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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73
votes
10answers
32k views

Why don't electrons crash into the nuclei they “orbit”?

I'm having trouble understanding the simple "planetary" model of the atom that I'm being taught in my basic chemistry course. In particular, I can't see how a negatively charged electron can stay ...
88
votes
7answers
11k views

Why do people categorically dismiss some simple quantum models?

Deterministic models. Clarification of the question: The problem with these blogs is that people are inclined to start yelling at each other. (I admit, I got infected and it's difficult not to raise ...
4
votes
2answers
977 views

Why are continuum fluid mechanics accurate when constituents are discrete objects of finite size?

Suppose we view fluids classically, i.e., as a collection of molecules (with some finite size) interacting via e&m and gravitational forces. Presumably we model fluids as continuous objects that ...
10
votes
3answers
464 views

Are there models/simulations of antigravitational antimatter-galaxies?

In the comments to another question's answer, I started wondering: Assuming antimatter possessed negative gravitational massĀ§ (which is not proven impossible to date, though deemed unlikely), ...
20
votes
6answers
1k views

Relativistic Cellular Automata

Cellular automata provide interesting models of physics: Google Scholar gives more than 25,000 results when searching for "cellular automata" physics. Google Scholar still gives more than 2.000 ...
8
votes
2answers
638 views

Do current models of particle physics explain the chemical properties of elements/compounds?

I have a particle system of seven protons and seven (or sometimes eight) neutrons (each formed by their appropriate quarks, etc.) bound together in a state that can be macroscopically described as a ...
4
votes
3answers
326 views

Guessing what a simple partial differential equation is describing physically

Is there an easy way to look at a partial different equation and get a sense of what kind of phenomena it is physically describing? I have an equation that looks like this: ...
3
votes
2answers
131 views

A problem of approximation [duplicate]

Possible Duplicate: Why are continuum fluid mechanics accurate when constituents are discrete objects of finite size? When we apply differentiation on charge being conducted with respect to ...
2
votes
2answers
542 views

Software for simulating 3D Newtonian dynamics of simple geometric objects (with force fields)

I'm looking for something short of a molecular dynamics package, where I can build up simple geometric shapes with flexible linkages/etc and simulate the consequences of electrostatic repulsion ...
0
votes
2answers
82 views

Should theory be the appropriate term? [duplicate]

Should theory be the appropriate term? I mean, for example, because of the quantum field theory we have been able to find the subatomic particles that it theorized and make the Standard Model. Why ...
26
votes
3answers
4k views

Why can't the Navier Stokes equations be derived from first principle physics?

At the 109th UCLA Faculty Research lecture, Seth Putterman gave a talk on Sonoluminescence. During the lecture he emphasized that "The Navier Stokes equations cannot be derived from first principles ...
3
votes
4answers
4k views

Bohr's model of an atom doesn't seem to have overcome the drawback of Rutherford's model

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 ...
3
votes
4answers
435 views

Formulation of general relativity

EDIT: I think I can pinpoint my confusion a bit better. Here comes my updated question (I'm not sure what the standard way of doing things is - please let me know if I should delete the old version). ...
3
votes
2answers
1k views

Approximating mean daily and hourly temperature beyond Fourier series

Summary: What "well-known" and short parametrized mathematical function describes daily and hourly temperature for a given location? If you look at the mean daily temperature graph for a given ...
2
votes
1answer
1k views

Physics of the electric hot plate

For an electronics experiment, I began wondering about the electric hot-plates (specifically the temperature dependence over time). If I were to measure the given temperature over time, I assume that ...
2
votes
1answer
411 views

Modelling noise with distance

I was wondering about the relation between noise with distance, assuming a point source, using sound as the method for communication and air as the medium of communication. Obviously as the distance ...
1
vote
1answer
53 views

Understanding the basic concepts of quantum mechanics using a model [duplicate]

I'm not an expert and I don't know if already exists something like the following model, but I wrote a simple (mental) model to understand the basic concepts of quantum mechanics. I want to know if ...
1
vote
4answers
714 views

How long does it take for an electric car to go from 0 to 60 mph?

I found the freefall motion equation which describes terminal velocity of a falling body, but I can't find a similar equation for a vehicle subject to constant traction force, so I tried determining ...
0
votes
2answers
2k views

Why would an electron in an orbit be accelerating continuously and would thus radiate away its energy and fall into the nucleus in a classical model? [duplicate]

I was reading this answer by madame anna v: You are right, the planetary model of the atom does not make sense when one considers the electromagnetic forces involved. The electron in an orbit is ...
0
votes
2answers
565 views

Point masses and infinite densities

Point masses are masses who don't have volume. It is said that they are infinitly dense, but I though division by zero is undefined hence you can't define the density for a point mass because ...