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This is a follow-on to https://physics.stackexchange.com/a/576885/117014. If we should not consider a vector and its "canonically" dual 1-form to represent the same object, then it seems that we should be able to say whether 4-momentum, for example, is a vector or a 1-form. I could ask the same thing about the electr... |
I want to evaluate the interference between diagrams in a BSM model whose relevant part of the contributions are
\begin{equation}
\begin{split}
A&=[\bar{u}_e(k_2)v_e(k_3)] [\bar{u}_e(k_1)u_\mu(p_1)] \\
B&=[\bar{u}_e(k_1)\gamma_\mu v_e(k_2)] [\bar{v}_\mu(p_1)\gamma^\mu v_e(k_3)]
\end{split}
\end{equation}
Using the pola... |
I'm working through Chapter 1 of Analytical Mechanics for Relativity and Quantum Mechanics, and in Section 1.8, they derive the equality in the question. To show this, they claim that
$$\dfrac{dT}{dt} = \sum_{n = 1}^N \mathbf{f}_n \cdot \mathbf{v}_n = -\sum_{n = 1}^N \mathbf{v}_n \cdot \nabla_n U(\mathbf{r}_1,...,\math... |
This question can probably be reduced to semantics and I have read the similar ones already asked.
On page 27 of the volume 2 of his series on QFT, Weinberg states:
...there is more to renormalizability than power counting; it is
necessary also that there be a counterterm to absorb every divergence.
In my understandi... |
Why the density of states in 2D is constant?
Or in 3D why DOS is related to E^1/2 and in 1D and 0D how we can explain the relations physically?
|
Which general formula for the box operator is correct, $\Box=g^{ij}\partial_i\partial_j$ or $\Box=\frac{1}{\sqrt{g}}\partial_i(\sqrt{g}g^{ij}\partial_j)$? I have seen both the definition being used when both produce different results, e.g. for 2-dimensional polar coordinate, former yields $\Box=\frac{\partial^2}{\parti... |
Consider a 2 body system as shown:
Consider the floor to be absolutely smooth and the coefficient of friction for the contact between $m_1$ and $m_2$ to be $\mu$. Now suppose I apply a force $F$ that causes the system to move, and that force $F$ is applied on the upper block ($m_1$).
Then, why does it ($m_1$) move fast... |
In (Curtright, Fairlie, Zachos 2014), the authors mention (Eq. (14) in this online version) the following relation, known as "Bopp shifts":
$$f(x,p)\star g(x,p)=f\left(x+\frac{i}{2}\partial_p,p-\frac{i}{2}\partial_x\right) g(x,p),\tag1$$
where the $\star$-product is defined as
$$\star\equiv\exp\left[ \frac{i}{2}(\parti... |
When the paper was close to the texts , the texts were pretty clearly visible (however I couldn't take a nice pic of that )
But when the distance between the paper and the text was increased (by just a little amount) , the texts disappeared (as in this picture)
I think it is happening because after lifting the paper ... |
As it is well known, one of the main motivations for the idea of inflation is the explanation of superhorizon CMB correlations: we observe the existence of perturbations with sizes larger than the size of the horizon at a time when we observe these perturbations, thus, if we want them to be produced by some casual proc... |
Very basic question here. Does the Maxwell Boltzmann velocity distribution deal with the speed of the centre of masses of multiatomic( like Nitrogen ,oxygen) species or with the exact speeds of atoms?
|
I am interested in the Fresnel diffraction pattern (over an entire observation plane, not just the value on-axis) due to a plane wave incident on both square and circular apertures.
I have two optics textbooks (Introduction to Fourier Optics by Goodman, and Optics by Hecht), and both give an analytic expression for th... |
I'm trying to get a better understanding of the Weyl correspondence which, as described e.g. on Wikipedia, gives "an invertible mapping between functions in the quantum phase space formulation and Hilbert space operators in the Schrödinger picture".
In particular, the Weyl transform of a function $f(x,p)$ is given by
$... |
Picture this: a localized, collimated laser-beam, say one light-second long (there is a range of different frequencies or TE/TM modes), is sent into an infinite ideal vacuum. By an ideal vacuum, I mean a vacuum containing no real particles. The spacetime is flat.
Will the beam of photons diverge in the course of time?
... |
I find Newton's second law of motion for point particles quite easy to grasp. However, I run into a lot of confusion when I deal a discrete particle/ continuous body system.
In these notes by Jaan Kalda, in page-1, he defines force as the product of inertial mass times the acceleration of the body, and then later in pa... |
I was theoretically considering building an airtight enclosure that shielded the insides from gamma/X-ray/ultraviolet radiation but did not block radio waves (so that communication would not be interrupted). Is this physically possible?
|
Formation of shock waves are common phenomena in Physics. Defining the Mach number as $M=v/c_s$ , where $v$ is the fluid velocity and $c_s$ is the sound speed, it is known that the flow jumps from supersonic to subsonic at the shock location. Here, $v=v(x)$ and $c_s=c_s(x)$, both functions of the radial coordinate $x$.... |
If I were to go from X to Y and then back to X, the NET work done by me would be zero. But, how will the energy remain constant? Really confused about energy and work here. Energy is the ability to do work, so if the net work is zero, the energy should remain the same. But, don't we utilize energy in moving from one po... |
I have a hard time understanding the I-V curve of a solar cell. I dont understand how in an short circuit a current can happen although there is no voltage? Isn't voltage the requirement for a current, so if voltage is zero, current must be zero? Or is there another driving force behind the current?
Second, where does ... |
Take a system with two ideal, rigid spheres in vacuum, being under zero net external force. Now suppose I want to make the spheres collide, which I do by pushing one of them towards the other.
Now consider the distance between the two spheres: let it be, say, x. As you can now obviously deduce, that as the 2 spheres co... |
If the two tiny, about-to-vanish black holes are of the same mass then such a particle should not go anywhere and remain stationary in the middle even as it gets enveloped inside the new unified event horizon. Now if the singularities were to vanish because of Hawking radiation before they get the time to merge into ea... |
I would like to find a clear definition for the following expression:
System A undergoes a reversible transformation
when the transformation is not adiabatic (when system $A$ is not thermally isolated). I'm going to try to explain what I have in mind. My question is something like:
do you see any limit, mistake, mis... |
Why is the square of the neutrino mass negative?
In arXiv:hep-ph/0009291 this is explained by giving the example of:
$$m^2_{\nu_e}= -2.5 \pm 3.3 \text{eV}^2 \tag{1}$$
"Thee negative value of the neutrino mass-square simply means:"
$$E^2/c^2 -p^2=m^2_{\nu_e} c^2 < 0$$
"The right-hand side in Eq. (3) can be rewritten as... |
It is often stated that the processes in quantum mechanics are reversible as they follow the Schrodinger's Equation : $$ - \frac{\hbar^2}{2m} \nabla^2 \Psi(x,t) + V(x,t)\ \Psi(x,t) = i \hbar\ \frac{\partial \Psi(x,t)}{\partial t} $$ which is valid for $t$ as well as $-t$.
I have a few doubts about the reversibility :... |
https://youtu.be/JzuamK0AyC4
According to this clip’s experiment, if the temperature of the third bottle increases, which raises the pressure, the water from the second bottle will then rise and could flow to the third bottle if the temperature is high enough.
Can anyone explain to me why that is?
|
At constant pressure,
$$ V\propto T$$
Letting the piston freely moving fixes the pressure of the gas to the atmospheric;
then heating the gas causes the $T$ to increase,
this causes the $V$ to increase by the same factor.
However, in the other direction, how can one maintain the pressure constant while changing volume?... |
Consider a coordinate system set up as follows:
One way to find the direction of the torque is to find the algebraic sign of the component of torque along the axis of rotation.
We can assign an algebraic sign to the vector component
of a torque along any axis by regarding that torque
component as positive if it tends... |
Can someone open my eyes my disproving the formula that I arrived. I understand it is wrong but where exactly is the mistake?
|
I'm reading from a lecture note on introductory quantum mechanics (here), which says on P.3 that "The expectation value of any time-independent operator $\hat{Q}$ on a stationary state is time-independent". It proceeds to prove the statement in the following way:
\begin{equation}
\begin{split}
\langle\hat{Q}\rangle_{\P... |
I am looking for a proof of that the determinant of deformation gradient $\bf F$ in a linearized setting is
$det \, {\bf F} = 1 + tr \bf \, H$
Where $\bf H$ is the displacement gradient.
|
In the context of special relativity, it is well known that 4-vectors are covariant under Lorentz transformations (which is a linear transformation in space-time), however are they covariant under general coordinate transformations (GCT)? Personally, I don't see why they shouldn't be. I mean in GR, when we refer to 4-v... |
Even we don't know much about scattering areas of photons and electrons does the fact that a photon scattering an electron at an angle mean that the photon cross-section area hits only a small lateral area of the electron causing it to move at an angle. If the photon cross-section area was greater than the electron's o... |
At the end of the day what the thermometer is measuring as temperature is energy of the air molecules (which could come in the form of kinetic energy). Now, imagine the following scenario :
Take a box with just one gas molecule (at speed x). It goes and hits the mercury of the thermometer. Thermometer will probably no... |
In the literature I have seen the following definition of an inertial frame:
A frame is called inertial if any material point interacting with no other bodies or fields moves with constant velocity in a straight line with respect to this frame.
It is claimed that if another frame moves uniformly with respect to an iner... |
We experience time dilation from speed and gravity, but we are in more than just the Earth's gravity field, but also the sun's and the galaxy's gravity field and we are both spinning at 1,670 km/h, orbiting the sun at 107,000 km/h and orbiting the galactic center at 720,000 km/h (these numbers are from space.com). What... |
I know that the Higgs mechanism has some analogous models to theories that describe the behaviour of quasiparticles in condensed matter, like in superconductivity and other spontaneous symmetry breaking byproducts.
I tried to ask a few experimental researchers in the field if the equivalent of the "Higgs boson" (not Hi... |
TLDR: The question: Does it make sense to calculate scattering amplitudes using an off-shell renormalization scheme?
I expand a bit by using a theory of a single self interacting massive scalar. I consider both the bare and renormalized objects by subscripts $0$ or $R$. We have $\phi_0 = \sqrt{Z_{\phi}} \phi_R, m_0 = Z... |
When pressing coffee, why does total volume of boiling water and coffee appear to decrease after grounds are pressed to bottom?
|
According to the ergodic hypothesis a system of $N$ particles represented by a point in $6N$ dimensional phase space comes infenetly close to every point in that phase space.
It is argued that the trajectories in phase space cannot cross and therefore the trajectory of a system has to discover every point of the phase ... |
Let's say I have a circle. Inside this circle, there exists an electron of energy $E$. The potential inside this circle ($r < R$) is $V$ and outside, it's infinity.
Can the wave function be a constant? Let's say I want a uniform distribution across the surface. Due to the boundary condition of $ \int_{0}^{R} |\psi |^{2... |
In my textbook, there is a theorem which states that if the position vector of a body is
$\overrightarrow r$ and the covered distance is $s$ such that $\overrightarrow r$ is a function of $s$ then $$\frac{d\overrightarrow r}{ds} = \widehat t$$
where $\widehat t$ is a unit vector which is tangential to the trajectory of... |
I have been interested in researching a lot about surface plasmon resonance (SPR) and I was wondering exactly how the thickness and the size of the prism affects the results? I could not find an equations or recommendations regarding how these factors might affect the SPR setup. Does this mean that I could in theory cr... |
I don't know if this is a stupid question or not, please tell me if it is.
I will use an example to illustrate my doubt.
Suppose I am moving to the right with a speed of $30ms^{-1}$. And sound wave moves at a speed of $343ms^{-1}$. If I am speaking during speaking. What is the speed of the sound wave moving to the righ... |
An electron beam strikes a barrier with one slit, and the resulting electron flux through the slit is detected. Then, two identical slits are opened on opposite sides of the original slit, both equally "illuminated" by the beam. What will be the flux at the center slit now? Does this answer imply that three times as ma... |
Take the (111) surface of a fcc lattice:
If we have a wave incident on the surface moving in a direction with a projection parallel to the orange line, then in principle we should observe diffraction in the scattering plane, since there is a periodicity in the surface in this direction.
However, what we would find is ... |
If light propagates slower than c in a medium like air, what happens to the way the photons 'experience' time? It is often said that a photon does not 'experience' time since it's simultaneity plane completely overlaps its world-line. But this happens not because it's a photon, but because it travels at c. If photons t... |
I had a question about the differences between a quantum state and a classical microstate.
Let's say we have an NVE ensemble, and we are trying to predict some property P of our ensemble. In our methods, we say that each microstate in out ensemble has some canonical coordinates $(\mathbf{r}^N, \mathbf{p}^N)$. The numbe... |
In the following article the mixing angle of the neutrinos is given by:
$$\sin^2 2\theta = \frac{\mu^2}{\mu^2 +[c\Gamma_\alpha E /M +M/2]^2} \tag{1}$$
where $\mu$ represents the Dirac mass , M represents the Majorana mass for the right-handed components and $\Gamma$ represents the collision rate .
But I was told that f... |
Please tell me if my assumption is correct.
So nuclear fusion does not occur with nuclei (with a nucleon number higher than 56) because the binding energy of the product nucleus is lower than the binding energy of the nuclei fusing together.
Due to the product nucleus having a lower binding energy (and thus lower mass ... |
Consider the O$(N)$ model in $d$-dimensions given by:
$$L = \frac{1}{2} (\partial_{\mu} \phi)^2 - \sum_{n} \frac{g_{2n}}{(2n)!} \phi^{2n} $$
Is there a reference where the beta functions $(\beta_{g_{2i}})$ of this model is calculated for general $n$, in general $d$? In particular, I wanted to verify my beta functions f... |
When I say that an event has frequency =0, does that imply that the event is impossible?
|
The retarded propagator for a massless scalar field is
$$
G_R(t,\mathbf{x} ;t',\mathbf{x}' ) = \frac{ \Theta(t-t') \delta\big( - (t-t')^2 + |\mathbf{x} - \mathbf{x}'|^2 \big)}{2\pi} \tag{1}
$$
which is supposed to satisfy the equation
$$
( - \partial_t^2 + \nabla_{\mathbf{x}}^2 )G_R(t,\mathbf{x} ;t',\mathbf{x}' ) = - ... |
In articles about Airy disks, I can't find whether they are talking about an aperture with a lens or mirror that focuses the light, or about a plain aperture.
Most of the time they are talking about imaging systems, where the light is getting focused, but their explanations, mathematical formulae and diagrams are the s... |
Well,
I want to derive the formula
$$ r = \frac{GM}{\sigma^{2}} $$
which happens to be the radius of the gravitational sphere of influence of a supermassive black hole inside a galaxy. How can I do that?
I'll accept any tips or indications that can help me to do that. If you need to know, is the stellar velocity dispe... |
I don't know anything about elementary particles, but reading the book by Zeidler on p158, table 2.8 one can observe the quark content of baryons and mesons. It is strange that the $\pi^0$ meson has either(?) quark components $u\overline{u}$ and $d\overline{d}$ and similarly $\eta$ has components $u\overline{u}$, $d\ov... |
I am trying to understand what exactly is meant by the following question:
What is the maximum wavelength that can be obtained with a given diffraction grating in (a) the first order (b) the second order. I know for order 1 the answer is $\lambda = d$ and for order 2 the answer is $\lambda = d/2$ but I don't know the ... |
When I think of a light beam, what first comes to mind is this:
Black lines are axes (both spatial axes, at a snapshot in time), and blue lines represent the surfaces of constant phase of a plane wave traveling along the horizontal axis.
However, obviously most light beams are not infinite in extent. This means that m... |
I'm a computer scientist and new to Ising Model.
I've learned that if such a system is left to itself it will converge to its minimum energy state. Here are the questions I have:
As the system is going toward its minimum energy, where does the extra energy go? Does it get transferred to the environment?
If the answer ... |
A magnetic dipole moment has the same magnetic field as if there were a current circulating in a loop in the same area. When doing problems involving magnetized materials, we often use this picture of "bound currents" to solve Maxwell's equations.
Now, imagine we have a ferromagnetic metal. When we apply a voltage bias... |
It is common to look at the orientation of a rigid body in term of a quaternion which encodes an axis and angle with a vector and scalar.
$$ \boldsymbol{q} = \pmatrix{ \boldsymbol{\hat{z}} \sin\left( \tfrac{\theta}{2} \right) \\ \cos \left( \tfrac{\theta}{2} \right)} \tag{1}$$
and then it is common to convert the rotat... |
I happen to be trying to motivate physically and intuitively the need to use topological spaces.
So without using emerging concepts such as differentiable manifolds or extremely formal concepts as continuity I ask you:
What is so fundamental about physics that motivates and requires us to use topological spaces?
|
As I understand it quantum mechanics can be used to describe objects that appear to behave classically, meaning that any classical orbit can be treated as a bound state in quantum mechanics.
I know a statement is logically equivalent to its contrapositive. This means that IF having no bound states in quantum mechanic... |
The free adiabatic expansion is described in my notes like this:
A monoatomic perfect gas is in equilibrium in half of the gas tank, which is thermally isolated (i.e. it does not exchange heat with the outside). We also assume that the gas tank is in the void, so that we can consider the external pressure to be equal t... |
So Einstein stated that gravity and acceleration are the same things in a local reference frame (please correct me if I misstated that).
Here is what I think I understand and want you to verify if it is correct:
In Special Relativity, the faster you go, the more time dilation and length contraction an outside observer ... |
Two boxes 1 and 2 are in a potential $V$ such as $V_1=0$ and $V_2=V_0$. The boxes contain an ideal gas, temperature and volume are constant and set to 1. Hence $N_i=P_i$ where
$N_i$ is the number of particles in box $i$ and $P_i$ is the pressure in box $i$.
The boxes are connected by a pipe and particles can thermally ... |
I'm reading a book called Teoria do electromagnetismo by Kleber-Daum-Machado Volume 1. More especifically a section about the effect of electric fields in dielectric materials, in there he describes a dielectric that fills the space and that we are grabbing a small piece $\Delta V$ to see the electric potential genera... |
I'm dealing with a 4-site Heisenberg's model with no external field:
$$
\begin{align*}
H = \sum_{i<j=0}^3h_{ij}, \quad where\ h_{ij} \equiv J_{ij}(\vec{\sigma_i}\cdot\vec{\sigma_j}) = J_{ij}(X_i\otimes X_j+Y_i\otimes Y_j+Z_i\otimes Z_j)
\end{align*}
$$
The total Hamiltonian matrix could be represented by a 16 by 16 mat... |
I saw somewhere on here that you can't exactly talk about length contraction in General Relativity, you can however talk about time dilation. So I was wondering if I made a light clock, with a bouncing photon between two mirrors, would I be able to tell the amount of length contraction in a curved spacetime.
So if I ha... |
I read in a book that a system of particles should have identical acceleration. Suppose the given figure. It is written that $G$ and $C$ cannot be considered as a system of particles as the acceleration is in different directions. But on Khan Academy he told that particles should only have magnitude of acceleration equ... |
If smoothness is defined by the friction between two surfaces, which surfaces have maximum friction?
For instance, sandpaper is considered fairly rough, but it's not the roughest surface in existence. What material could be considered the roughest surface?
|
Question. A wire horizontally over a bench has one end fixed and the other end holding some weight. The weight stretches the wire to produce some extension, say $\Delta x$. Someone puts a length marker somewhere on the wire except the two ends, and this marker indicates some extension, say $\delta x$. Does $\Delta x=\d... |
I imagine the magnetic field comes from the accretion disk. But what causes it to "spring" upward?
|
A ball is dropped from a height of 19.6 m above the ground. It rebounds from the ground and raises itself up to the same height. Take the starting point is the origin and vertically downward as the positie X-axis. Draw approximate plots of a versus t graph. Neglect the small interval during which the ball was in contac... |
Actually I know that axes are always perpendicular but after three axes we cannot draw any other axis that is perpendicular to all the other three axes.
can any one say how can we draw another axes which is mutually perpendicular
|
So in my Stat Mech course, we were introduced to the classical Ising Model:
$$H = -J\Sigma _{<ij>}S_iS_j - K\Sigma_i S_i$$
But from where does this come from? Is there any rationale behind this?
I want to know the origins of especially the first term (with J).
I guess since this has magnetic moments in the formula, is... |
Exploring the benefits of deadblow hammer physics in sports.
I play badminton, and have developed elbow pain that is aggravated whenever I smash (overhead forehand, like a tennis serve). This is caused by vibration transmitted through the racket, into my wrist, where it “jerks” on tendons connected to the elbow.
I’ve a... |
I have seen the derivation of this formula, and it was derived under the case that the object was placed on the principal axis of the mirror. If somebody knows, can they please share the formula to calculate the position of the image if the object is not placed on the principal axis.
|
How does one proof that the complex beam parameter $q_1$ of a Gaussian beam is altered according to
$$q_2=\frac{Aq_1+B}{Cq_1+D}$$
when passing through an arbitrary optical element with a known ABCD (ray transfer) matrix?
|
I want to do an experiment on magnetic levitation by increasing the magnetic field strength of the bar magnet. My experiment is mainly based on the effect on the levitation distance when we increase the magnetic field strength of the bar magnet. Any simple tips for conducting this experiment?
|
I am trying to evaluate the field equations in $f(Q,T)$-gravity and I'm not sure how to evaluate this term:
$$-\dfrac{-2}{\sqrt{-g}}\nabla_{\alpha}(f_{Q} \sqrt{-g}\enspace P^{\alpha}_{\enspace \mu \nu})$$
where $f_{Q}$ is the differential with respect to $Q$ of the chosen function, $\sqrt{-g}$ is the determinant of the... |
Suppose we have two-particle states
$$ |0\rangle^{(j)} = \frac{1}{\sqrt{2}} \big(|+m,-m\rangle - |-m,+m\rangle \big) $$
based on one-particle states in the SU(2) $j$-representation, where I use the notation
$$ |+m,-m\rangle = |j,+m\rangle \otimes |j,-m\rangle $$
with arbitrary $j = 1/2, 1, 3/2, \ldots$ and $m \le j$.
A... |
We know that for a sound wave traveling to the right, the centre of compression occurs at $s = 0$ and $\frac{ds}{dt} > 0$ (take right direction as positve i.e. traveling to the right too!). And centre of rarefaction occurs in $s = 0$ and $\frac{ds}{dt} < 0$. I have seen some explanation of this using simulation, I won... |
I am a little confused about symmetry breaking - in particular, what I see to be two different interpretations of it.
First, what I have seen taken to be the definition of a broken symmetry - we start with a Lagrangian with symmetry group $G$, but when we chose a vacuum state, this vacuum state has a different symmetry... |
If you have a reversible process, then everything is easy because the full container of substance would have homogenous properties, but, how would you deal with assigning state variables for irreversible processes? The variables vary both spatially and temporally, so like, it must be impossible to concretely label vari... |
I am doing some calculations of this paper: https://arxiv.org/abs/1711.08482 and in particular I am having trouble with 2 parts:
Dimensional Reduction (16):
I have managed to get equation (16) from the dimensional reduction of (14) (I will ignore the electromagnetic contribution):
We start from
\begin{equation}
S = \fr... |
Suppose that two particles $P_1$ and $P_2$ interact with each other and that $P_2$ induces an instantaneous acceleration $a_{12}$ in $P_1$, while $P_1$ induces an instantaneous acceleration $a_{21}$ in $P_2$. Then
these accelerations are opposite in direction and parallel to the straight line joining $P_1$ and $P_2$
... |
Question. An ultrasound pulse-echo technique is used to produce an image by reflection from many boundaries. If the transmitted pulse is too long, the image produced is of poor quality. Why?
My attempt. If the transmitted pulse is too long, then the pulse contains many wavelengths. After that, I would receive pulses c... |
according to me sensitivity of potentiometer should be like: with less increase in length , i am getting more volt that is 20 volt/l should be more sensitive than 10 volt/l because < i am getting more volts in less length, hence more sensitive potentiometer?
|
Edit: to people asking about details, I am not asking about drag. Take it to happen in vacuum, space, no drag, no other forces. I would like a general rule of thumb. This guy with e equals mv squared answered already.
This is NOT about relativistic speeds.
To go from point A to point B, in theory (maybe) I could use a ... |
The specific heat capacity as I recall from thermodynamics(and as Wikipedia defines it) is defined as
$$C_v= \frac{1}{M}\frac{dQ}{dT}$$
$C_v$ is specific heat capacity at constant volume, M is the mass
In statistical mechanics, after deriving the Boltzmann-Gibbs probability measure, the canonical partition function Z a... |
I have been trying to understand absorption of a photon by a massive object, specifically the transfer of momentum and kinetic energy between the two.
Starting from energy-momentum relation $E^2 = p^2c^2 + m_0^2c^4,$ or rather, for simplicity, setting $c = 1$:
$$E^2 = p^2 + m_0^2,$$
I can't understand how both the ene... |
Non-physicist asking.
Assuming the origin of the universe of your choice: If entropy only increases, at what point was it at its lowest value? Why? Was this value ever zero?
|
I have only basic knowledge in physics from school and I am struggling to find an answer:
Can a blanket with a worked-in mesh of silver threads really reflect electromagnetic field from mobiles and/or WLAN in order to shield a human sleeping underneath? I always thought a faraday cage would have to enclose the shielded... |
Suppose I have two mass rigid pendulum, both of whose masses
are equidistant from the pivot point at P. All three points lie on a circle of diamater D and subtend an angle $\alpha$ at the pivot. let the distance of each mass from the pivot point be $\ell$
My questions is:
1. why is it true that at equilibirium, the p... |
Why is the standard mass (Dirac) not compatible with $SU(2)$ symmetry?
I consider the standard mass this
$$ m\bar{e}e = m(\bar{e}_Le_R+ \bar{e}_Re_L)$$
|
I am working on some calculations on coupled transition dipole moments interacting with light pulses with different polarisations.
I am currently trying to find a way of writing $\theta_{\beta}$ and $\phi_{\beta}$ as a function of $\theta_{\alpha}$,$\phi_{\alpha}$ and of the internal angles (which are fixed) $\theta_{\... |
The quantum trajectory theory describes the behaviour of a quantum system under continuous monitoring. Initially it is theoretically studied in quantum optics and single atom scenario (e.g., ion trap setups). But as far as I know, experimental studies on quantum trajectories are mainly done in superconducting quantum c... |
The speed of light C is equal to 299 792 458 m/s at this speed it would take me 3.03 minutes to get to mars at the closest orbit but if I was going the speed of light would I not be at mars instantly
^ a summarize and better-formated version of the question that sums up all my questions in one question sorry for the ol... |
I have a mug warmer, which is a hot plate that I've measured heats up to 56C.
It came with a mug with a flat bottom, which gets its contents warmed up to about 53C after some minutes.
My understanding of the sytem is that the 56C of the hot plate is a boundary condition that would force the mug to eventually reach that... |
What is meant in the following paragraph (this is Yang-Mills original 1954 paper "Conservation of Isotopic Spin and Isotopic Gauge Invariance")
Where Equation (3) is the transformation of B field
Why B field is assumed to contain a term that is a linear combination of Pauli matrices?
Is it because equation (3) show... |
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