Table of Contents
Journal of Gravity
Volume 2015 (2015), Article ID 384673, 4 pages
Research Article

The Energy Conservation in Our Universe and the Pressureless Dark Energy

Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong

Received 5 May 2015; Revised 25 June 2015; Accepted 25 June 2015

Academic Editor: Kazuharu Bamba

Copyright © 2015 Man Ho Chan. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Recent observations confirm that a certain amount of unknown dark energy exists in our universe so that the current expansion of our universe is accelerating. It is commonly believed that the pressure of the dark energy is negative and the density of the dark energy is almost a constant throughout the universe expansion. In this paper, we show that the law of energy conservation in our universe has to be modified because more vacuum energy is gained due to the universe expansion. As a result, the pressure of dark energy would be zero if the total energy of our universe is increasing. This pressureless dark energy model basically agrees with the current observational results.