question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I am a novice in physics and a few things are not clear to me in electromagnetism:</p>
<p>Consider the experiment of giving a piece of metal positive charge (which I assume consists of protons), by keeping a piece of rod with negative charge close to the metal and touching by your finger the farther side of it from... | g15651 | [
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<p>I was thinking if I built a device with 7 clocks, synchronized to each other, one in the middle, one up, down, left, right, behind and in front of me, say 1 meter away, and I fired a laser from the middle and split it into six pieces would the light always arrive at all six "corners" at the same time?</p>
<p>If we ... | g15652 | [
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<p>Can someone please point me a way to compute
$$\int_0^\infty\frac1{s+t}\exp\left(-\alpha t+\frac{t^2\beta}{s+t}\right)dt$$
? How about the following one?</p>
<p>$$\int_0^\infty ds\int_0^\infty dt\,\frac1{s+t}e^{-(s+t)}e^{-\frac{st}{s+t}}$$</p> | g15653 | [
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<p>I have sucessfully derived the Lorentz matrix for the boost in $x$ direction and its inverse. So I know how to get these two matrices: </p>
<p>$$
\Lambda =
\begin{bmatrix}
\gamma & 0 & 0 & -\beta \gamma\\
0 & 1 & 0 & 0 \\
0 & 0 & 1 & 0 \\
-\beta \gamma & 0 & 0 & \gamm... | g15654 | [
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<p>In pre-calculus last week my teacher explained a scenario in which a man throws a rock down a well and takes 4 seconds for you to hear the rock hit the bottom. How far downs the well? Last years I took regular physics and learned that distance equals Velocity x Time. So knowing that gravity pulls with 9.8m/s/s I ass... | g15655 | [
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<p>Suppose at a time $t_{0}$ a car goes from 0 to 30mph at time $t_{1}$, and then maintains a speed of 30mph until $t_{2}$. After that minute it accelerates, reaching 60mph at time $t_{3}$.</p>
<p>I want to compare the work done, particularly between $t_{0}$ and $t_{1}$, and between $t_{2}$ and $t_{3}$. The laws of ... | g15656 | [
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<p>A <em>helium</em> balloon is tied to the seat of a car. The doors and windows of the car is closed. If the car now starts moving, in which direction will the balloon move- front or back? </p> | g15657 | [
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<p>Frictional force between solids operates even when they do not move with respect to each other. Do we have <a href="http://en.wikipedia.org/wiki/Viscosity" rel="nofollow">viscous</a> force acting between two layers even if there is no relative motion?</p> | g15658 | [
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<p>I understand that </p>
<p>$$\begin{align}
J = \sum F \Delta t &= \Delta p \\
\sum F &= \frac{\Delta p}{\Delta t} \\
&= \frac{mv_2 - mv_1}{\Delta t} \\
&= m \cdot \frac{\Delta v}{\Delta t} \\
&= ma
\end{align}$$</p>
<blockquote>
<p>$J$ is impulse, $p$ is momentum</p>
</blockquote>
<p>However,... | g15659 | [
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<p>On the question of motivation and evidence for dark matter, there are some illuminating (so to speak) answers on this site. I'd like to understand in detail the foundations of one of the lines of reasoning, as stated succinctly in <a href="http://physics.stackexchange.com/a/1036/8197">this answer</a>:</p>
<blockqu... | g15660 | [
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<p>In the semi-classical physics, the probability of the penetration through a barrier is given by
$$
p \sim \exp \left( - A_{0} (E) \right),
$$
where $A_0$ is the imaginary part of the action and $E$ is the energy. Now, my problem is that I do not understand the following relation:
$$
\frac{\partial A_0}{\partial E}=... | g15661 | [
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<p>I know that the earth's magnetic field is due to molten metal and ions flowing in its core. It has been found that the Earth's magnetic field changes its direction and it has even flipped once! </p>
<p>But, in order for this to happen the molten ions flowing in the core should also change its direction. What is cau... | g15662 | [
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<p>I have this problem here related with tunnel and ventilation.</p>
<p>As you can see at the picture below, it is a top view of the tunnel.
The tunnel has an inlet and an outlet. The air flows from the inlet on the left and exits at the outlet on the right. There is one branch/drift to this main tunnel road (it's wi... | g15663 | [
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<p>I am doing some simulations with the <a href="http://ab-initio.mit.edu/wiki/index.php/Meep" rel="nofollow">Meep code</a> to study some properties of a metal nanoparticle.</p>
<p>The situation is this: an incident electromagnetic wave on a metal nanoparticle. By now I know how to calculate the scattering, absorption... | g15664 | [
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<p>This was posted on here in someone's Phys.SE <a href="http://physics.stackexchange.com/a/10497/2451">answer</a>:</p>
<p><em>No, in the many worlds interpretation, every parallel universe is real, but in consistent histories, once you choose your projection operators, only one possibility is real, and all the others... | g15665 | [
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<p>Can anyone help me enlist 3 major differences between the quantum and classical physics of the behaviour of a particle in a box? I would like some insight into the differences without solving PDEs because I am not a physics student.</p>
<p>Thank you very much</p> | g15666 | [
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<p>Ron Maimon in many posts claimed that cosmological horizon is like a big black hole.</p>
<p>Black holes decrease as they evaporate and their radius decreases as well.</p>
<p>So what is with a cosmological horizon? </p>
<p>If cosmological horizon is just a black hole centered at the opposite side of the universe, ... | g15667 | [
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<p>Why does a capacitor charge only upto the voltage of the source? I mean in an r.c. circuit if we have a resistor that is in series with the capacitor then because of the potential drop there will be less amount of current flowing to the capacitor. So shouldn't its final steady state voltage value be equal to the pot... | g15668 | [
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<p>I'm confused:</p>
<p>In a tug of war game on rough ground who will win? The one who applies greater force on the rope or the one who applies greater force on ground?</p> | g15669 | [
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<p>Suppose an object is a distance $d_o$ from a first lens (which has a focal length $f_1$), where $d_o>f_1$. Behind the first lens is a second lens with a focal length $f_2$, such as to produce a virtual image a distance $d_i$ away from the second lens. How would I find the angular magnification of this system? (L... | g15670 | [
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<p>Commonly seen in physics(and statistics) are the concepts of moments of order zero(mass), one(center of mass), and two(moment of inertia). In statistics a third moment (referred to as skewness) also exists and is used. Actually, mathematically the moment can (of order n) be simplified to an operation in the form of:... | g15671 | [
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<p>This is something that I have wondered for a long time. How come when I walk around why do I not see random black spots where light has collided destructively and bright spots where it has collided constructively?</p> | g15672 | [
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<p>For years I have been hearing all sorts of conflicting information about global warming. Many say that scientists have proven that humans have been warming the Earth significantly with their actions. Specifically with the release of carbon into our atmosphere.</p>
<p>Others say that scientists have found other caus... | g15673 | [
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<p>Suppose I have acceleration defined as a function of position, $a(x)$. How to convert it into a function of time $a(t)$? Please give an example for the case $a(x)= \frac{x}{s^2}$.</p> | g15674 | [
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<p>Does a similar easy to read introduction like David Mc Mohan's Demystified books exist for LQG? I'd like something easier to start with than a paper but deeper than a popular book.</p> | g15675 | [
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<p>How many linearly independent eigenfunctions can be associated with one degenerate eigenvalue of the Hamiltonian operator? (Is there a limit since it contains a 2nd order differential operator?) Thanks.</p> | g15676 | [
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<p>Which of the following corresponds to a $ \psi(x)$, a wavefunction written in the position basis: $ x| \psi\rangle $ or $ \langle x| \psi\rangle $? If it is the second expression (which my textbook asserts), what is the meaning of the first expression? </p> | g15677 | [
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<p>Superheating of a liquid past its boiling point (retarded boiling) is a well-known phenomenon. However, is there such a thing as supercooling of gas past its condensation point?</p>
<p>Conversely, supercooling of a liquid (retarded freezing) is also well-known. Does the reverse ever occur: can I superheat a solid u... | g15678 | [
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<p>I am trying to create a plot for the electrical resistivity of high purity gold from 1 K to 1000 K. I found gold's resistivity at 300 K using the Wiedemann-Franz Law based on thermal conductivity data I was provided. I also have a table that has the resistivity of gold at 295 K By Mathiessen's rule, the resistivity ... | g15679 | [
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<p>I think about position, its time derivative speed, and its second time derivative, acceleration. I would like to identify a single word that can be used as a handle for the second time derivative of energy (i.e., the time derivative of power). If there is a widely used term, I'd prefer to use it. If not, I'd like to... | g15680 | [
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<p>I've been wondering whether there has been any experimental evidence for the existence of <a href="http://en.wikipedia.org/wiki/Anyons" rel="nofollow">anyons</a> or are they just objects of purely mathematical interest?</p> | g15681 | [
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<p>Let's suppose I have a signal $F(t)$ that is periodic, with two periodicities $P_1$ and $P_2$, with $P_1 > P_2$. Suppose that I know the values of the two periodicities.</p>
<p>Using the <a href="https://en.wikipedia.org/wiki/Fast_Fourier_transform" rel="nofollow">Fast Fourier transform</a> I can show the two va... | g15682 | [
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<p>When it comes to atoms electrons can't fall into the nucleus, which besides the off hand uncertainty explanation, I'm not sure which force prevents them from falling into the nucleus. I thought I heard it was the strong nuclear force-but is there a similar force preventing protons and electrons, outside of atoms, fr... | g15683 | [
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<p>I know that neon is used in advert signs due to its inertness. However, I am not entirely sure how the inertness is exploited. I think it is because Ne being inert means that after electricity frees an electron we can count on it returning to the ion left behind to emit a photon, whereas for more active elements, th... | g15684 | [
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<p>How does nature prevent transient toroidal event horizons?.. and does it really need to?</p>
<p><strong>Steps to construct a (transient) toroidal event horizon in a asymptotically flat Minkowski spacetime:</strong></p>
<ol>
<li><p>take a circle of radius $R$</p></li>
<li><p>take $N$ equidistant points in the circl... | g15685 | [
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<p><img src="http://hyperphysics.phy-astr.gsu.edu/hbase/particles/imgpar/pidec1.gif" alt="Pion Plus Decay"></p>
<p>Since the charged pions decay into two particles, a muon and a muon neutrino Fractional electric Charge disappeared, why?</p>
<p>The decay proceeds by the weak interaction $W^{+}$ and can be visualized i... | g15686 | [
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<p><a href="http://newsfeed.time.com/2012/02/22/einstein-was-right-all-along-faster-than-light-neutrino-was-product-of-error/" rel="nofollow">A "faster than light" neutrino discovery was actually the result of a loose cable</a>.
A fiber-optic cable in a GPS receiver at the European Center for Particle Physics ( CERN) n... | g15687 | [
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<p>I just don't get the concept behind why a lens or a mirror forms a reproduction of the object at present. Is it to do with the object blocking parts of the light source? I just don't understand why an image of that object is produced.
The question is essentially trying to understand <strong>what causes the image to ... | g15688 | [
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<p>We consider a particle, A receiving energy from a second one,particle B in a one dimensional collision.
$$E^2=p^2+m_0^2$$<br>
$$EdE=pdp$$
For particle A:</p>
<p>$$E_AdE_A=p_Adp_A{\;\;\;\;\;\;}(1)$$</p>
<p>For Particle B:</p>
<p>$$E_B dE_B=p_Bdp_B {\;\;\;\;\;\;}(2)$$
Now $$\mid dE_A\mid=\mid dE_B\mid{\;\;\;\;\;\;}... | g15689 | [
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<p>Reading the funny title of this <a href="http://www.theorie.physik.uni-muenchen.de/videos/strings2012/bousso/index.html">talk</a>, Black Holes and Firewalls, just made me LOL because I have no idea what it is about but a lively imagination :-P (Sorry Raphael Bousso but the title is just too excessively funny). Since... | g15690 | [
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<p>Could it be that there is simply a maximum gravitational force that two bodies of finite mass can exert on one another? This would occur at $r=0$, so maybe there is some really really really small $a$ in the universal gravity equation, making it
$$F=G\frac{m_1m_2}{r^2+a}$$
If $a$ was small enough, it would only bec... | g15691 | [
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<p>I have a conceptual understanding of some theoretical physics concepts, so without getting into the math, what is <a href="http://en.wikipedia.org/wiki/Exotic_matter" rel="nofollow">exotic matter</a>?</p>
<p>I have read some articles that say it is anything not normal, while others say it has a negative mass (is th... | g15692 | [
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<p>I'm curious why rockets are so big in their size. Since both the gravitational potential one need to overcome in order to put thing into orbit, and the chemical energy burned from the fuel, are proportional to the mass, so if we shrink the rocket size, it would seem to be fine to launch satellites. So why not build ... | g305 | [
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<p>Can a particular real force have different magnitude in different frames?</p> | g15693 | [
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<p>I was curious to know when was the first time (which year) the modified Arrhenius expression was proposed: $k=A(T^n)e^{\frac{-Ea}{RT}}$. I know that the simple Arrhenius equation $k=Ae^{\frac{-Ea}{RT}}$ was proposed by Svante Arrhenius in year 1889. Did he also propose the modified form in that year? Or someone el... | g15694 | [
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<p>This question is more astronomy related, I started thinking when I heard from one of my friends living in <a href="http://en.wikipedia.org/wiki/Jiamusi" rel="nofollow">Jiamusi</a>, that Sun rise at 02:00 and sets at 14:00, I know that this place is more near to north pole but why sunrise time so different there?</p>... | g15695 | [
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<p>Let me take QED for example to clarify my question: The textbook-approach(at least for Peskin&Schroeder) to quantize ED is to first quantize EM field and Dirac field as free fields respectively, and then couple them together perturbatively to represent the interaction, and we will have a fully quantized theory. ... | g15696 | [
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<blockquote>
<p>In electronics, a flip-flop or latch is a circuit that has two stable
states and can be used to store state information. [...] Flip-flops and latches are used as data storage elements. Such data storage can be used for storage of state, and such a circuit is described as sequential logic.</p>
</bloc... | g15697 | [
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<p>Do protons in the beam on LHC interact with photons? I wonder how a beam would look from outside. Is there a photo of a proton beam?</p> | g15698 | [
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<p>It is well known that the Lagrangian of a classical free particle equal to kinetic energy. This statement can be derived from some basic assumptions about the symmetries of the space-time. Is there any similar reasoning (eg. symmetry based or geometrical) why the Lagrangian of a classical system is equal kinetic ene... | g15699 | [
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<p>Is there any link between the law of maximum entropy and the principle of least action. Is it possible to derive one from the other ?</p> | g15700 | [
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<p>According to $a = v^2/R$, the circular velocity and radial distance between two attracting objects (such as planets), must remain in perfect proportion in order for orbital motion to take place. How is it possible for objects in nature to achieve this proportion perfectly?</p>
<p>Not only that, to maintain an orbit... | g15701 | [
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0.026395395398139954,
... |
<p>What is meant by an "inclined magnetic field"? How is it different from the usual magnetic field?</p> | g15702 | [
0.01490697544068098,
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<p>Doing some crude calculations (using the value of $H_0$ at this point of time only, since it is time dependent but not distance dependent thanks to Johannes answer) what is the radius of cosmological event horizon at this point of time? (not looking for the changes of CEH through time) </p>
<p>From <a href="http://... | g15703 | [
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0.020207861438393593,
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0.01295810379087925,
... |
<p>How do you measure the topological spin of an anyon? So how could an experimental setup look like? Is topological spin an observable at all?</p> | g15704 | [
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<p>OK, so I have water at a known pressure, lets say 12psi. I have 2 pipes, installed vertically, one 2" diameter, the other 1/2" diameter. To what height (in feet) will the water raise to in each case? I said it would be the same, but I can't explain why. Remember this is a static pressure, as the water is not flowing... | g15705 | [
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<blockquote>
<p>Positron is a particle which has the same mass as an electron . But it has positive charge on it . When electron and positron combine, they annihilate each other with the release of energy in the form of two very high energy photons.</p>
<p>if the energy released on annihilation of an electron an... | g15706 | [
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<p>In quantum mechanics we start with a Hamiltonian $H_0$ for which we know the exact eigenstates and energy eigenvalues. We perturb it by a known term $H$, and then attempt to compute (approximately) the new eigenstates and eigenvalues.</p>
<p>In general relativity, my understanding is we start with a metric $g_{\mu ... | g15707 | [
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<p>To get to the point - what's the defining differences between them? Alas, my current understanding of a spinor is limited. All I know is that they are used to describe fermions (?), but I'm not sure why? </p>
<p>Although I should probably grasp the above first, what is the difference between Dirac, Weyl and Majoran... | g15708 | [
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<p>We have a Nd YAG laser pumped Optical Parameter Oscillator in our lab. A technician came to our lab (my professor called him for its maintenance) and while he was working on it, he told me that because of the organic impurities in the air, the crystals got contaminated. He showed me a layer formation on the crystal ... | g15709 | [
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<p>In <a href="http://en.wikipedia.org/wiki/Neutrino_oscillation" rel="nofollow">neutrino oscillations</a>, neutrinos can convert from one flavor to another. This implies individual lepton number is not conserved. Doesn't it also imply that, if the neutrinos have mass, the mass should be of Majorana type? But I'm confu... | g15710 | [
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<p>If you rubbed a balloon with a towel, where would the electrons go: the balloon or the towel? Why?</p>
<p>I'm guessing the electrons would go to the object with a larger mass, but it's just a guess. :)</p> | g15711 | [
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<p>Can someone help me understand the "Doubling trick" at page 36 in <a href="http://inspirehep.net/record/887513/files/sis-2002-060.pdf" rel="nofollow">http://inspirehep.net/record/887513/files/sis-2002-060.pdf</a> (named "Scattering in Supersymmetric M(atrix) Models" by Robert Helling) or help me in some other way to... | g15712 | [
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0.03134... |
<blockquote>
<p>Suppose a point charge is located at the center of a spherical surface. The electric field at the surface of the sphere and the total flux through the sphere are determined. </p>
<p>1).What happens to the flux and the magnitude of The electric field if the radius of the sphere is halved?</p>
</bl... | g15713 | [
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0.0025319... |
<p>Why should the neutrino mixing matrix (PMNS matrix) be unitary? Is the unitarity dictated by experiments or is it a theoretical demand?</p> | g15714 | [
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<p>I'm reading a paper and don't understand some of the calculations. We are given an integral equation with asymptotic boundary conditions</p>
<p>$\rho_+(u)=\frac{1}{2\pi} \int\limits_{|v|>\mu}^{}\mathrm{d}v\,\frac{2\hbar \rho_+(v)}{(u-v)^2+\hbar^2}$</p>
<p>$\rho_+(u)=\ln(|u|)-\frac{1}{2} \ln\left(\Xi\right)+O(u-... | g15715 | [
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<p>What is physical meaning of $\kappa$ and $R$ in curved space?</p>
<p>$$dl^2 = \frac{dr^2}{1 - \kappa\frac{r^2}{R^2}}
+ r^2d\theta^2 + r^2\sin^2\theta d\phi^2$$</p> | g15716 | [
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<p>In solid state physics the electron density is often equated to $e|\psi|^2$. However, the Sakurai says (Chapter 2.4, Interpretation of the Wave Function, p. 101) that adopting such a view leads "to some bizarre consequences", and that Born's statistical interpretation of $|\psi|^2$ as a probability density is more s... | g15717 | [
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<p>Can somebody list all the quantum numbers (beside R-parity) that are conserved in vertex for SUSY particles in mSUGRA model?</p> | g15718 | [
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<p>Let's consider a ring laser where the laser must pass through the gain material before it is sent toward a partially reflective surface $\ R=1-T $. The other mirrors are perfect reflectors with $\ R_1=R_2=1 $. Furthermore the output irradiance of the setup is give as $\ I_{out} = I_{sat}(\gamma - \gamma_{th})L$ wher... | g15719 | [
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-0.... |
<p>Integer quantum Hall states has integer number of chiral edge current channels flowing around like supercurrent in a superconductor.</p>
<p>Are they truly dissipationless?
If so, what is the mechanism that protects the coupling of different channels or phonon scattering? (e.g. edge current of 2D topological insulat... | g15720 | [
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<p>Unfortunately I'm struggling to understand how do we get eq. (2.4.8) from eq. (2.4.7), p. 60; namely how $(\Lambda \omega \Lambda^{-1} a)_\mu P^\mu$ is transformed into $\Lambda_\mu^{\;\rho}\Lambda_\nu^{\;\sigma}(-a^\mu P^\nu + a^\nu P^\mu)$. Why there are those two terms in the end, and not just $2a^\nu P^\mu$? I b... | g15721 | [
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<p>When two charged particles having same charge $q$ are at rest, only electric force acts upon it: a repulsive force of magnitude $\frac{kq^2}{r^2}.$</p>
<p>Now let them move with a constant velocity perpendicular to the line joining them. Then one of the particles will produce magnetic field on other and the second ... | g15722 | [
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<p>The answer is 3. But according to me 2 shall also work in 2 Dimensions? Does anyone has a theoretical proof?</p> | g15723 | [
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<p>While working out the stationary states of a single particle in a 3d infinite potential box ($V=0$ inside a cuboid of known dimensions, $V=\infty$ everywhere else), I realized I had to assume the wavefunction was separable into a product of three functions, $\psi(x,y,z)=X(x)Y(y)Z(z)$, in order to find $\psi$. Why is... | g15724 | [
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<p>When I attach a Digital Multimeter (DMM) to read the resistance between my right and left hands, the resistance starts off high and reduces over time. It appears almost like "RC-type" behavior. Can someone explain to me what it is that I am seeing on the DMM in some detail?</p> | g15725 | [
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<p>Assuming you could measure the qualities of the radiation emanating from all around a black hole, could this be used to determine the internal geometry or makeup of the mass inside?</p> | g15726 | [
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<p>How is it possible to encrypt multiple images using fresnel transform and inverse the operation to de-multiplex those images?</p> | g15727 | [
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<p>I'm now learning quantum mechanics with Liboff. In the book it deals with "a compete set of mutually compatible observables" in order to make a state maximally informative. How can one find such set? It seems very hard unless commutation relation is an <a href="http://en.wikipedia.org/wiki/Equivalence_relation" rel=... | g15728 | [
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<p>During a physics lab we stumbled upon a little problem. The measuring device was unstable, oscillating between two values. We were told to write down the average with the half-difference between the values as error. There is also the error on the measure due to the instrument's resolution. </p>
<p>Now I have to con... | g482 | [
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<p>Is time simply the rate of change?</p>
<p>If this is the case and time was created during the big bang would it be the case that the closer you get to the start of the big bang the "slower" things change until you essentially approach a static, unchanging entity at the beginning of creation?</p>
<p>Also, to put th... | g15729 | [
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<p>The electron is particle.
The mass of electron is $9.10938215(45)\times 10^{−31}\, {\rm kg}$.</p>
<p>But why is the mass exactly what it is?</p>
<p>What in physics defines the mass of elementary particle?</p> | g15730 | [
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<p>I want to get a grip about the technical problems related to proving Penrose conjecture</p>
<p>Intuitively, it seems it should not be too difficult; just start by classifying it in 0-dimensional (i.e: Schwarschild singularity) and 1-dimensional singularities (i.e: Kerr singularities).</p>
<p>Assume we have a naked... | g15731 | [
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<p>Added: <strong>5 times down vote for now! Down voter is this religion or physics, please try to explain your decision.</strong></p>
<p>I'm confused about this.</p>
<p>In physics we know for a <a href="http://en.wikipedia.org/wiki/Vacuum" rel="nofollow">vacuum</a>, but I think that there is a contradiction in this ... | g259 | [
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<p>Statistically speaking, you're going to still encounter deviations from equilibrium, even though the expected value is equilibrium. But these rare deviations from equilibrium - which are inevitable - might have the power to do work. So does the universe inevitably descend towards a maximum-entropy state? Or is it on... | g15732 | [
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<p>What is the source of the loud noise of an MRI medical scanning machine? Is it due to some mechanical moving parts such as pumps, or is it an effect, similar to magnetostriction of superconducting electrical magnets?</p> | g15733 | [
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<p>I have read Brief History of Time in which he has wonderfully described the formation of universe. What is the frame of reference from which we are viewing the big bang? What is the frame of reference from which we are seeing the events associated with the big bang? Where is this frame situated?</p>
<p><strong>Edit... | g15734 | [
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<p>I am looking for an computer parsable (CSV, XML, JSON, since I didn't find anything, I am happy with almost everything) file (or collection of files) that contains the information you can find in a simple table of nuclides. There are several more or less usable "browsers" and of course Wikipedia's tables, but none o... | g15735 | [
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<p>Is a <a href="http://en.wikipedia.org/wiki/Reciprocal_lattice" rel="nofollow">reciprocal lattice</a> defined for non-Bravais lattices? I'm trying to work out one for <a href="http://www.google.com/search?as_q=hcp+structure" rel="nofollow">HCP structure</a> and not figuring it out.</p> | g15736 | [
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<p>We know $\Psi(x,t)$ is complex, but can $\Psi(x)$ be complex? I have seen <em>particle in a box</em>, <em>well</em> and <em>harmonic oscillator</em>. All have real solutions for time-independent Schrödinger equation. Hence, I am curious to know examples where it is complex. <a href="http://physics.stackexchange.com/... | g15737 | [
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<p>What is the difference between the <a href="http://en.wikipedia.org/wiki/Kolmogorov%E2%80%93Smirnov_test" rel="nofollow">Kolmogorov-Smirnov test</a> and the <a href="http://en.wikipedia.org/wiki/Chi-squared_test" rel="nofollow">Chi-squared test</a>?</p>
<p>When should we use one instead of the other?</p>
<p>I was ... | g15738 | [
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<p>How do you calculate the energy output if you know the volts, amps and time?</p> | g15739 | [
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<p>When it's raining, would you get less wet if you run or more wet?</p>
<p>I think you will get less wet, because rain is coming down in a constant volume and if you run you will have a shorter amount of time you will get less volume</p>
<p>I'm not too sure though, some people say when you run you are running into a... | g416 | [
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<p>Given a <a href="http://en.wikipedia.org/wiki/Routhian" rel="nofollow">Routhian</a> $R(r,\dot{r},\phi,p_{\phi})$, how do you derive Lagrange's equation for $r$? Do you just solve the following for $r$?</p>
<p>$$\frac{d}{dt}\frac{∂R}{∂\dot{\phi}}-\frac{∂R}{∂\phi}=0$$</p>
<p>And as a related question, what is the mo... | g15740 | [
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<p>Equation 1 represents an improvement over the intial assumption of constant mass velocity (i.e., $\rho v=\rho_o v_o$). We can now improve Eqn. (2) to get to Eqn. (3). My question is: what are the steps to obtain Eqn. (3)?</p>
<p>Equation 1 is:
$$\rho v = \rho_o v_o(1+\delta f[c,g]) \tag{1}$$</p>
<p>where $\rho$ ... | g15741 | [
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0.030314914882183075,
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0... |
<p>I think I understand that if given the two boson wavefunction of two different states
\begin{align}
\Psi(\boldsymbol{r}_1,\boldsymbol{r}_2)
=
\dfrac{
\psi_1(\boldsymbol{r}_1)\psi_2(\boldsymbol{r}_2)
+
\psi_1(\boldsymbol{r}_2)\psi_2(\boldsymbol{r}_1)
}
{\sqrt{2}}
\end{align}
the expectation value of an operator $\hat... | g15742 | [
-0.04462704062461853,
-0.015485374256968498,
-0.004174591042101383,
0.0027390283066779375,
0.07700134813785553,
-0.04648639261722565,
0.02800878882408142,
0.021620675921440125,
-0.012704131193459034,
-0.024557646363973618,
-0.07817260921001434,
0.054694682359695435,
0.0007762500899843872,
... |
<p>This question is about a <a href="http://arxiv.org/abs/1305.3955" rel="nofollow">paper from last year about Quantum Energy Teleportation</a>. </p>
<p>If I understand the main assertion of what QET is supposed to involve, basically you are teleporting energy as information, but without sending the energy directly. S... | g15743 | [
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0.027198363095521927,
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0.006707455031573772,
-0.008214717730879784,
... |
<p>There are several formulas to describe critical current in Josepshon S-N-S junction mainly based on <a href="http://arxiv.org/abs/cond-mat/9812297" rel="nofollow">Eilenberger and Usadel equations</a> for quasi-classical Green's functions. The starting point is the Nambu-Gorkov equation and then some simplifications.... | g15744 | [
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0.04999098554253578,
0.0178044... |
<p>OK, let me preface this by saying i am not a physics student, nor have i ever been. I am a software engineer working on a development degree. So this is homework but the assignment was just to create an app, i chose to do this app.. and the teacher said he couldn't assist because this is a development class not a ph... | g15745 | [
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0.030002973973751068,
0.04779919609427452,
0.00139... |
<p>The generic commutation relations for the angular momentum operator are $[J_x, J_y] = i \hbar J_z$, where the $J_i$, $i = x,y,z$ are the components of the angular momentum vector operator, $\mathbf J$. The spin components obey the same commutation relations. My question is, in all physical systems using a non-relat... | g15746 | [
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-0.017222752794623375,
-0.028913704678416252,
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0.015893515199422836,
0.012635353952646255,
-0.00843888521194458,
-0.001574699766933918,
-0... |
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