5 ms·
> About 27% is dark matter—the invisible force holding galaxies and the cosmic web together—while 68% is dark energy, which causes the universe to expand at an
by tppiotrowski 5y ago
> About 27% is dark matter—the invisible force holding galaxies and the cosmic web together—while 68% is dark energy, which causes the universe to expand at an accelerated rate.
I understand that matter slows and energy accelerates the expansion of the universe but how is this ratio calculated? It seems like we would need to know the strength of dark energy to arrive at this reasoning.
- LegitShady 5y agoIt’s based on actual observations, with some assumptions on the nature of the universe. As you said - dark matter is detected by extra “holds stuff together” force than observed masses would indicate exists from a host of phenomena (find the Wikipedia article on dark matter for more detail), and dark energy which is the energy required to make the universe expand at an accelerated rate is based on on distance-redshift relation, measurements of the cosmic background radiation, and theoretical additional non matter or dark matter energy required to form an ‘observationally flat universe’. The basics for both of these are discussed on the Wikipedia for both subjects. Disclaimer - I am not a physicist but I did stay at the holiday inn express last night and I do watch a lot of PBS Spacetime on youtube.
- LegitShady 5y agocant edit but "accelerated rate" should be "accelerating rate" and "dark matter energy" should be "non dark matter energy"