Principle Definition and 1000 Threads

Gauge Principle is successful in strong electroweak force modeling in the the form U(1), SU(2), SU(3) and in GR but it fails in SU(5) or attempted gauge symmetry between leptons and quarks, it fails in Supersymmetry, fails in Supergravity, and even fails in String Theory. Don't we even know...

An article at physicsworld.com suggests that arbitrarily small measurements can be made. Ozawa: "My theory suggests if you use your measuring apparatus as suggested by the maker, you can make better measurement than Heisenberg's relation" Regarding his opposition: "They now prove that if...

How do we prove Pauli's exclusion principle? My professor makes a Slater determinant and then merrily shows how it disappears when two columns or rows are same. That is not Pauli's principle, is it? It is based on an assumption that certain particles are described by certain states. So my...

Homework Statement So we have a test this Friday over several topics in modern mechanics. Our professor gave us last year's test to use as a study guide, but hasn't posted the solutions yet. I'm not sure I'm doing this one right so I was hoping someone could check my work! I feel like my...

I read the Quantum Physics section of the online version of Feynman lectures http://feynmanlectures.caltech.edu/I_02.html#Ch2-S3 and I don't understand how he can deduce electron momentum from the Uncertainty Principle. I agree that the momentum is uncertain but how can he deduce that it is very...

Is there a profound relationship between Principle of Least Action and Continuity Equation? Can we derive one from another?

We take for granted the fact that we can infer more about the past than the future. Considering the only difference between past and future is entropy, I wonder if the reason it is possible to have records of the past and not the future is entropy related. At the quantum level is the...

Ok, I http://en.wikipedia.org/wiki/Academic_genealogy_of_theoretical_physicists#Arnold_Sommerfeld that Heisenberg had studied under Arnold Sommerfeld, but I have just now learned that Sommerfeld proposed a sort of uncertainty principle in the first Solvay meeting. That was 1911. It seems...

original question: Consider light passing from one medium with index of refraction n1 into another medium with index of refraction n2. User Fermat's principle to minimize time, and derive snell's law (n1sintheta1=n2sintheta2). here is part of the solution key http://i.imgur.com/S1Pg9jC.png...

please note in the process proving bernoulli we use the CONTINUITY equation.Consider a situation wherein a pitot tube is used to measure pressure/velocity in a steady flow(picture attached for reference).Here we use bernoulli for pressure measurement.we apply the bernoulli theorem for a...

If we have an upward moving sphere with 0.4 m3 volume and 100 kg mass , according to Archimedes buoyancy force = 4000 N so acceleration = 40 m/s^2 But according to Atwood's principle , buoyancy force ≈ 1600 N acceleration = 16 m/s^2 what makes such big difference . ( ignore drag force and...

"Consider a solution of the diffusion equation ##u_{t} = u_{xx}## in {0 ≤ x ≤ L, 0 ≤ t ≤ ∞}. a) Let M(T) = the maximum of u(t,x) in the closed rectangle {0 ≤ x ≤ L, 0 ≤ t ≤ T}. Does M(T) increase or decrease as a function of T? b) Let m(T) = the minimum of u(t,x) in the closed rectangle {0 ≤ x ≤...

What Uncertainty Principle actually is? I searched on the internet and got an amazing answer that the energy could form out of thin air. Who could explain more specifically to me, who is in year 11.

Problem Find the minimum energy of the hydrogen atom by using uncertainty principle a. Take the uncertainty of the position Δr of the electron to be approximately equal to r b. Approximate the momentum p of the electron as Δp c. Treat the atom as a 1-D system My step 1. Δr Δp ≥...

need help understanding "Superposition Principle"..! hello everyone.. if we have a function y=f(x) then in-order to prove linearity we try to justify according to superposition principle as : let x1 and x2 be two inputs then f(x1+x2)=f(x1)+f(x2) please correct me if i am wrong upto here...

Archimedes principle of the force of upthrust = weight of water displaced by the body immersed , but is this law independent of the shape of this body. If we use the idea that the upthrust = P*A on the lower side - P*A on the upper side , if we use it on a rectangle or a square , the only change...

1. Hey, I have to find Maxwells equations using the variational principle and the electromagnetic action: S=-\intop d^{4}x\frac{1}{4}F_{\mu\nu}F^{\mu\nu} by using \frac{\delta s}{\delta A_{\mu(x)}}=0 therefore \partial_{\mu}F^{\mu\nu}=0 3. I have had a go at the...

Hello, Just discovered this forum as I'm so intensely curious about this question I sought out just such a place! I'm currently designing a circular patio using 6-in square blocks in concentric circles. While using a combination of Excel and Adobe Illustrator, I uncovered something...

Hello, I have this exercise and want to check if what i did is correct Homework Statement Nuclei, typically of size $10^{-14}$ m, frequently emit electrons with energies of 1-10 MeV. Use the uncertainty principle to show that electrons of energy 1 MeV could not be contained in the nucleus...

I've got a TI-89 Titanium I've taking a class in Mechanical Design and my professor informs me that we need to be able to solve the equation (equation 3-15) shown in the attachment. I've been trying to find a way to program it into my calculator, but haven't had any real success. The...

Why does light follows a path of minimum time? I.e., is there any theory or explanation behind the fermats principle?

onsider the following link: http://en.wikipedia.org/wiki/Principle_of_explosion Now, consider Schrodinger's Cat. Does this not imply the following statements? - A) The cat is alive before the box is opened. - B) The cat is not alive before the box is opened. Aren't both of these statements...

Homework Statement At a certain instant a particle (mass=0.5 kg) is moving in the +x direction with velocity 14 m/s. During the next 0.15 seconds a constant force acts on the particle, with Fx= −8 N and Fy= Fz = 0 N. What is the magnitude of the momentum of the particle (in kg*m/s) at the end...

/I'm having some doubt with D'alembert's Principle. The principle states that \sum_{i}(\vec {F}_i - \dot{\vec{p}}_i)\delta\vec{r}_i=0 but does that mean that each term of the summation must vanish too, or just the sum does? I know that mathematically there's no need that each term shall vanish...

If you had two synchronized clocks in two side by side elevators, and one sat on the surface of the Earth in 1 g for ten years, while the other one accelerated out into space, turned around, and then came back (all at one g, aside from escaping and reentering the Earth's gravity), would the...

I read somewhere that Heisenberg described his uncertainty principle by saying that you can't measure position more accurately than the wavelength of light (which makes sense), so Δx > λ. This is what I don't get. He then says that p=h/λ, so Δp > h/λ2 Δλ. He the multiplies and sets Δλ ≈ λ to...

As far as I understand, Hamilton's principle (a.k.a. "least action" or "stationary action") requires that you know both the initial and final location of a particle. Then, based on the requirement that the action must be stationary along any "possible" path, it will tell you what path(s) the...

Hey, you know the way einstein said that its impossible to tell if you`re in a box that is accelerating or in a gravitational field? But, don`t accelerating charges radiate? so theoretically, by looking at these charges you could in fact tell the difference ? I dunno, maybe I`m missing...

Galilean principle of relativity is for sure not absolutely true, isn't it? Say one has a pool full of water within a spaceship, if the spaceship is accelerated and then acceleration stops, one can look at the ripples in the pool, analyze their form and then tell, up to a certain degree of...

Homework Statement A spin-half particle is in a known eigenstate of Sz. Show that the product <S^2_x> < S^2_y> is consistent with the Uncertainty principle Homework Equations The Attempt at a Solution I know that the generalized uncertainty principle gives ΔS_x ΔS_y ≥ |<[S_x...

I have been going through my Physics textbook to brush up on my Quantum Mechanics before starting my next QM course next academic year and the Heisenberg uncertainty principle for position and momentum is written as ΔxΔp ≥ h-bar when I thought it was ΔxΔp ≥ (h-bar)/2. Other sources say it is...

Some time ago I asked about contact forces and was directed to read about the Pauli exclusion principle and the resulting L-J potential before a detailed explanation was given explaining why the electrons start interacting significantly, electromagnetically, even if the atom as a whole is...

I have been trying to pin down a precise definition of large-scale homogeneity, in the context of saying, per the Cosmological Principle, that all constant-time hypersurfaces (CTHs) of a foliation are large-scale homogeneous. Here is my attempt: Let M represent any coordinate-independent...

I am having a tough time understanding the principle of least action and I would really appreciate it if someone would clear it up for me. And from what I understand from it, it can be used to predict particle motion?

If the holographic principle says that the the observable universe could be represented as a two dimensional surface, and we accept the idea that the universe is itself a mathematical object, and cantor showed that we could in some cases represent higher dimensional sets within lower dimensional...

Dear all, Can the conservation of mass principle be applied to the mass flow rate of a refrigerant in an ideal refrigerator system? And what about for an actual refrigeration system? I'm reading the principle here but can't work it out. Says that it applies for steady flow, but I assume...

The totalitarian principle states that 'every process that is not forbidden must occur'. Isn't this principle self-obvious? After all, a process that is not forbidden can, by definition, occur. But, I think I am missing a layer of meaning implied by this statement. If that is so, would you...

When a fermion x approaches another fermion y does x send out bosons to y which tell it to get out of the way? In short, how does y know to get out of the way of x?

Hi Sir, I have seen in many IEEE magazines that, a six phase induction motor is having two 3 phase windings spatially separated by an angle of 30 degrees electrical. I have attached the 6 phase induction motor diagram. But I am not able to understand how the motor operates i.e. how the rotor...

How exactly would you describe the principle of a valve for flow control? In a globe valve for example the fluid flows through valve seat and generally leaves the valve with the outlet diameter being the same as the inlet diameter. My original assumptions were that Bernoulli's principle...

I am new to quantum mechanics. By hitting a particle with photon in vacuum we find its momentum and then again hit it with another photon to find its position . can we calculate backwards using conservation of momentum the position an momentum of that particle in both two states ( since we know...

Homework Statement A massless spring attached to a wall lies on a frictionless table. It has a block of mass 2kg attached to one end, initially the block is at rest. Another block, also of mass 2kg is sliding on the table top with a speed 8m/s. At t = o the moving block collides with the...

I learned about mach's principle from a book. But I can'understand the details of it. So can you please explain me what is mach's principle? Is it correct?

I've been studying for a test and have stumbled upon another type of problem I'm not comfortable with yet. I need help applying the argument principle - the practice problems in my textbook all consider only polynomials in the first quadrant. In solving this type of problem I consider...

This question is regarding the boson statistics and it’s relation to the uncertainty principle. Consider we have a vacuum state and we apply a field operator on it to create a particle at position x, we end up with state like \begin{array}{l} \left| \psi \right\rangle = {\psi ^\dag...

My qm textbook, aptly named "quantum mechanics", is by McIntyre, though it omits the proof for the uncertainty principle and simply states it as ∆A∆B ≥ 1/2|〈[A,B]〉|. In words, if that's unclear, this is 'the product of the rms deviations of A and B is greater than/equal to one half the absolute...

because Schrodinger equation is a linear differential equation. How do we show that Schrodinger equation is a linear differential equation?

Homework Statement Consider a random walker in one dimension, which can take right or left steps with equal probability. Assume that the walker starts at the location k>0 and there is an absorbing wall at point labelled as 0, that means if the walker reaches 0 the process stops and he stays...

Homework Statement On a horizontal pipe with flowing water on point 1 there is a vertical pipe with water up to some point. On another point 2, we have a pitot tube (L shaped) against the water flow and the lever on the vertical part is higher that on point 1. If the water flow stops what...

Homework Statement For the ground state of a particle in a rigid box, we have seen that the momentum has a definite magni- tude (h/2π)k but is equally likely to be in either direction. This means that the uncertainty in p is Δp≈ (h/2π)k. The uncertainty in position is Δx≈ a/2. Verify that...