Talk:Critical exponent

Is there any reason why the ordered phase always has to be lower in temperature compared to the disordered phase? Are there any counterexamples? AnonyScientist (talk) 08:29, 4 July 2008 (UTC)

I think reentrant nematic phases may be a counterexample. For thermotropic liquid crystals the sequence of phase upon cooling is liquid → nematic → smectic. There are some cases where, at high-pressures, a smectic→nematic occurs upon further cooling. Thermo53 (talk) 19:53, 7 April 2022 (UTC)

concrete example

This article goes straight to the math, without giving any concrete example of what quantity would be governed by such laws. In other words, it's mostly useless to anyone who doesn't already know the meaning of the topic. Homunq (talk) 09:22, 23 October 2011 (UTC)

discrepancy between the experimental value of alpha and the Ising-3D model result

I offer a very simple explanation: The heat capacity of the Ising model is not the isochoric heat capacity, for the Ising model does not have a volume as a parameter. The C of the Ising model is a heat capacity under the constraint that the “exchange reaction” spin-up ↔ spin-down is in a kind of chemical equilibrium. The equivalent of a real fluid would be an Ising model where the spin-up/spin-down ratio is fixed. Thermo53 (talk) 20:30, 7 April 2022 (UTC)

When you say Ising you mean O(2) right? Will if you publish a paper where you show that this particular effect explains the discrepancy quantitatively? Personally I am skeptical. The effect you are mentioning is well known as "Fisher renormalization of critical exponents". If you do a liquid Helium experiment at constant pressure it should theoretically give the same result as lattice O(2) model. Has been shown in many papers in the 1970s. PhysicsAboveAll (talk) 05:22, 23 April 2022 (UTC)