Model Definition and 1000 Threads

Provided the electron absorbs light of frequency ##f##, if the electron's initial energy was ##E##, is the energy now ##E + hf##? In other words, does it absorb all of that energy?

This function $$\frac{e^x - e^{-x}}{2}$$ is called the hyperbolic sine. I'll refer to it as "hypersine" for short. You could say it "splits the difference" between the rising exponential function e^x and the exponential function run backwards, e^-x which slopes downwards---you take the...

The way the Quantum Graphity model has been explained to me is that I should picture "space" as being represented by the quantum graph, with points in the graph being nodes of communication/interaction between various fields. So, as space expands, do the points become farther apart, separated by...

Homework Statement Hi, this isn't so much a specific question, but rather a project which I'm embarking on. As part of my coursework, I'm required to take up and work on a Physics project, and I've chosen a problem fro the 2011 IYPT. The problem statement goes like this: Build a model car...

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown >[/color] I need some ideas for a 8 grade level physics working model for a group project. I am thinking of flight or electro magnetism.

Why ISO-OSI model is considered as a reference model?

I'm reading the Thomas-Fermi model for many electrons atom. However the book I'm reading doesn't seem to provide a comparison between the result of calculation using this method with experimental measurement. I wonder if this method gives a good approximation at all. So, I would appreciate if...

Usually, I like to bring up Dark Matter whenever I discuss cosmology or astronomy with someone, and whenever WIMPS (Weakly Interacting Massive Particles) are brought up, the person usually responds saying, "but there is no particle on the Standard Model that possesses all the particles of a...

The Ford Model T, affectionately known as the Tin Lizzie, is thought to have been the first widely affordable/accessible automobile. Production of the Model T started in 1908. I'm looking for a cosmo-friendly time unit that is short enough to be real and familiar to all of us, but at least an...

A new experimental result from BESIII finds that there is isospin violation in the decays of J/Psi mesons in a path involving scalar mesons (with a narrow width in tension with world averages) and notes that a previous experiment found isospin violation in another decay chain...

In QM there is no cloning theorem that says "we can't clone or erase quantum state". But in classical macro world we can copy information and erase it. If we should describe classical information as a very complex quantum state then we shouldn't be able to copy or erase it, right? And obviously...

Homework Statement Check on labb41.jpeg (I am not used to formatting my mathematical equations on the web, I can only format in my local text-editing programs). Homework Equations Again, check on labb41.jpeg The Attempt at a Solution I have plot the solution to U(I) as according to the...

Hi! I feel like I've understood none of this stuff! A 1D chain of springs and masses modeling a chain of atoms has a dispersion relation ala ## \omega## ~ ##|sin(k a /2) |##, where ##k## is the wave vector and ##a## the distance between atoms. As far as I have understood, the debye model (in...

Does anyone know where can I find the deduction of all terms of the updated SM lagrangian? Although I have already looked at some lagrangians and theories like local gauge invariance, Yang-Mills theory, feynman rules, spontaneous symmetry-breaking and others, I wanted to see the deduction and...

Hi, I'm trying to get how well a known function fits to a set of data. I'm not interested in the data's line of best fit or anything, I just want to know how close it is to my model. I've tried using curve_fit and linregress but neither really give me what I'm after. My data follows a...

Hi Everyone, I am simulating(using HSPICE) HR neuron model using analog computer technique but I am not getting the required response. I am using uA741 model of opamp and MLT04 model of multiplier. I have tested these components individually and they are working fine. I doubt there is something...

Homework Statement Obtain the chemical potential of water as a function of temperature and volume using the Van der Waals model. Homework Equations μ=∂U∂N The Attempt at a Solution I don't really understand how to do this at all. Any help would be greatly appreciated.

Homework Statement (a) Find energies of states at ##(\frac{\pi}{a},0)##. (b) Find secular equation Homework EquationsThe Attempt at a Solution Part(a)[/B] In 1D, the secular equation for energy is: E = \epsilon_0 \pm \left| V(x,y) \right| When represented in complex notation, the potential...

http://arxiv.org/abs/1409.0868 Holomorphy without Supersymmetry in the Standard Model Effective Field Theory Rodrigo Alonso, Elizabeth E. Jenkins, Aneesh V. Manohar (Submitted on 2 Sep 2014 (v1), last revised 6 Nov 2014 (this version, v2)) The anomalous dimensions of dimension-six operators in...

If we consider de right-handed neutrino there would be more anomaly-free solutions than hypercharge for a U(1)?

This is take 2.0 of the earlier thread, which got a lot of help from George J., Jorrie, Wabbit, Ken G, and others. I'm exploring this simplification of the flat matter-dominated ΛCDM model (basically anything after year 1 million) to see if there is a presentation that would be suitable for PF...

Homework Statement Use the shell model to determine the parity and spin assignments for all the stable isotopes of calcium. Homework Equations n/a The Attempt at a Solution The stable isotopes seem to be 40Ca, 42Ca, 43Ca, 44Ca, 46Ca, and 48Ca I believe all of those isotopes except 43Ca are...

In this thread, I would like to discuss: "which is more natural for a simple cosmological model: taking the long term Hubble time as a timescale (as Marcus has done), or taking the Hubble time as a timescale". I will start by paraphrasing Marcus' OP and replacing his '##\Lambda##-timescale' with...

People queuing to pick up photos at an event. They have a bar-coded docket. By scanning the docket, printing is initiated on one of eight printers. Each printer takes 40 seconds to print a photo - the software chooses the least heavily loaded print queue - or uses a round-robin approach if print...

Homework Statement The question is how to get the mass term for the W Gauge bosons within the Left Right Symmetric Model (LRSM). My main struggle is with the Left-Right Mixing part. So the LRSM has the gauge group $SU(2)_L\times SU(2)_R \times U(1)_{B-L}$ and with an additional discrete...

I am modeling the injection of hot magma sills into the Earth's crust at varying rates (and varying sill heights for each rate). For instance, for a total of 16 km of magma ... 1a-n. 40, 400m high sills emplaced at rate of 5e-3 ma-1, 5e-4 ma-1, 1e-2 ma-1, , 2e-2 ma-1, 3e-2 ma-1, and 4e-2...

Homework Statement (a)Find how ##\rho## varies with ##a##. (b) Show that ##p = \frac{2}{\lambda^2}##. Find ##B## and ##t_0##. (c) Find ##w## and ##q_0##. What values of ##\lambda## makes the particle horizon infinite? Find the event horizon and age of universe. (d) Find luminosity distance...

I have several questions about the process of determining the value of cosmological parameters by LMS fitting tunctions of the form z = f(DL) (where DL is the luminosity distance to astronomical data points), for example, as shown in the following diagram: The five cosmological parameters I am...

I'm trying to get my head around what this means exactly. I've plotted the graph to help verse me with the functions that I've derived. From the free electron model, the wavefunctions are treated as planewaves of the form \psi_\mathbf{k}(\mathbf{r}) = e^{i\mathbf{k}\cdot\mathbf{r}} Due to...

Homework Statement In a course I am studying, I have been asked to calculate the distributed parameters of a line whose Pi model has been provided. I simply quote the question here for clarity of my question: Homework Equations C = \frac{{2\pi \varepsilon }}{{\ln \frac{b}{a}}} R =...

My target is to make a Adaptive cruise controller(ACC) for a car model. So i divided the task into two parts, first--- I made a speed following model, tuned a PID controller for it. Second---- I made a distance following model, tuned a PID for this. Now i integrated the two models into a single...

I'm studying periodic boundaries in 1D for which energy gaps occur, i.e. values of the energy which are not allowed, according to the Kronig-Penney model. My question is when these band gaps occur what happens to the wave-function, because it still has to be continuous, so it can't just...

This is a follow up to another thread (https://www.physicsforums.com/threads/something-about-calculating-the-age-of-the-universe.807250/), but I post it as a separate thread since it is not clear to me (a) this is actually correct, and (b) assuming it is, whether it actually provides a...

1) The Feynman Diagams which provide the dominant contributions are just those with the greater amplitudes? I have the doubt because I read could be more dominant contributions for a single process and I am not sure amplitude would be the same for them. 2) How to compute the cross section in...

Homework Statement On the average, a hydrogen atom will exist in an excited state for about 10-8 s before making a transition to a lower energy state. About how many revolutions does an electron in the n = 2 state make in 10^-8 s? Homework Equations L = mvr = Iω = nħ rn = n2a0/Z The Attempt...

Greetings all, This question can cover many sub-forums here, but I'll put it in General Math since I believe it deals with superposition. Now, I am studying a layered-earth model for programming purposes, and what I mean by that is, for example, we say air is one layer, grass is another...

Homework Statement In a particular region of the Earth's atmosphere, the electric field above the Earth's surface has been measured to be 148 N/C downward at an altitude of 260 m and 165 N/C downward at an altitude of 410 m. Calculate the volume charge density of the atmosphere, assuming it to...

The size of the universe (any time after year 1 million) is accurately tracked by the function $$u(x) = \sinh^{\frac{2}{3}}(\frac{3}{2}x)$$ where x is the usual time scaled by ##\sqrt{\Lambda/3}## That's it. That's the model. Just that one equation. What makes it work is scaling times (and...

I have my state vector containing $$[X, Y, v_x, v_y, \theta, r, a_x, a_y, b_{\theta}]^T$$ and I have them related by $$dX = v_x cos \theta - v_y sin \theta\\ dY = v_x sin \theta + v_y cos \theta\\ dv_x = a_x\\ dv_y = a_y\\ d\theta = r\\ dr = 0\\ da_x = 0\\ da_y = 0\\ db_\theta = 0\\ $$ Now...

I stumbled upon this article: http://www.comsol.com/blogs/exploiting-symmetry-simplify-magnetic-field-modeling/ Since the article does not contain any mathematical formulations, I was wondering how the boundary conditions can be expressed in terms of magnetic vector potential. From what I...

I am trying to build an interactive physics model for thr students in my school. I'm not sure how I can do it. I tried to write it on Java and C# with no success. I don't want it to be a web application. Which tools and languages I should use.

I wasn't sure whether I should post this question in this category or "High Energy, Nuclear, Particle Physics", but I decided to post here, since I want to get opinions from the people who are studying the topics discussed in this category, not the experts on standard model or particle physics...

Looking at an exposition of Kripke semantics, the relationship ||- in a Kripke model is obviously supposed to be similar to the model relation |= . A possible world (a node) looks suspiciously like a model for second-order formulas. But of course it cannot be this simple. What is the connection...

Hi, I was just wondering if someone could help clarify how pi - theta = phi? That is the link to the youtube video I was watching, the guys pretty good check him out if you want to learn how to derive the differential scattering cross section.

You know friedmann equations derived from kinetic energy and potantial energy conservation.I found these shell model for universe.Here I am curious about something. This shell is like a surface of sphere isn't it.I mean it has only surface and that surface mass is m.And we made our equations...

So I am trying to find the depth of immersion of this particular boat model, which has curvilinear edges (subparabolic edges) on each side. The figure of the pontoon is shown below So now when I place this pontoon in water, the height of the water that rises, called the depth of immersion is...

Homework Statement Population Dynamics: Logistic model. Suppose the environmental carrying capacity of the population is 100000 and the growth rate a t=0 is 5%. . If the population starts at 10000, how long does it take for the population to reach half the carrying capacity? dp/dt = A P...

Homework Statement *I am not sure if this should be in the computer science section or here? I am trying to graph the densities, of the Lotka-Volterra prey and predator model, as a function of time, i.e. ##p(t)## vs ##t## and ##q(t)## vs ##t##. Also, the phase space, i.e. ##p## vs ##q##, but...

Is there any c or c++ written spin-flip model for simulation of dynamics in VCSELs available? Thanks.

Dear all, how to 100% know if a process is allowed in standard model? And when a process is allowed, how to know what diagrams contribute, and what of those are the dominant ones? Thank you in advance.