# Tag Info

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Iodine - solid to vapor when heated under normal condition. In this context the word you need to search for is "sublimation"

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A universality class is an equivalence class of physical models – field theories, quantum field theories, or models of classical or quantum statistical physics – where the equivalence is defined by two or several models' having the same mathematical description of the behavior at very long time scales and distance scales. So if two models' behavior at very ...

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The boiling point of any substance may be defined as 'the temperature at which the pressure of its own vapors become equal to the external pressure'. So for example in the case of water, at 100oC, the vapor pressure become equal to approx. 1 atm. Now if you increase the pressure further, you would need to heat the sample more such that the new pressure is ...

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As you say, the correlation length, $\xi$, is a measure of domain size. Two spins that are within a correlation radius will have similar statistics. A system where there is such a scale can not be scale invariant. Indeed, scale invariance means that you can zoom in or out of the system and finds that it still looks the same. When there is a correlation ...

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Singularity in Force Laws If force laws were fundamental to nature, this would be a serious problem. Imagine, for example, the gravitational energy between photons. They are Bosons and can hence occupy the same quantum state; crucially, more than one of them can be and stay in the same position where the gravitational force (they have energy and hence, ...

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... r=0 is trivially excluded (for macroscopic objects at least) because they have well defined excluded volumes and cannot occupy the same space at the same time, hence one may argue that the divergence at r=0 case is a mathematical artifact Radius of elementary particles can be 0 if they are point particles (electrons are so far best thought of as ...

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I haven't done a calculation yet, but I would use an extrapolation based on the Clausius-Clapeyron formula: $$\frac{dP}{dT} = \frac{L}{T\Delta V}$$ You then take any two known thermodynamic quantities of water and water vapor and linearly extrapolate to that point where the difference is zero. A good choice could be the entropy, the entropy of water vapor ...

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As noted already, within classical physics, singularities such as $1/r^2$ signal a break down of the theory. If we are really interested in what is happening at the point of the singularity, we should use quantum physics. You can think of $1/r^2$ as the asymptotic scaling form of the quantum theory for large $r$. The actual singularity is not physical. On ...

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Ice cubes are colder than the water they are in, so the water freezes the two ice cubes together forming the bridge with the ice.

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I can't speak to singularities in the sense of general relativity, but your example of $1/r^2$ laws in classical physics is actually solved most of the time by internal structure. One of my physics professors used to always say that nature solves infinities with internal structure. For example, for a charged sphere of uniform charge density, the electric ...

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I can only offer a partial answer to the first portion of your question. one comes across functions that diverge at a given point, typical examples would be the Coulomb or the gravitational forces being ∝ 1/r², clearly they diverge at r=0... Gravitational force isn't actually proportional to 1/r². Take a look at the plot of gravitational potential on ...

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