Model Definition and 1000 Threads

Is there a meta-mathematical model of ZC (Zermelo Set Theory with specification scheme and axiom of choice but not remplacement and) that includes a minimun quantity of Gödel constructible elements of L hierarchy with all the ordinals until ω⋅2 and that it "lives" in all the meta-mathematical...

From what i have read, right or wrong, there seems to be an universe (age) problem for modern cosmologists, This is the best paper i have found on the subject. http://arxiv.org/pdf/1402.6433v3.pdf Abstract Many dark energy models fail to pass the cosmic age test. In this paper, we investigate...

Homework Statement Consider an HMM with two possible states, “R” and “G” (for “regulatory” and “gene” sequences respectively). Each state emits one character, chosen from the alphabet {A,C,G,T}. The transition probabilities of this HMM are: aRG = aGR = 1/4 aRR = aGG = 3/4 The emission...

¿Is there a minimal standard methamatematical model for Zermelo set theory in the sense that the other models contains this model ?

I have a question about the logistic fit they used on this paper: http://online.liebertpub.com/doi/pdf/10.1089/cmb.2005.12.1047. Its PDF page 5, or journal page 1051. They define all the variables and then say x0 and b define the shape of the model. If I am fitting 30 cycles of PCR data how am I...

Homework Statement [Picture of Problem](http://i.imgur.com/7q4yj8O.png) Homework Equations [/B] * It is dealing with drawing the DC model of a circuit * Now i know when drawing a DC Model, all capacitors are open (or ground) and AC sources are grounded as well. * In this specific problem, i...

I have looked around for help with this, including on existing threads, but I can't quite find what I'm looking for. I know that in the nuclear shell model we fill the shells in the same way as with electrons, so 2 protons in the first and 6 in the second etc, with the same being true for...

Homework Statement Homework Equations Whenever assuming a diode is "on", replace that diode with a 0.7 voltage source. Whenever assuming a diode is "off", replace that diode with an open circuit. The Attempt at a Solution The problem is pretty straightforward but the format of the circuit...

Hi all This is probably a naïve question to ask, but I am puzzled by it and need an answer. The first time I encountered the term 'partition function' that was in context of Boltzmann distribution. But the same formulas of manipulating a partition function ( to obtain free energy, temperature...

For a wavefunction at the Brillouin boundary we have: \langle k|H|k\rangle = \epsilon_0 (\vec k) \langle k'|H|k'\rangle = \epsilon_0 (\vec k+\vec G) \langle k'|H|k\rangle = V_G = \frac{1}{L^3} \int e^{i(\vec k - \vec k') \cdot \vec r} V(r) d\vec r \langle k|H|k'\rangle = V_G^* Using...

Hi, I was wondering if anyone here had any experience (preferably intimate) with the Weber-Davis solar wind model, i.e. ...

Homework Statement In this lab various thicknesses of a few materials are placed between a source of gamma radiation and a couple different detectors. It is reasonable to assume that some small change in the thickness of the shielding would produce a proportional change in the intensity of the...

Hi I was wondering why are model rocket engines disposable after one use? Is it because it is more economically feasible to buy a new model rocket engine than to repair a used one because the process of using a model rocket engine always ruins it? Also, if it is the case that model rocket...

Hey Guys, I know its an Odd Question but i have an assignment where i should be doing a tennis serve and taking a video of it, importing it on laptop and draw graphs and make conclusions about its position with time and compare my results with theories, so any suggestions on how to do that, in...

If your rocket is of a certain power range you need a certain license. My question is of you need these license's if you are only doing horizontal thrusts tests and never actually launching it vertically into the air?

Homework Statement a) Assume that a substance in a closed container is at thermal equilibrium with about half of its molecules in the gas phase and half of its molecules in the liquid phase. How could you use the Particle Model of Thermal Energy to explain which molecules are moving faster, on...

It is touted that modern physics has discovered what is actually responsible for force which are particles. Yet, the force responsible for EM is "virtual" particles and then you have the "W" particle in Electroweak. So it seems the issue is not all that clear. I know how the math works, but I am...

I don't think I've fully grasped the underlying ideas of this class, so at the moment I'm just sort of flailing for equations to plug stuff into... Homework Statement Show that in the mean field model, M is proportional to H1/3 at T=Tc and that at H=0, M is proportional to (Tc - T)1/2...

I have this problem for my reactor design course and I need some help wrapping my head around it. We have to design a plug flow reactor (PFR), which can be modeled as five equal volume CSTR's in series. The PFR has an inlet volumetric flow rate of ##q_{in}## which contains species ##A_i, i =...

What's the simplest, most direct way to derive the lagrangian of the SM? I saw earlier today: L[S M] = L[Dirac] + L[mass] + L[Gauge] + L[Gauge/psi] That seems like a good starting point. I like it because it says the SM Lagrangian is simply the sum of four lagrangians. The next step...

Which of the following do you prefer as possible solution to the cosmological constant problem or why QFT computes vacuum energy density that is 120 magnitude more than from observational data? Sometimes I think the metric (1.a) needs to change, but on other days I think QFT needs to change...

1. Problem Statement: Consider the scattering of an alpha particle from the positively charged part of the Thomson plum-pudding model. Let the kinetic energy of the α particle be K (nonrelativistic) and let the atomic radius be R. (a) Assuming that the maximum transverse Coulomb force acts on...

In practice I’ve found that a valid gravitational model of orbiting bodies only works when the force is computed with only the other mass and not both masses. Thus, the original equation does not work but the modified one does. Is using one mass ok or am I doing something wrong? thanks. [also...

Hi Guys, I'm looking into the Lorentz model Since the acceleration/de-acceleration of electron can cause radiation hence create force, can anyone tell me how to modify the above equation to include the term of radiation force? Thanks. jack

Hey, I've a short question. Is there any research attempting to constrain models of dark matter by assuming stable solution for the universe? I'm interested in knowing whether this gives any sensible constraints on the dark matter models. I'm still fairly new to studying dark matter but as I...

Hi i'm looking for some references (prefer books) or explanations as to how one couple electrons so an EM field in a second quantized formalism tight binding model. from what i know, one need to replace the hopping parameter with the same parameter multiplied by an exponent of the line integral...

Hi Guys, I'm new on this forum, currently studying Aerospace Engineering and am trying to produce the model of a radioisotope thermoelectric generator using numerical methods to solve the heat conduction equation as part of my research. The way it works is that I have a radioisotope source in...

Georgi in his book, for reference: http://www.people.fas.harvard.edu/~hgeorgi/weak.pdf he says that it is not obvious that the form of $$\Sigma = \sigma + i\tau_a\pi_a$$ is preserved under (2.6.6) $$ \delta \Sigma = i \epsilon_L^aT_a \Sigma - i \Sigma \epsilon_R^aT_a$$ But then he said, "But it...

this is related to the following thread: https://www.physicsforums.com/threads/gravitys-reaction-force.28395/ (but it doesn't seem to accept more replies so i posted here) my cuestions are: - ¿if gravity depends on mass, how come we define a black hole as an object so massive that photons (mass...

I was wondering if there is a way to build a model rocket that has the capabilities to reach space (not go into orbit though). It would seem to be very difficult to reach space from the ground, but if you launch it from a balloon some 30 miles up, would it be possible, if not, any easier?

Are there simple governing equations for FETs like there are for BJTs, and if so, what are they? For example, in the BJT case we have IC = β×IB IE + IC + IB I'm sure it depends on the type - MOSFET, JFET, etc. - so anything anyone could contribute would be helpful. From what I understand, the...

Is it possible to model memristance using op-amps? I searched google but found nothing.

Homework Statement B/c the textbook mentions that Einstein's heat capacity equation obeys a law of corresponding states...but, I don't really understand how this can be...I've tried to figure out, to no avail...so, any help would be welcome! Homework Equations Cv/NkB =...

Hello colleagues, hope you can help me. The Dicke model describes a system of N two-level atoms cooperatively interacting with a single mode of an electromagnetic field as follows...

Homework Statement Homework EquationsThe Attempt at a Solution For a), I initially tried to consider the component of the gravitational force of the moon acting normally to the Earth's surface. This would be F=F_0 cos(theta) where theta is the angle between a horizontal line going through A...

Hi, I'm really struggling to comprehend how the Bohr model solves the problem of accelerating electrons losing energy and decaying into the nucleus. I've read through a lot of discussions on line and on PF and all I keep on reading is stuff like, the quantization of energy levels leads to a...

Here is a question about the possible limitations of physics, specifically about whether a theory of everything can actually explain everything. Assume we have a theory of everything. Now, consider an electron e with all the relevant properties. Now, our theory of everything, being mathematical...

What is the difference between Hubbard and tJ model? Does anyone knows?

Hello loves, I know there are post very very similar to this, but I just needed some help understanding it. any help is truly appreciated. 1. Homework Statement A model rocket is launched straight upward with an initial speed of 50 m/s. It accelerates with a constant upward acceleration of 30...

Hello guys, actually I'am working on a model to describe the creep-behaviour of a concrete specimen. This model is based on a 'generalized maxwell-chain'. I attached a picture, where you can see it: The acting load is the tension \sigma, while E_0 and E_1 are the stiffnesses of the...

can anyone refer me to some good introduction to this O(N) model and also large N expansion. Thanks.

I am trying to build a model rocket for a contest. It goes up as a rocket but comes down as a glider. Vertical takeoff. Does not jettison any parts. Should glide down in large slow graceful circles. Judged based on total hang time. I have been able to avoid a outright nose dive by putting the cp...

I read in a magazine (namely Scientific American) that the Standard Model successfully combines Quantum Mechanics with General Relativity, but I also remember reading in The Elegant Universe that the Standard Model fails to do so. What's true and what's not?

Homework Statement I was asked to 'Use a very simple model to find how the Earth’s temperature should vary with latitude.' Homework EquationsThe Attempt at a Solution I was thinking about flux and how this should be proportional to the temperature. So I first thought about the area that is...

Hello, I've unfortunately a trivial question, but one I couldn't answer by reading my references. In the Weinberg-Salam model, why do we take the left electron and neutrino spinors to form a doublet? I'd like a "physical" answer, if possible, and a more formal one, which I think is based on the...

I want to calculate the change of state for N2 and dry air at pressures above 200 bar with a max of 300 bar. Ideal gas law is not applicable at these pressures, but looking at real gas models there are several to choose from, among others: Van der Waals Redlich-Kwong Virial Bender Can someone...

What is the full Lagrangian of Standard Model?How can we build a Lagrangian that satisfies both the symmetry SU(3) and the symmetry SU(2) at the same time?

Homework Statement A half-full water tank mounted on the top of a building is modeled as shown below. Find the shear force it can produce? m = 500 kg k = 1000 N/m model: https://app.box.com/s/qke2kbwag2mp9a23kkqq Homework Equations Transfer Matrix Method: Point & Field Matrices...

First assumption: the change of magnetic flux in time outside a conductor is zero. Last semester in circuit analysis we treated circuits with sinusoidal voltage variation as steady state circuits while using the phasor notation. But now that i know electrodynamics i begin to doubt my concepts...

We, as high school students have been taught that-because Bohr's model of an atom assigns specific orbits for electrons-that it is better than Rutherford's model. But what Rutherford failed to explain was why electrons don't emit EM waves & fall into the nucleus. I don't see how the introduction...