Fields Definition and 1000 Threads

In nonrelativistic QM, we usually describe the Hilbert space by choosing a complete set of commuting observables, so that the set of states that are eigenstates of all the observables can be used as a basis. For instance, the "wavefunction" is the state as expressed in terms of "states" with...

It seems to be widely accepted on this forum that fields, not particles, are fundamental. In other words particles are made of fields. I have seen particles described in various ways such as being excitations of fields or eigenstates with known energy. This creates a problem for high school...

Homework Statement So I have got the question below. I am asked to find the phase difference between the electric field and magnetic field of electromagnetic waves traveling in a plasma, using the electrical conductivity expression. Now I have found the frequency of the waves and I know that...

Both the gravitational and electric fields associated with matter are centered on the matter itself. However, for a bar magnet, the magnetic field seems to be emanate from discrete loops, only part of which pass through the matter of the magnet. What causes a magnetic field to have this...

Homework Statement Homework Equations F = k(q1q1/r^2) K = (mv^2)/2 The Attempt at a Solution I got number 18 easy enough, number 19 seems simple but I'm not getting the right answer. I'm calculating Force exerted by each charge on the new charge using F = k(q1q1/r^2) for the three charges...

Homework Statement Question attached: Hi I am pretty stuck on part d. I've broken the fields into real and imaginary parts as asked to and tried to compare where they previously canceled to the situation now- see below. However I can't really see this giving me a hint of any sort unless...

Homework Statement Over a region of radius R, there is a spatially uniform magnetic field B →. (See below.) At t =0, B=1.0T, after which it decreases at a constant rate to zero in 30 s. (b) Assume that R=10.0cm. How much work is done by the electric field on a proton that is carried once clock...

Homework Statement Let f1,f2, ..., fn : K -> L be field morphisms. We know that fi != fj when i != j, for any i and j = {1,...,n}. Prove that f1,f2, ..., fn are linear independent / K. Homework Equations f1, ..., fn are field morphisms => Ker (fi) = 0 (injective) The Attempt at a Solution I...

Homework Statement ##T(\phi_1\Phi_2\phi_3\Phi_4)## where ## \phi_1## is ##\phi(x_1)## and ##\phi## and ##\Phi## are two different fields. By Wicks theorem ##T(\phi_1\Phi_2\phi_3\Phi_4)= : : + contracted terms.## QUESTION Are the fully contracted terms (apologies for the bad notation I'm...

Hello, I will start my freshman year in mathematical physics this fall. When I was researching about fields of specialization in physics I came across medical physics. I found that medical physicists are well paid and their job prospect is great! As you probably realized from my major, I'm very...

Homework Statement Consider four real massive scalar fields, \phi_1,\phi_2,\phi_3, and \phi_4, with masses M_1,M_2,M_3,M_4. Let these fields be coupled by the interaction lagrangian \mathcal{L}_{int}=\frac{-M_3}{2}\phi_1\phi_{3}^{2}-\frac{M_4}{2}\phi_2\phi_{4}^{2}. Find the scattering amplitude...

@vanhees71 reminds us that which suggests something I've wondered about for a while, whether dark matter might be adequately modeled by generalized free fields, which do not have asymptotic free states. Ray Streater, in Rep. Prog. Phys. 1975 38 771-846, "Outline of axiomatic relativistic...

Homework Statement In an electromagnetic filed, the elctric field ##\vec{E}## forms an angle ##\theta## with the magnetic field ##\vec{B}##, and ##\theta## is invariant for all inertial observers. Finding the value of ##\theta##. Homework Equations Tranformations of fields perpendicular to the...

Homework Statement Scientist want to put a satellite into an orbit where the gravitational field of Earth is half its value at Earth's surface. The altitude of this orbit above the Earth's surface will be A.3R B. √2R-R C. 4R D.√2R Homework Equations Fg∝1/r^2 The Attempt at a Solution I know...

What fields in the future do you see blowing up? Will all the automated truck drivers and grocery clerks become software engineers? I’ve been thinking about this a lot lately.

Hi. Please let me know if the question is misplaced in the quantum forum. Is the next. Exist, in quantum terms, the electric and magnetic fields corresponding to a single photon? If yes, add another question. Is there any way to formulate the amplitudes of both fields in electrodynamic terms...

Homework Statement An oil droplet is suspended between two horizontal parallel plates with a separation of 0.4 cm. If the potential difference of 320V is applied to the plates, determine the number of electrons transferred to/from the droplet. Given/Known Values mdroplet = 5.2×10-6 kg d = 0.4...

Hi, let ##\gamma (\lambda, s)## be a family of geodesics, where ##s## is the parameter and ##\lambda## distinguishes between geodesics. Let furthermore ##Z^\nu = \partial_\lambda \gamma^\nu ## be a vector field and ##\nabla_\alpha Z^\mu := \partial_\alpha Z^\mu + \Gamma^\mu_{\:\: \nu \gamma}...

I wrote and solved this problem but am having serious doubts about the answer I obtained. Homework Statement Two point charges \pm q move along the z-axis with velocity \pm v. If they are at the origin when t=0, what is the electric field magnitude a distance r from the z-axis? Homework...

I know little about QED, QCD, and whatever the corresponding theory for the weak force is, and of course virtually nothing about the quantized theory of the gravitational force, which mostly doesn’t exist, so the following arguments and questions may be somewhat wrongly based where they refer...

Hi, Can anyone direct me to some literature that describes the numerical solution of full Maxwell's equations and Navier-Stokes equations for two-phase/multi-phase flows in coupled electric and magnetic fields. Thanks!

Hi, My question is what fields would a human resources (hiring/firing) manager hire someone who self-educates themselves on a topic? I know that computer software engineering/computer science/information technology can be self-educated with IT certifications and whatever. That's very clearly...

Homework Statement Problem Statement: A system consists of a long cylindrical anode of radius a and a coaxial cylindrical cathode of radius b (b < a). A filament located along the axis of the system carries a heating current I producing a magnetic field in the surrounding space. Find the least...

I'm having trouble figuring out how to solve Maxwell's equations for the electric field of an AC wire. I assume the Voltage waveform in the wire is 120sin(60t). This circuit only has a 14ohm heater in it, according to Ohm's law I=V/R. The current is equation to I(t)=120sin(60t)/14 It is...

Good day all! I have a question that has been in my head bouncing around for a while and I figured the best resource would be here as I can't find anymore related information (Or I am just looking in the incorrect spot). My apologies if this is in the wrong section I wasn't too sure where to...

Homework Statement 2. Homework Equations [/B] F = BIL sin(x) The Attempt at a Solution This isn't homework its a practice question so I have looked at the answer and its 0N however I do not understand why it is 0N. I have tried resolving the magnetic flux density so its perpendicular to the...

Homework Statement In a reference frame ##S## there is a particle with mass ##m## and charge ##q## which is moving with velocity ##\vec{u}## in an electric field ##\vec{E}## and in a magnetic field ##\vec{B}##. Knowing the relativisitc laws of motion for a particle in an EM field, find the...

Why does current produce a static magnetic field, but a static magnetic field doesn't produce current? Specifically, why is one true, but the inverse not true? I can accept that each rule individually is just how the universe works... but it sounds so contradictory when I examine both together...

Can an electrostatic field be used to create an oxide layer that has a permanent electric field? For a specific example; an aluminium domed van de graaff generator with no oxide layer. If it is turned on and allowed to contact oxygen, would the oxide layer store a permanent electric field?

Greg Bernhardt submitted a new PF Insights post Mathematical Quantum Field Theory - Interacting Quantum Fields Continue reading the Original PF Insights Post.

Homework Statement Copy the following diagram and draw field lines for both magnetic fields. Then, use them to determine the direction of the force acting on the conductor. HINT: Check your answer, using the right - hand rule for the motor principle. Their diagram: 2. Relevant equation n/a...

Hi All, I want to compute the ratio of two fields A,B from different sheets ( same workbook) , using Pivot ( tho "straight" Excel will do*). I tried using the Wizard, but , in the end, could not find a way of doing it: Any ideas, please? *I scewed big when trying this.

Greg Bernhardt submitted a new PF Insights post Mathematical Quantum Field Theory - Free Quantum Fields Continue reading the Original PF Insights Post.

Hello everyone, my question is: what are the criteria that must be satisfied for the pushforward of a smooth vector field to be a smooth vector field on its own right? Consider a smooth map \phi : M \longrightarrow N between the smooth manifolds M and N. The pushforward associated with this map...

Homework Statement There is a point between the Earth and the moon where the total gravitational field is zero. Given that the mass of Earth is 6.0*10^24 kg, the mass of the moon is 7.3*10^22 kg and the radius of the Moon's orbit is 3.8*10^8 m, calculate the distance of this point from the...

I was recently having a discussion about magnetic fields outside of a shielded power cable. My understanding up to this point was shielded cables only shields electric fields and not magnetic fields which are associated with current flow inside a cable. For the shielding to shield magnetic...

If a single point charge is moving, then the component of the electric field normal to the motion is larger (by the gamma factor) than if the charge were stationary. Now consider an infinite line of charges (with a small separation, the same between each charge). If the whole line is moving...

Most research into quantum-gravity is looking for a specific particle, the graviton, to represent the gravitational force at a quantum level. But they also acknowledge that it might be impossible to find the graviton particle, because gravity is so weak. Now, is it possible that we're looking at...

I'm curious about John Baez's book "Gauge Fields, Knots And Gravity" - I've read some of notes from his website and find his style of writing well matched to my style of learning. So, for personal interest, I was considering whether this book might be nice to read. That said, I'm not familiar...

If the speed of light is ~300 m/s in a vacuum, can the electric and magnetic fields of the wave be condensed such that it travels faster? The idea being that an outside force condenses these fields and lenghtens the wavelenght with no loss of energy thus increasing the directional speed. The...

Homework Statement Example 2:[/B] Homework Equations Flux=integrate -Pgx-Qgy+R of the proj. area on xy plane for z=g(x,y) The Attempt at a Solution Why do my attempt is wrong? The example is using the foundational formula while I use the stock formula from the book, why is there a negative...

Suppose a gravitational wave propagating through space encounters a strong magnetic field (for example the wave might pass through a magnetar with a B field strength of 10^{11} Tesla). Would there be any observable perturbation in the magnetic field itself? In other words would the gravitational...

Homework Statement The stream function Ψ(x,y) = Asin(πnx)*sin(πmy) where m and n are consitive integers and A is a constant, describes circular flow in the region R = {(x,y): 0≤x≤1, 0≤y≤1 }. Graph several streamlines with A=10 and m=n=1 and describe the flow. Explain why the flow is confined to...

Hi Guys, I have attempted the question below. Please have a look at my work and let me know if everything looks fine. Any feedback would be great. 1. Homework Statement Homework Equations F = qv/d a = F/m t = d/v qv = 1/2mv^2 x = vt + 1/2 at^2 The Attempt at a Solution

I'm not sure this is the best place for this question, and apologize if it isn't. I'm studying the classical field solutions on the first few chapter of Rajaraman's Solitons and instantons : an introduction to solitons and instantons in quantum field theory. Well, my question is about one of...

From wikipedia: "An electromagnetic wave such as light consists of a coupled oscillating electric field and magnetic field which are always perpendicular; by convention, the "polarization" of electromagnetic waves refers to the direction of the electric field." A polarizer is an object that...

In Quantum Field Theory, I am led to believe that there is a different field for each type of particle. When particles interact, it is an exchange of vibration between the fields. What mechanism is at play when one field influences another in this way? It seems I've only ever found...

The sources I've looked at claim the magnetic field is present because there are still some electrons in the neutron star. Here is how I understand their reasoning: a star's radius significantly decreases when it collapses into a neutron star, ultimately decreasing its moment of inertia. In...

Greg Bernhardt submitted a new PF Insights post Mathematical Quantum Field Theory - Fields Continue reading the Original PF Insights Post.

I'm reading a textbook on electromagnetism. It says that for two vector fields ##\textbf{F}(\textbf{r})## and ##\textbf{G}(\textbf{r})## their inner product is defined as ##(\textbf{F},\textbf{G}) = \int \textbf{F}^{*}\cdot \textbf{G} \thinspace d^3\textbf{r}## And that if ##\textbf{F}## is...