0
votes
0answers
66 views

Is it possible for oxygen in the ocean to undergo nuclear fusion?

Could the oxygen in the ocean undergo oxygen burning (uncontrolled self-sustained fusion) if struck by a very large meteor or exposed to a similarly devastating cosmic catastrophe? Is it possible for ...
0
votes
3answers
62 views

What is the difference between accelerating and boosting?

My professor claimed in class that there was a difference between an acceleration and a boost. I don't really understand the distinction. If you want to go to a different inertial frame of reference, ...
1
vote
1answer
36 views

How do you compute pressure at a pipe inlet if the pipe is leaking between the inlet and the outlet/pressure measurement point [closed]

This is a real world problem: I have a vertical pipe (a well ~800' deep); I have an unknown but reasonably fixed (artesian) pressure at the pipe inlet; I can only measure pressure at the pipe outlet; ...
3
votes
1answer
124 views

Effective resistance across 2 adjacent vertices of a dodecahedron with each edge $r$

What will be the effective resistance across 2 adjacent vertices of a regular dodecahedron (12 faces) with each edge having resistance $r$? Here is the source for the problem, it's problem 20. on ...
0
votes
1answer
82 views

How should speed be expressed in Frenet-Serret frame of reference? [closed]

I'm looking for the equation of motion of the ball on a vertical plane with a cylindrical profile. I guess that means I have to use the frame of reference of Frenet-Serret here. Why is the speed of ...
3
votes
2answers
160 views

Redshift due to a static gravitational field and the conservation of energy [duplicate]

I am standing on the surface of some planet. Gravity is described via General Relativity with some static metric (e.g. the Schwarzschild metric, so static means no time dependence, but the metric may ...
0
votes
1answer
48 views

Reflection of light on semi-infinite solid

The following statement is often made concerning reflection on glass: "When light is normally incident on a glass surface, about 4% gets reflected and the rest is transmitted. The reflected wave is ...
0
votes
2answers
38 views

Mass and friction

Assume I have a block of mass $m$ on a rough surface. Let's say I apply a force $F$ to the block to get it sliding. Common sense tells me that the heavier the block, the more force it takes to keep ...
0
votes
2answers
73 views

Thermodynamics and Newton's second law

Is it correct to say, that the Newton's laws (or a Newtonian system) is reversible if the friction isn't considered (the fact that the time is of second order $\frac{d^2x}{dt^2}$) and an isolated ...
9
votes
4answers
274 views

What is the real cause of the boiling (forming of bubbles) of water?

I've got a question about the boiling of water. I'm a first year physics student and from the Netherlands. I've searched alot about the boiling of water and this confused me. Everyone said something ...
2
votes
0answers
60 views

Is my expansion of the state $| x \rangle$ correct? [duplicate]

In my quantum mechanics textbook it says that the relation between the basis $|x\rangle$ and $|p\rangle$ is given by: $\langle p | x \rangle = \Large \frac{e^{-ip x/ \hbar}}{\sqrt{2\pi \hbar}} \, .$ ...
5
votes
1answer
79 views

Approximate cloning of a qubit, given multiple starting copies

Suppose I'm given several clones of a qubit in a pure unentangled state. That is to say, I'm given the state $(a \left|0\right\rangle + b \left|1\right\rangle)^{\otimes n}$. My goal is to make $d$ ...
1
vote
1answer
131 views

two object connected by a spring : momentum/energy topic [closed]

Here is my question below: Question Two objects A and B, connected by a light elastic spring with elastic constant 5.0 N/m, are initially at rest. The mass A is 2.0 kg and the mass B is 1.0 kg. ...
1
vote
1answer
25 views

What does it mean for a particle to be subjected to 'more than one' simple harmonic motion? [closed]

Also what can we say now about its --> Resulting Energy? -> Resulting Amplitude? -> Maximum Velocity? Please help as I am not able to understand the process going on. I also tried to represent this ...
1
vote
0answers
28 views

Energy of a relativist electron [closed]

I need to find a way to obtain $E = mc^2(\gamma -1)$ by starting with : $E = mc \cdot p = mc \cdot v \cdot \gamma$ with $ \gamma = \frac {1}{\sqrt{1-\frac{v^2}{c^2}}}$
1
vote
2answers
70 views

Variation of a Lagrange density Symmetries

So I am reading Goenner's Spezielle Relativitästheorie and I am currently in chapter §4.9.1 Variation under Inclusion of Coordinates p. 129. So basically we have: $$\delta W_\zeta=\int d^4x' \mathcal{...
1
vote
1answer
104 views

mass attached to spring rotates in a horizontal circle [closed]

So here is the question I have: A mass of 2kg rotates at 1m/s in a horizontal circle on a table at the end of a spring with an elastic constant of 50N/m. If the original length of the spring is 2 ...
0
votes
0answers
67 views

Electromagnetic scattering $T$-matrix in MATLAB

My problem with the inverse of the matrix T (in the photo) , the matrix consists of Bessel and Henkel functions in high order (the orders from 1 to 21), then the elements of this matrix arrived to ...
0
votes
0answers
35 views

How heat can be transferred away to cool down objects

Based on the 4 ways to transfer heat which is vaporazation, contact, radiation, and convection. If I needed to cool down an object for example a hot soup how would I do it, put it in the freezer to ...
1
vote
0answers
87 views

Faster than the speed of light? [closed]

Just a conceptual question here. I have read that this is impossible as nothing can travel faster than light. But if an observer were travelling faster than the speed of light from a particular point ...
1
vote
1answer
51 views

Help with the Ricci tensor and Chistoffel Symbols [closed]

I really am confused with certain notations of the Ricci tensor and the Christoffel symbols. I'm looking to evaluate $R_{00}$ from my lecture notes, but I'm a little stuck at one point. The Ricci ...
3
votes
2answers
106 views

In a double-slit experiment, why can't we discover which slit a particle went through by measuring when the particle was detected

In a double-slit experiment, interference implies that the particle has traveled different distances from the 2 slits. Since the speed of light is constant, it seems to me that the particle would ...
3
votes
1answer
308 views

How should Christoffel symbols be written (in LaTeX)? [closed]

I'm writing a summary of a lecture on relativity, and we've recently introduced the Christoffel symbols. It seems that the upstairs indices are the "leftmost" and the downstairs indices are somewhat ...
35
votes
4answers
5k views

Why is 7 TeV considered as a big amount of energy?

Considering that $7$ TeV is more or less the same kinetic energy as a mosquito flying, why is it considered to be a great amount of energy at the LHC? I mean, a giant particle accelerator that can ...
3
votes
0answers
44 views

What is $\mathrm{U(1)}$ vector and axial?

In hadron physics we talked about $\mathrm{U(1)_V}$ (vector) and $\mathrm{U(1)_A}$ (axial) as well as $\mathrm{SU(3)_L}$ (left) and $\mathrm{SU(3)_R}$ (right). There are certain relations between them ...
1
vote
0answers
66 views

How to construct the matrix of Hamiltonians for a hexagonal lattice

For part of a project I need to solve the TISE, HΨ=ESΨ (where H is the matrix with elements <Ψi|H|Ψj>, and S is a matrix with elements <Ψi|Ψj>) for different lattices. I've done this for a ...
1
vote
1answer
85 views

Help me understand Lepton universality

I understand that we have three pairs of Leptons (generations). $(\nu_e , e^-), (\nu_{\mu}, \mu), (\nu_{\tau}, \tau^-)$ But what is this principle of Lepton universality? I have obviously tried ...
1
vote
1answer
28 views

Calculating Dark enegy, dark matter and the rest [duplicate]

I have read that Dark energy composes roughly 68% of the Universe and that Dark matter composes about27% and everything else is less than 5%. Where and how did they come up with these figures?
2
votes
1answer
62 views

What the term 'phase' in a wave actually means? [closed]

I actually want to clear my conception about the phase. I have used it while dealing with wave equations. But could not get the actual significance of it. I have learned that, 'phase is a quantity by ...
0
votes
2answers
63 views

Density matrices vs Pauli matrices

Studying quantum mechanics, I have suddenly come to the conclusion that Pauli matrices are essentially density matrices for spin systems. Does it make any sense or I have missed something?
0
votes
0answers
76 views

Off-diagonal matrix elements of the Hamiltonian = transition rate?

Definition: In the tight binding Model $t_{xy}$ denotes the quantum mechanical amplitude that an electron hops (tunnels) from the site y to x. My Problem: In many models we have $t_{xy}=H_{xy}$ and ...
0
votes
2answers
58 views

Meaning of temperature during phase transition

Microscopically, temperature is related to the average kinetic energy of a system in thermal equilibrium. Both LIQUID water and GASEOUS steam can exist (independently) at a temperature of 100 degree ...
1
vote
1answer
58 views

How can a particle in circular motion be in translational motion?

I came across this: If a particle is moving in a circle it is in pure rotational motion about the centre of the circle, while for a moment it may be in pure translational motion about some other ...
1
vote
1answer
55 views

Pressure gradients at two different sized holes separating 2 chambers at different pressures [closed]

Why is the pressure gradient by the simplified Bernoulli equation higher at the smaller hole?
4
votes
1answer
59 views

Electron-Positron Annihilation in a Gravitational Field

When an electron and positron annihilate what happens to any gravitational energy they have? In a way the energy is 'shared' between these two particles and all the matter in space. It must take a ...
2
votes
3answers
64 views

Kinetic energy of a rotating object

in an exercise, a linear molecule is being subject to a force applied on the edge in its axis. Then $K_1=\frac{1}{2}mv^2$, all is well. Then in the second point of the exercise, the force is applied ...
1
vote
3answers
66 views

Homework - Young's Double Slit Experiment

I have attached the question as a picture. I simply don't understand where to begin this question. It is given that $l \gg d$. Why shouldn't the phase difference at $O$ be zero? What exactly is ...
1
vote
2answers
68 views

Self similar functions

I'm trying to undestand the self-similarity as an invariance of a function under certain transformation. For example I think $$f(\lambda x)=\lambda^\epsilon f(x)$$ could be understood as a self-...
0
votes
1answer
30 views

Basic PE question about moving a planet.

If you lifted enormous masses (eg. many gigantic rocks) at one point (A) of the planet's equator. Then after 180 degree planet rotation, released the potential energy by lowering the rocks (B). (*...
-2
votes
2answers
94 views

can we bend EM waves with any fundamental force except with gravity

can we bend EM waves with any fundamental force except with gravity....like a machine invented by nikola tesla actually,wat my question is there is a auto biography of nikola tesla....he says that ...
2
votes
2answers
137 views

Meaning of “realism” in quantum mechanics

When physicists doing work in quantum measurement, decoherence, Bells' inequalities etc. use the term "realism" what exactly do they mean? I'm looking for answers targeted towards, say, someone whose ...
0
votes
2answers
79 views

Can we determine the location of a radio station if we know the wavelength and frequency of radio wave emitted by that radio station?

let say that we can detect the wavelength and frequency of radio wave then can we detect that from where these radio waves are coming or from how much distance these waves are coming?
1
vote
2answers
47 views

Quantum mechanics of electron beam and measurement

I'm trying to understand the following phenomenon quantum mechanically: Problem statement If I'm shooting an electron beam (using a vacuum tube for example) and I have a measuring device at a ...
1
vote
3answers
68 views

Is energy related to work or is it an entirely different thing?

I was reading about work done and energy, and I got to know some things. Let's take a simple example: Suppose I move an object to a certain height. Here, I apply a force against the force of gravity ...
1
vote
2answers
129 views

Why can't the entropy of an isolated system decrease? [duplicate]

I read that heat cannot flow from cooler body to hotter because for that entropy of the system becomes negative. Why is that so? Why we cannot have negative entropy?
1
vote
2answers
70 views

How to estimate wind speed from a pressure difference?

Does a formula (or a rule of thumb) exist to estimate the wind speed between a high pressure area and a low pressure area given the pressure difference between the two areas? Only the wind resulting ...
1
vote
1answer
30 views

Coherence of pressure and mass flow in a pipe [closed]

What is the coherence of pressure and mass-flow in a horizontal pipe? Let's assume I have just one pipe with pressure = 1.5 bar at the input and through pressure-losses 1.2bar at the output. Is there ...
1
vote
0answers
72 views

Intuitions for the simplest model in which the evolution of the laws of nature arises from the natural selection of structures [closed]

The problem I’m trying to solve can be described as To create the simplest model possible in which the evolution of the laws of nature arises from the natural selection of structures. This approach ...
0
votes
1answer
20 views

Bayer filter mosaic [closed]

Hello, How a yellow or any other color that is not rgb light, get throw the Bayer filter since only allows the RGB value to pass ?
1
vote
0answers
33 views

What does the density of points (tail point of the vectors) represent in the geometrical representation of a vector field? [closed]

While trying to understand the divergence of a vector through the geometrical representation of the vector field, I found that pictures can be misleading. Even a vectors field which looks to be ...

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