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While studying the classic Doppler effect equation, I was curious to how the traditional equation of the doppler effect for sound, where the observer and sources are facing each other, gets effected once the observer is stationary and the source moves at an angle from the horizontal?
In Sakurai, there is a question (problem 5.12) about degenerated perturbation theory where the degeneracy is not lifted in first order. One is supposed to find the energy correction in second order for the Hamiltonian \begin{equation} H=H_0 +\delta H = \begin{pmatrix} E1 & 0 & a \\ 0 & E1 & b \\ a* & b* & E3 \end{pmatr...
Suppose I have two cylinders: a light one and a heavy one. Now, I let the cylinders roll down a ramp without slipping. My question is, which one will get to the bottom of the ramp first, and why?
In wikipedia page about hadrons the following image appears: I can understand why the intersection between hadrons and fermions are baryons, as a way to say a baryon is a kind of hadron composed of several quark fermions. However, what is the meaning of the intersection between hadron and bosons labeled in the picture...
Suppose a point initially located at (x,y) moves to (x',y') in a circular motion with angular velocity $w$. Then, the center of this circular motion (x*,y*) can be found by the following: where $\theta = w \Delta t$. I really do not understand how this relation holds. Do you have any ideas?
In Ballentine's book on QM in Chapter 3 he states, that if a state vector is transformed there is a corresponding transformation on the operators associated with observables. In math, if $$ |\mathbf{\psi'}\rangle = U|\mathbf{\psi}\rangle$$ and $$ A |\mathbf{\psi} \rangle = a_n |\mathbf{\psi} \rangle $$ Then there mus...
It seems that there is no nice derivation (either on this website or elsewhere on the web) of the standard formula for the redshift of a photon emitted in the Schwarzschild metric, as observed by an observer at infinity. The formula is: $$ \frac{\lambda_{\inf}}{\lambda_{\rm emitted}} = \left(1 - \frac{2GM}{c^{2}r}\rig...
To launch a rocket, fuel is burnt and is released in opposite direction relative to rocket and it pushes the rocket upwards because of third law of motion but the fuel molecules are not actually pushing the rocket upwards as it released in the opposite direction. So what is exactly pushing the rocket upwards or where d...
If an inductor is given to you and it is connected across a battery without any resistance in the circuit,then will the inductor stretch,compress or remain the same length?
We know that at point A and B there is same voltage.Then why electron moves from one point to the another one?
I would like to know the general method of converting between units. For example converting Joules to $\frac{g\cdot cm^2}{s^2}$ I assume it's possible because the SI unit of energy is $\frac{kg\cdot cm^2}{s^2}$ so is it as simple as going from J to $\frac{kg\cdot cm^2}{s^2}$ and then times 1000 to get $\frac{g\cdot cm^...
Let I be the current flowing across some junction as a result of N charge carriers of charge q. And let $\langle I (t) \rangle$ be its average. Assume a particle number distribution such that its fluctuation is given by $\langle (\Delta N)^2 \rangle=\langle N\rangle$. So $\langle I\rangle = q \langle N \rangle$ and by ...
I would like to ask if there is any mechanism that can increase the weight force of a body using electricity. For example, this mechanism is enclosed in a box which normally weighs 1kg but when electricity is supplied to the circuit, the box exerts a force equal to the force of a body of 500kg mass. There are no extern...
I have seen several attempts at building a consistent quantum-classical theory, i.e., a theory where a quantum (sub) system interacts with a classical one somehow. Examples: (1) https://iopscience.iop.org/article/10.1088/1742-6596/442/1/012006. (2) https://arxiv.org/abs/1802.04787 However, they tend to focus more on th...
From the wikipedia article In physics, a physical system is a portion of the physical universe chosen for analysis. Everything outside the system is known as the environment. The environment is ignored except for its effects on the system. Can we say this mathematically and very generally? This would first require a...
From an external point of view, an astronaut falling towards a black hole takes an infinite amount of time to reach the horizon, while the horizon vanishes in finite time due to Hawking radiation. Does the infalling astronaut agree about the black hole evaporating before she reaches it?
When we assume that mass m is directly at the center of L, and $\alpha$ is the angle between the rope and the horizontal, I am able to show that for equilibrium, $$\sin{\alpha}=\frac{m}{2M}$$ There is also a resultant reaction force from the roller due to the resultant of left side tension and weight of M (which are e...
I wonder if anyone knows if any experiment has been done using single-photon interference to form fringe by air wedge, such as Newton's rings. The air wedge could be formed between two flat glass plates or a convex special glass surface and an optically flat plate. The reason I ask is I don't know if this interference ...
When there is a charge between two parallel plates why is the sum of both forces always equal where ever it stands between those two plates? When I say both forces I mean the negative side interacting with the charge and the positive.
Let's suppose a muon emits Cherenkov light while travelling in a medium along a straight line. Let's suppose the motion is perpendicular to a wall which is instrumented with photomultipliers. Question: Should these PMTs "see" a ring or a solid circle? Note: I believe the true answer is a ring. Indeed I know that for ex...
Is $|\mathbf r\rangle$, the state of being exactly at $\mathbf r$, a direct sum or a tensor product of $|x\rangle$, $|y\rangle$ and $|z\rangle$. The same question for $|\mathbf p\rangle$. Now my attempt is the following: If it were a direct sum, i.e. $|\mathbf r\rangle = |x\rangle +|y\rangle + |z\rangle$ then the posit...
I have a power source connected to a resistor in series. I am asked, "what is the electromagnetic field in the circuit?" I know there is a magnetic field due to the moving current but is there an electric field also?
$$\vec{\nabla}\cdot(\vec{A}\vec{B})=\nabla_a(A^aB^b) \tag{1}$$ I'm trying to write left side of equations $(1)$ using abstract index notations. I'm sure $\vec{A}\cdot\vec{B} = A^{a}B_{a}$, which the contraction of index $a$ would give scalar. But when I'm a little bit confused when trying to put gradient in front of th...
Hi I have been trying to understand the standard model of particle physics and I don't understand why my textbooks says that the fundamental bosons are the exchange particles of the four fundamental forces of nature even though the pion is an exchange particle for the strong nuclear force and it is a meson so it is com...
In Gauge theory of weak interactions by Greiner and Müller, they show the following superb comparison of the interaction potentials between particles as a function of separation: I have never seen this graph anywhere else, and nor have I seen any information on how the lines it plots were or could be derived. Is ther...
Consider an open embedding $\varphi:\Bbb R^{1,1}_- \hookrightarrow (0,1)^2$ with $\varphi(x_1,x_2)=(e^{x_1},e^{x_2})$ I need to put a metric on $(0,1)^2$. Here’s what I know so far. I need to transport the Lorentz metric: $ds^2=dxdy. $ Since my map is a diffeomorphism I can push forward the Lorentz metric to $(0,1)^2$....
If an object falls and hit the ground with a force, the ground also pushes it back because of third law of motion but from where does the force coming in the ground particles and they are also pushed downwards at the same time due to force of object. So what actually applies force to the fallen object?
I don't know what is in a boiling water bubble and that is why I asked
If you look at a paper on fluid dynamics, you will see a paper that is performing CFD simulation with a mach number of 0. This means that the flow velocity is 0, so I thought that no flow would occur, but when I looked at the results, the flow existed and emitted vortices. What does mach number = 0 mean?
What I know is total angular momentum $\vec{j}= \vec{\ell}+\vec{s}$, here $\ell=3$ for $f$ state, $s=1/2$ for spin, so the total angular momentum should be $7/2$, is this correct? is there any other allowed values?
I started reading Quantum Mechanics and I'm being told that matter and light have both a particle and wave aspect to them. It is easy to understand the particle aspect of light: experiments show that light can push an electron out of it's orbit, so one imagines that light has to behave to some extent "as if" it was a p...
It was nighttime. I was flying on an airplane. As we were landing we passed over a highway. I saw cars below with their headlights on. I could see that the light from their headlights only lit up a certain distance in front of them. Any object that fell past that distance would have probably looked dark to the driver. ...
Why is it that most everyday cars have an engine and the center of mass in the front? With my limited knowledge in physics, my understanding is that pulling an object is much easier than pushing due to stability reasons and the car with com placed in the front(second diagram) should be much more unstable, but this is ...
Given two containers of equal volume, one tall and thin, one short and wide, containing the same liquid at the same temperature, pressure, etc... which one would cool faster?
When you have increasing energy levels in 2 or 3 dimensions how does the values of quantum numbers $n$ increase for each dimension? For example if you have ground state $E_1$ then you have for $(n_x,n_y,n_z)$ is $(1,1,1)$ in 3 dimensions. So does this mean for energy $E_2$ you have $(2,2,2)$ ? I've only learnt it in 1 ...
I'm trying to solve for the shape of the free surface of an incompressible, perfect fluid in a bucket which is spinning with (uniform) angular velocity $\Omega$. I know the solution is a paraboloid, and I know how to obtain it assuming the velocity profile $\mathbf{v}=v_{\phi}(r)\hat{\phi}$ where $v_{\phi}(r)=\Omega r...
This is a problem from my introductory physics textbook: The ladder shown in the figure has negligible mass and rests on a frictionless floor. The crossbar connects the two legs of the ladder at the middle. The angle between two legs is $60^{\circ}$. The fat person sitting on the ladder has a mass of $80$ kg. Find the...
As electricity is transferred in earth by earthing and lightning, why it does not become negatively charged?
It is written in my book that a disorederd state is more probable than an ordered state and hence every system tends to move spontaneously to a state of higher disorder or higher probability. But I think it depends on us since we can define any state as an ordered or disordered state. Suppose we have 3 unbiased coins a...
From my textbook, it says when the live wire touches the metal casing, a current will flow to the earth and blow the fuse located in the live wire. But through what devices will the current flow after it goes into the earth? Is it just simply that earth wire will be reconnected to the neutral wire, so it blows the fuse...
how can I approximate the angle $\theta$ of a pendulum $0.01 \mathrm{s}$ after releasing it with speed $0$ at an initial angle $\theta_0<\pi$? Recalling $$\frac{\mathrm{d}^2\theta}{\mathrm{d}t^2}+\frac{g}{l}\sin\theta=0$$ And what in the case when I have two pendulms with different initial conditions? I just need to ap...
Why do we see the lines in a star spectra displaced from the wavelength they belong to and so we need to calibrate the spectra ? Is it only because the relative motion of star and earth ?
So I've become rusty in Quantum Mechanics. What is $\langle x_1 |V(\hat x)| x_2 \rangle$? Where $V$ is the potential and $|x \rangle$ is the postion eigenket? $$ \langle x_1 |\hat V(\hat x)| x_2 \rangle = ? $$ Is it with $V(x_1) \delta(x_1 -x_2)$ but since the position operator can also act on a bra is it $V(x_2) \d...
For a blackhole of mass $M$, radius $R$ and Schwarzschild radius $R^*$ (where $R<R^*$), its density $\rho$ is defined as $$\rho=\frac{M}{(R^*)^3}.$$ One reason I read for using the Schwarzschild radius $R^*$ instead of the actual radius $R$ is that no measurements can be made inside of $R^*$ (i.e. for $r<R^*$). I know ...
Actually, this is part of a homework question in my classical mechanics class. The question requires me to derive the eigenfrequencies of the acetylene molecule's bending and stretching modes under the harmonic approximation. For the molecule $\rm H-C\equiv C-H$, with masses of the atoms $m_{\rm H}$ and $m_{\rm C}$, st...
In one of the postulates of Bohr's model of hydrogen atom it is said that "While the electron revolves, the electrostatic force between the electron and nucleus provides centripetal force. The derivation then follows: $F_e = F_c$ $\implies \frac{\textsf{charge of electron x charge of nucleus}}{4 \pi \epsilon_0 \times r...
I am quoting the following phrase from my book " ... in Einstein's picture, photoelectric effect arises from the absorption of a single quantum of radiation by a single electron ... " My question: Why can't multiple photons strike the electron at the same time? After emission from the metal, why doesn't the electro...
I have a question about semiclassical gravity approximation. For probing Hawking radiation, we usually treat gravitational theory as semiclassical assuming large $N$ matters. However, I do not know the reasons why we can drop quantum fluctuations of gravitational mode in large $N$ limit.
I love the gun in Minority Report. It seems to send a shockwave that can throw people and objects back. The gun has a rotating mechanism that triggers the action and loads a charge. Here's it in action: http://gph.is/29xazEx I Googled shockwave guns but it was mostly pressurized air inside of plastics tubes. Very uncoo...
Consider a system at rest with three bodies and let an external force applied. The bodies' masses are: $m_x$, $m_y$ and $m_z$. The bodies move together when a force is applied. So on my mind, the same force should be applied to each of these boxes,because boxes conduct forces.But when we use newton's second law to anal...
Well, the definition of electromagnetic waves in a couple of textbooks is stated to be, 'A wave produced or resulting from the accelerated motion of a charged particle'. My question is straightforward- If it is so, light should not be an EM wave, since photons are not charged. I know that light consists of oscillating ...
(Just so you know my background) I have taken a graduate course in quantum mechanics. I have also learned about information entropy in various places (statistical mechanics, information theory, dynamical systems). It recently occurred to me that the HUP might have an interpretation purely in terms of entropy. I pondere...
UV completion is procedure of extension of initial theory, which describe only low-enegry degrees of freedom of theory, to arbitrary energy scales. UV complete theory is one whose correlation functions or amplitudes may be calculated and yield unambiguously finite results for arbitrarily high energies. We start with co...
Question:In the arrangement shown in figure,the ends P and Q of an inextensible string move downwards with uniform speed u. Pulleys A and B are fixed. The mass M moves upwards with a speed- Actual solution: Let the speed of mass M be v.The length of the string will remain constant. So by constraint relationship, we ca...
Suppose we have $n$ Goldstone bosons which is obtained from the fact that the ground state $\eta$ is invariant under a subgroup $H$ of $G$. Each of these Goldstone bosons will be described by an independent field $\phi_{i}$ which is a smooth real function on Minkowski space $M^{4}$. These fields are collected in an $n$...
I know about cosmic strings. They are 1-D topological defects in space-time which may had been created during the symmetry breaking phase transition during the big bang. But my question is : Are there any ways using which we can create cosmic strings? And if there are any ways then what are those ways?
In Robert J. Sawyer's sf novel The Oppenheimer Alternative, a bunch of physicists try to find the composition of the martian atmosphere with spectroscopy. They say that to find water vapour or oxygen, a good technique is to use orbital quadrature, i.e., when the line from the Sun to the Earth and the line from Mars to ...
In many places and tutorials, gravity is often considered as a negative vector. I am confused as to why is that? I though I was missing something from trigonometry but it was just negative in first place. It is pointing downwards, but if we negate that vector, then it should move up. I need some explanation about this ...
When we attempt to measure a certain property of a particle, how and why does its wave function collapse? I've tried to find answers on my own, but they've been far too complicated for me to comprehend. Would appreciate any answer with limited complex jargon, and more simplistic explanation, if possible.
This is a problem from my introductory physics textbook: A cylinder is released from rest from the top of an incline of inclination $\theta$ and length $l$. If the cylinder rolls without slipping, what will be its speed when it reaches the bottom. This is of course easy to solve using the principle of conservation of...
I am struggling not only to come up with action/angle variables for the system, but more generally an appropriate Hamiltonian that takes into account the tilt of the plane. The system is as follows: "A plane pendulum of small amplitude (length) A is constrained to move on an inclined plane, as shown in the accompanyin...
It can be assumed I have taken introductory courses of GR (Carroll) and QFT(Schwartz). I skimmed through this book by Marcolli on Seiberg-Witten (SW) gauge theory. What I have understood after looking at it is: I will be needing Algebraic topology. Also, after looking into few supersymmetry lecture notes on arXiv I fou...
This is the radius that was given to us r= 6400km What I've tried is figuring out what is the force that would push the people off the equator,and what is the force that would "pull" people in. The force that would be pushing people off the equator would be the centrifugal force. Now to calculate the force I'd use this...
Does the quantum spin of a particle relate to its frequency and wavelength? I cannot seem to find anything on this. If I were to guess, it seems that as $E = hf$, and $\omega = 2\pi f$, and $spin_1 = h/2\pi$, then $E/\omega = spin_1$. Regards, Pete.
Once we have defines the angular momentum operators $L_z,L_y,L_x,L^2$ ($L^2=L_z^2+L_y^2+L_x^2$) suppose we focus on the eigenstates $|l \ m \rangle$ common to both $L_z$ and $L^2$: $$L_z|l \ m\rangle =\hbar m |l \ m\rangle$$ $$L^2|l \ m\rangle =\hbar ^2 l(l+1) |l \ m\rangle$$ suppose now that we want to talk about eige...
These are the pics of the speakers in my surface laptop. What are these white pellets used for. Similar pellets can be found in many tiny speakers of iPhones and Samsung phones.
I am following a lecture note on the QFT. But am a little confused about some parts related to the vacuum bubbles. We define the Feynman propagator, $D_{F}(x-y)$, as giving the amplitude for a particle emitted at $x$ to propagate to $y$ (where it can be measured). After following the LSZ reduction formalism and Wick's ...
I did a video (30 fps) of the motion of of a mass suspended vertically by just one spring in one side. This spring is held by a rope connected to a fixed rod, as shown in the picture. From the bottom to the top of the picture, we see, a bar of aluminium , another mass, a plastic ruler connected to the spring. The spr...
How do I calculate the value of the Planck constant in geometrized units? I cannot find its value anywhere.
We all know that putting some charge within a cavity in a conductor, makes its free electrons move in a way that those charges become electrically isolated from the outside world. But what happens if only one electron is put? If that's possible, what is the configuration of the induced charge on the inner surface (whic...
I gather that for the landau free energy, $L = \int d^{d}r (a\phi^2 + b\phi^4$) +... it makes sense to also include gradient terms like $(\nabla \phi)^2$, as the gradient represents the costs of domain interfaces. I have also read that gradient terms take into account local variation, and that near the critical tempera...
From what I understand, the notion of frames of reference took precedence over a notion of "absolute space" in classical mechanics. Did the luminiferous aether, aside from attempting to explain the behaviour of light, aim in any way to establish a preferred frame of reference ? It could seem to be a excellent candidate...
A boy jumps from rest straight upward from a flat, stationary concrete surface. The boy, of mass M, leaves the concrete surface with speed v and his center of mass rises a distance d to the highest point of the motion. How much work did the normal force of contact (N) between the boy's feet and the concrete do on the ...
I want to learn how to solve Harper's equation and plot the Hofstader butterfly spectrum numerically. Can anyone suggest references/links where this is done?
In the book I'm reading, the work done by a force acting on a particle is given as: $$W= m\int_{t1}^{t2}\dot{\textbf{v}}\cdot \textbf{v} \,dt = \frac{m}{2} \int_{t1}^{t2}\frac{d}{dt}v^{2}\,dt$$ I don't understand the second step, why can we say that $\dot{\textbf{v}}\cdot \textbf{v} = v \,\dot{v}$ ? Wouldn't that only ...
I am not sure if I am asking a very complicated question but I want to know exactly what is happening at the molecular level that exerting force along center of mass produces linear motion and not torque and force away from COM produces torque and not pure linear motion. Does force not get distributed properly or somet...
When reading some astrophysical papers I saw things like this: "The sources are variable on very short timescales, implying a compact emission region" How can we conclude or measure the source size, or emission region size (or its compactess) from the variability of the spectrum?
in the transformation from a Wye (star) to a delta (triangle) resistor network it is said that if we want to know the "resistance" between points $N_1$ and $N_2$ ($N_3$ should be disconnected) then $R_\text{Y}\left(N_1, N_2\right) = R_1 + R_2$ - which is obvious to me, as no current flows towards $N_3$. Furthermore it ...
I know that $\sin x$ or $\cos x$ curves can be said to be "in vibration," but what about $(\sin x)^2$?
Greetings I am having trouble to understand how the distribution should be if the dipole is not at the origin and not along z-axis. For a hertz dipole with length $d<<\lambda$ along z-axis at the origin of coordinate system we can say it has a distribution $\mathbf{J}=I_0 \mathbf{z}_0$. Assume now that the dipole is lo...
I know that in the world there are universal constants that are numbers with their respective units, but on the contrary, dimensionless numbers do not have physical units. So, although this question may sound a bit absurd, I would like to know how useful are dimensionless numbers? Or what relevance do they have in phys...
In 1d, for $V(x) = g\delta(x)$, integrating the TISE yields (assuming that $\psi$ is bounded$^\dagger$, so as to suppress the term containing $E$) $$ -\frac{\hbar^2}{2m} \left( \psi'(\varepsilon) - \psi'(-\varepsilon) \right) + g\psi(0) = 0 $$ for $\varepsilon\to0^+$. Now, this doesn't at all imply that $\psi$ has to b...
This question is about a mathematical subtlety arising in the computation of the partition function of a supersymmetric ensemble of some lower dimensional $D$-branes attached to a stack of higher dimensional ones. The general prescription to attack this problem is to add chemical potentials for the lower dimensional br...
If we have the wavefunctional $\Phi[\psi]$ which tells us the probability density for finding $\psi$. Let's say we know the exact field state at $t=0;$ $\psi(x,0)$. Can we use the wavefunctional $\Phi[\psi]$ to evolve the wavefunction to $\psi(x,t)$. Using something similar to Bohmian mechanics for fields because if we...
I am reading a famous paper by S.Hawking - "Quantum gravity and path integrals" https://doi.org/10.1103/PhysRevD.18.1747. On the third page left column there is a statement, after the derivation of the relation between area and entropy $S = A /4$ : The reason the classical solutions in gravity have intrinsic entropy w...
Given the operator $\vec{A}=\frac{1}{\sqrt{V}} \sum_{\vec{k}, \alpha} \varepsilon^{\alpha}\left(c_{\vec{k}, \alpha}(t) e^{i\left(\vec{k} \cdot \vec{r}-\omega_{k} t\right)}+c_{\vec{k}, \alpha}^{*}(t) e^{-i\left(\vec{k} \cdot \vec{r}-\omega_{k} t\right)}\right)$ and using $H=\frac{1}{2} \int d^{3} r\left(|E|^{2}+|B|^{2}...
I am reading this paper by Tatarskii, which serves as an introduction to the Wigner representation of quantum mechanics. There is a step in the paper involving the Weyl transform that does not seem valid to me. Define the ordered operator function assigned to the function $f(p,q)$ as $$ \begin{align} \left\{ f(\hat{p},...
Blackbodies emit a continuous spectrum of radiation, whereas a cavity with reflective walls at thermal equilibrium contains a discrete spectrum. According to Kirchoff, "smoothing out" the spectrum of the cavity radiation by looking at the average number of frequencies permitted by the cavity in a small frequency interv...
I have read that when representing the possible nuclides in the $(Z,N)$ plot, the stable nuclei located on the line $N=Z$ for $A<40$, and that this is due to the Pauli exclusion principle. I have read about it in this question, but this is still not entirely clear to me: why does the Pauli exclusion principle imply tha...
Consider the circuit in the attached image. The task is to determine the currents in the nodes A and B. The values of the different components are given. Any hints on where to start? I’ve considered replacing the current source with a voltage source and vice versa (the current source is connected in parallel with too m...
If I have two balls, one completely in the water (mass = 4m), and the other half submerged (mass = m), the volume of both balls is V = 15 cm^3. They are tied together with a string. How can I calculate the mass of each ball, the density of each ball, and the forces acting upon each ball? Thanks
The ITER Tokamak is designed to produce 500 MW of thermal output from 330 MW of input power, ignoring electric conversion efficiency. The heaters require 150 MW (to heat input plasma by 50 MW), the magnets require 80 MW, and the other subsystems require 100 MW (source). How much of this 330 MW input is actually physic...
I have that the electrical energy $E$ in Joules (J) is equal to $E = time \times current^2 \times resistance$. Reasoning with SI units, we can verify that this equation does return energy values in Joules. Indeed, the resistance is in ohms, or $kg⋅m^2⋅s^{−3}⋅A^{−2}$. So we get $s \times A^2 \times kg⋅m^2⋅s^{−3}⋅A^{−2} ...
I was studying current in a wire, now a doubt raise me up. If we have, for example, two wires of the same length connected one to the end of the other, but one wire has the area two times the area of the other. What will be conserved here? (Conserved in the sense that the magnitude of the quantity will remain the same)...
Let's assume that I was given the following circuit: Where the capacitor is fully charged at 6V, and a switch (not shown) will be closed at time t=0. From this, let's say that I pick the following directions of my currents in order to do nodal analysis (assume ground is on the middle bottom node): My simplified KCL e...
There is a lot of works on hard-sphere glasses where the spheres or other particles are squeezed and fail to find the global energy minimum being jammed in amorphous state. Is it possible to form a water glass by (perhaps, quickly) compressing water to very high density?
One of the canonical prescriptions to quantize a classical theory is to reproduce the *-Algebra of functions (functionals) on $M$ on a complex Hilbert Space. In relativistic quantum mechanics I saw the so called equal time second quantization, that is one usually substitute the field Poisson bracket with Commutator/Ant...
I'm watching Interstellar and as a huge gravity geek I'm loving it. I have some doubts about the accuracy of the wormhole visualizations, but I want to double check because I heard they had physicists advising them while making the film. Some of the shots while they are in the wormhole look kind of unrealistic like the...
I'm having a problem understanding why in the Poisson equation for gravitational potential, the term with the mass density has a positive sign, while for the electric potential, the charge density has a negative sign. Gravitational potential: $$\nabla^2\phi=4\pi G\rho$$ Electric potential: $$\nabla^2\phi=-\frac{4\pi}{c...
Suppose a model for a flux of (astro)particles $\dot \Phi(E,t)$ (from a supernovae) that depends on particle energy $E$ and time $t$ (from beginning of explosion), and 3 free parameters $T_a, M_a, \tau_a$ (in which, for simplicity I won't show the details). I have $\approx 20$ events from detection in which I have the ...