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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3answers
255 views

Am I correct in saying "falsifiability is the feature of a scientific theory to be tested"?

Falsifiability is usually defined as "the extent to which a scientific theory can be proven wrong". Does this mean that falsifiability is basically the extent to which a scientific theory is ...
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6answers
3k views

How exactly do physicists reject and accept theories/models in physics?

I'm curious about the rejection/acceptance of a theory/model in physics. Is the only criterion to accept a model/theory is the explanation of data? Or are there more criterions? For example, we still ...
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2answers
70 views

Why was Rutherford wrong and Bohr was right (then)?

I read that Rutherford was ruled out because he predicted that electrons revolve around the nucleus and Bohr stated that accelerating electrons emit electromagnetic radiation and should collide with ...
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0answers
26 views

Model of a runner on a plane

I want to create a simulation of people walking/running on a flat surface. To this end, I need to have a kinematic model of their motion. It should be sufficiently simple, treating each person as a ...
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1answer
54 views

Can postulates be proven wrong? [closed]

When Dalton gave his atomic theory, he postulated that atoms were the smallest indivisible part of matter. But now we know that they are composed of even smaller particles. So, the postulate has been ...
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1answer
85 views

Proof for property of proportionality used in deriving physical laws like law of gravitation and coulombs law

$$\text{F} \propto m_1m_2$$ $$\text{F} \propto \frac{1}{r^2}$$ Therefore $$\text{F} \propto \frac{m_1m_2}{r^2}$$ In physics one quantity $\text{F}$ is directly proportional to two other quantities ($...
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1answer
38 views

Extreme oscillations and values in heat equation on a 1D closed ring

I am trying to create a (very) simple model of heat diffusion along a closed rod (e.g., a ring) with an initial condition in which one segment is hotter than the rest. I'm using the following formula: ...
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2answers
83 views

Simple Harmonic Motion: Equating Pendulum and Curved Track [closed]

This scenario is taken from the 2018 NZ Scholarship physics exam: (Just in case the image doesn't load, it involves a wagon on a curved track (concave up). The wagon moves down from one side, to the ...
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2answers
62 views

Is it possible to make a magnetic box that will compensate Earth gravity allowing magnetic objects inside to fly on orbits like in space? [closed]

Is it possible to simulate solar system using magnetic spheres and some kind of box that will compensate the Earth gravity by magnetic force?
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0answers
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Mathematical prerequisites for M-theory [duplicate]

I am interested in learning M-theory; however I have no Idea as to what mathematics is required for it. Are the prerequisites the same as string theory? Is there more mathematical knowledge needed for ...
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2answers
132 views

Why is $\exp(-1)$ a good benchmark in many physics? [closed]

In many subjects in Physics (not only phys though), we often encounter a value which gives $\exp(-1)$, such as a time constant in circuitry ($\exp(-t/RC)$, $t=RC$ gives $exp(-1)$), lifetime, mean free ...
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0answers
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How to compute the Ocean tidal effect by giving the lat+long for specific location on a website?

I am quite new in this and interested in computation of contribution of the Ocean tidal gravity. I am following the website (http://massloading.net/ondemand_form.html) to get the data but I want to ...
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0answers
67 views

Stephen Wolfram Computational Model and the hypergraphs structure

I just discovered Stephen Wolfram`s project and model and I am fascinated especially since i had a similar ideea a few years ago without ever reading about it. I have a question regarding the ...
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7answers
4k views

Why are free parameters bad for a theory?

It is often said that one of the drawbacks of the standard model is that it has many free parameters. My question is two-fold: What exactly is a free parameter? My understanding is that the free ...
3
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1answer
146 views

Can artificial neural networks be effective theories?

Wikipedia describes "effective theories" as follows. In science, an effective theory is a scientific theory which proposes to describe a certain set of observations, but explicitly without ...
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3answers
86 views

Could processes and outcomes which are happening in colliders be simulated via mathematical model?

Colliding particles either for the purpose of getting fresh yet unexplained experimental results or as a mean of testing proposed theories appears to be a very crude experimental method. Could area of ...
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0answers
24 views

Controling the temperature in test tube

I am an electrical engineer and I am trying to control the water temperature in the test tube (laboratory application). But I can't measure the water temperature directly. I know what is the heater ...
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0answers
41 views

Equation of motion for a coil around a mass, attached with a spring driven by magnetic field?

First of all, thanks for reading and hello! First time poster on Physics Stack Exchange. I'm an electronics engineer (so forgive my poor maths below!) and tend to hang out there. I have a questions ...
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1answer
39 views

Why are fluid properties continuous with respect to spatial variables?

I get the intuition behind the continuum hypothesis in which we may treat a fluid as a continuous distribution of matter if we’re studying the fluid at a macroscopic scale. But the continuum ...
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1answer
67 views

How many quanta can travel at light speed relative to each other simultaneously? [duplicate]

How many quanta can travel at light speed relative to each other simultaneously? I know the concept of being "simultaneous" breaks down at a distance so let's assume for the sake of ...
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2answers
98 views

Do all physical processes necessarily imply a computation is taking place? [closed]

I would like to understand if any and all physical processes taking place, necessarily imply computations are also taking place. As a motivating scenario for the question, consider the following: ...
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2answers
115 views

About the tautology of physics quantities and laws [closed]

Physics quantities and laws, especially some fundamental laws and quantities, show property of tautology. For instance, mass and Newton's second law. My question is why physics quantities and laws ...
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0answers
23 views

Modes vs. Orbitals

I'm studying some very general, mathy, not-necessarily-realistic models which can be represented with fermionic operators or bosonic ones (not both though). One thing I keep seeing is the usage of &...
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3answers
196 views

Why does the national center for science education say “gravity is only a theory”? [closed]

I had someone show me that when you search “gravity is fact” on google you’ll get the National Center for Science Education saying things like “gravity is only a theory” Can someone just read these ...
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1answer
46 views

Why the heat transfer through the walls of a room is modelled as a 1D?

The heat transfer through a medium can be assumed to be one dimensional if the heat transfer happens predominantly along just one principal axis of the coordinate system. If the heat transfer through ...
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7answers
6k views

How seriously can we take the success of the Standard Model when it has so many input parameters?

The Standard Model of particle physics is immensely successful. However, it has many experimentally fitted input parameters (e.g. the fermion masses, mixing angles, etc). How seriously can we take the ...
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3answers
99 views

Simplest exactly solved model displaying a phase transition?

The classical example of an exactly solved model which displays a phase transition is the 2D Ising model. However, all the proofs I've seen of this have been very long and complicated. So, I wanted to ...
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0answers
19 views

Diagonalizing the BCS model as a Gaudin model

I've been looking at the BCS model through a few papers (listed at the bottom). I'm having trouble with many things but I think I've boiled it down to a few: -- In the first paper below (Ortiz), the ...
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1answer
59 views

Can a theory contain postulates of other theories?

I was reading about kinetic theory of gases and its postulates (assumptions). What I can't understand is for example in the derivation of: $$PV=\frac{2}{3}K$$ It uses the fact that: $$F =\frac{ΔP}{Δt}$...
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0answers
31 views

Floating Normalization of Experimental Data Sets while Fitting Multiple Models

I have $N$ data sets of unequal cardinality, and I am told we do not treat each data set with a normalization of $1$. Instead we let the the normalization float and fit it as though it were any other ...
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0answers
54 views

Didactic model for tipping dynamics [closed]

I would like to know if there are some toy models that describe a system dynamic from ecology or earth science with some feedback loops (eg. ice-sheet cover, rainforest-savanna cover, permafrost ...
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0answers
41 views

Modeling Golf Ball rolling around in golf hole

I am trying to model a rotating/rolling golf ball’s interaction with a golf hole. The boring case is just the ball rebounding in an elastic collision off the wall, with conservation of momentum ...
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4answers
200 views

What is a theory?

I was reading brief history of time by hawking and there I stuck on this line “A theory is a model of universe or a restricted part of it and a set of rules that relate quantities in the model to ...
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1answer
42 views

The meaning of "being mounted in horizontal frictionless bearings"

In the following scenario: In an Atwood's machine, there are 2 blocks. The pulley is mounted in horizontal frictionless bearings. When released from rest, the heavier block is observed to fall $x$m ...
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2answers
45 views

How to approach the questions of projectile motion in which two objects rebound in air? [closed]

I have tried multiple ways but failed several times so can anyone plz guide me about this.
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2answers
82 views

Is the Yukawa potential the more accurate potential to describe nucleons nucleons interactions?

According the Wikipedia the Yukawa potential is of the form: $$ V_{\text {Yukawa }}(r)=-g^{2} \frac{e^{-\alpha m r}}{r} $$ I know that the best theory to describe nucleons nucleons interaction is ...
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3answers
72 views

Modelling gas concentration in a room with exhaust fan [closed]

Asumme a ceramic kiln is placed inside a room of volume $V \ m^3$. There is an exhaust fan installed in the room to extract all the kiln fumes to the outside of the room (and building) with a constant ...
4
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2answers
200 views

Why do Drude/Sommerfeld models even work?

Sommerfeld's model for the electrons heat capacity works well on the extremes of high and low temperatures. While the model is quantum and assumes the electrons are an ideal gas, the reality is VERY ...
4
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6answers
298 views

Scientific evidence of reductionism

There are claims that the standard model is a theory which explains almost all phenomenon that we see in the world. I am wondering what scientific evidence backs this claim? Specifically, there is a ...
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1answer
99 views

What are the top-down and bottom-up approaches to holography?

I think I understand the main idea of top-down vs bottom-up: when trying to describe some phenomena using a particular theory, in t-d one starts from the complete theory and puts constraints so that ...
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3answers
80 views

Linear or quadratic air resistance with football?

I'm modelling a football shot as a projectile - is the air resistance force proportional to the speed or speed squared?
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2answers
90 views

Does science really have base for Its expriments? [closed]

For most of the macroscopic observations, everything has a reason, but going into the microscopic level, atoms, then the electrons, then quarks. Science has proved the existence of quarks by various ...
3
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1answer
24 views

Is there a statistical mechanical model with the same qualitative behaviour as polarity?

Every chef and chemist knows that oil and water do not mix and that this is due to the polar nature of the water molecule and the non-polar nature of the oil molecule. In fact if one starts the oil in ...
1
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1answer
86 views

How are solids described mathematically? [closed]

All shapes can be described by mathematical equations for example the unit sphere can be described as $x^2+y^2+z^2=1$, but not all shapes are that simple in nature. Most solids in nature very ...
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1answer
47 views

Are fundamental symmetries thought to be exact or just an approximation?

As title states, I wish to know whether fundamental symmetries (in the most general sense of the word, e.g. gauge symmetries, Lorentz invariance, diffeomorphism invariance, not necessarily just global ...
2
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1answer
63 views

Deformation of a sphere

I am currently building a computational model for a simulation of a rover landing on the surface of mars. As part of the assignment I need to model airbags being used to cushion the fall. (Assuming ...
1
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2answers
116 views

What are the implications of deterministic chaos: useful or detrimental? [closed]

I am new to the concept of chaos theory and as a layman I am struggling to understand what is the significance and implication of chaos in ecological systems such as the chaotic predator prey model. I ...
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4answers
721 views

How to know if the error is in a law or in uncertainty of the measurement?

I read these words in a (great) answer to this question: There are errors that come from measuring the quantities and errors that come from the inaccuracy of the laws themselves But how do we know ...
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6answers
3k views

Accuracy of physics laws

How accurate are physics laws? For example, for newtons' first law $F=ma$, if we can get a measurement of both force, mass and acceleration with a percentage of uncertainly close to $1\times 10^{-9}\%$...
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0answers
40 views

What did Freeman Dyson mean when he said this? [duplicate]

In this video, Freeman Dyson, when speaking of Fermi said the following thing, "...what does he think about the numerical agreement, and he said, 'How many parameters did you use for the fitting?...

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