain electrons and become a helium atom. If this is possible can it be done with two beta particles? Correct me I in wrong an explain why...
  42. K

    Will Magnetic Putty Form a Cube or Sphere When Swallowing a Rare Earth Magnet?

    I've attached a video of magnetic putty swallowing a rare Earth magnet. Will the resulting shape of the putty be cubed like the rare Earth magnet (equal distribution of magnetic forces along the surface) or will the shape be spherical (weird magnetic forces along the edges of the cube)...
  43. C

    Dependence of exchange interaction on system size in Ising model

    In the well known Ising model, without any external field (H=0), the energy (E), spins (s) and exchange interaction (J) are related as in the following equation $$ E = -\sum_{<ij>}J_{ij}s_{i}s_{j} $$ Jij is site dependent and consists of three components JAA, JBB and JABwhere A is say up...
  44. A

    Interaction tetween two waves soliton

    Hello if i have two waves soliton y=A \sech^2 (k(x \pm ct)), both solution of KdV differential equation how i find a equation for the interaction between the right and left waves \pm c i think on supperposition waves, y=A \sech^2 (k(x + ct))+B \sech^2 (k(x - ct)), but i don't understand if...
  45. E

    Interaction of EM waves with matter

    The interaction of light with matter, or EM waves in general, falls into 3 categories: transparent where they pass through, opaque where they are scattered, and shiny where they are reflected. What on the quantum mechanical level about the atoms electrons determines those properties? I think the...
  46. L

    Solving Dipole Interaction Problems

    Homework Statement See attachment Homework Equations The Attempt at a Solution Thus far I believe I am supposed to use calculate the interaction with kQq/Δr? I have tried summing over interactions so that 1/4∏ε*[(-Q)(-q)/(r-d/2+D/2) + (-Q)(q)/(r+d/2+D/2) + (Q)(-q)/(r-d/2-D/2) +...
  47. D

    Simulating Angular Momentum and Torque in Particle Interactions

    I am simulating protons and electrons in a simulator that runs 1 femto seconds per second up to 1 second per second. So it can accurately show the passage of charge particles through space with data being updated on their displacement, velocity and acceleration. However I am now adding in...
  48. M

    Electromagnet + P.Magnet interaction + C-EMF

    Hello :)I was working on a project for one of my classes, and it had to do with electromagnets + magnet's B field interactions(A simple demonstration of a few laws of electromagnetism). Basically its a simple configuration like this random photo I found...
  49. G

    Interaction picture and s-matrix

    Consider the S-matrix: <f|U(t,-t)|i> When going into the interaction picture, this becomes: <f_I|U_I(t,-t)|i_I> where the propagator is the interaction picture propagator, and the states are interaction states. Can you say that: <f_I|U_I(t,-t)|i_I>= <f|U_I(t,-t)|i> ? It...
  50. N

    How can scattering with interaction at all time be resolved using QFT?

    S-Matrix is calculated in that the interaction at infinite past and future time is zero.Then how can we solve the problem of ''scattering'' where the interaction presents at all time(e.g considering interaction of electron in an atom) with QFT?
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