# Tagged Questions

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### orthotropic materials solution of boundary value problems

What are the methods or approaches for the analytical solutions of boundary value problems in the theory of elasticity for orthotropic materials?
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### Homotopy $\pi_4(SU(2))=Z_2$

I am a physics student, recently I read a paper using Homotopy $\pi_4(SU(2))=Z_2$, I guess mathematicians have some visualization or explanation of this result. So I come here ask for help. CROSS-...
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### Impact of LHC on math ? [closed]

LHC (Large Hadron Collider) "... remains one of the largest and most complex experimental facilities ever built". May be it is even the most complex project in humankind's history(?). Such projects ...
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### David Hilbert on Complex Multiplication [closed]

I have tried vainly to understand the significance of the following statement attributed to David Hilbert: The theory of complex multiplication is not only the most beautiful part of mathematics ...
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### What is the current state of the mathematics of Higgs fields?

Topical. I know there are good mathematical theories in which "Higgs" is used, in a geometrical sense. Would someone care to explain? To clarify, I'd like to know about Higgs bundles on Riemann ...
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### How the spin value is related to mathematical nature of the field?

Fields are one of the following: scalars, vectors, spinors or some Lie algebra elements, right? And it's often said that scalars are spin-0 and vectors are spin-1. So, what's idea of correspondence ...
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### Best book for learning sensor fusion, specifically regarding IMU and GPS integration.

I have posted this in MathOverflow because the subject is primarily Math related. I have a requirement of building an Inertial Measurement Unit (IMU) from the following sensors: Accelerometer ...
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### Bosonic String Theory

I would like clarification of 26 dimensional Bosonic String Theory. A definition would be, that this is free bosons compactified on a torus and orbifolded by a 2-point reflection group (or ...
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### Self-tightening knot

Is there a way, for some finite L>1, to tie two pieces of rope together, such that any finite force is not enough to pull them apart? The type of rope I have in mind is something like cylindrical ...
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### Simple question on the foundations of spin foam formalism

To make it simple, take the spin foam formalism of ($SU(2)$) 3D gravity. My question is about the choice of the data that will replace the (smoothly defined) fields $e$ (the triad) and $\omega$ (the ...
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### Minimize Energy for Charge Distributions

I am considering [positive] charge distributions $\rho:M\rightarrow\mathbb{R}_+$ (nonnegative reals) with unit charge $\int_M\rho=1$ for convenience. Here $M$ is a nice-enough region, say a ...
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### What is the “Physically Consistent” proper subset of arithmetic?

Suppose 1st-order arithmetic is inconsistent along with Voevodsky http://video.ias.edu/voevodsky-80th. It nevertheless remains true that when you have 2 apples and 2 apples, you have 4 apples. ...
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### Orbits for homogenous complex polynomials under unitary rotation of variables

Let's have two complex homogeneous polynomials of degree $k$: $f(z_1,\cdots,z_n)$ and $g(z_1,\cdots,z_n)$. We consider rotations of variables in the form of $\vec{z}' = U \vec{z}$, where $U\in SU(n)$. ...
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### Maxwell Stress Tensor and Equations in Mathematician's Language [closed]

In my language, a differential two-form on $\mathbb{R}^4$ (viewed as a differentiable manifold with coordinates $t,x,y,z$) is a differentiable choice at each point of an alternating bilinear function ...
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### Topology of black holes

I've asked this question of some physicist friends of mine and I've never gotten a satisfactory answer: What is topologically possible for a neighborhood of a black hole? To clarify, I'm curious about ...
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### A soft introduction to physics for mathematicians who don't know the first thing about physics

There have been similar questions on mathoverflow, but the answers always gave some advanced introduction to the mathematics of quantum field theory, or string theory and so forth. While those may be ...
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### Flux through a Mobius strip

A friend of mine asked me what is the flux of the electric field (or any vector field like $$\vec r=(x,y,z)\mapsto \frac{\vec r}{|r|^3}$$ where $|r|=(x^2+y^2+z^2)^{1/2}$) through a Mobius strip. It ...
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### Which motion is exclusive in 3D or higher dimensions?

Hi guys, I have a simple question Linear movement can be found in 1D, 2D and 3D world objects Rotation can be found in 2D and 3D world objects. Now, are there any kind of motion can only be found ...
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### What is the geometric meaning of the third derivative of a function at a point? [closed]

What is the geometric meaning of the third derivative of a function at a point? This question is now asked on the sister site: http://math.stackexchange.com/questions/14841/what-is-the-meaning-of-the-...
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### Is there an analogue of mathscinet for physics?

I've been looking recently at some papers in physics, from journals that are not listed in mathscinet. Is there is a similar database for physics, with reviews and citation links? I'd like to see ...
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### Newton equations, second order equation and (im)possible motions

I am am currently studying Newtonian mechanics from a conceptional and axiomatic point of view. Now, if I am not mistaken, one (but surely not all) statement of Newtons second law about nature is, ...
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### Is symplectic reduction interesting from a physical point of view?

Do you think that symplectic reduction (Marsden Weinstein reduction) is interesting from a physical point of view? If so, why? Does it give you some new physical insights? There are some possible ...
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### How can simple physical “proofs” of mathematical facts be made rigorous?

Mark Levi's The Mathematical Mechanic is a book of examples of how physical reasoning can be used to solve mathematical problems; another couple of examples is in this blog post at Concrete Nonsense. ...
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### What kind of Lagrangians can we have?

In any physics book I've read the Lagrangian is introuced as as a functional whose critical points govern the dynamics of the system. It is then usually shown that a finite collection of non-...
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### Two interacting bodies in an external field

Hope, MO is the right place for this question (if not so: where would you pose it?). Consider a two-body system in classical mechanics. As long as the interaction depends only on the distance of the ...
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### Angle Maximizing the Distance of a Projectile

It is well-known that to maximize the horizontal distance traveled by a projectile fired from the ground at a given speed, one should fire it at a $45^\circ$ angle. What's less-known, though not too ...
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### Has the Lie group E8 really been detected experimentally?

A few months ago there were several math talks about how the Lie group E8 had been detected in some physics experiment. I recently looked up the original paper where this was announced, "Quantum ...
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### Literature for gauge field theory on the lattice in geometrical formulation

I have found an article by Huebschmann, Rudolph and Schmidt: http://www.springerlink.com/content/b8v216v0m8h16264/ about "A Gauge Model for Quantum Mechanics on a Stratified Space" and I am very ...
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### Why do Physicists need unitary representation of Kac-Moody algebra?

My advisor mentioned to me that he talked to Witten last summer on representation theory, and Witten told him that unitary representations of Kac-Moody algebra are important to working physicists. But ...
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### Particle Physics and Representations of Groups

This question is asked from a point of complete ignorance of physics and the standard model. Every so often I hear that particles correspond to representations of certain Lie groups. For a person ...
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### Derived Physics

Hello to all, This question will probably be closed down as being off-topic faster than one can say "string theory", but here it goes: I've noticed that the problems I'm working on -the structure of ...
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### Mathematical explanation of the failure to quantize gravity naively

One often hears in popular explanations of the failure to find a "Grand Unified Theory" that "Gravity goes off to infinity, but cutting off the edges gives us wrong answers", and other similar ...
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### Perpetuum Mobile

In 2 hours after posting this, I realized that preserving Liouville measure solves the problem completely. Sorry for disturbing... Construction of perpetuum mobile: Consider room with mirror walls ...
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### What is the meaning of symplectic structure? [closed]

Answers can come in mathematical, physical, and philosophical flavors. Edit: There seems to be a consensus that this question is not formulated well. I must respectfully disagree. My interest in the ...
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### Mathematical definition of running [closed]

This will be a tad hard to explain, so bear with me. Taking into account only the legs what would be an accurate definition of the position of the upper legs, lower legs and feet with respect to time? ...
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### Singular K3 — mathematical meaning?

There's a very interesting text by Cumrun Vafa called Geometric Physics. Here I'm particularly interested in Chapter 4, where we take a Calabi-Yau manifold presented as a degenerating fibration: ...
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### Something like mathoverflow in other sciences [closed]

Are the sites similar to mathoverflow in other sciences related to mathematics? statistics, computer science, physics, economics, etc? Let me explain what I mean by "similar": those are sites devoted ...
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### Prevalence of B-fields

I am wondering how B-fields, which are basic objects in Generalized Geometry, relate to the B-fields of Ben's question and the answers to it. In Generalized Geometry, the B-field is a (1,1)-form, and ...