We performed a finite-temperature quantum Monte Carlo simulation of the one-dimensional spin-1 2 Heisenberg model with nearest-neighbor interaction coupled to Einstein phonons. Our method allows to treat easily up to 100 phonons per site and the results presented are practically free from truncation errors. We studied in detail the magnetic susceptibility, the specific heat, the phonon occupation, the dimerization, and the spin-correlation function for various spin-phonon couplings and phonon frequencies. In particular we give evidence for the transition from a gapless to a massive phase by studying the finite-size behavior of the susceptibility. We also show that the dimerization is proportional to g 2 /Ω for T < 2J.

We investigate the antiadiabatic limit of an antiferromagnetic S = 1/2 Heisenberg chain coupled to Einstein phonons via a bond coupling. The flow equation method is used to decouple the spin and the phonon part of the Hamiltonian. In the effective spin model longer range spin-spin interactions are generated. The effective spin chain is frustrated. The resulting temperature dependent couplings are used to determine the magnetic susceptibility and to determine the phase transition from a gapless state to a dimerized gapped phase. The susceptibilities and the phase diagram obtained via the effective couplings are compared with independently calculated quantum Monte Carlo results.

The possibility of the existence of magnetic charges is one of the greatest unsolved issues of the physics of this century. The concept of magnetic monopoles has at least two attractive features: (i) Electric and magnetic fields can be described equivalently. (ii) In contrast to quantum electrodynamics models of monopoles are able to explain the quantization of electric charge. We suggest a quantum field theoretical model of the electromagnetic interaction that describes electricity and magnetism as equivalent as possible. This model requires the cross-section of Salam's ``magnetic photon'' to depend on the absolute motion of the electric charge with which it interacts. We suggest a tabletop experiment to verify this magnetic photon. Its discovery by the predicted effect would have far-reaching consequences: (i) Evidence for a new gauge boson and a new kind of radiation which may find applications in medicine. (ii) Evidence for symmetrized Maxwell equations. (iii) Evidence for an absolute rest frame that gives rise to local physical effects and violation of Einstein's relativity principle.Comment: 4 pages, no figures, late

Recently, Nodland and Ralston reported to have discovered a cosmic axis. We argue that their axis is supported by an earlier independent observation on the spin axes of galaxies in the Perseus-Pisces supercluster and explainable within the framework of Godel's cosmology.Comment: 1 page, no figures, Revtex, submitted to Physical Review Letter

Climate activist Greta Thunberg started her Skolstrejk för Klimatet on 20 August 2018. Her activity inspired the weekly international demonstrations of Fridays for Future. In this paper I review the scientific argumentation that justifies the demonstrations.