What is #darkmatter and #darkenergy ? Short answer : we don't Know Well , Long answer short : In the early 1990s, one thing was fairly certain about the expansion of the #universe. It might have enough energy density to stop its expansion and recollapse, it might have so little #energy density that it would never stop expanding, but gravity was certain to slow the expansion as #time went on. Granted, the slowing had not been observed, but, theoretically, the universe had to slow. The universe is full of matter and the attractive force of gravity pulls all matter together. Then came 1998 and the #Hubble #Space #Telescope (HST) observations of very distant supernovae that showed that, a long time ago, the universe was actually expanding more slowly than it is today. So the expansion of the universe has not been slowing due to #gravity , as everyone thought, it has been accelerating. No one expected this, no one knew how to explain it. But something was causing it. . We know how much dark energy there is because we know how it affects the universe's expansion. It turns out that roughly 68% of the universe is dark energy. Dark matter makes up about 27%. The rest - everything on Earth, everything ever observed with all of our instruments, all normal matter - adds up to less than 5% of the universe. . Dark matter is not than we are what it is. It is dark, meaning that it is not in the form of #stars and #planets that we see. Observations show that there is far too little visible matter in the universe to make up the 27% required by the observations. It is not in the form of dark clouds of normal matter, dark matter is not #antimatter, we can rule out large galaxy-sized black holes on the basis of how many gravitational lenses we see. . There are still a few dark matter possibilities that are viable. Baryonic matter could still make up the dark matter if it were all tied up in brown dwarfs or in small, dense chunks of heavy elements. But the most common view is that dark matter is not baryonic at all, but that it is made up of other, more exotic particles like axions or Weakly Interacting Massive particles. . . . . #science #sciencefacts #scientist #sciencetheory https://www.instagram.com/p/BvlPAUjBqtH/?utm_source=ig_tumblr_share&igshid=1hkqzbccpol2m
