7 research outputs found
Thermodynamics of continuous media with electromagnetic fields
The thermodynamics of an electrically charged, multicomponent continuous medium with electromagnetic fields is analysed in the non-relativistic limit. Applying locally the first and second law of thermodynamics and Maxwell's equations for a linear theory of electromagnetism, three equations characterising the continuous medium are derived: a thermostatic equilibrium equation, a reversible and an irreversible thermodynamic evolution equation. For a local thermodynamic equilibrium, explicit expressions for the temperature and the chemical potentials in terms of the electromagnetic fields are obtained. The linear phenomenological relations describe novel effects of non-uniform electromagnetic fields on the transport equations and account also for magnetoresistance and optical tweezer
Big bounce from spin and torsion
The Einstein-Cartan-Sciama-Kibble theory of gravity naturally extends general
relativity to account for the intrinsic spin of matter. Spacetime torsion,
generated by spin of Dirac fields, induces gravitational repulsion in fermionic
matter at extremely high densities and prevents the formation of singularities.
Accordingly, the big bang is replaced by a bounce that occurred when the energy
density was on the order of (in
natural units), where is the fermion number density and is
the number of thermal degrees of freedom. If the early Universe contained only
the known standard-model particles (), then the energy density at
the big bounce was about 15 times larger than the Planck energy. The minimum
scale factor of the Universe (at the bounce) was about times smaller
than its present value, giving \approx 50 \mum. If more fermions existed in
the early Universe, then the spin-torsion coupling causes a bounce at a lower
energy and larger scale factor. Recent observations of high-energy photons from
gamma-ray bursts indicate that spacetime may behave classically even at scales
below the Planck length, supporting the classical spin-torsion mechanism of the
big bounce. Such a classical bounce prevents the matter in the contracting
Universe from reaching the conditions at which a quantum bounce could possibly
occur.Comment: 6 pages; published versio
On the anomalous large-scale flows in the Universe
Recent combined analyses of the CMB and galaxy cluster data reveal
unexpectedly large and anisotropic peculiar velocity fields at large scales. We
study cosmic models with included vorticity, acceleration and total angular
momentum of the Universe in order to understand the phenomenon. The Zeldovich
model is used to mimic the low redshift evolution of the angular momentum.
Solving coupled evolution equations of the second kind for density-contrast in
corrected Ellis-Bruni covariant and gauge-invariant formalism one can properly
normalize and evaluate integrated Sachs-Wolfe effect and peculiar velocity
field. The theoretical results compared to the observations favor a much larger
matter content of the Universe than that of the concordance model. Large-scale
flows appear anisotropic with dominant components placed in the plane
perpendicular to the axis of vorticity(rotation). The integrated Sachs-Wolfe
term has negative contribution to the CMB fluctuations for the negative
cosmological constant and it can explain the observed small power of the CMB TT
spectrum at large scales. The rate of the expansion of the Universe can be
substantially affected by the angular momentum if its magnitude is large
enough.Comment: 13 pages, 6 tables, 4 figures, 36 references; version to appear in
Eur. Phys. J.