Model Definition and 1000 Threads

A model is an informative representation of an object, person or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin modulus, a measure.
Representational models can be broadly divided into the concrete (e.g. physical form) and the abstract (e.g. behavioural patterns, especially as expressed in mathematical form). Of particular importance in the modern context, conceptual models are central to philosophy of science, as almost every scientific theory effectively embeds some kind of model of the physical or human sphere.
In commerce, a model might instead reference a specific version or configuration of a product offering, rather than functioning as a representation of something else.
In taxonomic settings (e.g. biology, architecture, art) a model is sometimes a particular instance of a set of related entities (species, built structures, artistic compositions) chosen as a convenient reference point around which to build discourse; such a model is almost always chosen to typify some central tendency of the group, exemplify the group's defining characteristic, or reify the group's historical lineage.
Kinds of models include:

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  1. U

    Calculating Amplitude in Standard Model

    Hi! I'd like to ask you if my calculation of the amplitude on the mentioned process in the Standard Model is correct. The three diagrams contributing at lowest order should be where in the middle one the two Higgs boson are NOT forming a quartic interaction vertex. My attempt at calculating the...
  2. L

    I Fermi Gas Model: Energetic Degeneration & the Pauli Exclusion Principle

    In the fermi gas model, there is assumption that there is a 3D potential well, but there is "energetic degeneration" for each three index "nx, ny, nz". Now the problem is with that image, if there is degeration, for some level En there may be 10 distinctive state with same energy, so there is 20...
  3. Aceix

    MATLAB IEEE 13 bus MATLAB/python model

    Hi guys, I'm investigating balancing voltages on a network by injecting or absorbing reactive power with distributed generation. Is there a base python or MATLAB code model I can leverage? Thanks
  4. D

    How to automate tests on a physical model without real data

    I want to code up a (physical) model of an aircraft or car, and I want to create an automated integrated test to check that the code produces reasonable and realistic results. For example, I want to check that the path taken by the aircraft or car is physical and reasonable. However, I don't...
  5. W

    A Ground state of the one-dimensional spin-1/2 Ising model

    Hi, I know that the ground state of the spin-1/2 Ising model is the ordered phase (either all spin up or all spin down). But how do I actually go about deriving this from say the one-dimensional spin hamiltonian itself, without having to solve system i.e. finding the partition function? $$...
  6. M

    MHB Model the situation with a Laplace room

    Hey! 😊 An ice cream parlour offers 12 different types of ice cream, including vanilla ice cream. There are 8 people passing by, each of whom chosses a ball of ice cream. Of course, the ice cream parlour has taken good precautions, so that there is enough ice cream from each variety. Model the...
  7. A

    I Question about the Bohr model of atom and and electron in an orbital

    I have a question about what happen when an electron in the Bohr model of atom, gains energy because for example is "hitting" by a photon. Electron have an energy, and it is the sum of potential and kinetic. When they gain energy, they gain potential energy so they go further away from nucleus...
  8. A

    I Drude model with and without an electric field

    Why in the Drude model without e-field no energy is transfer by electrons to ions, but when there is an e-field electrons transfer energy to ions ?
  9. Dario56

    Owens - Wendt Model for Surface Energy of Solid - Liquid Interface

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  10. S

    A Any model or theory in physics akin to "Law without law"?

    When trying to explain from where did all the laws come from, John Wheeler proposed the anaphorism of "Law without law". He proposed that at the "beginning" there were no laws whatsoever, only pure chaos, and that they emerged from randomness and chaos when our universe was created. In his own...
  11. Z

    A New model for superconductivity

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  12. physics1999

    I Particle and wave model understanding -- help please

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  13. Dom Tesilbirth

    How to find the partition function of the 1D Ising model?

    Attempt at a solution: \begin{aligned}Z=\sum ^{N}_{r=0}C\left( N,r\right) e^{-\beta \left[ -NJ+2rJ\right] }\\ \Rightarrow Z=e^{\beta NJ}\sum ^{N}_{r=0}C\left( N,r\right) e^{-2\beta rJ}\end{aligned} Let ##e^{-2\beta J}=x##. Then ##e^{-2\beta rJ}=x^{r}##. \begin{aligned}\therefore Z=e^{\beta...
  14. L

    Stepper motor current/torque model

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  15. Safinaz

    A How Randall-Sundrum model has solved the hierarchy problem?

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  16. P

    A What are the difficulties of the rishon model?

    The risbon model model was inveted by Harari in 1981. It is a theory that lies beyond the standard model and explains the existence of quarks and leptons on the basis of jusr 2 elementary particles, the T- and V-rishon (heuristically that is, like the quark model did once for the plethora of...
  17. E

    Here is a 3D model I made of a large industrial steam turbine

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  18. C

    I Implementation of Correlated Gaussian Random Fields Model

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  19. Johan M

    Simplified rocket lateral dynamics model sign convention

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  20. M

    MHB Finding the Period of a Sinusoidal Model for Ice Cream Sales

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  21. J

    B Sine-Gordon model for better understanding of special relativity?

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  22. C

    UAP Report and the Standard Model

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  23. LucaCaiaffa

    I Motorcycle model and tire force

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  24. N

    Write a Linear Model For this Data

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  25. N

    Linear Model for Male Child Brain Weight from Age 1 to 3: y = 150t + 300

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  26. E

    Here is a 3D model of 13th century French cathedral that I made

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  27. person123

    Ball-and-Stick Quasicrystal Model

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  28. J

    I Particle and Event Horizons in the ΛCDM Model

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  29. Viky1147

    Calculate scaled down human model weight for practical experiment

    Hello, I need to scale down a human model by 1:20 i.e, i need a human model of 9 cm height scaled down. Help me calculate the weight of the 9 cm scaled down human model. Regards, Viky
  30. chaksome

    I Exploring the Spin-1 XY Model: Understanding the Hamiltonian and Its Parameters

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  31. Magnetons

    Why do we use Bohr's model of the atom in electrostatics?

    Why we use Bohr's model of atom in electrostatic?
  32. UFSJ

    A Magnetic exchange interaction by first principle (Blume-Capel model)

    Hi guys. I work with statistichal mechanics, applying classical spin models, as Ising model. I'm trying a collaboration with a colleague that works with first principle calculations. Does anyone know how to calculate the exchange interaction and anisotropic constant (of the Blume-Capel model)...
  33. Haorong Wu

    How to model light from a star?

    I am aware that a laser could be modeled as a Gaussian beam, e.g., $$E=E_0\frac{w_0}{w_z}\exp (\frac {-r^2}{w^2_z}) \exp (-i(kz+k \frac {r^2}{2R(z)}-\psi(z))).$$ Now I want to study the propagation of light emitted from stars. But I am not sure how to model it, especially by some kind of...
  34. Limebat

    Need help on model HHO propulsion systems

    Hey all, Lime here. I've been getting into HHO for a while, and I think I almost have my DIY generator up and running (waiting on eBay 18650 batteries). I was thinking a fun little project is to play around with a few concepts with my new found combustion source. Anybody here know a good way to...
  35. M

    I Is the model presented in the thread consistent with QM?

    I started another thread on this but it went off into other topics. Hoping to focus on the math here, specifically whether or not the model presented in here is consistent with QM. Let's measure the polarization at the same angle ##\alpha = \beta = \pi/3## (##\varphi_1=0...
  36. J

    I Temperature of the Universe based on the ΛCDM Model

    Using Jorrie’s calculator we can get the following T vs. t graph up to z = 20,000: In a log-log plot the above curve is represented by the red solid line in the figure shown below: The dashed line shows results for the small a limit using the equation T = 2.725 K / a. Here are some...
  37. M

    I Model used to refute Bell's theorem

    I’m looking over a recent paper mentioned in another thread. It claims to refute Bell’s theorem. At first glance, the model presented in the paper doesn’t appear consistent with QM. Here’s a simple example. Suppose we set both polarizers to the same angle ##\alpha = \pi /4##. In the model...
  38. F

    Question about a simple model for for back EMF

    Summary:: I've found an exercise about sparks caused by back emf. The exercise is based on a mathematical model of the current flowing in the circuit around the time when the switch is closed. I'm wondering to what extend that model is realistic The exercise I'm referring to proposes this...
  39. Z

    My model of bicycle spokes breaking

    The following equation comes from a paper by HP Gavin. LOG(stress)=-.3LOG(cycles)=4.12+.072Z where Z is the normal distribution. If you only have 1 spoke you place it in the middle of the normal distribution that is a Z score of 0. So if you have 36 spokes you divide the normal distribution into...
  40. D

    How Does Lorentz's Equation Transform into Cauchy's Law?

    Hello fellow physicists, I need to prove that when ##\omega << \omega_0##, Lorentz equation for refractive indexes: ##n^2(\omega) = 1 + \frac {\omega^2_p} {\omega^2_0 - \omega^2}## turns into Cauchy's empirical law: ##n(\lambda)=A+\frac B {\lambda^2}## I also need to express A and B as a...
  41. Prez Cannady

    A Question about extragalactic stellar motion

    We have direct mass models of stellar motion inside of galaxies (basically, find a happy medium between a sphere and a disc). And of course dark matter corrections to explain the deviation between model and observation. Is there any pattern at all to the motion of extragalactic stars passing...
  42. M

    A Just standard model and gravity, up to high energies? An update

    A recurring topic in particle physics, is the possibility of a "desert" above the electroweak scale: no new physics (new particles, new forces) until the grand unification scale or the Planck scale. It's important to remember that the Higgs boson mass was correctly predicted three years in...
  43. J

    A 1D transverse-field Ising model - classical vs quantum differences?

    The 1D transverse field Ising model $$ H(\sigma)=-J\sum_{i\in \mathbb{Z}} \sigma^x_i \sigma^x_{i+1} -h \sum_{i \in \mathbb{Z}} \sigma^z_i$$ is usually solved in quantum way, but we can also solve it classically - e.g. parametrize angles of spins ##\sigma^x_i = \cos(\alpha_i)...
  44. E

    3D model I made of the Fukushima Daiichi control room

    I spent the past week and a half making this 3D model using a program called Blender 3D, or the Fukushima Daiichi nuclear power plant control room.
  45. Admiralibr123

    I Algorithmic model for primary decay chains

    I have seen "radioactivedecay.py" python library which employs measured experimental data for its calculations. I have seen models that solve the system of differential equation with numerical algorithms to predict the proportion of nuclides at any given time. But I have yet to see a...
  46. J

    Model with SU(2) gauge symmetry and SO(3) global symmetry

    1.) The rule for the global ##SO(3)## transformation of the gauge vector field is ##A^i_{\mu} \to \omega_{ij}A^j_{\mu}## for ##\omega \in SO(3)##. The proof is by direct calculation. First, if ##A^i_{\mu} \to \omega_{ij}A^j_{\mu}## then ##F^i_{\mu \nu} \to \omega_{ij}F^j_{\mu\nu}##, so...
  47. George26

    Engineering Deriving the Wassiljewa mixture model equation

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  48. D

    B 2D Model of the Universe as an expanding ball

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  49. TheArrow

    Misc. Designing a Model Aircraft: Calculating Thrust and Lift for an Efficient Flight

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  50. DnA 9413

    Writing: Input Wanted How to model Eccentricity, Obliquity and Recession in Excel

    Hi Everyone, I'm writing a sci-fi book that looks at humanity's response to the end of life on Earth and their voyage to a new home. The first part of the book is how a large mass of dark matter in the relative vicinity of Earth (50 light years?) starts the process of extending the...
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