I have read quite different opinions about that, so can someone tell me what is the sign of the acceleration of the stars in the Universe if we accept that the center of the Universe is the beginning of the coordinate system? At least what is considered as correct finally :)

  • $\begingroup$ what center of the universe? $\endgroup$ – Yukterez Feb 18 '15 at 15:07

This is the classic misconception about the expansion of the Universe: there is no center of the Universe. The whole universe expands as one, not from a single point nowhere.

Knowing this it makes no sense speaking of the direction of an object due to the Universe. You could compare the directions of two objects in it though.

Therefore star's direction depend on where and how they where created and also the interaction with other stars and their home galaxy.

  • $\begingroup$ How does this relate to the Big Bang - didn't the Big Bang happen in the center of the Universe? Thanks $\endgroup$ – Vladi Feb 17 '15 at 12:18
  • $\begingroup$ One more thing - how the expansion of the Universe reflects on the speed of the Stars and Galaxies? $\endgroup$ – Vladi Feb 17 '15 at 12:25
  • 2
    $\begingroup$ That's the point: the Big Bang wasn't an explosion IN the universe, it was actually the Universe that went from being infinitesimally small to expand as we know it today. This expansion rate is the 'acceleration' you are looking for and it is known as the Hubble Law en.wikipedia.org/wiki/Hubble%27s_law But this is not the only 'acceleration' applied to objects in the Universe, the interactions between them are more significant. $\endgroup$ – Joan.bdm Feb 17 '15 at 12:32
  • $\begingroup$ Earth does, however have some drift relative to the cosmic microwave background radiation; about 600 kilometers per second: apod.nasa.gov/apod/ap140615.html $\endgroup$ – Wayfaring Stranger Feb 17 '15 at 15:28

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