Interactions Definition and 281 Threads

First, I am new to physics and only taking my first course in calculus based classical mechanics with topics covering thermodynamics and an introduction to general and special relativity. Everything here is pretty much a question, even if periods exist and not question marks. My teacher had...

As I have come to understand it - we have no current means of directly interacting with Dark Matter. We can only observe the gravitational effects that Dark Matter has on Baryonic Matter. My question is: What forms of detection have been attempted and determined to not directly interaction...

Hi, I'm new in this forum and I have a question about MCNPX. I would like to determine the position of each interaction between photons and matter (specially by Compton scattering.) And I would like to know how much energy the incident photon gave to the electron. Is it possible to do that with...

This question has two parts. On for the linear case, and one for the logistic case. Say X is a continuous variable and we want to see how x affects the response when looking between two different groups. Say G1=Group1, G2=Group2 In linear regression, we can plot the regression lines using the...

Homework Statement 2b. Suppose the a third wire, carrying another current i0 out of the page, passes through point P. Draw a vector on the diagram to indicate the magnetic force, if any, exerted bon the current in the new wire at P. If the magnitude of the force is zero, indicate that...

Homework Statement There are two problems: 1. At the instant the switch is closed determine the direction of the net force exerted by the magnet on the wire segment at the instant that the magnet is in the position shown. Explain. 2b. Suppose the a third wire, carrying another current i0 out...

Homework Statement You release a block from the top of a long, slippery inclined plane of length l that makes an angle θwith the horizontal. The magnitude of the block's acceleration is gsin(θ) .Use the expression you derived in the previous part to determine the speed of the block at the...

The common presentation for free field quantization proceeds with the Lorentz and Coulomb (##\phi = 0, \,\nabla \cdot \mathbf{A} = 0 ##) constraints. Then ##A## can be defined $$\mathbf{A} \propto \iint \frac{d^3 p}{\sqrt{2\omega_p}}\sum_{\lambda} \Big(e^{i\mathbf{p}\cdot...

Does anyone know how many times would an average protein fold in its lifetime? And how long do proteins live on average? Also, another quick question, somewhat related, any knowledge on how many "cascades" of different proteins making a conformational change on different new proteins can there...

For a ##\phi^{3}## quantum field theory, the interaction term is ##\displaystyle{\frac{g}{3!}\phi^{3}}##, where ##g## is the coupling constant. The mass dimension of the coupling constant ##g## is ##1##, which means that ##\displaystyle{\frac{g}{E}}## is dimensionless. Therefore...

Hi all! I have a question regarding the principal difference between QFT and string theory according to popular accounts. It is said that QFT deals with point particles leading to the well-known infinities in calculating the transition amplitudes whereas in string theory the interaction is...

Hi folks, I number of years ago, I asked a question about real particles interacting with virtual particles - since then, I've learned a little bit (maybe not too much :-), but I'm still curious about one thing. Original thread here...

I've been looking through the internet and I haven't found anything too clear on this: is it correct to assume a electrostatic interaction, say, between two stationary electrons as an exchange of virtual photons?

I'm an undergrad physics student trying to wrap my head around basic QM ideas, and the question I had was this: when we talk about the energy levels of an atom and the wavefunction of the electron around that atom, we talk about an electric potential that affects the shape the wavefunction...

Hello. Well, each and everyone of us know that Like Charges repel, while unlike charges attract. That's a normal high school physics fact. But what's the reason for that? Is it just an experimental fact, or even does have theoretical significance? Please do help. Thanks a lot Swapnil Das.

Homework Statement An atom with an excited-state configuration 1s22s22p63s23p64s23d14p1 With residual electron-electron interactions are taken into account, this configuration splits into atomic terms. List these terms labelled by their L and S quantum numbers Homework Equations L=|l1-l2|...

I know an electron is constantly flipping between two quantum spin states. I know that one spin takes slightly more energy than the other and it gets and drops this energy into and from the Higgs field, which gives it mass. The default behavior of all particles is to travel at the speed of...

I was watching this PBS Spacetime video, and something they said bugged me. They said that some subatomic interactions are occurring at time scales less than the Planck Time. And thus, this would also mean that these things are happening at scales less than the Planck Length as well. My...

In his book, Seven Brief Lessons on Physics page 18, Carlo Rovelli said: What is the name of the mathematical formula and the abstract space he refers to in this passage? And why can't these interactions occur in real space? Thanks.

Hi. General question: Is there a fixed way to find all invariant tensor for a generic representation? Example problem: Suppose you search for all indipendent quartic interactions of a scalar octet field ## \phi^{a} ## in the adjoint representation of SU(3). They will be terms like ##...

Electrons have a theoretical rest mass. They can move at varying speeds through space, unlike photons. They ehxhibit quantum-characteristics in their behavior. If an electron collides with, say, an atom, does conservation of momentum apply in the classical sense or does measurable mass (an atom...

Hi, Is there a list of basic interactions in the standard model? Does anyone know where I can find this list of basic interactions in the standard model?

It says everywhere that particle decay is not the only thing that creates entangled particles. "Quantum entanglement is a physical phenomenon that occurs when pairs or groups of particles are generated or interact in ways such that the quantum state of each particle cannot be described...

So I have not been able to find too much information about this. Specifically in the context of the double slit experiment. I've seen just about the only video on Youtube that tries to explain this, but I did not understand-- I felt like somethings were not explained. I am acquainted with why a...

Hi all, Some processes can not happen at the tree level, but it happen via loops, like for Higgs decay to pair of glouns or pair of photons, (h -> gg), (h -> y y) . For instance, effectively h -> gg written as ##~ h~ G^a_{\mu\nu} G_a^{\mu\nu}~ ## which is Lorentz and gauge invariant .. Now if...

Hi, My question about CP- violation, but it has many parts, so I appreciate any help about.. First: I know that, any complex coupling leads to CP - violation, so if for example A is a complex scalar, and H is a real scalar, interaction as: A HH will be forbidden if we considered CP...

Recently, I read two chapters from March's advanced organic chemistry. I came across gauche effect and SN2 reactions. In both phenomena, ##\sigma-\sigma^*## orbital interactions is involved. In gauche effect present in 1,2-diflouroethane, the C-F bonding orbital becomes an antibonding orbital so...

why do scalar interactions(for example the higgs vev or its components) reverse the chirality of the interacting particle?? i think this is the key for understanding the mass generation of fermions, but i can't think of a logical reason of the reversed chirality.

Hi, So I recently got a new job, and when I was being instructed on how to close my department, I noticed that they used quite a bit of chemicals on the same surface (it's a salad bar). I was wondering if any of these chemicals could interact, and if so, what the products would be. First, the...

I was recently taught the concept of nuclear forces in school.According to what was taught,nuclear forces were introduced to explain the stability of the nucleus.So,my question is that,can't we say that the nucleus is stable only due to neutron-proton and proton-proton interactions?Why are...

[Mentor's note: split off from the thread https://www.physicsforums.com/threads/first-loophole-free-bell-test.829586/ as this is a general question about Bell's Theorem, not the specific experiment discussed in that thread] It says in the paper ... ... and the 'CHSH-Bell inequality' all...

Why is it required that interactions between fields must occur at single spacetime points in order for them to be local? For example, why must an interaction Lagrangian be of the form \mathcal{L}_{int}\sim (\phi(x))^{2} why can't one have a case where \mathcal{L}_{int}\sim\phi(x)\phi(y) where...

Does the orbital of an electron change when it experiences a spin-orbit interaction, and if so, how?

basic question- neutrinos pass through matter because they are only subject to the weak interaction whereas photons interact with matter because they are subject to EM? Does the small mass of the neutrino contribute to this - if there was a neutrino with the mass of a proton how differently...

Let's try something simple and hope this goes better than my last two threads. :( The problem can be stated thusly: ---- Given thermal neutrons emitted at a source S interacting with a mean interaction length of L and an evaluation point P distance d away from S, what is the average number of...

Protons are in very close proximity with each other in a nucleus. This means there is constant electromagnetic interaction, of which the exchange particle is a photon. What determines the wavelength of this exchange photon? How do they exist in the nucleus: constantly being emitted, or staying...

Hi there, I've been reading a textbook on Physics as applied to nuclear medicine, in particular focusing on how photons interact with matter. The textbook states (without reference) that "there are nine possible interactions between photons and matter, of which only four are of significance to...

I have been getting ready for my Intro to Modern Physics final. The professor likes to ask a lot of questions like Which of the following neutron reactions proceeds via the electromagnetic force? Or something like this... I have been looking all over the internet and my textbook. All I can...

Homework Statement Additional instructions: Analyze the motion of the system in an inertial frame of reference fixed to the table on which M1 slides. You can't analyze the system with Newton's Laws in the frame of M1 because M1 will accelerate, and that frame will not be inertial. When you...

Hello, I'm trying to better understand entanglement in the context of measurements and interactions. (1.) Are uncertainty and entanglement linked together? Are the eigenstates of an observable entangled since a measurement of one of them collapses the wavefunction to a single eigenstate, making...

Quite a simple query really, The question wants me to draw a Feynman diagram for a number of particle interactions, some are not possible, some are. This interaction: proton + antiproton ----> 3 gamma This would require each quark (uud) to annihilate with its anti matter counter part. This...

Good day all, I'm taking a course on hyperfine interactions this semester. It is organised in the alternative way that we, the students prepare some part of the course notes (e.g. treat magnetic dipole term, electric quadrupole term etc.). The problem I have is that the course notes we...

hello! is there a book or something, to have an overview of the possible interactions between waves and matter? for example ultrasound can ignite flammable liquids for example lasers can ionize materials what are the possible material transformations that can take place? ionization...

Hi all - in the question below I could do with some help on the "..explanation for the relative strengths..." bit, as I can't think of anything to say. 1. Homework Statement Compare and contrast the properties of the strong and weak interactions. Include in your account an explanation for the...

I was wondering. For fermions someone can find that the Lorentz group is isomorphic to SU_L(2) \times SU_R(2) . However in the Standard Model there is only left-handed neutrinos interacting with the rest of matter. If Lorentz was not partially violated, wouldn't someone expect for the left and...

is it explained? (proximity = between protons and electrons distance) is it a dispersion field (a more general term for boson field, but for everything, cause' i don't know what is right) or is it about something else in total? i tried to find it, but yahoo answers came up... can someone point...

Say I have a large spacetime lattice set up on a supercomputer where I calculate the scattering cross section of two spinless electrons of equal and opposite momentum via lattice QED. To get the right results we must add the amplitudes for every possible "path" the field can evolve from initial...

is it true that: 'as energies interact, they change properties, possibly creating massive matter in the process or vice versa' ?

Do you have any source where I can check for the neutralino (higgsino or chargino/bino -like) interaction processes? In general I'm trying to find the amplitudes in the Appendix A of: http://journals.aps.org/prd/abstract/10.1103/PhysRevD.47.376 But without seeing a Lagrangian, I can't...

When the Z boson is around can a neutrino interact with a particle other than an electron? And how does the neutrino find the electron if the neutrino is neutral and does not interact electromagnetically?