Table of contents

We discuss the fluid state of matter at high temperature and pressure. We review the existing ways in which the boundary between a liquid and a quasigas fluid above the critical point are discussed. We show that the proposed 'thermodynamic' continuation of the boiling line, the 'Widom line', exists as a line near the critical point only, but becomes a bunch of short lines at a higher temperature. We subsequently propose a new 'dynamic' line separating a liquid and a gas-like fluid. The dynamic line is related to different types of particle trajectories and different diffusion mechanisms in liquids and dense gases. The location of the line on the phase diagram is determined by the equality of the liquid relaxation time and the minimal period of transverse acoustic excitations. Crossing the line results in the disappearance of transverse waves at all frequencies, the diffusion coefficient acquiring a value close to that at the critical point, the speed of sound becoming twice the particle thermal speed, and the specific heat reaching 2. In the high-pressure limit, the temperature on the dynamic line depends on pressure in the same way as does the melting temperature. In contrast to the Widom line, the proposed dynamic line separates liquid and gas-like fluids above the critical point at arbitrarily high pressure and temperature. We propose calling the new dynamic line the 'Frenkel line'.

Light propagation through a single gain layer and a multilayer system with gain layers is studied. Results obtained using the Fresnel formulas, Airy's series summation, and the numerical solution of the nonlinear Maxwell-Bloch equations by the finite difference time domain (FDTD) method are analyzed and compared. Normal and oblique propagation of a wave through a gain layer and a slab of a photonic crystal are examined. For the latter problem, the gain line may be situated in either the pass or stop band of the photonic crystal. It is shown that the monochromatic plane-wave approximation is generally inapplicable for active media, because it leads to results that violate causality. But the problem becomes physically meaningful and correct results can be obtained for all three approaches once the structure of the wavefront and the finite aperture of the beam are taken into account.

Methods for searching for non-Gaussianity in the WMAP data are reviewed and the associated problems related to the cosmic microwave background (CMB) data analysis are discussed. Evidence for non-Gaussianity has been obtained by various methods and from a number of multipole ranges. Different approaches to searching for non-Gaussian CMB data are sensitive to different manifestations of non-Gaussianity, which sometimes are due to the primordial non-Gaussianity and sometimes to galactic foregrounds and/or systematic residuals remaining after the data analysis that are difficult to take into account.

The nonlinear effect of parametric oscillatory instability in the gravitational wave laser detector (antenna) is considered as a factor that considerably reduces the sensitivity of the device. It is shown that in an antenna with a circulating power above a certain threshold value, excitation of Stokes optical modes occurs in Fabry-Perot resonators and of test mass elastic modes. Parametric oscillatory instability in gravitational wave interferometers of the second (LIGO, Virgo, LCGT, GEO-600) and third (ET — Einstein Telescope) generation with different types of pumps is examined. The effect discussed has been observed not only in gravitational wave laser interferometers, but also many times in other opto-mechanical systems. All current methods for suppressing parametric oscillatory instability in gravitational wave interferometers are also discussed, both passive and active.

Conditions are obtained for the existence of a fast-moving surface electromagnetic wave (with a speed close to the speed of light in the vacuum) on a flat interface between the vacuum and an isotropic dissipative medium with a permittivity . The interfaces considered include vacuum–seawater, vacuum–metal, vacuum–plasma, and vacuum–dielectric. Conditions for the existence of negligibly damped surface waves are considered for extremely high (vacuum–seawater, vacuum–metal) and very low (vacuum–plasma, vacuum–dielectric) values. It is shown that at least in these two limit cases, the phase wave velocity and the group wave velocity pass synchronously through the speed of light in the vacuum, which can be considered the reason why surface waves exist at the interface between vacuum and a collisionless plasma (with and ) and do not exist at the interface between the vacuum and a weakly absorbing dielectric (with and ). In the first limit case, it is shown that both the phase and group velocities pass at , implying that a surface wave exists at the vacuum-metal interface (with ), but that a surface wave (Zenneck's wave) cannot exist at the vacuum–seawater interface (with ).

It is argued that, historically, the concept of the existence of hypothetical superluminal particles called tachyons was preceded by the concept of a faster-than-light process. The latter concept, put forth by Lev Yakovlevich Strum (1890 – 1936) of the Soviet Union, contained within it the formulation of what later came to be known as the 'reinterpretation principle' of tachyon theory, a principle which proved instrumental in solving the problem of cause and effect in faster-than-light motions. L Ya Strum's results on this subject are briefly discussed, and his professional career is outlined.

A scientific session of the Physical Sciences Division of the Russian Academy of Sciences (RAS) devoted to the "Physical properties of graphene" was held on 28 March 2012 in the conference hall of the Lebedev Physical Institute.

The agenda of the session announced on the RAS Physical Sciences Division website http://www.gpad.ac.ru included the following reports:

(1) Falkovsky L A (Landau Institute of Theoretical Physics, RAS, Moscow; Vereshchagin Institute of High-Pressure Physics, RAS, Moscow) "Magnetooptics of graphene";

(2) Varlamov A A (The University of Rome Tor Vergata, Italy) "Thermoelectric properties of graphene."

The papers written on the basis of these reports are given below. • Magnetooptics of graphene layers, L A Falkovsky Physics-Uspekhi, 2012, Volume 55, Number 11, Pages 1140–1145 • Anomalous thermoelectric and thermomagnetic properties of graphene, A A Varlamov, A V Kavokin, I A Luk'yanchuk, S G Sharapov Physics-Uspekhi, 2012, Volume 55, Number 11, Pages 1146–1151

This letter is aimed to briefly highlight the fact that, along with many probabilistic models (including the random graphs and chains currently in wide use), there is a direct universal approach to describing the formation of stochastic structures with probability unity in random media (in 'chaos'), i.e., in almost all random field realizations. The mathematical level adopted is accessible to early undergraduate students. It can thus be concluded that clustering in chaos is not only a physical phenomenon but also a universal phenomenon inherent in nature—with some provisos, of course.

The fact that the first living structures were learning in the process of evolution resulted in no evolutionary step being completely random. This learning was impossible without 'memory' about the past: survival-enhancing situations should be remembered to accumulate experience for survival and reproduction in the future.