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What exactly is $n_{\textrm{i}}$? It is said to be the intrinsic charge carrier, but for pure semiconductors, $n_{\textrm{h}} = n_{\textrm{e}} = n_{\textrm{i}}$, is $n_{\textrm{i}}$ not the sum of both $n_{\textrm{e}}$ and $n_{\textrm{h}}$ and refers to the total no. intrinsic charge carriers per unit volume?
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Recently I have been studying Kinetic Theory Of Gases, with one of the topics as collision frequency. I know that collision frequency is inverse of relaxation time which is also the measure of number of collisions per unit volume per unit time. But I am stuck while calculating "number of collisions per unit distance". ... |
Through reading Nenciu's rigorous proof on the Adiabatic Theorem and Gell-Mann-Low Theorem, I found:
Since the limit $t_0\to-\infty$ does not exist for $U(t,t_0,\epsilon)$, in order to make use of the adiabatic theorem, we first compute $U_I(t,t_0,\epsilon)P$ and then limit $t_0\to-\infty$.
I am confused on why the l... |
In the book "Loops Knots Gauge Theory and Quantum Gravity" when trying to define a loop representation, one needs to integrate over the space of connections (modulo Gauge transformations). There, they say this space is non-linear and inf-dim. What does it mean for a space to be non-linear?
(The space of 1 forms is a ve... |
If I have a light beam (a straight line)
it goes through a box of dust, which has travelling length $l$, dust molecule cross section $\sigma$, dust number density $n$.
how to calculate the expectation value of the number of dust particles that will be intersected by the line of sight?
my book says it is just $\tau = n\... |
Can we measure the one-way speed of light by passing light through angularly shifted apertures in two disks solidly connected and spinning at a known angular velocity?
Here is the apparatus I would make to measure the speed of light in one direction.
(I will use real numbers and units for dimensions to make the importa... |
In formula 2.2.62 of Green Schwarz Witten:
$$
(\frac{1}{2}\sum_{n=1}^m\,k\cdot\alpha_{m-n}\,e^{i\, n \,\tau})V(k,\tau)\tag{2.2.62}.
$$
I am having a problem working out the factor of $\frac{1}{2}$. Let us write:
$$
V(k,0)=\exp{(\frac{k\cdot\alpha_{-1}}{1}+\frac{k\cdot\alpha_{-2}}{2}\dots)}\exp{(-\frac{k\cdot\alpha_{1}}... |
It is quite common[1][2] in the study of physics in the context of category theory to say that one of the fundamental difference between classical mechanics and quantum mechanics is that classical mechanics is based on the category of sets, $\mathbf{Set}$, while quantum mechanics is not. However, what this means exactl... |
Consider the position vector field $\vec{r}=(x,y,z)^T$. What would be a vector potential $\vec{A}$ for this field? I was thinking of something like $\vec{A}=(yz,zx,-xy)^T$, which gives
$$\nabla\times A=(-2x,2y,0)^T.$$
But that is not exactly correct.
|
This paper mentions two conditions crucial for the classical ghost imaging experiment which are:-
the spatial incoherence of light, and
a measurement time $\ll \tau_{coh}$.
Why is the spatial incoherence required?
It mentions the reason that
a high degree of mutual spatial correlation is
present in both planes, as ... |
I am reading An Modern Introduction to Quantum Field Theory by Maggiore. On page 28, it says
Using the property of the Pauli matrices $\sigma^2 \sigma^i \sigma^2 = -\sigma^{i*}$ and the explicit form of $\Lambda_{L,R}$, it is easy to show that
$$
\sigma^2 \Lambda^*_L \sigma^2 = \Lambda_R.
$$
From this it follows that
... |
(All SI unit used in this question)
The electric potential U is defined in electrostatic field that The electric field is the (negative) gradient of some scaler verctor, if and only if the electirc field is conservative, namely ,Or the Integral of the electric field is $0$ when the path is closed. This is only ture wh... |
Say we have two slits in the xy-plane. The x distance between them is d. Why do we, when calculating the resulting amplitude of the wave, consider only the phase difference of two secondary radial wave sources of equal y coordinate? Why do then we need two slits, but not just two tiny holes?
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Do quasars collapse and make a galaxy or do they eventually spew out enough matter to make one? Because I heard they are the center of galaxies, and I wonder if they can collapse from their own gravity or from becoming unstable, and if so, what would happen?
|
Does anybody know why the cosmic web is shaped like a web? I feel like it would be more likely that it is more like a galaxy with a supermassive black hole in the center, if that were true, what would happen?
|
The graph of dielectric constant is not linear with respect to increasing frequency.
Polarization mechanism cannot keep with the frequency, and hence the dielectric constant abruptly drops. I get that.
But what/why are the kinks at the drop of atomic and electronic polarizations?
|
Recently I asked a question that was considered a duplicate. However I felt that the related question didn't answer my doubts. After a bit of pondering I have realized the core of my discomfort with the concept of QFT fields, so I am asking a new question, different from the previous one, hoping that this time it won't... |
Does the cosmic web follow Gaussian distribution? If so, is that the reason it resembles the human neuron system? Does the human neuron system follow Gaussian distribution too?
(sorry if this deviates from physics a bit)
|
In Landau & Lifshitz "Mechanics", it is said that from the time/space homogeneity Lagrange function is independent from time/position. I always thought that homogeneity means that motion equations don't change with the time/space shift. So if i took the same initial conditions, i got the same trajectory. How to prove t... |
Is it possible for a star to be so big that its gravity can bend light like a black hole? If so, would the star appear dark or bright, or would it collapse on itself?
|
I have been trying to obtain an analytic solution for a daughter radionuclide's activity (or just the number of daughter atoms), as a function of $t\geq0$, resulting from the decay of a parent radionuclide specifically for the case where $\lambda_{parent}=\lambda_{daughter}$ (and no alternative decay modes so branching... |
As a high school student studying electrostatics, I understand that the electric potential at a point closer to a charged particle, is nearly infinite, then why there exist a finite potential difference between two charged objects that are in contact with each other? For example between an electrolyte and its electrode... |
Can someone define the transverse acceleration with an example and what is the difference between the transverse acceleration and the tangential acceleration , if it mentioned in a textbook i will be satisfied ?!
|
What if Phoenix A collided with UY Scuti? Phoenix A is estimated to be 100 billion times bigger than the suns radius, while UY Scuti is estimated to be 1700 billion times bigger than the sun. What I want to know is would UY Scuti (a star) have any effect on Phoenix A (a black hole.)
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I am very new to physics so don't know a whole lot yet, so please correct any incorrect vocabulary you may find. Papers that are easy for beginners to understand are also very welcome!
Context:
I am doing a project on spectroscopy using a phone/web camera, and a diffraction slide which I believe works kind of like a c... |
If photons don't have mass, how come gravity can bend light? Because if photons have no weight, wouldn't they not be affected by the fabric of spacetime?
|
I was reading this paper (PDF), "On Einstein Clusters", and in equation (34) they write the effective potential of a particle moving in this system as $$V_{eff}(r)=e^{\nu/2}\sqrt{1+\frac{\tilde{L}^2}{r^2}}.\tag{34}$$ I'm trying to understand where they get this result from, especially since it seems the rest of their s... |
When one first encounters gravitational waves in a standard GR lecture or a standard textbook like Carroll's "Spacetime and Geometry", they are often "defined" as follows: The metric $g$ can be split up into $g_{\mu\nu} = \eta_{\mu\nu} + h_{\mu\nu}$, where $\eta$ is the standard Minkowski metric and $h$ is a perturbati... |
For an oblique shock to form, there has to be an angle in which the flow turns into itself. Usually, that angle is caused by flow separation, in which the separation is caused by a normal shock first, I think (this is what I've thought so far).
The first leg of a lambda shock is considered an oblique shock. For that to... |
For simplicity, we suppose $\epsilon_0=\mu_0=1$ and that the photonic structure is only made of perfect metal and vacuum.
The electric field and the current density are related by the Green's function, writtern as $E=GJ$, so the energy of light is
\begin{equation}
\mathcal{E}=\int dV(\frac{1}{2}|E|^2+\frac{1}{2}|H|... |
Context
The Lagrangian, $L$, of a free particle is derived many places including in Section 8 of Landau's Theory of Classical Fields. The well-known result for a free material particle of mass $m$ and speed $v$ is
$$
L = -mc^2\sqrt{1-\frac{v^2}{c^2}},
$$
where $c$ is the speed of light. It is known that in many respect... |
So say there is an object that is in the form of gas and dust and a core that weighs 10 earths is in the center and there is a sphere of gas around it that weighs 50 Earths, so the final mass is only 60 Earths and say after collapsing the radius is 5 Earth radii.
So technically the object doesn't collapse into a black ... |
Some time ago, I read in Landau's Theoretical Physics Course you could derive Maxwell's equations using the Lagrangian formalism, and I find this to be exciting. Unfortunately, I don't have access to the book and even if I had it, I'm not sure I could understand it, since I haven't learnt anything about tensors yet, an... |
I previously posted a question regarding the expectation value described below, but it was closed because the question was not developed enough. Since I was given the option to delete it, I deleted it; however, now I think I have developed some additional ideas and observations and therefore I am posting this related q... |
Suppose we have a satellite orbiting Earth with a component made of 6061 aluminium alloy.
Would cosmic radiation cause the element and isotope ratio of the component to change in a clearly measurable way over time? (Say, 10, 25 or 50 years)
|
As we know, objects with a large gravitational field can bend light, but, my question is, Can molecules bend light? Since molecules have a small amount of gravity, couldn't they bend light in at least a small measurable amount?
|
I know the usual derivation (as well as the Foldy–Wouthuysen derivation) to obtain Schrödinger equation from the Dirac equation. See for example U Alberta Phys 512. But it it possible to go from
$$i\hbar c \overline{\Psi}\gamma_\mu \partial_\mu \Psi-mc^2\overline\Psi\Psi$$
to
$$i\hbar \partial_t \psi=\frac{\hbar}{2m} ... |
In the introduction of chapter 6 of Ring and Schuck's book "The nuclear many-body problem" it is stated that "the Hartree-Fock method partially takes into account the particle-hole part of the interaction, that is, the long-range part of the force" and also "the short range part of the force which causes particle-parti... |
Suppose we have 2 infinite sheets, one lies on $z = 0$ with potential $V = V_0$ and another at $z = a + b$ with potential $V = 0$. There are two slabs of dielectric material with permittivity $\epsilon_1$ and $\epsilon_2$. The dielectric interface lies at $z = a$.
Here's my attempt at the question:
Dielectric material ... |
It's well known that a human hair can diffract light (plenty of demos out there, all you need is a laser pointer and a strand of hair). I've been thinking, however: how can one model this process? The resulting diffraction pattern is pretty similar to that of a single slit (logical, since it's a single hair). However, ... |
What is the math involved in calculating how often a total solar eclipse happens. Can you predict it by just looking at the period of the moon around the earth and the period of the earth around the sun?
Edit: I am not asking why it doesn't happen more often but the minimum information you would need to determine it ha... |
I was studying about how could we generate electricity using triboelectric nano-generators, the thing which was confusing to me was why the aluminum balls are shown to have a positive charge whereas the surrounding enclosure bears a negative charge.
Do we have to start with an already charged object or I am missing so... |
Oscillators in a black body (electrons) can only have energy equal to $E = nhf$ ie it is a linear relationship. so if an electron drops from energy level $n$ to a lower energy (jumping 1, 2,3 ... shells) this I believe the energy is proportional to $1/n^2$. how do these ideas coexist?
|
So of course when stuff falls into black holes, the geodesic for anything ends in that singularity. However, isn't it technically true that a light ray that originates from the sun and then hits the Earth and then the absorption of that light ray by matter count as the end of that geodesic? So singularities aren't the ... |
Consider a rod hinged at one end and moving in the vertical plane. If it's horizontal and free falls, we can apply energy conservation to find it's angular velocity at bottom as work done by hinge is 0.
Similarly, there are countless other examples, where we conserve energy and assume work done by hinge force to be 0 a... |
If you take two blocks on a frictionless plane (each block is 1kg) with one wall and perfectly elastic collisions, if you collided the block on the right with the one on the left (wall is on the left) there would be 3 collisions. if we replaced the block on the right with a 100 kg block, there would be 31 collisions. I... |
Can anyone please link to or sketch a diagram demonstrating how a complete (and clear) image can be formed of a distant celestial object with a central obstruction blocking part of the line of sight in a reflector telescope?
A written explanation would also be appreciated!
|
I've heard that a cosmological constant can be used to model dark energy (e.g. $\Lambda$-CDM model), and that the constant $\Lambda$ should be positive. But my (quite small) understanding of dark energy is that it acts to expand things, which should correspond to $R_{00} < 0$ rather than $R_{00} > 0$, where here $R_{\m... |
I am trying to understand this paper/set of notes. I have already seen the following related question: Does the stationary phase approximation equal the tree-level term? but had some trouble following the accepted answer as I am still new to this topic.
They consider a path integral of the form
$$\int[d\phi]e^{iS[\phi]... |
In a photovoltaic cell is basically a pn-junction where free electrons are created by a photoelectric effect.
Now I am interested to understand the electric field inside the depletion layer for various situations:
a) no solar energy input; open circuit
b) no solar energy input; closed circuit
c) solar energy input; ope... |
Suppose the voltage in the primary coil in a capacitor be
Vprimary = Vosin(wt)
According to my understanding, as the (AC) current in the circuit increases, the Magnetic flux across the secondary coils increases. This induces an EMF that drives current in the secondary coil to nullify the increasing Magnetic flux. Hen... |
if not why?
is it possible in future?
Because if it is possible there may be chance of more advance invention
|
I am self-studying the book “James H. Luscombe, Core Principles of Special and General Relativity”. In “CHAPTER 9 : Energy-momentum of fields” of the book, it starts by introducing Noether’s theorem and then shows that invariance under spacetime translations implies conservation of field energy and momentum:
$$T^{μν}≡g... |
So i was told that the magnetic force on a current carrying wire b/w two points is constant and irrespective of the shape of the wire (Taking an uniform magnetic field). I was looking for proofs on the net and i couldn't find one which mathematically proved it for any general squiggly line b/w two points.
I came up wi... |
For the topic of quantum random walk, a simple example is considering a 1D lattice fermionic model, expressed as
$H = \sum_{i} c_i^\dagger c_{i+1} + h.c.$
Assuming there is one fermion located at the $m$-th lattice point at $t=0$, i.e. the wave function can be expressed as $|\varphi\rangle = |m\rangle$, one find that t... |
It's a standard result that the three well-known quasiprobability distributions can all be expressed in terms of the "$s$-ordered characteristic functions" as
$$
W(\alpha) = \int\frac{d^2\eta}{\pi^2} \chi_W(\eta) e^{\alpha\bar\eta-\bar\alpha\eta},
\\
P(\alpha) = \int\frac{d^2\eta}{\pi^2} \chi_N(\eta) e^{\alpha\bar\eta... |
Suppose a car is moving up an inclined plane, it experiences resistive force proportional to its mass and square of speed. First, it carries a cart of twice its mass up an inclined plane and it can have maximum speed $v$. Then, it moves up the incline without cart, and now it can have maximum speed $2v$.
I assumed th... |
I am just trying to get an intuition for the Griffiths equation no. 2.45, where work done to establish a field E is given by
Say we want to solve it for electric field due to an electron (point-charge)
\begin{gather}
W = \frac{\epsilon_0}{2} \int\limits_{all \, space} E^2 d\tau
\end{gather}
Int... |
I am working on a project draft and in an existing device, hot air up to 160 °C is generated for drying processes.
I have found old documents where densities of air are reported at three different temperatures:
30 °C --> 1.16 kg/m³
100 °C --> 0.84 kg/m³
150 °C --> 0.61 kg / m³
Now I used tables to confirm those values ... |
I've been studying convection and come across empirically-derived formulas for calculating the Nusselt number for various geometries.
For my particular use case, I'd like to measure the actual convective losses inside an enclosed box with air as the fluid, for an enclosure heated from below and losing heat above.
I'm c... |
The electric field strength at a point in a charging capacitor $=V/d$, and is the force that a charge would experience at a point. This doesn't seem to make sense, as all the capacitor is is 2 plates, one positively and one negatively charged, and we have an equation to represent the electric field strength at a point... |
How to perform the Fourier transformation of the series: $$ \sum_{<l,m>}(-1)^{l+1}(a_{l}^{+}a_{m}+a_{l}a_{m}^{+})$$ where the sum is over the nearest neighbours (l,m), l=1 to N,and there is periodic boundary condition, $$a_{l+N}=a_{l}$$ First, I rewrite the above expression as : $$ \frac{1}{2}\sum_{l,\delta}[a_{l}^{+}a... |
I am looking for a first-order correction on the intensity of the field generated by a (neodymium) magnet in the presence of an external magnetic field $B$ (possibly generated by another magnet). For simplicity, we may assume that $B$ and the magnet magnetization $B_r$ are collinear (but not necessarily with the same o... |
so i was just thinking that may be the reason of that we cannot measure a quantum particle position and velocity may be because continuously it's being hit by electromagnetic radiation and since we need light which is electromagnetic radiation to measure the position and velocity of light so since the light has already... |
In the article
Ehrenfest Relations for Ultrasound Absorption in Sr2RuO4, Sigrist M., Progress of Theoretical Physics, Vol. 107, No. 5, May 2002
A superconductor with proposed p-wave pairing and order parameter of the structure $\vec{d}(\vec{k})=\hat{z}(k_x\pm i k_y)$ is discussed. The article lists the "standard" mul... |
In the lectures on QFT I'm following we define the renormalized QED Lagrangian as
$$\mathcal{L} = \dfrac{1}{4} (F_0)_{\mu\nu} (F_0)^{\mu\nu} + \bar{\psi}_0 (i \bar{\partial} - (m_0)_e) \psi_0 - e_0 \bar{\psi}_0 \gamma^\mu \psi_0 (A_0)_\mu,$$
where we have $(A_0)_\mu \equiv \sqrt{Z_3} A_\mu $, $(\psi_0) \equiv \sqrt{Z_\... |
I passed green laser light from air to water but to my suprise the light doesn't bend towards normal even though I changed the angle of incidence.It goes undeflected ,Is it because of its higher frequency?
|
The Gaussian laser pulse
$$
E(t) = E_0 e^{\frac{-2\ln 2}{\tau^2} t^2} \cos{\omega t}
$$
(where $\tau$ is the intensity FWHM) is often troublesome in numerical simulations due to the infinite temporal length of it's envelope, which can introduce artifacts unless a very wide temporal window is used. A widespread solution... |
Andromeda will collide with the Milky Way in about 4.5 billion years. What I want to know is, will the Milky Ways nucleus reactivate when we collide with Andromeda, will it combine with Andromeda's nucleus, or will they both explode?
|
I am trying to understand why the Dirac Lagrangian is invariant under charge conjugation.
The Dirac Lagrangian is:
$$\mathcal{L} = i\bar{\psi}\gamma^\mu \partial_\mu\psi - m \bar{\psi}\psi $$
I know that under charge conjugation the flowing formulas are correct:
$$
\hat{C} \, \bar{\psi}\psi \, \hat{C} = +\bar{\psi}\psi... |
Actually, I already asked a similar question Coupling of supergravity to matter which has remained unanswered. So this time I will be less general.
In the very interesting paper arXiv:2212.10044 [hep-th] Simple Supergravity from G. Dall'Agata & Marco Zagermann they show in a very intuitive way how to promote supersym... |
I want to obtain the topological charge or winding number of the map
$$
f_n(\mathbf{r})=(\sin \theta \cos (n \varphi), \sin \theta \sin (n \varphi), \cos \theta)
$$
and my lecture notes say that it is given by
$$
Q=\frac{1}{8 \pi} \epsilon_{i j k} \int d^2 S_k f_n \cdot\left(\partial_i f_n \wedge \partial_j f_n \right)... |
Here’s something that has always bothered me in my physics lectures. Suppose I want to calculate the work done by electromagnetic forces onto one charge
$$
\begin{equation}
dW = \vec{F} \cdot d\vec{s} = Q \vec{E}\cdot\vec{v} dt
\end{equation}
$$
Now if I want to expand this idea to a continuous charge distribution... |
For quantum mechanics, a certain property of a subatomic particle, e.g. the spin of an electron, which can be either up or down, is a "superposition of states," and one of the two conditions, e.g. the fact that it has spin up or down, doesn't manifest itself until the situation is experimentally observed. In fact, from... |
$G$-$\text{WZW}$ model on a Riemann surface $\Sigma$ at the level $k$ is defined as
$${\displaystyle S_{k}(\gamma )=-{\frac {k}{8\pi }}\int _{\Sigma }d^{2}x\,{\mathcal {K}}\left(\gamma ^{-1}\partial ^{\mu }\gamma ,\gamma ^{-1}\partial _{\mu }\gamma \right)+2\pi kS^{\mathrm {W} Z}(\gamma )}$$
Where $S^{\mathrm {W} Z}(\g... |
I was watching a video(https://www.youtube.com/watch?v=XoVW7CRR5JY) about how electric and magnetic fields are related, and I understand that electric and magnetic fields are the same and the only different thing is the perspective of observing.
But one thing during the video that made me wonder was the way a magnetic ... |
I would like to understand (ideally with a nice pedagogic reference), why the fidelity of quantum gates in long ion chain decreases with the number of ions in the chain.
In this reference, it is explained on page 27 that it is because the Lamb-Dicke parameter decreases with the total number of ions in the chain. This p... |
If the fabric of spacetime isn't bound by the limit of the speed of light (the universe is expanding faster than the speed of light), could humans somehow wrap a spaceship in a bubble of the fabric of space time and go faster than the speed of light?
|
In two-photon absorption (TPA), the relative polarization of the two photons about to be absorbed simultaneously by an atom is crucial in determining the TPA rate. However, there is a lack of discussion in the literature regarding the significance of the relative phase of the two photons in determining this rate. For i... |
What is the equation for the speed of a molecule at a specific temperature? I saw two equations $v = \sqrt{\frac{3 k T}{m}}$ and $v =\sqrt{\frac{3RT}{m}}$. What is the difference?
|
I have heard many people mention that heisenberg uncertainity prinicple doesn't really allow 'violation of energy conservaiton for a short time'. i.e, virtual particles, are just a mathematical tool. If so, how are the ranges of fundamental forces explained?.
Electro-magnetic field is long range, as its force carrier i... |
What is called matter and what is called antimatter is just a convention, isn't it? For example, suppose we call the bottom, the charm and the down quark antimatter and we call the strange, top, and up quark matter. So then one can say that for some particles there was a little bit more matter in the early universe, wh... |
Suppose we charge a body with negative charge. We then place it inside a Faraday shield that has openings in the form of vertical slits. A coil surrounds the shield. If we start rotating the Faraday shielding itself, will a current be produced in the coil?
|
On Michele Maggiore book on QFT (page 91) is stated, out of nothing, that "observables are made of an even number of fermionic operator" and similar sentences is in Peskin book (page 56).
Is there any physical and mathematical reason for that?
|
It is written in my book that when a capillary tube is of insufficient length, the liquid does not overflow and the shape of the liquid meniscus changes, but the angle of contact remains the same. I did not understand that how it is possible because,
$$r=R\cos\theta,$$
where
$R$ is the radius of curvature of liquid me... |
which of the following is valid forward active mode large signal model of npn bjt transistor ,here a),b) similar and c),d) are similar I want to know a) or c) which of them is best and valid equivalent to npn bjt, I think for me circuit A) makes more sense because in actual npn bjt both Ic and Ib current passes throug... |
I recently set up a numeric solver of the Schrödinger equation and can receive solutions for single-particle quantum mechanical problems. I became interested in simulating atoms, since there is a closed-form solution only for hydrogen.
The coulomb potential for hydrogen is simple to model, since we can apply the Schröd... |
I tried solving this simple Newton's 2nd law problem using the energy principle instead as an excercise. The results were different... What did I do wrong? Below are my results:
|
If we're asked to believe that the explosive aspect of a supernova results from a rebound of residual free falling matter off of the stellar core, shouldn't we also be asked to believe that transition to Neutron Star occurred first and the edge formed, faster than the residual free falling matter falls, faster than gra... |
If you are in a car crash, you will likely have on a seatbelt because they are supposed to help you from getting injured/harmed. But, I don't think they are that much of a help. First of all, say you crashed at like 56 mph. A seat belt will not restrict the speed you are moving at very much, seeing as in a car you can ... |
My intuition says 'no'. I know from my knowledge of spaceflight that every orbit includes the point at which delta-v was last spent; you can't use only a cannon on the ground to put something into a stable orbit because the last point delta-v was applied is on the ground.
I would think a similar limitation would apply... |
In the linearization of GR, when $g_{\mu\nu} = \eta_{\mu\nu} + h_{\mu\nu}$, and $|h| \ll 1$, it is said (for example here) that 'to linear order the “$\Gamma\Gamma$” terms go away' in the formula for the Ricci tensor.
It is like to say that, if a function is small, the square of its first derivative (in the case, the $... |
Have a look at this frame from footage recorded during Operation Hardtack I - Test POPLAR
Clearly the bit on top is extra hot, and it seems to be above the main fireball, or at least not part of the sphere. If you look at the video, you'll see the ball actually forms earlier, gets relatively more incandescent and push... |
When I see that wording utilized, I have some confusion about what that means. Are the particle/anti-particle pairs each themselves popping in and out of existence, meaning the exact same particle exists for a time, but then that same exact particle ceases to exist, but then that same exact particle exists again, over ... |
Lorentz, Einstein et. al. assume time is the variable which changes in a gravity well or as speed approaches $c$. That's the commonly accepted model.
For nearly 50 years I've wondered if anyone else has considered introducing a hypothetical, "universal" rate of reaction U. Wherever t appears in all physical, chemical o... |
The Heisenberg uncertainty principle states that the product of standard deviations (or variances) for incompatible observables has a non-zero lower bound (with a zero lower bound reserved for compatible ones). However, not all probability distributions have well-defined moments, such as mean and variance. For example,... |
Hi I've probably got a very basic question but I'm really confused about this. If I have a vector that starts at the origin and points to say (3,-3) so the 4th quadrant, and I am wanting to split apart my vector into its x and y components, are we typically measuring the angle with respect to the x or y axis? I'm confu... |
So I know that we feel weightless during a free fall as there's no normal force acting on us or my other way of thinking is that considering a lift and both lift and I fall with $g$ then no normal force between us to make me feel my weight and if lift is accelerating up then I will feel my weight more as I am experienc... |
new to this so be kind.
I have a question regarding polarisation of light. I got taught that in order to transform any arbitrary input state (fully polarised) into any arbitrary output state in polarisation, you need two quarter and a half wave plate (in order QHQ).
However, I've been doing some simulations with Jones ... |
Consider the attached image.
Light is passed through a circular prism in the form of a disc (by refraction) in a way so that the the angle made by the refracted ray with the normal is 45 degrees.Assuming that the prism is of glass and the surrounding medium is air and the critical angle for the glass air interface is ... |
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