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It's important to appreciate that when you talk about a singularity at the Big Bang or the centre of a black hole you are really referring to a singularity in a particular mathematical model. A black hole (usually) means the Schwarzschild metric, and the equations that describe this become singular at $r = 0$. The Big bang means the FLRW metric, and the ...

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Superheating and supercooling should be possible whenever there is a first order phase transition. This includes a wide variety of magnetic, structural, and electronic phase transitions. The physical mechanism is the same as in the water-ice transition: in a first order phase transition. the energy functional is still a local minimum at the old phase, there ...

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To describe the final stages of black hole evaporation will require a theory of quantum gravity, and no such theory exists at the moment. So your question cannot be answered: we simply don't know what happens when a black hole disappears. I have seen a presentation (I'm afraid I don't have the link) where the final stages of evaporation were calculated ...

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The definition of temperature in the kinetic theory of gases emerges from the notion of pressure. Fundamentally, the temperature of a gas comes from the amount, and the strength of the collisions between molecules or atoms of a gas. The first step considers an (elastic) impact between two particles, and writes $\Delta p = p_{i,x} - p_{f,x} = p_{i,x} - ( - ... 2 This is a simple (yet not simple to solve!) transient heat transfer problem using cylindrical coordinates. There are solutions available in handbooks if you do not want to go through the math and Bessel function solutions arise. Its been a while since I have done this myself. The boundary condition is the tricky part. If you use a constant temperature for ... 1 NaCl melts at around 800°C. Molten NaCl has a density of about$1.556 \frac{g}{cm^3}$[1], at room temperature (solid) it has one of$2.71\frac{g}{cm^3}$[2]. Sadly I could not find a value for the density at barely underneath melting point but I strongly assume that the density is a strictly monotonously falling function of temperature. Therefore solid NaCl ... 1 It is because you wouldn't hide in the corners like your kitty does! A electric radiator is designed to be directional and therefore it doesn't heat the unnecessary part of your room. It makes you feel warming in front of it, but some part of the room don't get heated like those corner and the ceiling. In comparison, a vacuum cleaner heating the gas ... 1 I will start by answering the second question. Let's consider the case of two species of liquid in a box, with a partition separating them. The irreversible process you describe is to remove the partition. A reversible process would be to have the partition actually composed of two separate independently movable partitions. One of these does not interact ... 1 This very nearly a duplicate of Does infrared rays pass through polarized glass? if you ignore the bit about polarisation. There is a useful collection of articles about the optical properties of glass on the Schott web site, and in particular there is one titled TIE 35: Transmittance of Optical Glass. The article is freely downloadable, though you need to ... 1 Actually I think I disagree with the answer by BMS (the group of asymptotic symmetries of asymptotically flat spacetimes?). However I am not sure to have understood BMS'answer completely. In my opinion, there is no difference between the definition of work in pure mechanics and work in thermodynamics (I stress that I am speaking of thermodynamics and not ... 1 Here is one issue where thermodynamics and mechanics could differ in the definitions of work. In mechanics, a non-careful, ambiguous, but common definition for the work done by a force$\vec{F}$is$\int\vec{F}\cdot d\vec{s}$. The problem with this is that we're not told which infinitesimal displacement$d\vec{s}\$ to use; one could use (1) the infinitesimal ...

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