3 ms·

What observations differ from general relativity?

• pdonis 6y ago
  Observed galaxy rotation curves (the speed of rotation of stars around the galaxy's center as a function of distance from the center) cannot be accounted for using GR and the observed distribution of visible matter in the galaxies. You need to postulate some extra matter that is not visible ("dark matter") to account for the observed rotation curves using GR. That is the discrepancy that originally prompted physicists to postulate dark matter. Since then the same postulate has also been used to improve the match between theory and observation in other areas, notably our model of how the early universe evolved.
• Beldin 6y ago
  For a start: the speed at which stars rotate around the center of a galaxy. This should be due to gravity, yet the speed of stars further from the center isn't slower (as it should be). This holds true for the vast majority of galaxies. A specific amount of extra (not yet observed) mass distributed in the right way throughout the galaxy could explain this.