The kinematics and the dynamical interpretation of cosmological expansion are reviewed in a widely accessible manner with emphasis on the acceleration aspect. Virtually all the approaches that can in principle account for the accelerated expansion of the Universe are reviewed, including dark energy as an item in the energy budget of the Universe, modified Einstein equations, and, on a fundamentally new level, the use of the holographic principle.

PACS: 04.50.Kd, 95.36.+x, 98.80.−k (all) DOI: 10.3367/UFNe.0182.201209c.0941 URL: https://ufn.ru/en/articles/2012/9/b/ 000312382200002 2-s2.0-84872102260 Citation: Bolotin Yu L, Erokhin D A, Lemets O A "Expanding Universe: slowdown or speedup?" Phys. Usp. 55 876–918 (2012) BibTexBibNote ® (generic)BibNote ® (RIS)MedlineRefWorks Received: 25th, May 2011, revised: 24th, February 2012, accepted: 13th, March 2012 Оригинал: Болотин Ю Л, Ерохин Д А, Лемец О А «Расширяющаяся Вселенная: замедление или ускорение?» УФН 182 941–986 (2012); DOI: 10.3367/UFNr.0182.201209c.0941