General Definition and 1000 Threads

Hello! I started learning relativity recently and I'm an engineering student. I can't stop drawing similarities between the nature of gravity and behaviour of continuous media in the field of continuum mechanics. Is there some direct connection and if so, has something like this been explored...

Homework Statement Find general solution of the given problem in the picHomework Equations All I need to know is where they found the fundamental set of solutions. The Attempt at a Solution All I need to know is where they found the fundamental set of solutions. Please see pic. All I want...

Hello, a derivation of the lorentz transformation for an arbitrary direction of the relative velocity often makes use of writing the spatial position vector of an event as the sum of its component parallel and perpendicular to the velocity vector in one inertial frame and then transforming both...

Under some circumstances, whenever I call DEVCCG to diagonalize a general complex matrix, the program gets stuck inside and never returns. I do not even get out an error code so that I may continue with the rest of the program. I assume the iterative diagonalization inside the procedure does not...

I will have 1 week to study for general GRE. I hear it has very little impact on admission. Is this true? Is that enough?

Hello! I am in 3rd year of engineering in Biochemical engineering. I want go for a Ph.D in High Energy Physics in the US (and I will be an international applicant). So, I will have to write both the General GRE and Physics GRE. I want to know how important is the General GRE score. Do I need to...

In his book (Relativity) published in 1920 Einstein said that in General Relativity the speed of light is affected by gravity and therefore isn't a constant: In the second place our result shows that, according to the general theory of relativity, the law of the constancy of the velocity of...

Hi, I want to be an engineer but am not completely decided on what kind. I was wondering if I get a general engineering degree and get a specialization in electrical engineering, will this allow me to pursue a job as an electrical/electronics engineer out of college? Any help would be...

This is using dimensional analysis, and I'm stuck on this question, but I'll show what I have so far. The questions is: If there is 3.34x1022 atoms in a CH3OH sample. What is the mass of this sample, how many moles are there of this sample, and how many molecules are in this sample? Initially...

DaleSpam submitted a new PF Insights post Understanding the General Relativity View of Gravity on Earth Continue reading the Original PF Insights Post.

Pretty straightforward question. The Einstein-Hilbert Action says that the Lagrangian for Gravity is ##L=R(-g)^{1/2}## where ##g## is the determinant of the Metric Tensor and ##R## is the Ricci Scalar (Actually I am not sure if the determinant of the metric should be included there). From this...

This feels like a strange question but it's something I've often wondered so I was curious about other peoples opinions. I'm currently half way through a Chemistry degree and have been doing reasonably well. However I feel that the chemistry knowledge I have is only good for helping me answer...

Evening all, I'm blessed to be doing well in school, on time to graduate, with no major setbacks. However, I have a few worries that I could use some sage advice on. I'm currently a junior in EE and CE. My first BS was in Exercise Science with a gpa of 3.0. I currently have a school GPA of 3.8...

Hello Everyone, I am working through Schutz's A first Course in General relativity. On page 294 he defines the equations (11.52) to simplify equation (11.49) and calculated the deflection of light around the sun. I know that he wants to simplify it and also to preserve the effect of the mass M...

Stanford's Physics profile on GradSchoolShopper.com lists their incoming class's GRE scores as: "The average GRE scores for admitted students in 2014–15 were: Verbal-171, Quantitative–176; Analytical–4.42; Physics Subject–928." How do we interpret these general GRE scores? Everywhere I look...

Hi all, I was unsure where to put this thread as I read the main topic title in the topology/analysis forums and decided to post it here. I am looking for a chart/graph/website that helps me understand the basic terms such as: -neighborhoods -Boundary points -Singularity points - "Function is...

What is the difference between General metric gαβ and flat metric ηβα in GR? Elaborate answers are appreciated.

Background: Undergraduate majoring in physics to work in research, hopefully in astrophysics or cosmology. 1.5-2 years behind where I should be academically and (if all goes well) about to start courses relevant to major. My questions are these: 1) How should I study basic mathematics...

Hi all, I'm preparing for my bachelor thesis. I have to study some articles for the mimetic dark matter. But before this my advisor sad to me to study from Landau Vol. 2 Field Theory some General Relativity(it's my first time that I study it), chapters 10 and 11(Particles in a gravitational...

Love to learn GR but lack or dislike doctoral mathematics. Here is a list of books through which one can catch the essence of the subject and also learn its mathematics without much pain to the eyes- 1. At first, one should DEFINITELY refer to...

Hello! (Wave)I found the following in my lecture notes:$$u_t=u_{xx}, x \in \mathbb{R}, t>0 \\ u(x,0)=f(x)$$ $$u(x,t)=X(x)T(t)$$ $$\Rightarrow \frac{T'(t)}{T(t)}=\frac{X''(x)}{X(x)}=-\lambda \in \mathbb{R}$$ $$X''(x)+\lambda X(x)=0, x \in \mathbb{R}$$ $$X \text{ bounded }$$ The characteristic...

Hello! I have two uncertainties (hehe) about two concepts from a QM time-dependent Schrödinger equation video. The video is I cannot move on further if I don't fully grasp everything he explains in the video. My two issues are: 1) The general solution for the time-dependent Schrödinger...

I have just been asked why we use curvilinear coordinate systems in general relativity. I replied that, from a heuristic point of view, space and time are relative, such that the way in which you measure them is dependent on the reference frame that you observe them in. This implies that...

This week (Jun 7-12, 2015) at Penn State: General Relativity and Gravitation: A Centennial Perspective http://event.gravity.psu.edu/index.shtml There will be a live stream of the plenary sessions. For the updated schedule and link to the streams, consult...

I am looking for a reference describing the far-field electric and magnetic field of a dipole. However, I want a general formula for an arbitrary scalar function, and not specifically the usual formula which assumes a continuous sinusoid: $$ \mathbf{B} = -\frac{\omega^2 \mu_0 p_0 }{4\pi c}...

hi, I looked up the existence and uniqueness of nth order linear ode and I grasped the idea of them, but still kind of confused why we get n numbers of general solutions.

Hi, GR explains the perihelion precession of Mercury, the deflection of light and the gravitational redshift pretty accurately. However, predictions for larger scales seem to be quite wrong, and physicists introduce stuff like the cosmological constant, dark matter and energy. Why are they...

Say you have a box with a round marble on it. Classically I would have no problem describing that, but how is it done in general relativity? Do one just assume that the marble is round and that the box is ... boxy... in the 3D subspace at a certain foil of time? (Foliation is the correct term...

Hi everyone, I am trying to find the general solution for the following ode: y'' +gy' + 10y = e2xcos(x) The solution states that the answer is y = 1/145 (5cos(x) + 2sin(x))e2x + (Acos(x) + Bsin(x))e-3x I was able to correctly find the homogeneous part of the equation as e-3x (Acos(x) +...

Hello! I am reading GR and got confused about the principle of General Covariance. The principle of General Covariance says that the laws of physics take the same form in all reference frames. Since the laws are same in all reference frames, any experiment performed should give identical...

I am compiling a list of schools to apply to once I finish my lower-division coursework at Community College. Harvey Mudd is among the schools I am considering. I know Harvey Mudd is highly-regarded and their engineering program is ranked number 1 among schools where a master's degree is the...

The general Uncertainty Principle is written in Griffiths' Intro to Quantum Mechanics 2nd Ed. Section 3.4, Page 109, Eq. (3.139) without dependence on the wave function itself. While it is written in R. Shankar's Principles of Quantum Mechanics 2nd Ed., Section 9.2, Page 239, Eq. (9.2.12) with a...

Let f and g be twice differentiable real-valued functions. If f'(x) > g'(x) for all values of x, which of the following statements must be true? A) f(x) > g(x) B) f''(x) > g''(x) C) f(x) - f(0) > g(x) - g(0) D) f'(x) - f'(0) > g'(x) - g'(0) E) f''(x) - f''(0) > g''(x) - g''(0) The correct...

Hi all, I have been teaching myself some programming by using Alice 2.3 freeware. My question is whether/to what degree, the structures used in Alice generalize: Alice's main items are : methods, events, functions, parameters, variables. Is this also the case for general programming...

2nd order ODE has a form y''+p(x)y'+q(x)y=f(x)and if we assume f(x)=/=0 for every x, then y''+p(x)y'+q(x)y=/=0 so in this case we can't specify general solution of 2nd order ode?

"In quantum gravity, the problem of time is a conceptual conflict between general relativity and quantum mechanics. Roughly speaking, the problem of time is that there is none in general relativity. This is because in general relativity, the Hamiltonian is a constraint that must vanish. However...

http://arxiv.org/abs/1503.08640 New first order Lagrangian for General Relativity Yannick Herfray, Kirill Krasnov (Submitted on 30 Mar 2015) We describe a new BF-type first-order in derivatives Lagrangian for General Relativity. The Lagrangian depends on a connection field as well as a...

I found the picture but I painted very wrong .

I read somewhere that speed can be higher then c in General Relativity.Can you show me a website

In paper Phys. Rev. B 29, 3153 – Published 15 March 1984 general potential form is introduced and from that form one can obtain different class of period potential V(u,r)=A(r)\frac{1+e\cos (2\pi u)}{[1+r^2+2r\cos (2\pi u)]^p} ##-1<r<1## , where ##r## is real number, ##m,p## are integers...

To be honest, I don't know any physics. I am a high school student who has taken high school physics, but America's education system isn't known for teaching much more than Newton's laws. I have, however, taken Multivariable/Vector calculus, so I have a decent math background. I was wondering...

I read about relativity and some people claim to be incomplete so what is the incompleteness.

Space does not exist, so time can http://arxiv.org/abs/0909.1861 Can someone explain to me, what this article means by "space does not exist"?

Is there something in General Relativity whose value is 9.8 m/s2 at the surface of the Earth?

The more work I do in the field of EE, the more I realizing that my general circuit analysis skills are usually the root of my confusion and could use improvement. Even after putting on my break-a-big-problem-into-smaller-pieces hat, I still find myself confused about the relationships between...

I am currently junior in high school and I am thinking about double major in physics and computer science. But there are some generals questions that I don't really understand. As far as I understand for each major you have classes that you have to take. If the classes overlap then you just...

Homework Statement See attached picture Homework Equations For any rectangular prism, the formulas are the following: Surface Area = 2(lw + wh + hl); l is length, w is width, and h is height. Volume = lwh; l is length, w is width, and h is height. For a square-based prism, the formulas are...

My friend and I were discussing this, and google didn't seem to reveal any result. Much like how Bohr's theory managed to derive the Rydberg constant without much effort, has the gravitational constant been found in terms of other quantities yet? It just seems bizarre that Newton proposed a...

Homework Statement I am doing an egg drop project write up, and one of the components is to draw a general egg drop device diagram, and to write down the general forces which would act upon the egg drop device, both inside it, and outside it. Any suggestions? Homework EquationsThe Attempt at a...

I have little problem in understanding emf in a circuit. There are three types of emf mentioned in textbooks and the first two are very similar: 1. The emf provided by a battery or other stationary power source. The emf is actually the voltage difference provided to the circuit. 2. The emf...