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I am trying to correctly wrap my head around the density of states concept, wonder if anyone can help....
When looking at the classical graph that is used to describe this concept, we have density of states on the y axis and energy on the x-axis. I understand that if you integrate under a curve between two points you c... |
Consider a tube of linearly varying cross section... Now consider a section of the tube...There are pressure on the ends of this section due to the fluid... Now consider the walls, there is a pressure perpendicular to the walls and thus a reaction pressure(or force say). Now divide the forces into their horizontal and... |
I have another question relating to band theory, wonder if anyone can help?
If I am correct, in band theory we have this idea of creating N different energy states for N atoms that are in a system (with a sigma and sigma* orbital being created for each orbital that the one atom had) The electrons from the N atoms popul... |
When defining the dispersion relation in a waveguide we have an equation that also includes a cutoff wave-number. This cutoff wave number depends on the geometry of the waveguide.
$$
k_z = \sqrt{\omega^2/c^2 - (m\pi/a)^2 - (n\pi/b)^2},
$$
where $a,b$ are the dimensions of the waveguide and $n,m$ are the mode numbers.
I... |
I am currently studying about the thermal conductivity of rods, as I am reading a Idea popped up in my mind that is ,
Is the concept of wheat stone bridge Valid to thermal resistors ?
|
Is it possible to derive uncertainty principle from QFT?
Which kinds of perturbation (particles, monopoles, ...) are rule out by this principle?
|
Lorentz transformation along with inverse Lorentz transformation for 1 spatial dimension are 4 equations containing 4 variables. The equations are:
$x'-\gamma (x-vt)=0$
$t'-\gamma (t-\frac{vx}{c^2})=0$
$x-\gamma (x'+vt')=0$
$t-\gamma (t'+\frac{vx'}{c^2})=0$
And the four variables are $x$, $x'$, $t$ and $t'$. So we have... |
My brain seemed to stop during a review. Why is d (vt)/2 instead of vt?
|
Apologies for the "unscientific" way of asking this. I have been trying to look this up but haven't gotten a clear answer.
In general relativity, it's said that time itself stretches in the presence of energy.
Is this true in String Theory as well? As best as I can tell, the answer is "no". Rather, because of the extra... |
Over on worldbuild.se there have occasionally been questions where the answer is that there would be a sudden large imbalance between the number of protons and electrons. The answers have also stated that the results would be apocalyptic to a degree that I find unintuitive (and it's quite possible that I just don't hav... |
The figure 2.54 is taken from the textbook Jean-Marc Laheurte, Christian Ripoll, Dominique Paret, Christophe Loussert, “UHF RFID Technologies for Identification and Traceability”, 2014, John Wiley & Sons. It says radiation efficiency of patch antenna increases for higher substrate thickness. But the figure 1 taken fro... |
If each isolated photon interferes with itself as a wave, and the unbound photons' wave equations for position extend the entire universe (with decreasing amplitude), would faint interference patterns still show up at the extreme ends of the detector (e.g. 20ly away from center), and would they show up faster than ligh... |
This is inspired by this music.SE question, which I attempted to offer an answer for, but the more I think about it I am still quite unsure about it.
As physicists, we often try to describe features of experimental data using minimal models to capture the essential details of the system. I'm hoping to get some insight... |
If it's lack interaction keeps dark matter from behaving like matter and ending up distributed like matter. Then why did it gather at the galactic gravitational well in the first place and why end up with a distribution that causes constant rotational speeds. Does this constant rotational speeds increase the likelihood... |
As a layperson reading Yes, Stephen Hawking Lied To Us All About How Black Holes Decay, if I understand correctly Hawking radiation is a property of the curvature of space and not specifically of black holes.
So, if any mass produces very tiny amount of Hawking radiation, in the very long term are all objects losing th... |
I'm trying to develop and intuitive understanding of the Friedmann equation. I'm afraid I get lost with the relativistic derivation as it's just a lot of crank-turning. When I derive it from the Newton iron-sphere concept, I can see that the constant of integration has the physical interpretation of 'total energy at ... |
The $cGh$-cube is a way to visualise todays theoretical physics framework(s).
This representation gives the impression $c$, $G$, and $\hbar$ could be viewed as variables between $0$ and $1$. This is not the case. These are constants (supposedly).
In the case of special relativity it is obvious how this can be correcte... |
Why is the potential difference across the ends of a conductor equal to the product of the electric field and length of the conductor?
Explain this considering I am in high school.
|
What happens to the perception of loudness when 4 identical devices placed around the listener play a sound sample? Will they sound 4 times "louder" than 1 device?
What if they're a bit out of sync?
|
Suppose we have a compound which has been given energy (either in the from of heat or light). Now, its electrons would absorb this energy and kick up to higher energy levels. But, it would also re-emit this energy either in the form of heat or light. My question is: what determines whether the electron will non-radiat... |
I consider a generic signal $X(t)$. We could imagine to fix ideas $X(t)=\sqrt{R}I(t)$ ($R$ being a resistor and $I$ current flowing through it)
The energy of this signal is defined as $E=\int_{-\infty}^{+\infty} |X(t)|^2 dt$. The motivation of calling this "signal energy" can be seen from my signal example (it would gi... |
Suppose we have two qubits in the state $(a|0⟩+b|1⟩)|0⟩ $, to which we apply the following circuit.
Specify the state of each qubit after we applied the circuit to the state (a|0⟩+b|1⟩)|0⟩ . Let the first qubit be in the resulting state α|0⟩+β|1⟩ , and the second in γ|0⟩+δ|1⟩ . Specify the resulting amplitudes α,... |
If we want to hit a target by a stone or missile we have to consider and calculate the interaction of the surroundings with the thrown object precisely. Can you show a mathematical model or trajectory how a bowler hit the stumps by swinging or reverse swinging the ball?
|
The nuclear force spin dependence term of deuterium is easy to explain, its was explained before in this site in question 288357. But what about larger nuclei with higher mass numbers other than 2?
The main point of my question: Can spin term in nuclear force vary with nuclear mass number?
|
I am totally new to optics design. I am currently trying to play around with infinity-corrected objective lens and trying to image a slide with a Basler camera. I was able to get my system working with a $160$ mm tube length, $20\times$ finite objective lens and the camera. I was able to get decent magnified slide imag... |
Consider a one-dimensional integral
$$I(g)=\int dx\, e^{-x^2-gx^4}$$
One can formally expand it perturbatively order by order in $g$ so that
$$I(g)=\left<1\right>-g\left<x^4\right>+\frac{g^2}{2}\left<x^8\right>+O(g^3)$$
where $\left<f(x)\right>:=\int dx\, e^{-x^2}f(x)$. This expansion is asymptotic but that's fine. I t... |
A cable factory ships cables in spools of 100 km each. The overall length of each spool is known with great precision, it's 100 km sharp.
In order to speed up the sale process, distance markers are placed on the cables at regular intervals, so when customers need a piece of cable smaller than 100 km, the length is alre... |
What makes the trace-free tensor (or part of it) so important?
As in trace-free Ricci tensor or Weyl tensor.
|
"Heat" can be defined as:
"energy in transfer to or from a thermodynamic system" (From Wikipedia).
I have seen other definitions, but they all include the term "transfer".
A search in google scholar for "heat transfer" yields almost two million results.
But if "transfer" is already in the definition of "heat", then it ... |
I came across this equation: $T_m= \sqrt{6}T_e $.
Can anyone tell me how this equation is derived? This is how I tried to, but I got stuck after some time.
So the time period of a simple pendulum on the earth= $2\pi\sqrt{l/g}$
The time period of a pendulum on the moon is $2\pi\sqrt{l/(g/6)}$
Now how do I create an equa... |
For each materials phonon band structure there are three acoustic phonon bands (2-LA and 1-TA for bulk or ZA,TA and LA for 2D materials).
Now, I have this straightforward question that "Why there is no ZA acoustic mode in bulk 3D materials whereas it appears in 2D materials (monolayer type)"?
|
I was looking at the following identity that's often used in time evolution:
$$ (e^{xA/n}e^{xB/n})^n \approx (e^{x(A+B)/n})^n$$
This holds when $(\frac{1}{2}(x/n)^2[A,B])^n$ is small. I'm wondering what "small" means. If we consider a physical system with $H = K+V$ (a kinetic and potential term). So in this case, we ar... |
Suppose I let a block fall from a height above a vertical spring. Any air drag is ignored. I want to find the maximum compression the spring will undergo. Is it possible to use the work-energy theorem over the Course of the entire motion?
The confusion is due to the fact that the spring force doesn't act throughout the... |
The Bloch Theorem says, that in a periodic potential $V(\vec r) = V(\vec r + \vec R)$ the wavefunction is
$\psi(\vec r) = e^{i\vec k \cdot \vec r} u_k(\vec r)$
For the energies, there is always graphs like that below, showing the splitting of the energy bands at the zone boundaries, when switching from the free electro... |
Suppose there is a many-body eigenvalue problem
$$
H(r_1,\cdots,r_n) = - \frac{1}{2} \nabla^2|_{r_1\cdots,r_n} + V(r_1,\cdots,r_n).
$$
This potential is symmetric and the hamiltonian does not depend on spin, but the solution should be for spin 1/2 particles. I am struggling to interpret the symbol $\sigma_i$ mathematic... |
Why does a rotating wheel have kinetic energy $K=\frac{1}{2}mv^2$ associated with its movement?
I will clarify.
Let's say I have a rotating wheel in an empty void which has an angular velocity $\omega$, then its total energy will be $E=\frac{1}{2} I \omega^2$, as the wheel is not moving. Now suppose I put this wheel on... |
I am working on relativity equations and I need help on this
This is assuming $c$ could be calculated from $G$
Can we write $c$ in terms of $G$ in $e=mc^2$
Has anyone tried to unify them?
I mean both "determine" mass
|
In Introduction to Quantum Noise, Measurement and Amplification, on page 64 is computed the power spectral density of noise on a classical waveguide. I am really struggling to understand a step of the calculation.
We consider a classical 1D waveguide. We study the physics by looking at the fluctuations of voltage waves... |
It seems that both $SU(5)$ model and flipped $SU(5)$ model are legal grand unified theories (GUT) for the standard model gauge group. In Wikipedia, it says that:
The flipped $SU(5)$ model has a gauge group breaking down
$$(SU(5) × U(1)_ χ )/ Z_5 \to (SU(3) × SU(2) × U(1)_Y )/ Z_6 $$
The flipped $SU(5)$ model represen... |
More specifically, why does having two objects of different weights make the balance lean to one or the other then stop partway? Why does the balance not just keep tilting until it falls to the side? How can something be heavy enough to tip the balance but not heavy enough to make it tilt the rest of the way?
|
The answers to Can the Lorentz force expression be derived from Maxwell's equations? make clear that Maxwell's equations contain only information on the evolution of the fields, and not their effects upon charges; the Lorentz force equation is an added equation.
Does this imply that any arbitrary time evolution of a cu... |
a).Do atomic nuclei have natural angular frequencies?
b).What would be the external force to drive the oscillator(atomic nucleus)?
|
When studying spin waves excitations in the Heisenberg Hamiltonian people often use Schwinger Bosons representation or Holstein-Primakoff which is a specific case of Schwinger Bosons. This leads you naturally to the description of the magnon. What if instead we used instead of a bosonic representation we used a fermion... |
I was wondering how to calculate the mass of water that evaporates if I were to expose the water to some amount of heat given by Q. $Q=ml$ ($l=2.26\times10^3kJkg^-1$) is the standard way to calculate the amount of water that vaporizes. However this method only applies to boiling water at $100^\circ C$, so are there alt... |
I do not understand how a polarized material (steady state, no free current, no free charge) can generate a depolarizing field.
Based on https://en.wikipedia.org/wiki/Demagnetizing_field,
I "intuitively understand" that since
$div(\vec B)=0 $
$\vec{rot}(\vec B) = \mu_0 \vec{rot} (\vec M)$
$\vec H = \frac {\vec B}{\mu_0... |
Taking angular momentum for example:since $L^2$ commute with $L_z$,we have simultaneous eigenfunctions $Y_{lm}$. Define $L_{+} =L_x+iL_y$,we know $[L^2,L_+] = 0$ so the operator $L_+$ will not change the eigenvalue (for $L^2$) of the previous eigenfunction. Since $[L_z,L_+] = i\hbar L_+$, we know it will increase the e... |
The Mach-Zehnder interferometer (FIG. 1) is constituted by two arms. It is said to be (un)balanced if the two arms have (un)equal lengths. The difference in lengths generates different interference effect (for example, for some differences in lengths, photons should be detected by only one of the detectors). However, ... |
In the double slit experiment, the observer doesn't know which slit the photon went through so the wavefunction is modelled as going through both slits at once and thus there's interference on the other side. But this seems too observer dependent because two different observers who have access to different information ... |
While applying Gauss' Law, the electric field at a point on the Gaussian surface has to come from superposition of electric fields of all the charges, whether outside or inside the Gaussian surface. However, the charge $Q$ has to be only from inside the surface. The law somehow implies that the flux due to a charge is ... |
I am a JEE Aspirant and preparing for this competitive exam . I saw this problem
For this Problem , all options given are correct . I am able to figure out Option A , but I cannot figure out other option using formula for rms velocity , average velocity. could you please tell what am I missing . Thanks in advance .
|
The zero point energy of a vacuum is different depending on speed and gravity. The zero point energy of the curved geometry of spacetime near a blackhole is higher compared to a distant observer, so to a distant observer it looks like there’s positive energy radiation where there should be zero energy. That energy diff... |
In TASI Lectures on Emergence of Supersymmetry, Gauge Theory and String in Condensed Matter Systems from lattice Hamiltonian, which describe fermions on honeycomb lattice:
$$
H_f = -t_f \sum_{\langle ij \rangle} (f_i^\dagger f_j +h.c.)
$$
From this, author obtain in continum limit:
$$
\mathcal{L} = i \sum_{n=1}^{2} \ba... |
Suppose we are given vapour pressure P and surface tension T of a liquid at a particular temperature.
What will be the radius r of the smallest spherical droplet that can be formed without evaporation?
|
The frame-connection formulation of pure General Relativity in 4 dimensions is given by the action
$$
S_{4d}[e, \omega] = \frac{1}{2 \kappa} \int \varepsilon_{IJKL} e^I \wedge e^J \wedge F^{KL},
$$
where $e^I = e^I_{\mu} dx^{\mu}$ is the frame field, $\omega^I_{\;J} = \omega^I_{\;J\;\mu} dx^{\mu}$ is the spin connectio... |
In partially inelastic collision, the objects involved in the collisions do not stick, but some kinetic energy is still lost. Friction, sound and heat are some ways the kinetic energy can be lost through partial inelastic collisions. Suppose there are two blocks on a frictionless surface. These blocks undergo partially... |
In quantum mechanics state of the system is determined by wave function, which evolves according to the Schroedinger equation, or by Pauli/Dirac equation which are derived from Schroedinger equation for particles with spin. But we have also the Pauli principle, which arose from relativistic quantum field theory and req... |
A charged particle moves with a velocity near a wire carrying an electric current,and suppose I see the particle from a frame moving with same velocity in the same direction . I will see the charge at rest . So,will the magnetic force becomes zero in this frame?
|
In a stack, tower or chimney aimed at exploiting the updraught of air due to the stack effect, would the material that the stack is constructed from impact the flow velocity up the stack? Would the level of insulation due the selected construction material (e.g. concrete vs steel) potentially lead to more or less of a ... |
A sound wave is much slower than a gamma wave, But the only difference is their frequency/wavelength. But if a gamma wave is faster than a sound wave due to frequency/wavelength, why for example arent gamma waves faster than infrared and visible light faster than infrared?
|
I found this task in an older exam of quantum mechanics and it was about the harmonic oscillator and thought it would be a good practice for myself. The task goes as:
$\text{The normed eigenstates}\ |n\rangle \ \text{can be calculated from the zero state as:}$
$$|n\rangle= \frac{1}{\sqrt{n!}} (a^{\dagger})^n|0\rangle$$... |
This question is about pages 95 and 96 of Carroll's book: Spacetime and Geometry.
We have the formula for the covariant derivate:
$$\nabla _\mu V^\nu=\partial _\mu V^\nu + \Gamma _{\mu\lambda}^\nu V^\lambda$$
We want the covariant derivate to be a good tensor operator, so we impose that the right hand side of this equa... |
Exploiting conservation laws it is possible to show that if we have a bar pendulum in a massive box on plane without friction,
the equation that rules the function $\theta=\theta(t)$ (pendulum angle with respect to vertical) is
\begin{equation}
\frac{2}{3} l \ddot{\theta} - \frac{1}{2} \frac{m}{m+M} l \ddot{\theta} \c... |
I know that the TV and radio waves that are received and transmitted are non mechanical waves.
However during storms or bad weather in general, the television signals get weaker and the program becomes laggy or terminates.
My electrician told me it is because due to the clouds the waves cannot reach the receiver proper... |
So I've been doing a course in Thermodynamics for a while and one of the questions that occasionally struck me was "How do I practically calculate the difference of internal energy between two arbitrary states, A and B?"
Thermodynamics by H.B. Callen provides a really good insight into this and according to him, Joule,... |
We were asked to calculate $\Delta x \Delta p$ for the $\psi_0,\psi_1$ of the harmonic oscillator.And so we calculated the answers and verified that $$\langle T \rangle +\langle V\rangle = (n+1/2)\hbar\omega\tag{1}$$ and that indeed they do follow the uncertainty limit.
But why can't we chose what to measure more prec... |
I'm looking at this equation:
$$\tilde{\vec E}(\vec r,t)=\tilde{\vec E}_0e^{i(\vec k\cdot r-\omega t)}\hat n \tag{1}$$
I thought that $\tilde{\vec E}_0$ was the polarization vector, but then he added $\hat n$ which is supposed to be the polarization vector... So I don't understand, what is the meaning of the amplitude ... |
Consider an entangled bipartite quantum state $\rho \in \mathcal{M}_d(\mathbb{C}) \otimes \mathcal{M}_{d'}(\mathbb{C})$ which is positive under partial transposition, i.e., $\rho^\Gamma \geq 0$. As separability of $\rho$ is equivalent to separability of its partial transpose $\rho^\Gamma$, we know that $\rho^\Gamma$ is... |
The Schwarzschild metric describes the gravity of a spherically symmetric mass $M$ in spherical coordinates:
$$ds^2 =-\left(1-\frac{2GM}{c^2r}\right)c^2 \, dt^2+\left(1-\frac{2GM}{c^2r}\right)^{-1}dr^2+r^2 \,d\Omega^2 \tag{1}$$
Naively, I would expect the classical Newtonian limit to be $\frac{2GM}{c^2r}\ll1$ (Wikipedi... |
I know that theoretically, neutronium cannot exist. However, no work was done until now even looking for neutronim around us. So my question is that, if neutronium actually existed with some minimum mass number (above 2, excluding the observed unbound dineutron in 2012), can we observe them?
They don't interact with op... |
I am writing code to find the heat capacity $C_v$ of a canonical $NVT$ ensemble. We know that,
$$C_v = \frac{\langle U^2 \rangle - \langle U \rangle ^2}{k_B T^2}$$
I have written a Metropolis algorithm to see how a standard $NVT$ system evolves.
This is how I plan to calculate $\langle U \rangle$:
$$\langle U \rangle =... |
Small black holes have collosal tidal forces at their event horizons. But there are black holes large enough where a man can cross the event horizon without being ripped apart. But does the tidal force not increase after the crossing? Is it because space cascades downwards and helps alleviate the growing tidal pressure... |
Given the quantum-optics coherent states
$|\alpha \rangle = \exp \Big(-\frac{|\alpha|^2}{2}\Big) \sum_{n=0}^{\infty} \frac{\alpha^n}{\sqrt{n!}} |n \rangle$
Show that
$\langle (\Delta X)^2 \rangle_{\alpha} = \langle (\Delta P)^2 \rangle_{\alpha} = \frac 1 4$
Where
$|n \rangle$ are the photon number states
$X=\frac{a+a^*... |
The principle of least action says that a body moves in such a way that the action value $S=\int L dt$ is stationary (often minimal). The principle is written as $$\delta S =0 \ .$$
In contrast, Schwinger's quantum action principle between an in and an out state is
$$ \langle{\rm out}| \delta S |{\rm in}\rangle = \frac... |
In a standard Atwood machine physics problem, the string going over the pulley is considered massless. So does that imply mass = 0 or mass = dm? General question: what is the difference between 0 and an infinitesimal number?
|
Ok, so I know there have been some variations of this passed around and answered already, but I still can't quite understand how this works, so I want to clarify some particular points in this.
Lets start with Einstein's relativity of simultaneity thought experiment. Specifically the variant where a person stands in th... |
When I was in school, I learned about alchemists, a group of scientists who sought a way to convert other materials into gold. They were never successful, so whenever I studied or read about them, they were portrayed as failures or foolish people, and that’s the impression I had about them.
However, more recently, I wa... |
In the formula description there is one extra partial derivative compared to the example solution. What's the difference here? What's the physical implication of the last partial derivative in the description when we're already taking the derivative of each variable? Isn't it unnecessary?
|
Minkowski space describes a flat spacetime and a Ricci-flat manifold is a solution of GRT without curvature. Shouldn't they be the same? So, what's the difference?
|
If we put a little stick through a ring, extend our arm holding the stick, and start twisting (we perform circular motion), then the ring will move outwards until it falls from the stick.
What is the trajectory followed by the ring, from an observer that stares from above? I believe that we may assume that the force ex... |
A bit of a weird question, but at the moment after the big bang, how much gravity would a person 'standing', say a metre away experience compared to one standing a metre away from the centre of a black hole (say the supermassive one at the centre of our galaxy). I know it's beyond the event horizon, so I would mean fro... |
There are a lot of questions about crossing the EH (event horizon) of a black hole on this site.
Some of them suggest, that when you cross the horizon, nothing special happens, you don't even notice crossing the horizon, and some suggest that it is even impossible to detect the horizon locally.
Nothing special happens... |
Imagine a $x$-$y$ plane, which induces an acceleration field obeyed by the equation $ a= -\frac{C}{z^2} \vec{k}$ where $z$ is the perpendicular distance from the plane to the ball and $C$ is just some constant. Now a ball is thrown from a height of 1 meter from the plane, find trajectory of the ball for an oblique pro... |
I've been studying Liouville's theorem lately. The statistical mechanics textbook by Kardar proves the theorem by showing that $dq\cdot dp$ is unchanged for each coordinate for an infinitessimal rectangle of length and width $dq$ and $dp$.
My thought is:
this proof shows that the $2n$-volume of a set in an $2n$ dimens... |
I know one can simply excite a nucleon from a nucleus by radiating gamma rays on that nucleus, or knock the nucleus with neutrons or protons.
But how can we knock out a proton specially to change one element to the another? Are there any special methods for such process?
|
I'm researching on transformers and curious to know about what this shape is called (the actual core block, ignore the wires around it).
|
Charged black holes are usually associated with the weak gravity conjecture at extremal limit, according to the well-known relation, i.e. charge to mass ratio. Now my question is that how the weak gravity conjecture and wormholes are related?
|
Spin coherent states are often introduced as "the most classical states of a finite-dimensional system", or as the analogous of coherent states of light for finite-dimensional systems. See e.g. (Radcliffe 1971) and (Chryssomalakos et al. 2017).
One way to define them (using a notation similar to Radcliffe 1971) is as t... |
I've been thinking about the problem of how to block or mitigate road noise. Rather than using a physical structure, is it possible to generate directional sound (by any means) that could/would interfere with sound waves coming from a road - without the generated interference itself creating noise for the listener? In ... |
In QFT we upgrade global symmetries to local symmetries and in order to keep the Lagrangian invariant we must add another gauge field. This produces the forces in the standard model. I understand the mathematical structure as described in Peskin and Schroeder and in Schwartz (I'm not up to the point of understanding co... |
I'm looking for formula if any or shortcut math, for following problem.
Let's say we have 3 sine waves with frequency 100, 70, 20. Assuming all 3 start on point-0, each wave cycles based on it's own frequency, but when do these 3 waves together reach point-0 as in the beginning.
|
I'm having a bit of trouble understanding the gravitational potential energy. Suppose I have two masses $m$ and $M$ rotating around one another. Theres the gravitational force between them $F=-G\frac{mM}{r^2}$ and there's the potential energy $U=-G\frac{mM}{r}$.
Is the potential energy here the energy of both masses? o... |
At the melting and vaporising stages, it is said that the temperature does not rise because the energy is used to break the bonds rather than increase the temperature.
Why is this the case?
Why can't energy be used to do both?
I would have thought that energy expenditure is somewhat random, so I am not really comprehen... |
Imagine a universe without time, or more specifically without the Flow of Time. Everything will be a 2D projection and nothing more. No movement, no interaction, and in other words no Change.
But our universe is not like this. We have movement, we have interaction, and our world changes in many ways. But there is a cat... |
In the Schwarzschild metrics (Plank units):
$$ds^2=-\left(1-\frac{2m}{r}\right)dt^2+\left(1-\frac{2m}{r}\right)^{-1}dr^2+r^2\left(d\theta^2+\sin^{2}\theta d\phi^{2}\right),$$ we can have a Black Hole (from here SBH) if $m>0$ or a Naked Singularity (from here SNS) if $m<0$, from definition a Naked Singularity is a curva... |
In electron proton deep inelastic scatterings, the sea quarks or gluon PDFs are only dominant at low value of $x$. Thomson explained this in his book Modern Particle Physics (see page 194) by arguing
...in reality the proton is a dynamic system where the strongly
interacting quarks are constantly exchanging virtual gl... |
The principle of relativity suggests that all inertial frames are indistinguishable. But if I consider the rest frame of a photon (i.e. an IRF traveling at speed $c$ w.r.t. me), then won't it be distinguishable from my rest frame? And both are IRFs.
For example, time is not well-defined for the photon rest frame. I've ... |
Or, do two particles have to be 'anti' in every sense of the word? (Opposite charge, opposite chirality, etc.)
Edit: Just to clarify... Antiparticles can have multiple properties that are 'anti' of each other... An antiparticle can even be considered going backwards in time...
BUT, do two particles only have to have o... |
I want to look at the complex wave function $\psi$ in quantum mechanics.
If a complex number $a + bi$ is multiplied by $i$ it is rotated by 90 degree in the complex plane.
What does this mean for a complex scalar field, i.e. the wave function $\psi$?
I know, that $i\psi$ is as well a solution of the Schrödinger equatio... |
If you take drinking glass (or similar object) from rim side, very close to your ear, you can hear sound, like wind.
Don't need to rub your finger around glass rim, or cause sound somehow, that sound exists by itself.
Question, what causes that sound?
|
I am not a physicist, but I know the first law of thermodynamic (conversation of energy), and I have connected this with an idea that came to my mind some time ago to create perpetual motion machine which impossible according to the first law of thermodynamic.
This spinning wheel is made of ferromagnetic material ,So ... |
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