0
votes
0answers
7 views

Can we use the LHC to place an upper limit on possible space time uniformity

From wikipedia "X-ray and gamma-ray observations of quasars used data from NASA’s Chandra X-ray Observatory, the Fermi Gamma-ray Space Telescope and ground-based gamma-ray observations from the Very ...
0
votes
1answer
5 views

How exactly does atmospheric pressure work?

Imagine a smooth wheel. Now imagine it is divided up into four "pizza slices". We came up with an idea where you would put the bottom two "slices" along with the top left "slice" in a very low ...
0
votes
0answers
3 views

Is the Hall coefficient a resistance?

The Hall coefficient is defined as this: $$R_H=\frac{E_y}{j_xB_z}$$ Always as $R_H$. I am currious as to how to use this coefficient? Is it the y-direction resistance/resistivity (it is very close ...
1
vote
0answers
10 views

Gravitational Collapse

Consider a spherically symmetric cloud of mass $M$ with radius $R$ and uniform density $\rho$. The gravitational collapse is governed by Newton's second law \begin{equation} \ddot{r} = - ...
0
votes
0answers
4 views

Chromatic aberration in human eye

A lens focuses the different colours of white light at different points. Since our eye has a convex lens there should also be such an aberration but we see objects clearly with normal eye. I want to ...
-1
votes
0answers
5 views

According to the Standard Model, did all the quantum fields originate from a single field?

I mean the electron field, electromagnetic field,... were all of them unified into a single field?
5
votes
3answers
139 views

Is there any tension in a massless spring that connects two free falling bodies in different horizontal planes?

Two bodies A and B of same mass $m$ are attached with a massless spring and are hanging from a ceiling with a massless rope. They are in same vertical plane but not in same horizontal plane. Now the ...
0
votes
1answer
13 views

Why can't we precisely define physics?

While reading a textbook, I came across this statement: "A precise definition of physics is neither possible nor necessary." I was curious why it is not possible but the textbook never ...
1
vote
1answer
95 views

Is it possible to calculate the energy of a spark?

I am not a physicist, but this question came to me and I need to answer it, and I think that you guys can help me. Actually my question is just like in the title. Is it possible to calculate the ...
0
votes
0answers
4 views

Radio galaxy lobes

A radio galaxy has giant radio lobes, each of the approximate diameter 20kpc. Protons of up to 9$\times$1019 eV remain trapped inside these lobes. What is the magnetic field that confides them? I ...
0
votes
0answers
8 views

When the exponent of sum is a product of exponents?

In quantum mechanics we solve the Schrodinger equation in terms of exponential $$\left|\psi(t)\right\rangle = e^{-it(\alpha\hat{X} + \hat{Y})}\left|\psi_0\right\rangle$$ where $\hat{H} = ...
1
vote
1answer
38 views

Is there any other momentum besides the Poynting momentum stored in an electromagnetic field?

I am having some conceptual difficulties with energy and momentum stored in the EM field. The force density at a point is $\rho E + j\times B$ Because of conservation of momentum, and because the ...
0
votes
0answers
6 views

Is it impossible to find the exact analytic form of the molar volume of liquid and gas in phase transition from the van der Waal equations?

I want to find the molar volume $v_g , v_l$ of gas and liquid respectively in the coexistence curve of phase diagram with given temperature when ideal van der Waal gas $$ P = ...
0
votes
0answers
11 views

Schwarzschild proper time and redshift

I am studying Schwarzschild metric: $ds^2 = -(1-\frac{2m}{r})dt^2 + (1-\frac{2m}{r})^{-1}dr^2 + r^2(d\theta^2 + sin^2\theta d\phi^2)$ and in particular the redshift phenomenon. Where could I find a ...
0
votes
2answers
19 views

Effect on capacitance when capacitor number increased

What happens to total charge and potential difference when number of capacitors increased in series and parallel combination?
-3
votes
1answer
44 views

Overloading stresses wooden planks beyond their elastic range, causing them to fail? [on hold]

info: In a video on youtube in an unsafe way a car is boarding a ship going over two wooden planks. It looks to me that there two 2x10" wooden boards support a 5,000 lbs car/truck (a not so light ...
1
vote
0answers
16 views

Quark-gluon plasma: status

Can we say that a QGP has been observed or is there only suggestive evidence? Is the idea that string theory, through the AdS/CFT correspondence, could help to understand this new state of matter ...
1
vote
3answers
852 views

why F is to be defined as ma?

I am currently using classical mechanics as a tool to learn how to construct a theory as an end. Therefore, I have a few questions, and a few reasonings behind them (I only consider reality, not ...
0
votes
3answers
87 views

Doppler shift and special relativity

I have been listening to an audio course on Special Relativity. In the course the teacher repeatedly says that the "laws of physics are equally valid for all uniformly moving frames of reference". ...
0
votes
2answers
37 views

Hawking Radiation and Curvature

From a simple point of view in GR/QM we take a virtual pair creation and presumable they reunite shortly in flat space-time probably representable by a space-time warpage that generates geodesic ...
0
votes
0answers
22 views

Physics at home [on hold]

I have just finished my a levels (not physics) and have decided to do a foundation degree in physics next year at uni. Where would be a good place to start gaining essential knowledge in maths and ...
0
votes
1answer
27 views

Why does the ball lose contact if it has velocity $>\qquad or \qquad< \sqrt{rg}$, while moving over a smooth sphere of radius $r$?

Let a ball of mass $m$ is given a velocity over the the top of a smooth sphere of radius $r$. The equation of motion at the topmost point will be $$mg - N = m\dfrac{v^2}{r}.$$ As $v$ increases, $N$ ...
1
vote
1answer
29 views

Standardising shadow length on sundials

The sundial is fundamentally flawed in that the length of each hourly shadow changes with the seasons. If the base of the sundial was engineered to move cyclically on an anual basis however, the ...
-4
votes
0answers
13 views

simultaneous emails [on hold]

I need to explain to someone that two emails exchanged at the same moment CANNOT result in the recipients NOT receiving those emails. I understand that this is impossible. I'd like to show your ...
1
vote
1answer
29 views

Special OPE in $\beta\gamma$ system

I would like to find the OPE $$\beta(z)\gamma(w)^{-1}$$ given $$\beta(z)\gamma(w)~\sim~\frac{1}{z-w}$$ from the $\beta\gamma$-system in CFT. Is it possible?
1
vote
2answers
131 views

Thomas - Fermi screening

I read in Ashcroft & Mermin's Solid State text that for the Thomas-Fermi approximation to be applicable, the external potential needs to be "slowly varying," What does it mean for a function (in ...
2
votes
2answers
32 views

Why must the supersymmetry generators be spinors?

I have read in a few places (for example, at page 5 here) that the supersymmetry generators must be spinors. Quoting the reference mentioned The generator of the symmetry must relate two types of ...
0
votes
0answers
20 views

Apparent depth and real depth in terms of viewing angle [on hold]

What is the apparent depth of an object in water in terms of : depth of object( $h$) refractive index of water ($\mu$) angle with which it is viewed from above ($\theta$) What I know : 1. ...
0
votes
0answers
26 views

How sketch the renormalization group flows in the $(\lambda, e^2)$ plan for scalar QED?

I have obtained beta functions of renormalization group for scalar QED: $$ \beta (e) = \frac{e^3}{48 \pi^2} $$ $$ \beta(\lambda) = \frac{1}{24\pi^2}(5\lambda^2 - 18e^2\lambda + 54 e^4) $$ which give ...
1
vote
1answer
103 views

Wait… why exactly does farady's ice pail experiment prove Gauss's law?

You'll notice there are no equations in this: that's because this is a question of morale, not of math. But a humble one at that! I come to learn, not to expound. But don't let that limit the form ...
0
votes
4answers
213 views

Which of the following has higher resistance - milliammeter or ammeter?

The question is the same as the heading - Which of the following has higher resistance - milliammeter or ammeter ? Now my teacher's and my answers don't match. It is assumed that the spring constant ...
3
votes
2answers
74 views

Minimizing the Lagrangian action of an impossible problem

I'm working my way through Structure and Interpretation of Classical Mechanics (SICM), and am stuck on an exercise in Section 1.4: Exercise 1.6. Minimizing action: Suppose we try to obtain a ...
4
votes
0answers
68 views
+50

Link between Hawking-Bekenstein Black hole entropy and entanglement entropy

I'm currently doing a project on two sided Ads-Schwarzschild black holes in the context of Ads/CFT. I want to show that the entanglement entropy between the two CFTs corresponds approximately to the ...
1
vote
0answers
14 views

Are Cosmic Microwave Background (CMB) photons entangled?

Suppose we'd like to know whether two cosmic microwave background photons emitted from different parts of the sky have any quantum correlation with each other. We could measure polarization of two ...
-1
votes
1answer
42 views

At what distance does a negatively charged atom not influence a moving free electron?

Don't know if it would be Gauss's law or Coulomb's law or both that would come into play here... but imagine a single negatively charged, stationary Hyride anion (H-) and a single free electron ...
-1
votes
1answer
37 views

Does earths gravitational force decreases?

I feel that attractive gravitational forces on Earth is somewhat similar to attractive magnetic forces. However, because the magnet loses some of its attractive force over time, will gravitational ...
2
votes
2answers
23 views

Can the Fermi energy lie into the band gap?

Fermi energy $\rightarrow$ highest energy level filled at $T=0K$ Fermi level $\rightarrow$ Energy level where we have a chance of $50\%$ to find an electron. Now in my course text they say that for ...
7
votes
4answers
152 views
+100

Is there a definite boundary between a powder and a fluid?

Given a powder of solid substance what will happen if we make the granules smaller and smaller mechanically? Will this eventually make a liquid or gas from the powder? Can there be gaseous substanse ...
1
vote
0answers
20 views

What kind of volume does the event horizon of a Kerr black hole enclose?

I'm sorry if this is a naive question, I'm not too good with General Relativity. I'm aware that a rotating black hole is described by the Kerr Metric, and black holes of this kind have ring ...
1
vote
0answers
26 views

What does white hole look like on a graph paper?

Like a black hole looks like this, what does a white hole looks like? The reason I ask is because I would've imagined that it would look like the exact opposite, i.e. piercing out upwards. But it ...
-1
votes
1answer
36 views

Classical Mechanics, The Theoretical Minimum: error in answer to partial derivatives exercise?

I'm reading Leonard Susskind's Classical Mechanics, The Theoretical Minimum, and I'm on the interlude on partial derivatives. There is an exercise that asks you to find all of the first and second ...
1
vote
2answers
442 views

How to write Schrodinger equation when a particle with some spin quantity and orbital angular momentum

Quantum mechanics: Suppose that there is a particle with orbital angular momentum $|L|$. But the particle also has spin quantity $|S|$. The question is, how do I reflect this into Schrodinger ...
2
votes
1answer
79 views

triangular symmetry of surface tension configuration of small grains on water

This is freshly ground pepper on water. Why is there a triangular configuration of the water around the pepper fragment? Surely all these pepper fragments have different shapes? You can clearly see ...
0
votes
4answers
61 views

Units about weight

We know that weight is measured in Newtons. Since, $weight= mass\times gravity$. What will be the units of Newton? Will that be $N = kg\times g$ ? But we always measure our weight using the unit $kg$! ...
1
vote
0answers
22 views

Earth connection through resonant inductive coupling with Schumann resonances possible?

I have been playing around with Tesla coils for a while now, but one limiting factor for portability is the fact that it requires an earth connection on the secondary coil. Since a Tesla coil works ...
-1
votes
0answers
37 views

When will Hamiltonian operator give a result that is not proportional to the function it acts on?

$$\hat{H}=-\frac{\hbar^2}{2m}\frac{\partial^2}{\partial x^2}+V(x),$$ $$-\frac{\hbar^2}{2m}\frac{\partial^2\Psi_n}{\partial x^2}+V(x)\Psi_n = E_n\Psi_n.$$ I was told that $\Psi$ is an eigenfunction ...
0
votes
0answers
15 views

Non-trivial integral with the Bose-Einstein distribution and Cosine function

When I consider the Casimir interaction between an atom and a perfect conducting slab I find the following non-trivial integral: $$\int\limits_0^\infty {\frac{{\cos \left( mx \right)}}{{x + ...
-2
votes
1answer
52 views
5
votes
2answers
129 views

What type of non-differentiable continuous paths contribute for the path integral in quantum mechanics

Consider the path integral for a 1D particle subjected to a potential $V(x)$ in imaginary time $$ \int_{x(0)=x_0}^{x(T)=x_T} [dx] \, e^{- \int_0^T d\tau \left[\frac{1}{2}\dot{x}^2 + ...
3
votes
1answer
700 views

“Derivation” of the Heisenberg Uncertainty Principle

Ok, so I posted this in the mathematics StackExchange, but got no response. The question I outline below is my textbook's "derivation" of the Heisenberg Uncertainty Principle. The "derivation" my ...

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