Comment Re:That's a pretty bold statement... (Score 1) 346
This has been attempted as an explanation for dark matter, namely that the effects of gravity are different over large distances. It is called modified newtonian dynamics (MOND). The problem is that this theory is not consistent over a range of scales, if you tweak it to work on galaxy scales, it can't work on scales that contain clusters of galaxies for instance. Both galaxies (rotation curves) and clusters (virial equilibrium arguments) show evidence of dark matter.
Dark energy evidence exists not simply from SNIa arguments as described by other posters here, but from simply the CMB alone, which indicates that the universe has flat geometry, but has only a small amount of mass. Flatness can be achieved then only by an additional "dark energy" contribution. The evidence is quite strong that there is an additional source of energy in the universe in large amounts which goes up with the scale of the universe during expansion.
CMB data also indicate that very little of the mass in the universe is baryonic, thus requiring dark matter. This is confirmed by the theory of big bang nucleosynthesis, which relies on completely different observations of the abundance of light elements in the universe and the measured ratio of protons to neutrons.
Dark energy evidence exists not simply from SNIa arguments as described by other posters here, but from simply the CMB alone, which indicates that the universe has flat geometry, but has only a small amount of mass. Flatness can be achieved then only by an additional "dark energy" contribution. The evidence is quite strong that there is an additional source of energy in the universe in large amounts which goes up with the scale of the universe during expansion.
CMB data also indicate that very little of the mass in the universe is baryonic, thus requiring dark matter. This is confirmed by the theory of big bang nucleosynthesis, which relies on completely different observations of the abundance of light elements in the universe and the measured ratio of protons to neutrons.
