Yes. Andromeda galaxy is moving towards us instead of moving away. This exception does not rule out that the galaxies are moving away. Because there is a reasonable scientific explanation behind this exception.
The Universe consists of less than 5% interactive baryonic matter, about 26% non-interactive but gravitationally interactive dark matter, and more than 68% dark energy - with an effective mass <0.
Galaxies or clusters of galaxies have zero-gravity spheres outside the gravitational influence, where there is a tug-of-war between gravity and anti-gravity, with dark energy causing antigravity. Dark energy, at least on the intergalactic scale, can only be effective in space unless such galaxies are gravitationally bound clusters, mega or superclusters.
A galaxy, gravitationally bound but not externally bound to a cluster of galaxies, will be affected by dark energy. That is, an independent galaxy or an independent cluster of galaxies will be affected by dark energy, whereas gravity will have no effect on dark energy-dominated space. Dark energy has no effect within the influence of gravity, and gravity will have no effect where dark energy dominates.
The effective mass of dark energy is much greater than the combined mass of ordinary matter and the effective mass of dark matter. So antigravity caused by dark energy overcomes gravity. Therefore, galaxies move away and the space between galaxies appears to expand.
The Milky Way and Andromeda belong to a small cluster of Local Group galaxies known as the Virgo Cluster. Since the Andromeda Galaxy is also gravitationally bound to the Milky Way Galaxy and bound to the Local Galactic Cluster, the distance between Andromeda and the Milky Way Galaxy does not increase, but rather decreases.
However, regardless of the merger of Andromeda and the Milky Way, the galactic clusters to which these galaxies belong will be overruled by dark energy in the distant future.
No comments:
Post a Comment