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Hohm, Uwe

doi:10.1016/j.chemphys.2014.10.010

Cited by 4 publications

(7 citation statements)

References 36 publications

(50 reference statements)

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“…According to our proposal we obtain the lower bounds from the corresponding Planck units. In the case of the ratio l s T thermophysical data can be found in [83] for the same gases as in the case of η/s [11]. The results are shown in figure 1.…”

Section: Thermal Conductivity Diffusion and Entropymentioning

confidence: 94%

“…They report a value in the range of D 11 ≈(58.5 K 67)·10 −9 m 2 s −1 in the critical region. This gives an experimental value of » ¼ ( ) D s 4.2 4.8 11 · - D s 10 K s m kg 14 3 11P P . This is even 94 orders of magnitude above the Planck limit given in (5).…”

Section: Thermal Conductivity Diffusion and Entropymentioning

confidence: 98%

“…In addition to table 2 the Planck units of entropy = S k P B and linear momentum = p m c P P are also used [71,75]. In the case of the indeterminacy relations (3)-(5), (7), (8), (10), (11), (13), and (14) the exact lower bounds are recovered. For the remaining five relations only a factor of (1/2) or (1/4π) is missing.…”

Section: The Planck Unitsmentioning

confidence: 99%

“…For all systems studied so far it has been shown that κ>κ 0 holds well. Interestingly, the minimum value κ min of κwas observed in the vicinity of the critical point of ordinary systems [11], of high-energy matter [12] and also of high-temperature superconductors [13]. It was observed for ordinary fluids [11] that the minimum value κ min of κof the rare gases and other small molecules is in the range between κ min ≈(9 K 100) κ 0 .…”

Section: Introductionmentioning

confidence: 97%

“…[4][5][6][7][8][9][10]. Because entropy and shear viscosity are common thermophysical properties with a clear definition for ordinary matter, this inequality has been tested with experimental data for ordinary fluids like the rare gases, H 2 , N 2 , CH 4 , and CF 4 [11]. For all systems studied so far it has been shown that κ>κ 0 holds well.…”

Section: Introductionmentioning

confidence: 99%

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Conjecture of new inequalities for some selected thermophysical properties values

Hohm

2019

J. Phys. Commun.

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In 2005 it was rigorously shown with string theory methods that there is a lower bound for the ratio of the shear viscosity η and the volume density of entropy s=S/V given byHere we extend this result in a heuristic manner to other ratios of thermophysical properties. We conjectured that there are rigorous non-zero lower bounds for the Lorenz number L as well as other combinations of equilibrium and transport properties. We suggest that the lower bounds and the corresponding inequalities can be written in terms of the Planck units. We show that some of the proposed new inequalities set severe constraints on the behavior and properties of ordinary matter.

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Section: Thermal Conductivity Diffusion and Entropymentioning

confidence: 94%

Section: Thermal Conductivity Diffusion and Entropymentioning

confidence: 98%

Section: The Planck Unitsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Conjecture of new inequalities for some selected thermophysical properties values

Hohm

2019

J. Phys. Commun.

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From strong to weak coupling in holographic models of thermalization

Grozdanov

Kaplis

Starinets

2016

J. High Energ. Phys.

105

232

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We investigate the analytic structure of thermal energy-momentum tensor correlators at large but finite coupling in quantum field theories with gravity duals. We compute corrections to the quasinormal spectra of black branes due to the presence of higher derivative R 2 and R 4 terms in the action, focusing on the dual to N = 4 SYM theory and Gauss-Bonnet gravity. We observe the appearance of new poles in the complex frequency plane at finite coupling. The new poles interfere with hydrodynamic poles of the correlators leading to the breakdown of hydrodynamic description at a coupling-dependent critical value of the wave-vector. The dependence of the critical wave vector on the coupling implies that the range of validity of the hydrodynamic description increases monotonically with the coupling. The behavior of the quasinormal spectrum at large but finite coupling may be contrasted with the known properties of the hierarchy of relaxation times determined by the spectrum of a linearized kinetic operator at weak coupling. We find that the ratio of a transport coefficient such as viscosity to the relaxation time determined by the fundamental non-hydrodynamic quasinormal frequency changes rapidly in the vicinity of infinite coupling but flattens out for weaker coupling, suggesting an extrapolation from strong coupling to the kinetic theory result. We note that the behavior of the quasinormal spectrum is qualitatively different depending on whether the ratio of shear viscosity to entropy density is greater or less than the universal, infinite coupling value of /4πk B . In the former case, the density of poles increases, indicating a formation of branch cuts in the weak coupling limit, and the spectral function shows the appearance of narrow peaks. We also discuss the relation of the viscosity-entropy ratio to conjectured bounds on relaxation time in quantum systems.

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Perspective: Excess-entropy scaling

Dyre

2018

The Journal of Chemical Physics

206

205

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This article gives an overview of excess-entropy scaling, the 1977 discovery by Rosenfeld that entropy determines properties of liquids like viscosity, diffusion constant, and heat conductivity. We give examples from computer simulations confirming this intriguing connection between dynamics and thermodynamics, counterexamples, and experimental validations. Recent uses in application-related contexts are reviewed, and theories proposed for the origin of excess-entropy scaling are briefly summarized. It is shown that if two thermodynamic state points of a liquid have the same microscopic dynamics, they must have the same excess entropy. In this case, the potential-energy function exhibits a symmetry termed hidden scale invariance, stating that the ordering of the potential energies of configurations is maintained if these are scaled uniformly to a different density. This property leads to the isomorph theory, which provides a general framework for excess-entropy scaling and illuminates, in particular, why this does not apply rigorously and universally. It remains an open question whether all aspects of excess-entropy scaling and related regularities reflect hidden scale invariance in one form or other.

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On the ratio of the shear viscosity to the density of entropy of the rare gases and H2,N2,

Cited by 4 publications

References 36 publications

Conjecture of new inequalities for some selected thermophysical properties values

Conjecture of new inequalities for some selected thermophysical properties values

From strong to weak coupling in holographic models of thermalization

Perspective: Excess-entropy scaling

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