We present a detailed Chandra study of the galaxy group NGC 1550. For its temperature (1.37±0.01 keV) and velocity dispersion (∼ 300 km s−1), the NGC 1550 group is one of the most luminous known galaxy groups (Lbol = 1.65×1043 erg s−1 within 200 kpc, or 0.2 rvir). We find that within ∼ 60 kpc, where the gas cooling time is less than a Hubble time, the gas temperature decreases continuously towa...

Entropy in computer security is associated with the unpredictability of a source of randomness. The random source with high entropy tends to achieve a uniform distribution of random values. Random number generators are one of the most important building blocks of cryptosystems. In constrained devices of the Internet of Things ecosystem, high entropy random number generators are hard to achieve ...

Near-critical quantum circuits close to equilibrium are ideal physical systems for asymptotically large-scale quantum computers, because their low energy collective excitations evolve reversibly, effectively isolated from microscopic environmental fluctuations by the renormalization group. Entropy flows in near-critical quantum circuits near equilibrium as a locally conserved quantum current, o...

In a previous work (M. Campisi. Stud. Hist. Phil. M. P. 36 (2005) 275-290) we have addressed the mechanical foundations of equilibrium thermodynamics on the basis of the Generalized Helmholtz Theorem. It was found that the volume entropy provides a good mechanical analogue of thermodynamic entropy because it satisfies the heat theorem and it is an adiabatic invariant. This property explains the...

“Residual” entropy (3–12 J mol 1 K 1) is present near 0 K in some crystals composed of nonsymmetric molecules, for example, CO, N2O, FClO3, and H2O. It is detected only by the difference between spectroscopic calculations of the absolute entropy of the gaseous chemical and calorimetric measurements of its heat capacity (and phase changes) from 0 K to the temperature of the gas. Calorimetry, lik...

Entropy is one of the fundamental quantities which links emerging research areas like flexibility and defect engineering in inorganic-organic hybrid materials. Additionally, a delicate balance between entropy and enthalpy can lead to intriguing temperature-driven transitions in such materials. Here, we briefly overview traditional material design principles, highlight the role of entropy in the...

Black holes are thermodynamic objects, but despite recent progress, the ultimate statistical mechanical origin of black hole temperature and entropy remains mysterious. Here I summarize an approach in which the entropy is viewed as arising from “would-be pure gauge” degrees of freedom that become dynamical at the horizon. For the (2+1)-dimensional black hole, these degrees of freedom can be cou...

The geometric entropy in quantum field theory is not a Lorentz scalar and has no invariant meaning, while the black hole entropy is invariant. Renormalization of entropy and energy for reduced density matrices may lead to the negative free energy even if no boundary conditions are imposed. The presence of particles outside the horizon of a uniformly accelerated observer prevents the description...

We define correlational ~von Neumann! entropy for an individual quantum state of a system whose timeindependent Hamiltonian contains random parameters and is treated as a member of a statistical ensemble. This entropy is representation independent, and can be calculated as a trace functional of the density matrix which describes the system in its interaction with the noise source. We analyze pe...

One of the main applications of the stochastic matrix method is the evaluation of the probability of finding boroxol rings and dendrites in a boron oxide glass. In this work, we calculate the configurational entropy of B2O3 using this probability and Shannon’s definition of entropy. The isentropic temperature is evaluated obtaining a very good agreement with experimental data. Entropy is introd...