What is Model: Definition and 1000 Discussions

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. 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...
  2. 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 ?
  3. Dario56

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

    Owens - Wendt model is used for calculating surface energy on liquid - solid interface and it is given by following equation: $$ \gamma_{sl} = \gamma_s + \gamma_l -2(\sqrt {\gamma_l^d \gamma_s^d} + \sqrt {\gamma_l^p \gamma_s^p}) $$ So, if we use liquid and solid of known surface energy as well...
  4. 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...
  5. Z

    A New model for superconductivity

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  6. physics1999

    I Particle and wave model understanding -- help please

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  7. 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...
  8. L

    Stepper motor current/torque model

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  9. Safinaz

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

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  10. P

    A What are the difficulties of the rishon model?

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  11. E

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

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  12. C

    I Implementation of Correlated Gaussian Random Fields Model

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  13. Johan M

    Simplified rocket lateral dynamics model sign convention

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  14. M

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

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  15. J

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

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  16. C

    UAP Report and the Standard Model

    Here is the report submitted https://www.bbc.com/news/world-us-canada-57619755 "UFO report: US finds no explanation for sightings The US government has said it has no explanation for dozens of unidentified flying objects seen by military pilots. A Pentagon report released on Friday says of...
  17. LucaCaiaffa

    I Motorcycle model and tire force

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  18. N

    Write a Linear Model For this Data

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  19. N

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

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  20. E

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

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  21. person123

    Ball-and-Stick Quasicrystal Model

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  22. J

    I Particle and Event Horizons in the ΛCDM Model

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  23. Viky1147

    Calculate scaled down human model weight for practical experiment

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  24. chaksome

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

    I am reading a paper about quantum many-body scar based on the spin-1 XY model. I noticed that he write down the Hamiltonian as follows $$ H=J \sum_{\langle i j\rangle}\left(S_{i}^{x} S_{j}^{x}+S_{i}^{y} S_{j}^{y}\right)+h \sum_{i} S_{i}^{z}+D \sum_{i}\left(S_{i}^{z}\right)^{2} $$ which is a...
  25. Magnetons

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  26. UFSJ

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

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  27. Haorong Wu

    How to model light from a star?

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  28. Limebat

    Need help on model HHO propulsion systems

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  29. 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...
  30. 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...
  31. 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...
  32. 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...
  33. 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...
  34. D

    Cauchy's law from Lorentz model

    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...
  35. 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...
  36. 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...
  37. 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)...
  38. 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.
  39. 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...
  40. 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...
  41. George26

    Engineering Deriving the Wassiljewa mixture model equation

    Hello, I'm in the process of deriving the Wassiljewa mixture model equation for a binary solution. I have to find an expression gE which represents the excess g term which is added to gIS, the ideal solution, to predict the g for a real solution. I have gotten up to a point but now I'm stuck...
  42. D

    B 2D Model of the Universe as an expanding ball

    Can a simplified 2D model of our universe be an expanding ball? Where the surface of the ball is the 2D universe time is the vector normal of the ball measured in imaginary number i. So light will move at 45 degree to any vector normal. The expanding ball gets bigger because time is causing it...
  43. TheArrow

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

    Hello Everyone, I'm planning on designing a model aircraft that would be powered by an Arduino and electric motor. I'm interested in pursuing an aerospace degree and I figured the best way to get a headstart would be be to dive right into a project. This is also probably overthinking/overdoing...
  44. 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...
  45. amjad-sh

    I Two-site "tight-binding model"

    Hello, I've been asked to compute the time-resolved RIXS spectrum for an electron on a two-site "tight-binding model" in the presence of a strong electric field. What it is meant by the term two-site here? does it mean a system of one electron and just two atoms? Thanks
  46. L

    A Ising model open chain and periodic boundary conditions

    One dimensional Ising model is often treated as open chain system with free ends. Then when external field is added it is treated with cyclic boundary condition. Can someone explain me are those methods equivalent, or not?
  47. JD_PM

    High Energy Books on the Standard Model of elementary particle physics & beyond

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  48. DrPhysics

    Ibach Luth - Solid State 1.11 (QM model for Van der Waals' equation )

    Hi Everyone, can you guys please help me with the exercise attached? I knot that according to the book, van der Waals interaction is “charge fluctuations in atoms due to zero point motion.” This is correct once you understand that they are not talking about zero point motion of nuclear...
  49. E

    This is a 3D model I made of the Edmund Fitzgerald great lakes ship

    These are images of a 3D model I made of the legendary Edmund Fitzgerald, a great lakes bulk carrier ship, which famously sank in lake superior in 1975.
  50. E

    Have you seen this stunning 3D model of a VVER reactor made with Blender 3D?

    Made using Blender 3D, version 2.9, rendered in eevee. https://www.artstation.com/artwork/oAmVDw
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