Summary
We analyse the isotropization of homogeneous cosmological models including phenomenologically the contribution of vacuum polarization to the energy content of the Universe. The combined effect of dissipative processes at early epochs and of vacuum at relatively late epochs guarantees the isotropy of the Universe at large times for arbitrary initial anisotropies, provided the Universe expands forever and the vacuum has positive energy density and negative stresses with a sufficiently hard equation of state. Isotropy at the present epoch is secured by a negative deceleration parameter consistent with observation.
Riassunto
Si analizza l'isotropizzazione di modelli cosmologici omogenei includendo fenomenologicamente il contributo della polarizzazione del vuoto al contenuto energetico del-l'Universo. L'effetto combinato di fenomeni dissipativi in epoche remote e del vuoto in epoche relativamente tarde garantisce l'isotropia dell'Universo a tempi grandi per anisotropie iniziali arbitrarie, se l'Universo si espande per sempre e il vuoto ha densità d'energia positiva e sforzi negativi con equazione di stato sufficientemente «dura». L'isotropia all'epoca presente è assicurrata da un parametro di accelerazione negativo consistente coll'osservazione.
Резюме
Мы анализируем изотропизацию однородных космологических моделей, включая феноменологический вклад поляризации вакуума в величину энергии вселенной. Совместное влияние диссипативных процессов на ранних стадиях и влияние вакуума на относительно более поздних стадиях гарантирует изотропию вселенной при больших временах для произвольных начальных анизотропий, при условии, что вселенная расширяется и вакуум имеет положительную плотность энергии и отрицательные давления. Изотропия в современную эпоху обеспечивается отрицательным параметром замедления, согласующимся с наблюдениями.
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Fabbri, R. Isotropy of the universe and equation of state of vacuum. Nuov Cim B 56, 125–136 (1980). https://doi.org/10.1007/BF02738362
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DOI: https://doi.org/10.1007/BF02738362