Terms Definition and 1000 Threads

I would like to know more about the beginning of time in terms of entropy. How can we explain the formation of a more ordered universe from a more ordered condensed structure that exploded and evolved to what the universe is right now? Where did the gravity come from and what is it's effect in...

Homework Statement The translation operator T(a) is defined to be such that: T(a)ψ(x) = ψ(x+a) Show that: T(a) can be expressed in terms of the operator p = -iħ d/dx and T(a) is unitary. Homework Equations T(a)ψ(x) = ψ(x+a) p = -iħ d/dx The Attempt at a Solution I honestly...

Homework Statement For two concentric conducting spheres (radius a and b, b>a) that form a capacitor with charge q on the inner sphere and -q on the outer sphere, express the electrostatic energy in terms of q and -q and the potential difference between them.Homework Equations Gauss's Law, the...

I posted this first in Astronomy but it belongs in General Physics. With a little research, anyone can convince himself or herself that the following statements are true: a) that in one second light travels a distance equal to 30.0 times the distance between the north pole and the equator and...

The Problem is when I Compute the Inverse I have to solutions sech^{-1}(x) = ln(\frac{1\pm \sqrt{1-x^{2}}}{x}) : 0<x\leq 1 And this not function which of them I will choose Another Question is how can I prove without the graph that csch (x) is one - to -one thanks

Homework Statement The terms of convergent series \sum_{n=1}^\inftya_n are non-negative. Let m_n = max{a_n, a_{n+1}}, n = 1,2,... Prove that \sum_{n=1}^\inftym_n converges. Show with a counter-example that the claim above doesn't necessarily hold if the assumption a_n\geq0 for all...

I was reading on planetary motion and have gotten hung up on a "rearrangement of terms" that the author skimmed over. It reads that: r=e(k+rcos(θ))=(ek)/(1-ecos(θ)) It's been a while since I've been in a math class: I just can't follow how to get from a to b. Is there anyone who can walk...

When we refer to terms in an equation, what EXACTLY are we referring to? Suppose for example we have: ab + bc + cd = A Suppose somebody refers to term "ab". Are they referring to the syntactical NAME "ab", the IMAGE of ab (i.e., it's value), or the ARGUMENT (a,b) which belongs to some...

Hi All, I wonder if the modulation of RF waves (Amplitude Modulation, Frequency Modulation, and Phase Modulation) can be explained in terms of photons. Thanks, Srini

Hi, Just have a few questions about this chapter if anyone here is familiar with it... 1) Does anyone know why the k^2_i \to -m^2 limit is imposed in (67.4), is it just because he wants external particles to be physical and hence on-shell? I derived this equation from the one directly above...

Hello, There is a definition of simple-connectedness for a region R of the complex plane C that states that a region R is simply-connected in C if the complement of the region in the Riemann Sphere is connected. I don't know if I'm missing something; I guess we are actually consider...

Homework Statement Determine the values of x for which the function, for n>=1, is increasing, decreasing, bounded below or bounded above. The function is (x^n)/n Homework Equations The Attempt at a Solution I thought about taking the derivative of the function, and setting it to 0. To find...

Homework Statement a large positive charge +Q fixed at some location in otherwise empty space, far from all other charges. A positive test charge of smaller magnitude +q is launched directly towards the fixed charge. Of course, as the test charge gets closer, the repulsive force exerted on...

Hi Guys, I have a question. Can we attempt to explain the phase change of a carrier wave in terms of photons? For example consider GPS signal. It is BPSK modulated, in which phase change of 180 degrees happens for multiple of 1540 cycles of the carrier. How is the phase information...

How do the "d" terms in differential equations work? Hi, I was hoping someone could explain how the "d" terms in differential equations work? For example, d2y/dx2 = 4x3 +1 To solve I have been rearranging to get, d2y = (4x3 +1)dx2 and then doing a double integral of each side...

Homework Statement The total cost of repaying a student loan at an interest rate of r% per year is C=f(r). a. What is the meaning of the derivative f '(r)? b. What does the statement f '(10)=1200 mean? Homework Equations The Attempt at a Solution For part a I think the...

So I'm computing a second order Taylor series expansion on a function that has multiple variables. So far I have this I(x,y,t)=dI/dx(change in x)+dI/dy(change in y)+dI/dt(change in t)+2nd order terms Would it still be a better approximation than just he first order if I included some...

Homework Statement arctan(sin((3 / 4) * pi) * 2) = 0.955316618 I want to express that in terms of a fraction with reference to pi. The Attempt at a Solution I thought of first dividing that by pi itself, and then convert the resulting number into a fraction and tack pi on at the...

"Most physicists do not recognize temperature, Θ, as a fundamental dimension of physical quantity since it essentially expresses the energy per particle per degree of freedom, which can be expressed in terms of energy (or mass, length, and time). Still others do not recognize electric charge, Q...

Homework Statement Find the general solution of Airy's equation f'' - zf=0 satisfying the initial conditions f(0)=1, f'(0)=0 as a power series expansion at z=0. Express the result in terms of the Gauss hypergeometric series. The Attempt at a Solution After subbing...

\frac{\partial z}{\partial t}=\frac{\partial z}{\partial x}+\frac{\partial z}{\partial y} \mbox{Let }z=T(t)X(x)Y(y) T'(t)X(x)Y(y)=T(t)X'(x)Y(y)+T(t)X(x)Y'(y) \Rightarrow \frac{T'(t)}{T(t)}=\frac{X'(x)}{X(x)}+\frac{Y'(y)}{Y(y)} \Rightarrow \frac{T'(t)}{T(t)}=A \wedge...

I am recently reading the articles "Search for squarks and gluinos using final states with jets and missing transverse momentum with the ATLAS detector in sqrt s=7 TeV proton-proton collisions". However, as my limited knowledge, many technical terms that I am understanding as a result I am now...

I will love forever whoever can show me the steps of how to get the following equation in terms of y=[...] This is not a homework question. I have a calculus book that has given me some progress, such as expanding the equation to a mixture of terms and first order partial derivatives, and I...

Homework Statement The volume of a fixed mass of an ideal gas is doubled while the temperature is increased from 100 K to 400 K. What is the final pressure in terms of its initial pressure pi? Homework Equations in terms of pi? what?? does that stand for ' pressure initial or...

Does the below sound ok? 1. Interference is caused between coherent waves 2. When we try to find which-way we break the coherence a) When we try to "partially" find which way, we partially break the coherence and hence a "partial" interference pattern 3. DCQE is explained by the fact...

Hello, Let's say we have f[x_,y_]:= whatever then we say expr1 = D[f[x,y],x] which is some complicated expression. How can we get the answer in terms of f[x,y]? That is, how can we get expr1 to look like: expr1 = f[x,y]*this term + pi*Sqrt[f[x,y]] + et cetera? Thanks Gurus

Homework Statement Express the components of Fμν in terms of E and B.Homework Equations I have find sonewhere the final 4*4 matrix solution but i don't know what are the steps i have to follow in order to obtain it. The Attempt at a Solution

If I'm not mistaken, the 3 flavours of neutrino are supposed to have different masses, right? Why then, if you had, say, an electron neutrino traveling along with a certain value of (kinetic + mass) energy, and then it oscillates into a muon neutrino with a different mass, could that be allowed...

My problem is this: I have an algebraic expression, and I want to express it in terms of one variable divided by another. It's a fairly large expression, and I'd like to do it in mathematica before attempting it by hand. I've tried Simplify, FullSimplify and Solve, but none of these have done...

Hi all: The solution to my problem requires solving 16 PDE's at once. This shouldn't be hard - but you'll know what my problem is in a minute. The 16 PDE's : ∂/∂t (I+i) + Kn*μi ∂/∂x (I+i) + I+i = I0 ∂/∂t (I-i) + Kn*μi ∂/∂x (I-i) + I-i = I0 for i's ranging from 1 to 8. That comes...

Ok. I know this may sound like a stupid question but for the life of me i can't find definitions for these terms. I am working on developing a PVDF polymer based piezoelectric film and need to know what the terms Uniaxial and biaxial mean. I am using an electrospining method to make the fibers...

What does "Activity" mean in terms of radioactive decay? I came across this term "activity" in text regarding radioactive decay and half lives. It is defined as "number of nuclei in a sample that decay within a given time." That definition if fine but then when presented in a graph life...

Homework Statement Sin x / x = 1/ (2)^1/2 how do I solve for x? I know x is 1.392 The Attempt at a Solution I thought I might be able to use some series expansion, but it gets quite messy. Help please?

Anybody here who could explain to me in the simplest terms what is so special about the Lie group SO(8) and what is meant by triality? I know some Lie and representation theory, mostly from physics books. As I understand there are vector and spinor representations for so(n). If n is even...

Homework Statement "Expressed in terms of the constants in this model, how high is the lowest point of the cable? (Assume the correct dimension to be in metres)"Homework Equations Equation for the shape of a hanging cable. [PLAIN]http://img59.imageshack.us/img59/8672/eqn6142.png edit: P, g...

According to my CM text, Lagrangian Mechanics can be used to derive Newton's laws. We define the Lagrangian as L=T-V. Now, how do we know what T is? Is it defined to be 1/2mv^2? The only way I know how to derive that is using the work energy theorem which feels like 'cheating' since I am...

Homework Statement http://img88.imageshack.us/img88/1679/problemhup.png Homework Equations The Attempt at a Solution [PLAIN][PLAIN]http://img535.imageshack.us/img535/8075/solutionz.png That is how far i have got, using that sinh(x)=1/2(e^(x)-e^(-x)) I have to express h in...

Hello, i am reading on the Bohr Model. There are some parts i just do not understand. in classical mechanics, an object, such as an electron, revolving ina circle may assume an infinite number of values for its radius and velocity. Why is this? Therefore the angular momentum (L= mvr) (...

For multivariate normal distributions, Isserlis' theorem gives us moments in terms of cross-correlations, e.g., \operatorname{E}[\,x_1x_2x_3x_4\,] = \operatorname{E}[x_1x_2]\,\operatorname{E}[x_3x_4] + \operatorname{E}[x_1x_3]\,\operatorname{E}[x_2x_4] +...

Homework Statement If F(x,y)=0 find d^2y/dx^2 in terms of the partial derivatives of F(x,y). Homework Equations dy/dx= -Fx/Fy The Attempt at a Solution I tried to differentiate dy/dx with respect to x again, I thought I can get d^2y/dx^2 . But I couldn't find it. Actually I don't...

Homework Statement Say we have a given sum, S. I have to, as part of a more general problem in a program, find all possible distinct terms x1,x2,x3,x4 which when added, give that sum, and the ways they can be rearranged. Meaning i have to find all 4-tuples that adding one's members gives S...

Homework Statement I want to check that the QED lagrangian \mathcal{L}=-\frac{1}{4}F^{\alpha\beta}F_{\alpha\beta} + \bar\Psi(i\displaystyle{\not} D - m)\Psi where F^{\alpha\beta} = \partial^\alpha A^\beta - \partial^\beta A^\alpha, \ D^\mu = \partial^\mu - ieA^\mu is invariant under charge...

In layman's terms: what does the term "in layman's terms" mean? Please explain that to me. Everyone is using it and I don't get it. It bugs me so much I can't sleep.

So I'm always having troubles with memorizing the three-phase reaction terms, such as eutectic, eutectoid, peritectic and peritectoid. Are there any meanings of the prefix and suffix? Are there any tricks to memorizing the names and meanings (reactions) of these terms? Thanks a lot!

Homework Statement Find the mass and center of mass of the solid E with the given density function p. 38. E is bounded by the parabolic cylinder z = 1 - y^2 and the planes x + z = 1, x = 0, z = 0; p(x,y,z) = 4.Homework Equations The Attempt at a Solution I've been trying to find a solution to...

Hi I wonder if anyone could help me with this. I'm studying a crystal whose luminescence is excitonic in nature. Since the excitation density is high (with femtosecond laser pulses) exciton-exciton interactions have to be taken into account. The following kinetic equations are used to...

Find the acceleration vector in terms of u subscript r and u subscript \theta r = a(4-cos\theta) and d\theta/dt = 6 Im pretty sure to take the derivative: r' = a(4+sin\theta) r" = a(4+cos\theta) what should i do next?

Hi! As a part of a mathematical construction I used the rate of change of F(s) with s, i.e. dF/ds. F and s are smooth functions. The problem is that s(u,v,w) is a function of u, v & w and actually I need to find the rate of change of F with respect to u, v & w. The question is: what does...

Can someone please explain to me how exactly you write down a metric, say the FLRW metric in matrix form. Say we have the given metric here. ds^2 = dt^2 - R(t)^2 * [dw^2 + s^2 * (dθ^2 + sin^2(θ)dΦ^2)] Thank you.

Homework Statement In a sentence like "Tina is tall", "Tina" is an entity (type e), "is" is an identity function and "tall" is an function of entities to truth values (e-> t or et). The denotations are something like this: Tina = Tina' , is = \lambdax.x and tall = tall'. So in lambda terms the...