0
votes
0answers
4 views

Virtual geomagnetic pole

Magnetic measurements have been made on some lavas found at 60ºN and 90ºW. The inclination angle is 37º. If the horizontal direction of magnetism of these lavas is due west, calculate the position of ...
0
votes
0answers
5 views

Probabilities with a qubit

A two-state quantum system has orthonormal energy eigenstates ψ1 and ψ2, with energy eigenvalues E1 and E2 = E1 + ∆E (∆E > 0). These energy eigenstates form a complete set of wavefunctions for the ...
0
votes
0answers
9 views

Probability of intersetellar scattering by photons of different wavelength

The following problem was part of a homework for my Cosmology class: ...
2
votes
3answers
29 views

Why do Signs Fall?

My question in this post is, why do signs with large angles fall? For example, fold a piece of paper in half, set the angle between the two halves, and place it on the floor; it will stand or collapse ...
2
votes
0answers
8 views

Formation of supermassive black holes

Scientists have found very bright source of light which they call quasar and the are found to be supermassive black holes. So these black holes are so massive that they cannot be formed by a ...
0
votes
0answers
10 views

Fourier and inverse fourier transform in QFT

According to my lecture notes, the inverse Fourier transform of an operator $\phi(p)$ is given by $$\phi(x) = \int \frac {d^3\mathbf p} {(2\pi)^32E_{\mathbf{p}}}\phi(p)e^{-ip\cdot x},$$ and the ...
0
votes
0answers
12 views

Lorentz transformations on momentum space Weyl spinors

The Weyl spinor in momentum space can be given by the inverse Fourier transform: $$\psi_L(x) = \int \frac {d^3\mathbf p} {(2\pi)^32E_{\mathbf{p}}}\psi_L(p)e^{-ip\cdot x}.$$ In addition, Lorentz ...
2
votes
1answer
23 views

How can the Andromeda Galaxy alone have more mass than the Local Group?

I was reading about the Local Group, and it is stated that the total mass of the group is $1.29±0.14 × 10^{12}$ Solar masses. The number actually felt a bit low to me because I know the Milky Way ...
0
votes
1answer
13 views

Difference between solid and gases thermal expansion

The coefficient of linear expansion is $$\Delta L = L \,\alpha \Delta T,$$ where $\Delta t$ can be the difference of any two temperatures. However, in volume expansion of gases, $$\Delta V = V ...
0
votes
0answers
11 views

In analysis, why do we break the incident field into perpendicular and parallel components but not the other field?

(reference: http://www.amanogawa.com/archive/docs/EM13.pdf) In the analysis of perpendicular and parallel polarization, why is that the analysis is done whereby we break the obliquely incident field ...
0
votes
0answers
10 views

How to model drag coefficient during initial acceleration

Using a $0.4\text{ m}$ cubic parachute (cruciform design with holes in the corners for stability), a drag coefficient of about $1$ is expected for Reynolds numbers about $10^4$ (velocities about $1 ...
1
vote
1answer
23 views

How to account for inertia in kinematics?

Alright, I'm only in AP Physics and I asked my teacher and he couldn't help me... I'm making a 2D physics engine and I'm having problems when it comes to gravity between objects and I think its ...
0
votes
1answer
7 views

Water behaviour under theoretical near-infinite pressure conditions

I've asked a similar question here but the answer given shows the behaviour of water under general conditions. I'd like to know what the behaviour of water is like as pressures increase towards ...
2
votes
1answer
12 views

Question about wavelength of EM wave in dielectric

Many websites (http://maxwells-equations.com/materials/permittivity.php) lists out the following formula as to how you can compute the wavelength of an EM wave in a dielectric $$\lambda_d = ...
1
vote
0answers
27 views

How do Lorentz transformations act on position kets $|\mathbf{x}\rangle$?

The Hilbert space of one particle can be spanned by position kets $|\mathbf{x}\rangle$ or by momentum kets $|\mathbf{k}\rangle$. If we denote $|k^\mu\rangle = \sqrt{2E_{\mathbf k}}|\mathbf{k}\rangle$, ...
0
votes
1answer
13 views

How does one figure out how fast water is moving through a water intake on a dam?

Say the dam is hoover dam for example. The intake is where the water flows in to turn the turbines that generate electricity. I want to know if there is an equation that describes the speed of the ...
0
votes
0answers
6 views

Non-minimal coupling (Pauli Coupling) of gauge field with a non-relativistic scalar field

I am wondering if it makes any sense to non-minimally (say, Pauli-like) couple an external gauge field with a non-relativistic scalar field: \begin{equation} p_\mu \rightarrow p_\mu - e A_\mu + ...
0
votes
1answer
27 views

Finding Lagrangian with Non-holonomic constraints

I am stuck working on a problem that involves finding the Lagrangian for a free particle constrained to move on the surface of a disk of radius $a$. The particle collides elastically with the edge of ...
0
votes
1answer
24 views

EPR Paradox resolution: the spin is fixed at creation but its measurement isn't?

The Wikipedia article on the EPR paradox uses the example of an electron and positron created from a common source, each moving in an opposite direction to the other. Detector A is used to measure the ...
3
votes
1answer
32 views

Can unpolarized light be created from polarized light?

I have a question regarding this topic. According Stokes Parameters theory, unpolarized light could be described as a superposition of two independent beams of equal intensity and orthogonal ...
0
votes
0answers
18 views

Combining Moment of Inertia Tensors

In a physics simulation of rigid bodies, if I have a cube with a known mass and moment of inertia tensor, and I attach it to another cube with a known mass and moment of inertia tensor such that its ...
0
votes
0answers
16 views

Examples of systems with linear response behavior

I've checking the linear response theory and there are 3 fundamental assumptions. 1) Linearity of the response of the system to an external excitation, 2) Stationary response function: ...
0
votes
2answers
35 views

What unit would the answer be in?

So I have used this formula: $$W= PV_1 \times \ln\frac{V_2}{V_1}$$ and I have converted my values to cubic meters and pascals. So Work Done, $W$, what would be the unit for that answer? I already ...
0
votes
3answers
28 views

Conceptualization and modelling of spin

I'm trying to get a decent understanding of the bell inequality, and so am trying to understand spin both conceptually and mathematically. When I picture spin, I imagine a sphere rotating about its ...
0
votes
0answers
26 views

Maxwell's Equations for Accelerated Conductors

I asked a question about accelerated conductors in a magnetic field but nobody unfortunately answered. That is: Ohm's Law for Accelerated Conductors Maybe, I could not state my question well. I ...
-1
votes
1answer
26 views

the twin paradox [on hold]

about einstein twin paradox i don't understand how time will pass differently to one of the twins,it might feel differently but if i traveled to another country and got back in 2hours i might feel ...
2
votes
2answers
58 views

Are Mathematics the language of the universe? [on hold]

I am a high school student and next year i am going to be a physics major, so this year i put all my effort on physics and mathematics, since it a great tool for physicists. But now i wonder, in ...
0
votes
1answer
22 views

What would Negative Energy act like?

So I heard that if you want to make a wormhole you need negative energy. What is special about Negative Energy that allows it to do that? What are the properties of Negative Energy compared to normal ...
0
votes
1answer
18 views

Scale factor and energy density

I'm looking at some solutions of the Friedmann equation at this website: Solutions to Friedmann equation If I look at the first problem (Problem 1: matter or radiation in a flat Universe) and click ...
0
votes
0answers
25 views

Radially free falling observer [on hold]

I am a student. i read in a paper for a radially free falling observer in a Schwarzschild metric, the relation between the Unruh vacuum state and the proper time was given as $$UH := \tau_0 −4\frac ...
1
vote
1answer
23 views

Physical Meaning Of $ dQ/T $ Regarding Clausius Inequality: Is it related to Energy Loss in form of heat or Something Else?

What is the physical meaning of term $ dQ/T $ in Clausius Inequality $ dQ/T \le dS $ ? Physically we can relate entropy to number of microstates of a system, which relates to number of possible ...
3
votes
2answers
33 views

Why does a cooling car engine crackle?

Why does a cooling car engine crackle? What determines the frequency of the crackles?
-1
votes
0answers
44 views

Can you debunk this “Perpetual” (ie, very long term) motion machine? [on hold]

In the following design, gravity is "always" pulling down. There's a parallelogram-shaped box containing a magnet, and underneath the lowest corner of the box is another magnet to repel the first ...
0
votes
1answer
39 views

Point-like nature of particle interaction and wave function non-locality

Let us consider the Hamiltonian for the hydrogen atom $$ ...
-2
votes
0answers
19 views

How to write Laplace equation for this problem? [on hold]

How to write Laplace equation in below example. we have two plate with surface S,If we have charge surface density in boundary,obtain potential between two plate. explicitly explain for me how to ...
0
votes
2answers
42 views

If a photon is exists in 'timeless' state, how can objects around it move? [duplicate]

My understanding is that light does not experience time. In attempting to understand what the universe would be like from the perspective of a photon, the answer I get is that the universe would be ...
2
votes
2answers
30 views

Interpretation of systems in different state of matters BUT almost identical configuration

For a start, let me clarify that by "almost identical configuration" I mean same volume, temperature and number of molecules (but different pressure). One could for instance take two identical systems ...
0
votes
0answers
5 views

What is harmonic and fundamental bands in IR spectroscopy?

What is harmonic and fundamental bands in IR spectroscopy? I'm trying to find exact definitions. I guess that fundamental is $1\leftarrow 0$ transition (the most intense and energetic) and harmonic ...
0
votes
0answers
12 views

Postion of a cylinder rolling down an inclined plane [on hold]

I know that the acceleration of a uniform cylinder of known mass rolling down an inclined plane WITHOUT slipping with an inclination of $\theta$ is: $\frac23 g \sin\theta$. Suppose this term is called ...
0
votes
0answers
34 views

Green function integration problem [on hold]

When I'm trying to find the Green Function of Helmholtz equation for a cube $0≤x,y,z≤L$ $$\nabla^2u+k^2u=\delta(\vec{x}-\vec{x}')$$ where $u=0$ on the surface. I set to find the green function where ...
0
votes
0answers
10 views

States in valence and conduction band

I often see a Hamiltonian in second quantization written for the valence and conduction band. Now, I was wondering: What are the single-electron states that form the prouct state they act on? So what ...
1
vote
0answers
34 views

What makes Lattice Yang-Mills hard?

I've been reading up on non-perturbative Yang-Mills, and have found the following equation: $$Z[\gamma, g^2, G]=\int \! \prod e^{-S}\mathrm{d}U_i$$ Now I don't know much about computational physics, ...
3
votes
1answer
40 views

A true singularity at $t=0$, coordinate independent Big Bang

Consider a flat Robertson-Walker metric. When we say that there is a singularity at $t=0$, clearly it is a coordinate dependent statement. So it is a "candidate" singularity. In principle there is ...
0
votes
1answer
11 views

What concepts/rules apply for multi-stage pumping of water

For single stage (ie one pump) water transfers calculations for pressure loss are commonly done by adding the elevation difference of the start and end of the pipe line to the friction losses that ...
1
vote
1answer
26 views

Finding the potential between two spherical shells [on hold]

How to find the potential in region $a<r<b$ I know that the general solution for Laplace's equation is $$V(r,\theta)=\sum_{l=0} \left[A_l r^l +\frac{B_l}{r^{l+1}} \right]P_l(\cos{\theta}).$$ ...
0
votes
0answers
11 views

Excitation probability given pulse bandwidth and atom linewidth

Consider photon source producing photon pulses with a frequency distribution $f(\omega)$ and a glass tube filled with a gas. The atoms of the gas can be excited by photons with a frequency of ...
0
votes
0answers
19 views

Capillary action height

How to calculate height of the liquid (let's say it's water) in the capillary (so height of capillary action) if you only have r given, r = 0.3 mm - r is radius of capillary. The equation I would use ...
0
votes
0answers
13 views

Equal volumetric rate versus area open to flow [on hold]

A vertical water disposal well has been drilled and cased. There are two horizontal rock formations that the wellbore intersects and these formations will be targeted for water disposal. To allow ...
1
vote
0answers
9 views

Evaluation of the anomalous dimensions of fields in SUSY $SU(5)$

The general formula for the anomalous dimension can be found in Martin΄s review article (hep-ph/9709356v6), on page 62 relation (6.5.4). In the case of $SU(5)$ and especially in the paper of ...
1
vote
1answer
83 views

Visualisation of electron

first things first, I'm not by any means a physicist nor a student of physics. I study graphic design. Theme of my bachelor thesis is visualisation of physical and mathematical phenomenons, long story ...

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