Questions tagged [models]
DO NOT USE THIS TAG just because the involved physics is based on a model. All physics descriptions are inherently model-based. This tag is reserved specifically for addressing model development, validity, simplification, or other meta-model questions.
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General Relativity "doesn't quite work" without dark matter?
I am taking an astrophysics course, and my astro professor said that "we need to introduce dark matter because Einstein's general relativity doesn't quite work without it".
I wanted to ...
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Can a atomic model based solely based on relativity (General,special) be useful in describing gravity as quantum mechanics fails to describe gravity? [closed]
Similar to various mechanics such as Hamiltonian, Newtonian, and Lagrangian, building an atomic model based on both general and special relativity is conceivable. While the quantum mechanical model of ...
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If an equation describes some physical phenomenon is the assumption that it works in all cases? [closed]
I may be misunderstanding the general idea and the following specific example, but I was told that Dirac predicted the existence of the positron based on a formula for the motion of the electron(?) ...
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Can anyone suggest a calculation model for estimating the location of a dropped object falling from a height?
I'm trying to find models that allow me to calculate dropped objects, specifically, a model where I can consider lateral displacement due to wind force and vary the weight and resistance force of the ...
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Graphical representation of an arbitrary tensor
I am interested in finding graphical models for tensors. To begin with, let's think about graphical models of tensors in 2D and 3D. If possible, I would be interested in the graphical representations ...
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Torque profile with fixed boundary condition
I am trying to find a simple treatment of elasticity theory of a scenario where I have a thin rod attached to a disc (radius $r_0$), and the disc is held fixed at its edge. Now I apply some torque to ...
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Equations modelling a snowboarder/skier on a jump
I am currently a highschool student elaborating an internal assessment for my mathematics AA HL course (a sort of research paper we must elaborate for the IB) and was looking into the relationship ...
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Is there a missing variable in the double slit experiment? [closed]
I've been reviewing the double slit experiment lately and I believe it is missing a few crucial things. Thickness of the wall is my primary focus. How could I add thickness into the equation? I'm ...
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Optical Properties of Heavily Doped Silicon in the Visible and Near Infrared
I am looking for a model of the changes in the complex refractive index of doped Silicon based on the doping level and type in the visible and near-infrared wavelengths (400-1000 nm). I have seen ...
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Are there any laws of physics that are always true?
I understand that "laws of physics" is a bit of a misleading term since all they really are is just us applying a logical statement about observed physical phenomena in a way that allows us ...
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What exists in the world according to the special relativity? [closed]
Before I learned about special relativity, I thought that only one 3-dimensional state of the world exists. Then, like in game of chess, in one "turn" previous state is destroyed - and the ...
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What's the difference between observable and unobservable objects in a physical theory?
Both can help explain physical effects, but I'm looking for a rigorous definition of “observable” and “unobservable.”
For example, how is the experimental evidence for the existence of particles such ...
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What are Quantum Field Theories?
Every time I read about quantum field theories, I wrongly assume and associate the theory to the Standard Model, that is, our current theory of particles and interactions.
However, it seems that the ...
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Is the informational approach to thermodynamics generally accepted as "correct"?
This question is about the "ontology" as it were of statistical mechanics. In my limited reading of (equilibrium) statistical mechanics texts, I have encountered two viewpoints for what is &...
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Is math really fundamental or would it not matter if physics did not depend on math? [closed]
Can you disprove this please because it's been bugging me and I don't know much about physics at all as I'm only in 10th grade. It's one of those weird thoughts but I would like confirmation to keep ...
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Why did these algae grow like this in the pool? Are these curves the gravitational equivalents of the bell curve?
My friend sent me these pictures of a pool that has been abandoned for a long time, and we are curious about the reason behind the peculiar growth of algae in this pattern. The needle-like towers of ...
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Near-field diffraction
I want to calculate near field diffraction loss due to the presence human blockages which are modeled as cylinders with random heights and diameters in indoor mm wave network
as mentioned in " ...
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Near-field diffraction model
I want to calculate diffraction losses due to the presence of human blockages which are modeled as cylinders with random heights and diameters, what is appropriate method that can I use in case of ...
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Determine time taken for light to travel between points through circular, sub-wavelength aperture
Background
I'm working on numerically modeling some physical phenomenon using electromagnetics simulation software. I have a particular physical setup modeled, wherein I've noticed some non-intuitive ...
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Nancy Cartwright's distinction [closed]
Nancy Cartwright introduced an interesting distinction in the context of her study of the history of the evolution of our understanding of superconductivity. She emphasized the distinction between ...
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If two models generate identical predictions, must one be mathematically reducible to the other?
If two models always generate identical predictions of measurable observables given identical inputs of measurements over a given domain, must one be mathematically reducible to the other over that ...
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What is the meaning of an imaginary part of position in Lorentz-Drude model?
Some time ago I got to know about Lorentz-Drude model, which predicts dependence of complex permittivity $\varepsilon = \varepsilon_1 + i \varepsilon_2$ from classical assumptions.
In the model, ...
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Best spacetime metric for a cylinder
I am studying a rotating cylinder model in general relativity. The interior metric is given, but I am trying to express the exterior metric. It has to be practical and describe spacetime around a ...
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What percentage of Mars' surface would be under the water if we dropped all of the water from moon Enceladus on it? [closed]
Enceladus, one of the Saturn's moons that is known for water geysers, is estimated to contain a body of water as big as a ball $220 ~\mathrm{km}$ in radius. That's about $\sim 4.46 \times 10^{7} ~\...
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How can we determine the energy scale of a physics theory?
It is very common in physics, when we refer to the most diverse theories, on the most diverse length scales, we also refer to their energy scale. It is through the energy scale that we classify a ...
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Modeling evolution of continuous mean-field model?
Suppose $f(i,t)$ indicates state $i$ at time $t$. Are there examples of exactly solvable models where $f$ is described by differential equations similar to one below?
$$\frac{\partial}{\partial t} f(i,...
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Thin accretion disk model
For thin accretion disks the radial pressure gradients are taken to be negligible and so only the gravitational force is considered. Why is this assumption justified?
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How can I mathematically model the entrainment of air through a window?
The Problem
Suppose I have an open window with an area $A$, and a uniform wind source (a fan) pointing towards the window, positioned at a distance $s$ away from the window.
At the exit of the fan, ...
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In physical calculations, is the elimination of higher-order small quantities an approximation or a strict equality in mathematics?
Physics sometimes uses a technique called the method of differentials, which seems magical and not very systematic. This makes me unsure which variable I should take the differential of, and sometimes ...
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Brinkmann (or Darcy) porous media
I have an equation physics related modeling question. I have a column which is completely full with soil. I use the Darcy law to solve flow field on the system but the numerical commercial solver that ...
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Does a point mass have constant mass?
Expanding on the title, I am hoping for a little bit of insight into the philosophy of Newton's mechanics as a physical theory. My question, essentially, is does a point mass have constant mass by ...
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In this time dilation explanation, shouldn't gravity and mass affect the example?
recently i've started "exploring" general relativity, and found this example explaining time dilation caused by velocity:
The example was taken from https://en.wikipedia.org/wiki/...
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Is there any physical situation where the electric potential is discontinuous? [duplicate]
I am wondering if the fact that "the electric potential is continuous" should not be added to the set of axioms of physics.
I have never seen a problem where the potential is discontinuous, ...
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Time scale of earthquake simulations on scaled building models
The effect of earthquakes on a building can be investigated by creating a scaled down model of the building, and simulate an earthquake on a shake table.
A recording of a natural earthquake can be ...
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What are the Equations for Climate modeling of alien planet?
I am studying complex dynamic system and I would like to analyze the climating formation of a possible alien planet considering climate as a complex system .
For this I do not want to use a whole ...
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Is there a way to mathematically model the stress/strain graph of a material after the limit of proportionality? [closed]
I am currently working on an application that simulates physics experiements, and am struggling to find a way to model the graph after the limit of proportionality. I have constrained the simulation ...
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How to find a modelling function?
I have a list of boundary conditions, inequalities and general facts about a real world scenario involving probability distributions that evolve according to some parameters, but I'm struggling to ...
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Will the probability for tunnelling go completely to zero? [closed]
According to quantum mechanics, the probability for quantum tunnelling (of an object) never become completely zero, no matter how "big" is the height and the thickness of the barrier.
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What is the current most accurate model for the generation of binary black hole gravitational waveforms? [closed]
As you know there are a lot of models to choose from, and there is constant improvement in both gravitational waveform generation and detection methods. Now some of the most used GW generation models ...
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What is the difference between mechanics and analog?
What is the difference and the relationship between mechanics and analog/analogue? I have noticed that mechanical things are often considered analog.
Note: The difference between digital and analog is ...
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Prey-predator dynamical system
I'm working with a prey-predator differential equation system and I have a problem with the competitive exclusion principle.
In its simplest form, this principle states that if there are 2 predators ...
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Does a log-linear leak tell us anything about the properties of the leak?
I used a pressure tester on a Subaru 2001 and a stopwatch to record the time and pressure at regular intervals of pressure. I pumped it up to about 17.5 PSI and began recording.
From this data I fit ...
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How is it possible that we can model the same physical situation with different topological spaces?
Question came up when reading this answer. How is it possible that we can choose different topological spaces to model a same physical scenario?
If we have such different spaces, so many things will ...
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Where do discontinuities in the electromagnetic field occur?
At a superconductor is what I know of, but what are some other cases?
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How do physicists "discover" those equations that describe a physical phenomenon? [closed]
I have been looking for the answer to that question for a long time, I have spoken with people who according to them "know" about physics, the answers they always give me is "they do it ...
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What processes are used to enumerate stable operating regimes and testable hypotheses?
It seems that in physics there are two key processes,
Phenomenology: Constructing a qualitative description of the phenomenology through experiment, observation, and explanation
Synthesizing: Taking ...
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In which cases do KCL and KVL fail to apply in circuits?
For which circuits will KCL and KVL be applicable?
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Trying to estimate the path of a projectile with equations on graphic calculator. Need help
When a projectile is released with a very high velocity, it will not follow basic projectile motion because the Earth’s curvature will hinder those equations. In a crude sense, the Earth will curve ...
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Introducing a hyperbolic speed limit to a parameterized system
I have function $S$ representing a trend-fitted vector for five variables parameterized by time, $S(x(t),y(t),z(t),f(t),g(t))$ where $x,y,z,f,g \in C^2(\mathbb{R})$ (making $S \in C^2(\mathbb{R}^5)$) ...
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Projectile motion as realistic as possible (at least computationally)
I want to know how would one set up the equation of motion of a projectile, that takes the most effects into account as possible (such as air resistance, lift, the projectile's extension, Earth's ...
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