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Conservation of information in quantum mechanics is a hypocrisy as much as it is so in classical mechanics. It is not conserved in the same sense as energy, charge, or momentum. When sages like Hawking and Penrose discuss whether does “information” survive destruction in a spacetime singularity, they mean something utterly different from the concept familiar ...


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Many 3d glasses use circular polarization, where one lens uses left-hand polarization while the other uses right-hand polarization. This lets the viewer tilt their head a bit without losing the 3D effect, where linear polarization would let the image bleed through into the other eye.


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My theory would be that your eyelids, like windscreen wiper, wipe away some of the exes water on your eyeball. Due to adhesion between the water and the eyelids the surface of this water is slightly curved near the eyelids and if the eyelids are close enough near each other this surface basically acts as a concave lens, which I tried to demonstrate in the ...


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Well, here's my first answer on Stack Exchange! All light, not just visible light which we see, consists of many different electromagnetic waves. These are all part of the electromagnetic spectrum. The "color" of the light we see is defined by the wave's wavelength. http://science.csustan.edu/chem1112_4/beers%20law/beers%20law081.htm Here is a ...


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Much of the vapor you see at that stage is unburned material, not a true "smoke" which would be ashes or non-burnable material. A true solid is very difficult to burn. Most fuels instead volatilize as the temperature rises, increasing the surface area. This material coming from the heated fuel appears similar to smoke. A visible flame is the burning of ...


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It's an optical illusion. The trees at all distances will move in a direction opposite your motion, but the nearer trees will appear to move faster than the ones farther away. If your eyes get used to the speed of the nearer trees, it may look like the farther ones are moving in the opposite direction.


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Math already done by others, but my first impression would be yes and no. Yes, because any load requires energy from somewhere; No, because electrical loads less than a major sound system are so insignificant you will never notice outside of a lab. Driving up one decent hill will consume more gasoline than the added load of your laptop over the entire tank, ...


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This is really just a footnote to alemi's answer. The electricity for your car is supplied by the alternator, and the torque required to turn the alternator depends on the current it's supplying. As you draw more current more torque is required to rotate the alternator and the car has to use more power to do it. So yes, plugging in your laptop will increase ...


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$$ 110 \text{ hp} = 82 \text{ kW} $$ This is 1000x what the laptop draws. You won't notice. To put that change in perspective, you would see a similar increase in the power (85 W) used by the car if your speed changed from 65.00 mph to 65.02 mph, since $P \propto v^3$ (at high speed, the power goes as the velocity cubed) as per this answer, so $ ...


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Let's try to validate and quantify the conjecture first raised by Carl Witthoft in a comment to the question, which is basically that the sky only appears less blue in the second picture because a lot more light is scattering off of the windows towards your camera. If this is true, we ought to be able to see it. The first thing to do is convert the pictures ...


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There is a favorite question on graduate schools' qualifying exams in physics, Why the sky is blue? The answer is the Rayleigh scattering. Shorter wavelength photons are more likely to change the direction in the atmosphere which is why the bluer, shorter-wavelength light is overrepresented in the light coming from random directions of the sky. I ...


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Using a commercial aerosol can to spray fuel is actually fairly safe, for two reasons, both of them mentioned by LDC3. At the nozzle exit, the fuel is liquid, so flame cannot propagate into the can. If, somehow, it were possible, the propellant used in aerosols is not flammable, so no combustion can occur inside the can. What can happen is that, with ...


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These notes supported by this thesis say the flame propagation in a hydrocarbon/air premix is $0.4-0.6$ m/sec. Since yours is not premixed, it will be slower. The aerosol will slow down quickly as it exits the can due to air resistance.


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First, it's very unlikely that the fire will enter the can since there is no oxygen inside the can. Second, the fire probably won't reach the nozzle since the fuel needs to vaporize before it can burn. It's a liquid inside the can. Although you could singe your fingers if you use the wrong fuel, or you have your finger over the front of the nozzle. Once ...


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Without repeating the mathematics of @alemi's answer, let's just think about one other thing: Buoyancy is a function of depth - that is, as you descend your lungs are compressed and your buoyancy decreases, then goes negative (depending on the fat content of your body - if you have enough fat, you remain positively buoyant at any depth since you do not need ...


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I like Jerry Schirmer's answer, but I was worried that instead of modelling you swimming as fast as you can as a constant force, I thought it would be interesting to consider swimming as fast as you can as a constant power. This seems more logical to me as if you are really trying to go as fast as you can, you will be limited by how hard you work, how fast ...


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OK, lets solve this in as simple an approximation as possible. I"m going to assume that the whole trip happens at the appropriate terminal velocity, and that acceleration times are very small. Furthermore, I"m going to model the resistant force${}^{1}$ of the water as $F = cv^{2}$, for some constant $c$. On the way down, you have the the resistant force ...


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An answer to v1 of the question (that didn't emphasize the sides): According to this cooking website, the pressure cooker valves are designed to be naturally "open." As the water heats up, the pressure inside will be slightly higher than outside (which is why you see steam escaping). At some point the valve is designed to "close" once a certain minimum ...


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Incense burning is much more of a smoldering reaction. You've got a porous medium that retains heat well and admits oxygen poorly. The propagation is mostly limited by the ability of heat to conduct along the stick and the ability of gases to pass in and out of the solid structure. Conduction doesn't care about gravity and The viscosity in those small ...


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Incense is a much better object for this puzzle than a candle. When a candle burns, the wax is melted. Normally the melting wax has to travel up the wick before it burns, and that gives a relatively constant rate of burning. When you place the candle horizontally (or upside down), some of the melting wax can fall away without burning. Consequently the flame ...


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No, this is not a golden-ratio spiral. Its closest relative is the Archimedean spiral, whose fundamental equation is $$r=a+b\,\theta.$$ This is the spiral traced out by the water thrown out by a horizontal sprinkler as it rotates: because its horizontal velocity is constant, the radius $r(t)$ of a given drop at time $t$ increases linearly with $t$, whereas ...


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Firstly, a Fibonacci spiral and a golden spiral are not quite the same thing, although they are pretty close. In this image from Wikipedia, the green curve is a Fibonacci spiral, and the red curve a golden spiral, with overlapping areas in yellow: They are close enough that for the purposes of your question we can consider them to be the same. In any ...


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The answer is NO. (with the help from Antonio's comment) Any golden ratio spiral is tangential to rectangles at vertexes, which is not the case with spiral created by water in this picture. There are other discrepancies, but this is the easiest to spot and explain.


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Yes it is possible but as BarsMonster points out it isn't like an optical mirror. X-ray reflectors are used in the construction of nuclear weapons and are critical to increasing the yield. How they work is the initial fusion reaction releases high energy radiation, this is then reflected back into the reaction mass increasing the energy levels of the ...


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Unfortunately X-ray and gamma mirrors are impossible to build the way you think - mainly because there is much less interaction with the matter comparing to UV - it will go through all materials commonly used for making mirrors. Even for EUV light (wavelength of 13.5nm) building effective mirrors is a royal pain. As wavelength of X-Rays is very small (down ...


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Another reason is that due to the inertia of the water the plastic can't accelerate as quickly and it needs to accelerate very quickly to make those noises. http://www.quora.com/Physics/Why-do-some-types-of-plastic-wrappers-make-so-much-noise-when-crumpled


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I think there are 3 factors : 1- gravity, 2- the upward movement of water by wave propagation (and this is the on that works in opposition to gravity) & 3- the displacement of water towards shore. The latter is caused by the fact that the front-face of the water moves slower than the hind-face which causes the shape of the wave to curl.Now, how does the ...


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If you mean listening in the air while crushing the bag under water - the main reason is due to the different acoustic impedances of air and water. Transmission of the sound of the bag popping through the water probably plays a secondary role. Acoustic impedance is defined as $I =\rho c$ where $\rho $ is the density of the medium, and $c$ the sound speed ...


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The surface formed by the bubble is such that its energy is minimized. Since increasing the interface between a liquid and air increases its energy due to surface tension, the bubble tends to reduce its radius, which implies that the pressure inside it must be higher than the pressure outside, and following this reasoning you may also get a quantitative ...


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I think the shaking action causes the batteries to move slightly, thus 'scraping' the contact area on the batteries and the contact elements in the remote. This improves the conductivity, and so on. Certainly I've had success opening the battery compartment and physically rotating the batteries and/or scraping the contacts gently. I think it's unlikely ...


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Most telephone handsets will not start ringing the instant a ring signal is received through the telephone line. Possibly this is to avoid them ringing due to random bursts of noise on the line, though I would guess this isn't much of a problem with modern digital lines. I use a SOHO phone system and I can see the system status signalling a call a second or ...


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Batteries contain various liquids that are important for the voltage to be produced. Sometimes, the liquid – even water – may turn to gas and it is permanently lost, along with the capacity. Sometimes, the liquid just moves to one side of the battery which is also bad. Shaking a weak battery may homogenize the concentration of the liquid across the battery. ...


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I will amplify my comment: Hearing aids operate in one of two modes, acoustic coupling or telecoil coupling. Hearing aids operating in acoustic coupling mode receive and amplify all sounds surrounding the user; both desired sounds, such as a telephone’s audio signal, as well as unwanted ambient noise. Hearing aids operating in telecoil coupling mode ...



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