question stringlengths 37 38.8k | group_id int64 0 74.5k |
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<p>In a recent publication, <a href="http://prl.aps.org/abstract/PRL/v107/i17/e170404" rel="nofollow">Experimentally Faking the Violation of Bell’s Inequalities</a> (Gerhardt 2011) (<a href="http://lanl.arxiv.org/abs/1106.3224" rel="nofollow">arXiv version</a>), the statistics of quantum mechanics is faked using classi... | 990 |
<p>Let's say I saw the barrel of a gun with a 45° angle, what would be the effect on the trajectory of a bullet fired through that barrel ?</p>
<p>Would the bullet be less stable (I guess), would it make the gun fire with an angle, and would that be toward the "small" end ?</p> | 5,553 |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://physics.stackexchange.com/questions/11321/confused-about-the-role-of-mass">Confused about the role of mass</a> </p>
</blockquote>
<p>why is it that two object of varying mass will fall at the same speed in a frictionless enviorment like th... | 85 |
<p>In the steam bath at the health club, why is the "steam" thicker first thing in the morning before it has been used all day and the walls are "hotter"?</p> | 5,554 |
<p>I am kind of new to this eigenvalue, eigenfunction and operator things, but I have come across this quote many times: </p>
<blockquote>
<p>$\psi$ is the eigenfunction of an operator $\hat{H}$ with eigenvalue
$W$.</p>
</blockquote>
<p>First I need some explanation on how do we know this? All I know about operat... | 5,555 |
<p>Could anyone explain what "extending the solution" beyond the past light cone means? Say, for example, if I have a metric (no coordinate singularities), how can I extend it to the outside of the past light cone?</p>
<p>Up to know, I only could find the extension argument in the context of Schwarzschild solution, wh... | 5,556 |
<p>I would like to consult a nice reference that explains the theoretical background of SC generation in optical fibers in detail but more or less self-contained. I would also like to have your opinions on nonlinear optic books that present material at introductory level.</p>
<p>Thanks in advance</p> | 5,557 |
<p><img src="http://i.stack.imgur.com/LKYC5.png" alt="enter image description here"></p>
<p>If we sprinkle iron fillings on a sheet of glass placed over a short bar magnet. The arrangement of iron fillings will be similar to the one shown above. </p>
<blockquote>
<p><a href="http://physics.stackexchange.com/questi... | 5,558 |
<p>Does the negative potential energy in the gravitational field have to be considered in calculating the total mass of the system in question (because of $E=mc^2$)? </p>
<p>If so it seems to me that the adding this negative energy to the calculation would slightly diminish the strength of the gravitational force ove... | 5,559 |
<p>Why is it that the <a href="http://en.wikipedia.org/wiki/Kruskal%E2%80%93Szekeres_coordinates" rel="nofollow">Kruskal diagram</a> is always seen extended to all 4 quadrants when the definitions of the $U,V$ coordinates don't seem to suggest that the coordinates are not defined in, say, the 3rd quadrant. I can see th... | 5,560 |
<p>What is the difference between <a href="http://en.wikipedia.org/wiki/Spin_glass" rel="nofollow">spin glass</a> and <a href="http://en.wikipedia.org/wiki/Quantum_spin_liquid" rel="nofollow">spin liquid</a>?</p>
<p>Do they both originate from frustration?</p> | 5,561 |
<p>I have a cylindrical pipe of internal diameter of around 5mm, with pressurised fluid flowing though it. If I have holes at the wall of the pipe, how do I calculate the pressure loss due to water leaking out through those holes?</p> | 5,562 |
<p>There is a analog between harmonic oscillator $x=\frac{1}{\sqrt{2\omega}}(a+a^\dagger)$ and quantum field $\phi=\int dp^3\frac{1}{(2\pi)^3}\frac{1}{\sqrt{2\omega_p}}(a_p e^{ipx}+a^\dagger e^{-ipx})$, which is used to quantize the field operator.</p>
<p>However, one thing confuse me is about the coefficient $\frac{1... | 5,563 |
<p>My background is that of a mathematician. I have a question about the two Dimensional Ising Model. I think the terminology I use is similar to the physical.</p>
<p>I'm trying to understand the following passage in the article on the <a href="http://arxiv.org/abs/math/9907186" rel="nofollow">arXiv</a> about strong M... | 5,564 |
<p>Normally high-altitude balloon experiments end with the balloon popping and the payload falling back down to be reclaimed. </p>
<p>But if a second balloon was attached to the payload, one which was only partially inflated at launch, then could you keep the balloon aloft for a very long period of time? A sort of ext... | 5,565 |
<p>"Nonlinear Wightman fields" are my current response to a wish to do interacting quantum field theory differently, no matter how successful what we currently do may be. The following image of a single page "poster" attempts to get across why I think the mathematics is interesting, with the intention that an ordinary ... | 5,566 |
<p>Given two parallel wires carrying a current (e.g. 2 and 3 Amperes) and the distance between them, 5 cm, how do I determine the magnitude of the magnetic field at a point M mid-distance between the wires (2.5 cm from each)?</p>
<p>The wires are located in a vacuum with ${\mu}=4\pi10^{-7}$.
If I use the formula
$$B=... | 5,567 |
<p>Let's say a space-faring society wants to make a space station that has a large volume filled with air (or other gas), but no gravity. Using normal pressure tanks will require gathering an <a href="http://physics.stackexchange.com/questions/21286/amount-of-material-required-for-a-pressure-tank">amount of material p... | 5,568 |
<p>I just had this idea of orbiting a planet just by jumping and then flying upon it on its orbit kind of like superman. So,</p>
<p>Would it be theoretically possible or is there a chance of that small body to be & remain its unity?</p>
<p><img src="http://i.stack.imgur.com/MNhD5.jpg" alt="Orbiting an asteroid by... | 5,569 |
<p>I need help with a physics problem, I don't know much about dampers, how can this be solved?</p>
<p><img src="http://i.imgur.com/ybpcQ.png" alt="spring"></p>
<p></p>
<p>we have
$y_0(x)=\mu\sin(\Omega x)$</p>
<p>We arrive at this equation for motion (where we define $b$ and $w_0$ ourselves, and $z=y(t)-y_0(t)$)</... | 5,570 |
<p>I read somewhere that a quantum field can be thought of as a tiny bowl at every point in space with a ball doing SHM (quantum harmonic oscillator). It was given that the amplitude of this SHM is quantized, and each quantum signifies a particle. (i.e. if the ball rolls with minimum amplitude, there are no particles i... | 5,571 |
<p>Let's say a spinning star radiates mass-energy only from it's pole regions. How does the loss of mass-energy effect the angular momentum of the star?</p> | 5,572 |
<p>Suppose that Alice and Bob are both holding speakers emitting sound at a frequency $f$. Alice is stationary while Bob is moving towards Alice at twice the speed of sound.</p>
<p>In the case of Alice, if I forget for a minute that she is holding a speaker herself, and just think about the Doppler effect from Bob mov... | 5,573 |
<p>Ok, so I understand the eye has 3 different types of receptors and I've seen the process of converting from RGB to CMYK. However if in physics I can specify a color using a single number (its frequency) why do computers need 3 (RGB) or 4 (CMYK) numbers to specify the same color? Is there some kind of disagreement in... | 5,574 |
<p>Does string theory explain the weird things that happens at the quantum level, especially wave-particle duality? </p> | 5,575 |
<p>Just wondering. I know a negative electric charge moving though a coil will induce a voltage in the coil. My question is, would a positive charge, say an ion beam, moving though a coil also induce a voltage?</p> | 5,576 |
<p>The metaphor of a surface (typically a pool table or a trampoline) distorted by a massive object is commonly used as a metaphor for illustrating gravitationally induced space-time curvature. But as has been pointed out <a href="http://physics.stackexchange.com/questions/3009/how-exactly-does-curved-space-time-descri... | 5,577 |
<p>What is the basis for black hole evaporation?</p>
<p>I understand that Hawking-radiation is emitted at the event horizon, a theoretical result originating in General Relativity and Quantum Field Theory, but it seems to me that additionaly one has to assert an integral conservation law for mass/energy, ie. for a sph... | 5,578 |
<p>In Griffiths' ED book he derives the field of a moving charge by two ways:</p>
<ol>
<li><p><a href="http://en.wikipedia.org/wiki/Li%C3%A9nard%E2%80%93Wiechert_potential" rel="nofollow">LW retarded potential</a>.</p></li>
<li><p>Lorentz transformation of EM fields.</p></li>
</ol>
<p>(eq10.68 and eq12.92 and the dis... | 5,579 |
<p>I use several shape, several type of material (glass, metal, plastic), I use two different balances with 0.01g of accuracy. I put oil on gasket, and put upside down (like that I can see if water escape). But always it's the same result, when I put one, two or more effervescence tablets, the weight decrease:</p>
<p>... | 5,580 |
<p>In paper by Barnich and Brandt <a href="http://arxiv.org/abs/hep-th/0111246" rel="nofollow">Covariant theory of asymptotic symmetries,
conservation laws and central charges</a> they defined the Riemann tensor like this:</p>
<p>$$R_{\rho\mu\nu}^{\quad \ \ \lambda}~=~\partial_\rho \Gamma_{\mu\nu}^{\ \ \ \ \ \lambda}+... | 5,581 |
<p>Wick rotation of quantum field theories to Euclidean path integrals with a nonnegative measure everywhere is a wonderful tool. Not so with Lorentzian path integrals. Events far separated in coordinates can have zero or arbitrarily tiny interval separation in relativity. Ultraviolet divergences crop up for infrared s... | 5,582 |
<p>Every year millions of car tires are worn down on our highways, yet the roads are not all black from the rubber, neither are the sides of the roads black. Where does all the rubber go?</p> | 5,583 |
<p>I am preparing to teach Grade 9 Static Electricity next week and am going crazy trying to figure out what is happening in one of my experiments. I have a short piece of PVC pipe, 4 inches diameter, and I rub it with wool to charge it negatively. I can observe excellent repulsion when I touch it with my foil bit (dan... | 5,584 |
<p>For my electrical engineering course, we had to build a simple DC motor that can lift a coin. I have tested the motor, and here are the results:</p>
<ul>
<li>rotational speed (no load): 3630 RPM (380 rad/sec)</li>
<li>Current with load (9g): 3A (limited)</li>
<li>Current with no load: 0.7A</li>
<li>Maximum weight l... | 5,585 |
<p>Is there a way to describe interactions between systems with particles of different species, that is to say with different statistics?</p>
<p>For example:
I am placing a boson next to a free fermion gas. How can I write down interaction
Hamiltonians that make sense? By interaction Hamiltonians I mean Hamiltonians... | 5,586 |
<p>Given a 2-loop divergent integral $\int F(q,p)\,\mathrm{d}p\mathrm{d}q$, can it be solved iteratively? I mean</p>
<ol>
<li>I integrate over $p$ keeping $q$ constant</li>
<li>Then I integrate over $q$</li>
</ol>
<p>In both iterated integrals I use dimensional regularization.</p>
<p>Can it be solved iteratively? I ... | 5,587 |
<p>Recall that the <a href="http://en.wikipedia.org/wiki/Fermion_doubling">fermion doubling</a> is the problem in taking the $a \to 0$ limit of a naively discretized fermionic theory (defined on a lattice with lattice spacing $a$). After such a limit one finds themselves with an additional amount (precisely $2^d$) of f... | 5,588 |
<p>I am going through the introductory chapter's of Schwinger's <a href="http://physics.stackexchange.com/questions/98694/source-theory-alternative-to-qft">Source theory</a>. He writes,</p>
<blockquote>
<p>It [Source Theory] is a phenomenological theory, designed to describe the observed particles. No speculations a... | 5,589 |
<p>Hotels usually install peepholes in their doors so that a person inside a suite can see who is at the door without having to open it.</p>
<p>I understand that there should be a convex lens within the peephole so that the person inside can easily see the person outside, but what I'm wondering about is the trick such... | 5,590 |
<p>I have a question in my book</p>
<p><img src="http://i.stack.imgur.com/7yZhT.png" alt="http://i.imgur.com/P5R55sR.png"></p>
<p>The question is very easy, but then my solutions manual gave me unexpected answers</p>
<p><img src="http://i.stack.imgur.com/cam6h.png" alt="http://i.imgur.com/tSMmJEY.png"></p>
<p>I don... | 5,591 |
<p>I have read about the <a href="http://en.wikipedia.org/wiki/Uncertainty_principle" rel="nofollow">uncertainty principle</a>. And it applies to electrons. Then how is it that we can get exact tracks of electrons in cloud chambers?? That is to say that how is it that the position is fixed? I think I am missing a cruci... | 5,592 |
<p>Anyone knows where I can find an errata (or any related material, such as solution sheets, etc) for this book? Thanks.</p>
<p>Note: This is not a physics question, but this book is so popular among physicists that I can't think of anyone else better to answer it.</p> | 5,593 |
<p>What numbers did Halley, Cook, et al. have? What was the strategy by which they calculated the AU? </p> | 5,594 |
<p>When changing the curved space co-ordinate into a flat space co-ordinate if a cone. I got the result transformation that i cannot get a transformation at the vertex(apex) why?</p> | 5,595 |
<p>Pretty much what the title says. My base question is this. Assuming I take a piece of steel, and a piece of PVC plastic and I measure both their temperatures and find they are the same. I then take a look at the vibration speeds of the individual molecules would they be the same as well?</p>
<p>Here's a rough examp... | 5,596 |
<p>As I've understood it, the area under $F$-$s$-graph is the work done, so then :$$W(s)=\int{F(s)ds}$$
I am also given this equation ($W_k$ is kinetic energy, which is equal the work done to set the object in motion):
$$W_k=\frac{1}{2}mv^2$$
Does this mean that work is also the area under a $m$-$v$-graph, like so:
$$W... | 5,597 |
<p>An identity exists for CG coefficients:
$$\langle j_1 m_1 j_2 m_2 |J M \rangle = (-1)^{j_1+j_2-J} \langle j_2 m_2 j_1 m_1|J M\rangle,$$</p>
<p>But why is there a phase factor $(-1)^{j_1+j_2-J}$?</p>
<p>It seems to me that
$$|JM\rangle =\sum_{m_{1},m_{2}}|j_{1}m_{1}\rangle\otimes|j_{2}m_{2}\rangle\langle j_{1}m_{1... | 5,598 |
<p>A particle in a cyclotron requires more and more force to maintain the same acceleration as it accelerates.</p> | 5,599 |
<p>The observer is outside the water; the stones are underwater (say, 1 m below surface, if that matters). This produces a higher pitched sound for the observer than when both the observer and the stones are in air.</p>
<p>Is this because it takes more energy for sound waves to travel through water than through air, a... | 5,600 |
<p>Before this post gets marked as duplicate, I've checked book <a href="http://physics.stackexchange.com/questions/12175/book-recommendations">book recommendations</a> among other posts but I don't think they really answer this fairly niche question.</p>
<p>I am looking to compile a list of books, online courses, or ... | 201 |
<p>I am trying to understand intuitively what a <a href="http://en.wikipedia.org/wiki/Phonon">phonon</a> is, but for the moment I find it quite difficult (having a limited background in quantum mechanics, an undergraduate course in non-relativistic QM). In fact, I find it hard to formulate good questions, so I hope my ... | 5,601 |
<p>I assume it is some kind of quantity. Google only made things more confusing. </p>
<p>I get that it has something to do with circuits. </p>
<p>I also get what a <a href="http://en.wikipedia.org/wiki/Elementary_charge#Quantization" rel="nofollow">discrete charge</a> is. In fact, I thought charges were, by definitio... | 5,602 |
<p>My problem is when I take a picture (a close one) the straight edge looks a little curved. In a standard camera, like a CyberShot. </p>
<p>I would like to know if there is some relationship between the curvature of the glass and that effect or if you know more information about that.</p> | 5,603 |
<p>Background:</p>
<p>Currently I am studying a course on non-linear dynamics. We have been studying about
attractors only intuitively, so I do not have a definition for an attractor. Let me give you a couple of examples.</p>
<p>Consider a problem where a ball is slipping in a parabolic valley. It is clear
intuitivel... | 5,604 |
<blockquote>
<p>The result of an imbalance of electrons between objects is called static electricity. It is called "static" because the displaced electrons tend to remain <em>stationary</em> after being moved from one insulating material to another.</p>
</blockquote>
<p>Please can any one explain to me what does it ... | 5,605 |
<p>Lets suppose a spaceship travels with v = 0.9c relative to the Earth. The time inside the spaceship would pass slower than on Earth. Would the astronauts measure a different speed (that means, a different one that the observer on Earth does) in relation to the same reference frame (Earth)?</p> | 5,606 |
<p>I was wondering how Young's Modulus effects the resonant harmonics of a vibrating (string instrument) string. I know that the string's fundamental frequency is $$\frac{1}2 \times \text{Length} \times \frac{\text{Tension}}{\text{linear density}^{1/2}}$$ that Young's Modulus for a material is - $$\frac{\text{Force}\ti... | 5,607 |
<p>If you look at the commutation relation of the position and momentum operators (in 1D position space), you get:</p>
<p>$$[\hat{x}, \hat{p}_x] = [x,-i \hbar \frac{\partial}{\partial x}] = i \hbar$$</p>
<p>All this says to me is that if you prepare a system in state (A) and measure the position, the system is now in... | 5,608 |
<p>If the mass of the universe were cut in half, would it affect the speed of light?</p>
<p>Would it be twice as fast?</p>
<p>Would it stay the same?</p>
<p>Do we have instruments that are sensitive enough to measure the speed of light at different positions relative to high-mass objects to empirically answer this q... | 5,609 |
<p>I need to consider a couple of examples of systems which have energies that are intensive variables - not extensive. I'be been thinking about this and I am not coming up with anything. My understanding is that extensive variables (at least wrt usual energies) scales with mass or length (system size). It also seems t... | 5,610 |
<p>In physics, a pseudo-scalar is a quantity that behaves like a scalar, except that it changes sign under a parity inversion such as improper rotations while a true scalar does not.</p>
<p>Can someone show me the graphical picture or illustration that how a scalar changes under rotations? </p>
<p><strong>Why we can'... | 5,611 |
<p>How does ice become thinner in a no-frost fridge? I thought ice can't evaporate at all since, well, it's below freezing temperature and it's solid, too. In my other yes-frost fridge, the ice never becomes thinner, but thickens over time, so I have to de-frost it.</p>
<p>I don't believe the no-frost fridges have som... | 5,612 |
<p>I'm currently going through statistical physics, especially on Fermi energy when I came across a term called "quasi-continuum", what exactly is it?</p> | 5,613 |
<p>I am having a little bit of trouble with this following problem - </p>
<p>Suppose a particle has initial velocity and is moving with a constant acceleration. After t seconds its velocity is v. What will its displacement be in 2t seconds?</p>
<p>I have tried to solve this on my own with the help of these equations ... | 5,614 |
<p>Russian officials are seriously talking about <a href="http://gizmodo.com/report-russia-will-shut-down-all-u-s-gps-stations-wit-1575641874" rel="nofollow">shutting down US GPS ground stations within their borders</a> and <a href="https://twitter.com/DRogozin/status/466224135018782722" rel="nofollow">Deputy Prime Min... | 5,615 |
<p>If I put a ping pong ball in a vacuum, would it pop? If so, at what point would it happen? Any standard table ping pong ball is acceptable.</p> | 5,616 |
<p>I am working on a problem in which I shall find the normalised solution to the 1D particle in a box. Solving for the particle in an asymmetric potential is quite straight forward, but I run into trouble when the potential is symmetric:</p>
<p>$$
V(x) = \begin{cases} \infty & x < -\tfrac{L}{2} \\ 0 & - \f... | 5,617 |
<p>I'm looking for the resistivity and magnetic permeability of molten gallium arsenide, but can only seem to find the values for the solid material at room temperature (e.g., <a href="https://en.wikipedia.org/wiki/Electrical_conductivity#Resistivity_of_various_materials" rel="nofollow">Wikpedia</a>). Not even temperat... | 5,618 |
<p>Around 9pm (GMT) on June 9th, we noticed that the two security cameras had gone dark. Around the same time, a photo voltaic sensor responsible for keeping the yard lights on at night also failed.</p>
<p>In the morning the cameras were back to normal, which means that only the LEDs, responsible for night vision on t... | 5,619 |
<p>Is it possible to measure gravity other than cause and effect. Gravity is a principle which can only be measured by cause and effect. Ie since an object falls we assume there must be something pushing it down and since this principle holds true for a variety of scenarios, we hold it as true. Is that all we have to g... | 5,620 |
<p>This <a href="http://physics.stackexchange.com/q/67561/">question</a> quotes Hawking saying: </p>
<blockquote>
<p>[...] <em>you enter a world where conjuring something out of nothing <strong>is</strong> possible (at least, for a short while). That's because at this scale particles, such as protons, behave accordi... | 5,621 |
<p>From <a href="http://www.atomicarchive.com/Effects/effects3.shtml" rel="nofollow">The Blast Wave</a></p>
<blockquote>
<p><em>A fraction of a second after a nuclear explosion, the heat from the fireball causes a high-pressure wave to develop and move outward producing the blast effect. The front of the blast wave,... | 5,622 |
<p>Would like to ask a question, but first i would like to say <strong>Hello Everybody</strong> in a way that plays the system, since some geniouses decided that one should not be able to say hello in a question.</p>
<p>The <a href="http://en.wikipedia.org/wiki/Uncertainty_principle" rel="nofollow">uncertainty princip... | 5,623 |
<p>I am trying to see if I am doing a problem correctly. Problem </p>
<blockquote>
<p>Suppose you carry a 50kg sack of potatoes up two flights of stairs, a total height of 10m. How much work did you do? If it took you 20seconds, what was your power outlet?</p>
</blockquote>
<p>(I am NOT looking for the answer, I am... | 5,624 |
<p>This question has a flavor which is more mathematical than physical, however it is about a mathematical physics article and I suspect my misunderstanding occurs because the precise mathematical definition of the concepts used is different than what I think. But then again, it might be some foolish mistake on my part... | 5,625 |
<p>Consider $N$ qubits. There are many complete sets of $2^N+1$ mutually unbiased bases formed exclusively of stabilizer states. How many?</p>
<p>Each complete set can be constructed as follows: partition the set of $4^N-1$ Pauli operators (excluding the identity) into $(2^N+1)$ sets of $(2^N-1)$ mutually commuting op... | 5,626 |
<p>In their proof, Hohenberg and Kohn (<a href="http://prola.aps.org/abstract/PR/v136/i3B/pB864_1">Phys Rev 136 (1964) B864</a>) established that the ground state density, $\rho_\text{gs}$, uniquely determines the Hamiltonian. This had the effect of establishing an implicit relationship between $\rho_\text{gs}$ and th... | 5,627 |
<p>I am currently studying affine Lie algebras and the WZW coset construction. I have a minor technical problem in calculating the (specialized) character of $\widehat{\mathfrak{su}}(2)_k$ for an affine weight $\hat{\lambda} = [k-\lambda_1,\lambda_1]$. Given the generalized theta function
$$\Theta_{\lambda_1}^{(k)}(z,\... | 5,628 |
<p>I just bought a small <a href="https://www.sparkfun.com/products/11676" rel="nofollow">OLED screen</a> and was wondering is it possible to make a screen surface a little bit bigger ( 2x ) by projecting it through some optics on translucent surface. It reminds me of viewfinders in some old cameras or SLR lens adapter... | 5,629 |
<p>Why do we assume that in normal modes, particles oscillate in form cos (wt) ?</p>
<p>How do we know that the general motion of particles can be expressed as a superposition of normal modes?</p>
<p>In both French and Crawford, the assumption of harmonic motion is made without any proof, please help.</p> | 5,630 |
<p>In the Lorenz gauge, we have a beautiful relation between the four-current and the four-potential:</p>
<p>$$\Box A^{\alpha} = \mu_0 J^{\alpha}$$</p>
<p>To get $A$ in terms of $J$, however, we have to use a considerably uglier formula; or, at least, this is the formula presented in textbooks:</p>
<p>$$A^{\alpha}(t... | 5,631 |
<p>In the frame of photon does time stop in the meaning that past future and present all happen together?</p>
<p>If we have something with multiple outcomes which is realized viewed from such frame? Are all happening together or just one is possible?</p>
<p>How the communication between two such frame s work meaning ... | 195 |
<p>According to Einstein's <a href="http://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence" rel="nofollow">mass-energy relation</a> mass and energy are interchangeable. Can you provide some examples where:</p>
<ol>
<li><p>Mass gets converted into energy.</p></li>
<li><p>Energy gets converted into mass.</p></li>
... | 46 |
<p>I was browsing the NEXRAD radar feeds (I'm not an expert, just figuring them out) and I came across the following signature (visit the link to view the radar image)</p>
<p><a href="http://cl.ly/3n0y0p0g2M0K2B313g3U" rel="nofollow">http://cl.ly/3n0y0p0g2M0K2B313g3U</a></p>
<p>The radar in question was operating in ... | 5,632 |
<p>Is there any speed different between blue or red color? Is there speed different? or there are same speed? </p> | 5,633 |
<p>Let's say I would want to light up Venus, such that we can see Venus all day long and not have to wait for a Venus Transit. What kind of light would I need for it? How powerful would it need to be?</p> | 5,634 |
<p>Let me explain.</p>
<p>My shower is inconsistant in how hot it gets. Whenever I turn on the shower, I always put my hand really close to the water, but not touching it, so I can feel the heat radiate from the shower. That way, if I can feel it from a distance, I know it is too hot.</p>
<p>I also notice that if the... | 5,635 |
<p>My understanding is that dark energy, or equivalently a positive cosmological constant, is accelerating the expansion of the universe and I have read that this gives empty space-time positive curvature, ie de Sitter geometry. I also understand that parallel geodesics converge when curvature is positive and diverge w... | 5,636 |
<p>I need a concise definition of a fluid flux and an accompanying example. I've never taken a single physics course before, but I'm required to understand this concept so I can do the calculations for a Complex Analysis class. </p> | 5,637 |
<p>As I understand neutrinos, there are three different flavors, all with different masses. Although the masses of these neutrinos have not been directly measured, their mass differences have been. Current experiments, KATRIN and Project8 are going to measure neutrino masses and we shall know soon enough. Regardless, t... | 5,638 |
<p>How can someone calculate the power in watt that a runner produces, when he runs uphill and downhill?</p>
<p>Is there any algorithm? It is important to take under consideration the uphill and downhill elements of the run.</p>
<hr>
<p>Thank you for your answers but i am confused since i don't have a background in ... | 5,639 |
<p>if you have water flowing through a 6 or 4 inch pipe what would the pressure be if tapped off through a 1/2 inch BSP tap. What would the equation be to find out the pressure at different flows?</p> | 5,640 |
<p>As we know electrons continuously revolve around the nuclus without falling in it at a high velocity beating it's force of attraction. My question is where do electrons get energy to revolve around the nucleus and withstand its force of attraction.</p> | 202 |
<p>In an unbiased PN junction, when the carriers recombine to form a depletion layer , it is said that immobile ions are formed.</p>
<p>We know that the conduction band electrons in N type are not associated with any particular atom. So when the conduction band electron diffuses to the P type region, which atom become... | 5,641 |
<p>First let me state that I am not, nor ever have I been, a physics student. I am working on an idea for a book I'm writing.</p>
<p>This is a thought experiment that posits the existence of a computer system that, to cut right to the point, has within its memory banks the thoughts, memories, and experiences of every... | 5,642 |
<p>Vafa proposed <a href="http://arxiv.org/abs/hep-th/0008142" rel="nofollow">a duality</a> when embedding <a href="http://arxiv.org/abs/hep-th/9811131" rel="nofollow">the Gopakumar-Vafa duality</a> into superstring theory. Vafa's duality is about a correspondence N=1 supersymmetric gauge theory and superstring propaga... | 5,643 |
<p>A ball (radius $R$) has three layers. For $0<r<a$ it is a conductor with free charge $+Q$. For $a<r<b$ it is a linear dielectric $\epsilon$ with free charge embedded in it with density $\rho_{free}(r) = \left(\frac{\rho_0}{a^2}\right)r^2$. From $b<r<R$ it is a conductor again with some amount of ch... | 5,644 |
<p>In a previous question (<a href="http://physics.stackexchange.com/questions/65979/calabi-yau-manifolds-and-compactification-of-extra-dimensions-in-m-theory">Calabi-Yau manifolds and compactification of extra dimensions in M-theory</a>), I was told that the $G(2)$ lattice can be used to compactify the extra 7 dimensi... | 5,645 |
<p>Two light sources emit light at the same moment but in opposite directions. At what speed the distance between two light fronts is increasing? <strong>c</strong> or <strong>c</strong> * 2?</p>
<p>Note, that there is only one coordinate system here - a system, where these two light sources are placed and they don't ... | 109 |
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