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. M

    I Field Renormalization vs. Interaction Picture

    When introducing renormalization of fields, we define the "free Lagrangian" to be the kinetic and mass terms, using the renormalized fields. The remaining kinetic term is treated as an "interaction" counterterm. If we write down the Hamiltonian, the split between "free" and "interaction" terms...
  2. Diracobama2181

    Is There a Relationship Between Dipole and Wire Interaction Energy?

    Part a was not much of a problem. I got that $$m=QR\omega \hat{z}$$. From that, I get $$A_{dip}=\frac{\mu_0}{4\pi}\frac{QR\omega}{r^2}\hat{\phi}$$ (using $$\theta=\frac{pi}{2}$$. My problem occurs in part b. I know there is a potential energy relation for two dipoles, but what would I use for a...
  3. M

    What is the electrical equivalent circuit for this interaction?

    A textbook gives an example of an ideal mass striking an ideal string here: This is drawn as an equivalent electrical circuit as follows, where each R represents one of the two string segments the mass interacts with (ie. the string segment to the left of the mass and the string segment to...
  4. S

    I When is weak interaction a force?

    When is weak interaction actually a force, rather than merely cause of some process? Not in beta decay - it is process. There are simpler weak interaction processes around: elastic scatterings that change only momentum but not taste. But those are still processes and are over as the particles...
  5. Riotto

    I Single-particle phase spaces for a system of interacting particles

    For a system of interacting particles, is it possible to define single-particle phase spaces? If not, why?
  6. M

    Wick contraction in scalar QED

    While writing out the Dyson series due to the time ordering above I encountered the two expressions $$T(\mathcal{L}_{int}(x))\quad \text{and}\quad T(\mathcal{L}_{int}(x)\mathcal{L}_{int}(y))$$ I was able to write out the first term in terms of contractions using Wick's theorem and then finally...
  7. J

    I Understanding the Absence of Rabi Oscillations in the Interaction Picture

    When working on the interaction picture you can show that in a certain rotating frame the Hamiltonian of a 2-level system (for example) becomes uncoupled. This implies that in such frame there are no Rabi oscillations or other dynamical phenomena, this seems weird to me and I would like to know...
  8. Zala Jaydevsinh

    I About L-S interaction or spin orbit coupling

    I want to understand this topic but I can not understand very well so please suggest any reading for good conceptual grasp of this topic.
  9. Diracobama2181

    A Solving Spin-Spin Interaction for Total Spin Commutation

    Let there be four spin (1/2) particles at the corners of a tetrahedron, coupled such that the total hamiltonian is given by $$H=\sum_{i\neq j} S_{i} \cdot S_{J}$$. How would I go about showing that each component of the total spin $$\sum_{i} S_{i}$$ commutes with the hamiltonian. Work so far...
  10. binbagsss

    A Kubo Formula Deriviation - interaction picture, complete eigenbasis

    Hi I'm looking at David Tong notes on QHE http://www.damtp.cam.ac.uk/user/tong/qhe/two.pdf (page 56), I've attached the relevant screenshot below also. I understand we are working in the interaction picture whereby states evolve via the Unitary Operataor EQ 2.10 in the notes(I think this is...
  11. mastrofoffi

    Interaction energy between nonpolar particles

    I tried an approach where I build the interactions one by one and then add them all to find the total potential energy. The electric field of particle 1 induces a dipole moment on particle 2 given by ## \mu_2 = \alpha_2 E_q(2) ##(by ##E(2)## I mean the field evaluated at the position of particle...
  12. CuriousCop

    I Observation = interaction, question from a dummy

    Greeting all! So I apologize if this has been explained to death and if so, please advise as I do not want to clog up the forums with the same questions over and over. A little background first, a coworker and I routinely talk about astrophysics and quantum mechanics( yes, somewhere out there...
  13. S

    I Interaction of Neutrons with Matter

    For Elastic neutron interactions with matter, they mentioned that the neutron will collide with atomic nucleus and the recoil nuclei quickly become ion pairs and loose energy through excitation and ionization. How does this nuclei become ion pair? It is when the neutron interact with it and...
  14. J

    B Interaction of light with atoms

    One description of the interaction light with atoms states "Light waves incident on a material induce small oscillations in the atoms, causing each to radiate a small secondary wave in all directions". And another that "A photon with the right energy causes an electron to jump up to the next...
  15. Student abc

    I Interaction path = mean free path?

    Are the interaction path and mean free path of a particle the same thing?
  16. L

    A Timescale of virtual photon interaction in particle scattering

    I'm studying the electron-proton deep inelastic scattering. In the notes that I'm studying from the author states that the time-scale for a virtual photon to interact with a proton is ##τ\sim\frac{1}{Q}##, where ##Q## is the momentum transfer with ##Q\gg M##, which is the mass of the proton. I...
  17. T

    B Laser interaction & plasma states

    Summary: specific modulation of lasers will cause ionisation, how is this being used in plasma physics? Just a simple question
  18. N

    I What exactly is the amplitude of an interaction?

    I've been reading Griffths' intro to elementary particles and I encountered this symbol that looks similar to "M" called amplitude, which can be calculated by analyzing the Feynman diagram of an interaction. What exactly is it? When I hear amplitude I imagine waves, but not sure what this one's...
  19. fluidistic

    A Can the electron-electron interaction have an impact on the conductivity?

    Can the electron-electron interaction have an impact on the conductivity? Google seems to point out that yes for some 2d materials such as graphene. But what about 3d materials? Intuitively, any lost momentum by an electron would be gained by another electron, so in average, this e-e...
  20. B

    A Understanding & Solving Electron/Phonon Interaction Problems

    I am wondering if there is a book with solved example problems I can follow so that I can carry out the following calculation: I have a set of unperturbed electron Green functions $g^{r0},g^{a0},g^{<0},g^{>0}$ and phonon Green functions $d^{r0},d^{a0},d^{<0},d^{>0}$ which are for a central...
  21. P

    I Electrostatic interaction in the Simulation Hypothesis

    How will the repulsion of electrons occur in the simulation hypothesis? The electrons will also create electrostatic fields around yourself ?
  22. C

    I Dark Plasma charged under unbroken U(1)' gauge interaction

    https://arxiv.org/abs/1512.06471 In the paper, dark plasma (that is, NOT baryonic plasma) was suggested. I'd like to know if it is compatible with many cosmic phenomena (like bullet clusters). Can you think of one where the data (especially new ones) don't support it? In baryonic matter...
  23. ABlibo

    Understanding Energy Levels and Transitions in Magnetic Fields

    Don't know how to relate the equations. Thanks for your help.
  24. P

    I Weak interaction between electrons

    The two electrons will be repelled by electrostatic force, but they interact with weak force, means that in addition to the electrostatic force between the electrons there will be weak force?
  25. Clara Chung

    I LS coupling and spin orbit interaction

    Why do you need a weak spin orbit interactions in individual electrons in order to use the LS coupling? From what I know, we are free to combined angular momentum whenever [L1, L2]=0 and this should be true on the orbital angular momentum (and spin) of the electrons because they are...
  26. S

    I Interpreting SM Lagrangian "differential particle" terms

    The Standard Model Lagrangian contains terms like these: ##-\partial_\mu \phi^+ \partial_\mu\phi^-## ##-\frac{1}{2}\partial_\nu Z^0_\mu\partial_\nu Z^0_\mu## ##-igc_w\partial_\nu Z^0(W^+_\mu W^-_\nu-W^+_\nu W^-_\mu)## How should one interpret the "derivative particle fields" like...
  27. B

    Photons and solar wind/plasma interaction?

    Can the suns photons accelerate the plasma/solar wind away from the sun? or is there no interaction between them?
  28. K

    I Why does LHC have 8 interaction points?

    Hello! I attached a picture of the LHC main rings. I see 8 interactions points labeled, even if there are only 4 experiments (and the other 4 points don't even intersect). What are these 4 other points? Thank you!
  29. L

    A How to calculate the on-site interaction in optical lattice

    We know the on-site interaction in optical lattice can be expressed as U=4pi*ħ2 a/m ∫d3x |w(x)|4 It's simply understood in a 3d system. But how to calculate this term in 1d and 2d system?
  30. K

    B Is entanglement severed after the first interaction?

    Do we know if entanglement between two entangled particles is completely severed after the particles interact? By interact I am generally thinking of interacting with the measurement device. Maybe another way of asking my question: In an EPR like experiment, if you put one of the entangled...
  31. arpon

    I Form factors and Interaction term of the Action

    Consider, two fields interact with each other and the interaction term of the action is given. Now the Lagrangian density is Fourier transformed and the interaction term of the action is expressed as an integral over the momentum space. How is the integrand related to the form factor?
  32. D

    B The Nature of Measurement and Interaction in Quantum Mechanics

    I am still confused about the difference between measurement and interaction. I mean when electrons are traveling from source to the screen through the slits, there are air molecules in their way. And even if the electron double slit experiment is carried out in total vacuum in a completely...
  33. D

    Does Stiff Soil Resonate with Short Storey Buildings During Seismic Movements?

    Stiff soil like tuff rock is said to be in resonance with short storey buildings (like 2 to 3 storey).. meaning during seismic movement the response in the short storey buildings would be greater. Is there any formula that can relate the two... like does stiff soil has the same frequency as...
  34. S

    I Time period in which an interaction with a π-meson happens?

    The longer-range inter-nucleon force is not a direct result of the gluon field, but is indirectly affected by a quark-antiquark pair (meson). If this ‘residual’ strong interaction between nucleons is mediated by a π-meson, then what is the maximum time period in which the interaction takes...
  35. C

    I Strong force as exchange of mesons, or of quark and antiquark

    The (residual) strong force between nucleons can be desribed as - The exchange of a meson (from a nucleon to the other), as in picture b) - The exchange of a quark and an antiquark: in picture a) one nucleon "gives" a quark and receive an antiquark and it's the opposite for the other I do...
  36. Gene Naden

    I Weak interaction - is it a force?

    A friend, well-read in popular accounts of physics, posted the following question to me: is the weak force attractive or repulsive? Now I have read about the weak interaction. I know that it violates parity, that it is involved in beta decay, that it unifies with the electromagnetic interaction...
  37. C

    I Measuring characteristic time of strong and weak interaction

    Consider a scattering between two particles a and b that produces two particles c and d: d is stable, while c decays in two other different particles e and f. The first interaction is by strong force (time of interaction ##t_1\sim 10^{-23}s##, which is also the time of generation of c and d)...
  38. Leonardo Machado

    A Beta equilibrium for free and interacting nucelar models

    Good evening. I'm currently studing dense matter and nuclear matter above 10^8 g/cm^3, and i know well how to insert a beta equilibirum condition in a free Fermi gás at T=0. \sqrt{K^2_{F,n}+m^2_n}=\sqrt{K^2_{F,p}+m^2_p}+\sqrt{K^2_{F,e}+m^2_e} But how do i insert the same condition of...
  39. Soffie

    B Why is this interaction forbidden?

    So I'v been told that this interaction : e- + e+ = mu- + e+ isn't allowed. Why not? I thought maybe because the mass of the muon is so much bigger, so would violate energy conservation, but the electron/positron could be moving relativistically and thus have enough energy. Apparently the...
  40. Soffie

    B Distinguishing between interactions (decays and collisions)

    I always struggle to know which force (strong nuclear, electromagnetic, weak, gravity) is responsible for an interaction. For example, pi+ + pi- = neutron + pi0 I would say its strong force responsible, because quarks are involved. But the pions are also charged, so how do I know it's not...
  41. G

    I I want to read about the electron nucleus interaction

    My unreliable memory is that although Schrödinger's equation treats the interaction between an electron and the nucleus as unquantised, it is more generally thought to be mediated by an exchange of quanta between electron and nucleus. I want to check on this and get a better understanding. Can...
  42. Superfluid universe

    I What is the charge for the weak interaction?

    We have the electric charge for the electromagnetic force, the color charge for the strong force. What is the charge for the weak force? Thank you. :)
  43. N

    A Electron-Hole- or Many-Electron Exchange Interaction

    Hello together, I'm interested in the electron-hole exchange energy. I would like to see how and have a proof why electron-hole exchange works. Is it symmetric or antisymmetric? More specific, I would like to have a proof that exchange with paired electrons in a molecule can be neglected...
  44. O

    I Interaction time between charged particles

    Hi, I was wondering that if there is some kind of interaction time between two charged particles. Imagine an electron shoot to ionize an atom. This electron interacts one of the electrons in the atom. Does the ionization depend on the velocity of the incoming electron? Is it possible that when...
  45. B

    I Universe's First Stars Interaction with Dark Matter

    https://www.space.com/39837-first-stars-universe-fingerprints-dark-matter.html...
  46. hilbert2

    A Coupling constants with fractional dimensions

    Most QFT texts, such as Peskin&Schroeder and D. Tong's lecture notes, contain a mention that the renormalizability of an interacting theory requires the coupling constants to have correct dimensions, making scalar fields with ##\phi^5 , \phi^6, \dots## interactions uninteresting. Maybe there are...
  47. heavybuilder

    I Standard Model (Forces interacting with Matter)

    Not the best at physics but trying to understand the standard model. So can someone please tell me if this is right or not and if not, can you explain me why? Higgs bosons reacts with everything that has mass. Electromagnetic force reacts with everything that has charge. Weak force reacts with...
  48. M

    I Exploring Emergence: Examples, Theory, and Experiments for a School Project

    For a school project, I've got to choose a subject. I chose "Emergence", but I have to narrow it down a little bit. So, that's why I'm creating this topic. The definition of emergence that I use: By emergence, I mean the fact that proprieties of one scale implies other proprieties by changing...
  49. Tom Rauji

    Automotive Suspension interaction with car

    I need help or guidance at a physics level understanding suspension interaction with a vehicle chassis. Here is the problem. I have a very high horsepower car with small tires. The race tracks are prepped with a glue. It is very easy to go over 1500 HP with a pretty high gear ratio. For...
  50. M

    Integration of an interaction force to find potential energy

    Homework Statement A particle that can move along the x-axis experiences an interaction force Fx=(3x2−5x) N where x is in m. Find an expression for the system's potential energy. Express your answer in terms of the variables x and the constant of integration C, where C is in joules. Homework...
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