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. T

    Magnitude and Direction of a charge interaction

    Homework Statement What is the direction of the force \vec{F} on the -10 nC charge in the figure? Give your answer as an angle measured cw from the +x-axis. Problem 26.39 in Physics for Scientists and Engineers Second Edition by Knight Magnitude of the force is 4.3E-3 N Homework Equations As...
  2. M

    Interaction betwen position eigenstates of particle

    If a (charged) particle is in superposition of two different positions A and B is it interacting with itself by electric forces (and gravitational force)? Is it true that the particle is in both places A and B simultaneously?
  3. M

    Fluid Surface Interaction (FSI)

    Hello all, This is my first post on this forum, I am trying to find out about Fluid Surface Interaction (FSI), but have not found much information on it, I have two questions at the moment: 1) Can anyone recommend any literature/books on Fluid Surface Interaction? 2) I know that FSI...
  4. J

    Origin of Attractive Electron Interaction

    I have started to learn BCS theory and I am not been able to find a derivation of the effective attractive electron-electron interaction which is assumed to explain the Cooper pairing. Can anyone point me to a reference where I can find this derivation? Jan.
  5. C

    Black Hole Annihilation & Photon Interaction

    Lets say i had a black hole out in space , and then i had another black hole made out of anti-matter , and they came together after they annihilated each other and produced photons , would the photons kind of orbit each other because they could not escape the intense G field , i realize...
  6. M

    Decoherence by macroscopic interaction

    From my understanding decoherence occurs whenever a quantum object interacts with a macroscopic sized object. So for instance a measurement involving a photographic plate registering a particle will cause decoherence of the wavefunction, which appears to us as the wavefunction collapsing...
  7. J

    If Higgs-matter interaction is weak, can it be altered?

    I have heard that the coupling between Higgs to matter is weak, that it is a correspondingly weak effect. If this is true, is there any way that that effect can be made weaker or stronger? Or asked another way, what is it that sets the magnitude of the level of effect? Thanks
  8. H

    Can Slowing Down Photons in Solids Enhance Photon-Photon Interactions?

    In textbooks one is told that, two beams of light shall propagate independently without any interactions. However, from QED, we have learned that, they can actually interact with each other, but the effective strength is remarkably tiny and hardly discernible. This insignificance is largely due...
  9. S

    Relationship between Interaction Energy and Melting Temperature

    Homework Statement So this is not really a homework problem, but it is an academic-related problem which I want to solve. Suppose in my current research position, I'm making synthetic Collagen heterotrimers, composed of A,B,C monomers, which form into a triple helix arrangement. Each monomer...
  10. T

    Flux attenuation, given interaction cross section

    It strikes me that this may well be fairly easy, but i can't quite get my head round the correct way to lay this problem out (at least in a mathematical sense). If you are considering a neutron flux onto a fully understood material, and you also know the neutron interaction cross section of...
  11. MathematicalPhysicist

    Question regarding CP symmetry and weak interaction

    I have the next decay: B^0 \rightarrow D^+ e^- \nu_e The question is: employ CP symmetry on the particles in this process, what reaction would you get? and what would happen if CP symmetry breaks? Now if I employ CP symmetry I get: B^0 \rightarrow D^- e^+ \bar{\nu_e} But in my...
  12. G

    Feynman diagram for a strong interaction decay

    hey, i want to find the lowest order strong interaction feynman diagram for the following process: \Sigma^{++}_c \rightarrow \Lambda^+_c \pi^+ the quark composition is: \Sigma^{++}_c = (c u u) \ \Lambda^+_c = (c u d). \pi^+ =( \bar{d} u ) an image of a correct process is attached...
  13. 3

    Interaction scalar field invariance

    The problem: http://www.gobigbang.nl/cft/cft.jpg An attempt of the solution: http://www.gobigbang.nl/cft/DSCN2722.JPG My problem is question c. I don't have a clue how to see that the improved current is conserved... Can anyone help me? Update I managed to solve the question by using the...
  14. B

    Tritium neutron collision interaction

    Hi all I have been searching the internet but not with much luck. What can be expected to happen when a tritium is bombarded with a neutron of suitable energy? Will a neutron be knocked off or not? Regards bmeagle
  15. A

    Measuring Hyperfine Interactions: Artemis' University Challenge

    Hello, my name is Artemis. These days I study at University of Science and Technology in Cracow. Due to the fact that semester is almost over one of my tutors asked me to do a quick presentation about "Ways of measuring hyperfine interactions". I would appreciate it a lot if anyone of you could...
  16. D

    Dipole-Induced Dipole Interaction

    Homework Statement Given a permanent dipole, call it pNO, at the origin pointing along r1 (general vector, not along any particular axis). A polarizable atom as at position r2. What is the induced dipole moment, call it pHe, of this atom in terms of pNO and r2? Homework Equations...
  17. V

    [nuclear physics]Understanding what's type of interaction is

    Homework Statement My problem is on questions like "say if the following interactions are allowed or prohibited, and explain why." where the interactions are something like p + p -> K^+ + K^- or e^- + p -> n + \nu_e The Attempt at a Solution Now the first one is not allowed...
  18. snoopies622

    About the interaction of light and solid matter

    Last week I posted the following question here: https://www.physicsforums.com/printthread.php?p=2735375 "Is it possible to predict the color of a solid object based on its molecular formula?" It wasn't completely ignored but the thread did come to an abrupt end after only three...
  19. S

    One has to wonder about photon interaction, and when to think of them

    One has to wonder about photon interaction, and when to think of them as a particle and when as simply a wave. A friend of mine told me to think of them as a wave, because they are without mass. But why should I view it that way, when even theoretical mass is mass, such as weak force. So how...
  20. C

    Radio Waves & Interaction with Matter

    When radio waves go through certain walls , I was reading about this , do they go through the wall because their wavelength is too long to interact with the matter in the wall , Does it haft to do with the crystal spacing in the matter , and in some cases is it like light going through...
  21. G

    Prior interaction as an unwarranted assumption of EPR

    "Prior interaction" as an unwarranted assumption of EPR I think it should be understood that the concept of "entanglement" is not native to the mathematical formalism of QM, but only comes to us with Einstein's assumption (in the EPR paper) that there is an initial, composite wavefunction that...
  22. D

    Equation of motion and operators in the interaction picture.

    Homework Statement I have a question that says: What is the equation of motion for a general operator in the interaction picture. I.e. how does the time derivative of the operators behaves ? Show this. And then I have to find the time development for the annihilation and creation operator...
  23. P

    What Causes Metals to Reflect Light?

    what makes a metal sheet to reflect light? why doesn't individual metal atom reflects light?
  24. S

    What is residual Coulomb interaction and why does it exist?

    Towards the end of my atomic and quantum course my lecturer makes a note of residual Coulomb interaction and does a few graphs to show the concequences of it are (such as some states not being allowed do to symmetry) and that they favour larger values of angular momentum, but doesn't really...
  25. P

    Interaction in QED: Electron/Proton Attraction & Repulsion

    Why according to QED two electrons repel each oteher while electron and proton attract. What are Feynman diagrams for these proceses. Thanks for help.
  26. P

    Question on a Hypothetical Interaction- Minimum Energy- Bosons

    Homework Statement If there was a hypothetical interaction that occurs on, say, a scale of 10^{}-30m, where would one look for signatures of boson associated with this interaction. By that I mean what would the minimum energy be approximately where I would look for those signatures. Also...
  27. P

    QFT - interaction between field

    Let's assume that we have two fields which doesn't interact at the beginning. But after some time this fields start to weakly interact. Interaction lasts only finite period of time. The density of lagrangian is: L = \partial_{\mu} \psi \partial^{\mu} \psi + m^2 \psi^2 + \partial_{\mu} \phi...
  28. I

    Spin orbit interaction and LS coupling

    I hope someone can help me out here. I am having difficulty understanding what the difference is between the spin orbit interaction and LS coupling scheme in atoms. I know the spin orbit interaction (or spin orbit coupling) is due to the interaction of say an electron's spin with it's orbital...
  29. K

    Time reversal and Coulomb interaction

    I have read that charge is supposed to be invariant under time reversal. Now, if I consider two like charges placed some distance from each other, I expect them to repel and go away from each other. In a time-reversed frame, I expect them to approach each other. Since the separation is...
  30. N

    How Do Fermion and Scalar Fields Interact in Lorentz Invariant Terms?

    What is the most general reasonable form of the Lorentz invariant interaction term between a fermion field \psi and a scalar field \phi? A common choice for the interaction is something like \psi^{\dagger}A\psi\phi, with A being a Lorentz invariant matrix (like \gamma^{5}). However, I don't...
  31. S

    No Spin-Orbit Interaction Elements thru Ca: Explain

    Homework Statement List all of the elements through calcium that you would expect not to have a spin-orbit interaction that splits the ground state energy. Explain. Homework Equations Not quite sure, but I'll list a few. If there are two electrons: L=|l1-l2| to |l1+l2| S=|s1-s2| to...
  32. C

    Fermion Wavefunctions: Exchange Symmetry Explained

    Homework Statement I was trying to work through some quantum physics questions and I was getting a bit confused. I know that for fermions the wavefunction must consist of spin and spatial parts of the fermionic wavefunction with opposite exchange symmetry (ie antisymmetric spin and symmetric...
  33. L

    Proving Interaction picture field satisfies KG eqn

    Hi, I'm just trying to convince myself that the field in the interaction picture (IP) \phi_I(x,t)=e^{iH_0t}\phi(x,0)e^{-iH_0t} satisfies the Klein Gordan equation: (\tfrac{\partial^2}{\partial t^2}-\nabla^2+m^2)\phi_I(x,t)=0 . I have so far worked out that the time derivative is...
  34. S

    Charged particle interaction

    Homework Statement What is the force of attraction between a uranium nucleus(atomic number 92) and an electron at a distance of 0.1 nm? Homework Equations F = kQ1Q2/r2 The Attempt at a Solution F= 8.99*109*92*1.6*10-19*(-1.6*10-19)/0.1*10-9 Please let me know the attempt at a...
  35. S

    Shift in energy due to weak interaction

    Homework Statement A particle is in a box of length L on x-axis. 0<x<L. What is the first order shift due to V(x) of the wavefunction? Homework Equations H=p2/2m Sin=sqrt(2/L)cos(npix/L) En=n2pi2hbar2/2mL2 V(x)=kx2/2 The Attempt at a Solution I'm super confused because the shift in the...
  36. B

    Minimum speed of interaction of matter

    hi physicists, i have a gnawing question that could be put to rest with experiment but i lack the tools and challenged in ideas. we all know that the speed of light in vacuum is the maximum that can be attained in the universe. also light does not accelerate to that speed, it just begin to exist...
  37. M

    Is Physical Contact Really Possible or Just an Illusion of Forces?

    Ok, I was thinking about this the day. Let me know how far off I am on this. As we go smaller and smaller on physical scales we find that 'solid' objects are actually comprised of 'atoms' and 'empty space' <--- loose definition, the relationship of which is in proportion to the density. Like...
  38. M

    Can Two Protons Exist in an Atom's Nucleus Without Neutrons?

    Hi, I am a young physics student who wonders a lot about the atom, especially it's nucleus. I thought about the atom and realized that there could never be a nucleus of two protons because they both would reject each other. I have made some calculations and realized that the gravitational force...
  39. I

    Riemann surface of four closed string interaction (Zwiebach section26.5)

    There are three kinds of light-cone string diagrams for four closed string interactions. As displayed by fig. 26.10, 26.11 and 26.12 of section 26.5 of Zwiebach's book. For each light-cone string diagram, it is characterized by two parameters, the time difference of the two interaction...
  40. tom.stoer

    Coulomb interaction and non-trivial topology

    I have a question regarding the Coulomb interaction in spaces with non-trivial topology. Suppose we have D large spatial dimensions (D>2). Then the Coulomb potential is VC(r) ~ 1/rD-2. Usually one shows in three dimensions that the Coulomb potential VC(r) is nothing else but the Fourier...
  41. I

    Hydrogen spin-orbit interaction

    For a particular energy level in hydrogen, with quantum numbers n and l, one will find when considering the spin-orbit interaction, the level is split into two fine structure levels with energy separation: \Delta E_{s.o.}=\beta_{nl}(l+1/2) I was trying to prove this result. The spin of an...
  42. M

    Dirac-delta term in a non-relativistic interaction

    Hi everyone, I'm studying electron-electron scattering, starting with the Dirac equation it ends up calculating the invariant transition amplitude, defined as: -iM=(ie{\overline{u}^f}_A}\gamma^\mu u^i}_A) \frac{-ig_{\mu\nu}}{q^2}(ie{\overline{u}^f}_B}\gamma^\nu u^i}_B) With u_A and u_B the...
  43. T

    What is the Interaction Hamiltonian in Quantum Mechanics?

    Homework Statement Write out: H_{SE}(\left|\right\beta,i_{\beta}\rangle\otimes\left|\right e_{j}\rangle) and exp(-iH_{SE}t)(\left|\right\beta,i_{\beta}\rangle\otimes\left|\right e_{j}\rangle) Where...
  44. K

    Understanding Force Pairs in Accelerated Systems: Explained for Beginners

    This is going to be a very elementary question, but I am having a hard time wrapping my head around it for whatever reason. In static equilibrium, like a book on a table, I have no problem seeing that the force exerted on the table by the book is equal and opposite to the force exerted on the...
  45. DocZaius

    Understanding Weak Interaction Field in Beta Decay

    I've had trouble understanding how the weak interaction could be field based, like classical gravity, or electromagnetism. My limited understanding of the interaction so far had been that left handed leptons and quarks would have an event spontaneously happen to them (such as decay). I thought...
  46. B

    Interaction of EM waves with media at boundaries

    Please see the diagram attached, I don't understand how my lecturer is resolving the E-field in the perpendicular case. He obtains: E_i = \bold{y} e^{-i\omega(t - \frac{n_1}{c} (-xsin \theta_i - z cos \theta_i))} How has he obtained the (-xsin \theta_i - z cos \theta_i) part from that...
  47. B

    ‘Identities are performed in interaction’. Discuss.

    What choices do we make about our language use?
  48. H

    Is Electroweak Interaction a Unified Force at High Temperatures?

    I (moderately) understand the basics of the electromagnetic and weak nuclear forces, but I recently heard of a combined electro-weak theory. It apparently states that two forces are different manifestations of a single force at very high temperatures. Does this mean that the photon...
  49. S

    Fourier Transform quartic interaction

    Hi all, This might be simple but I haven't figured out a way to do this. Basically I have the result in coordinate space and 3+1 spacedimensions, to order lambda^2, \frac{(-i \lambda)^2}{2!} \int dx dy (i D_F(x-y))^2 (i D_F(x1-x)) (i D_F(x2-x)) (i D_F(x3-y)) (i D_F(x4-x))...
  50. A

    Electrostatic magnetic-field interaction

    simple eg: negatively charged van de graaff generator top and a magnet. Put magnet near top. Would the magnetic field push the electrons of the charged surface to the sides and deeper into the metallic top?
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