Search
- https://phys.libretexts.org/Bookshelves/College_Physics/College_Physics_1e_(OpenStax)/34%3A_Frontiers_of_Physics/34.04%3A_Dark_Matter_and_ClosureThe motion of stars in galaxies and the motion of galaxies in clusters imply that there is about 10 fold more mass as in the luminous objects we can see. The indirectly observed non-luminous matter is...The motion of stars in galaxies and the motion of galaxies in clusters imply that there is about 10 fold more mass as in the luminous objects we can see. The indirectly observed non-luminous matter is called dark matter. Why is dark matter a problem? For one thing, we do not know what it is. It may well be 90% of all matter in the universe, yet there is a possibility that it is of a completely unknown form -- a stunning discovery if verified. Dark matter has implications for particle physics.
- https://phys.libretexts.org/Bookshelves/Astronomy__Cosmology/Big_Ideas_in_Cosmology_(Coble_et_al.)/16%3A_The_Early_Universe/16.04%3A_The_BeginningYou will know that the early Universe was extremely dense and that changes happened rapidly. You will know that the Planck time is the earliest era we can probe. You will know that at the Planck time ...You will know that the early Universe was extremely dense and that changes happened rapidly. You will know that the Planck time is the earliest era we can probe. You will know that at the Planck time all four forces are thought to be unified. You will know that all of space and time were created in the beginning.
- https://phys.libretexts.org/Courses/University_of_California_Davis/Physics_156%3A_A_Cosmology_Workbook/01%3A_Workbook/1.21%3A_Hot_and_Cold_Relics_of_the_Big_BangAs the temperature and density drops, the reactions necessary to maintain chemical equilibrium can become too slow to continue to do so. This departure from equilibrium can occur while the particles a...As the temperature and density drops, the reactions necessary to maintain chemical equilibrium can become too slow to continue to do so. This departure from equilibrium can occur while the particles are relativistic, in which case we have "hot relics," or when the particles are non-relativistic in which case we say we have "cold relics." The cosmic microwave and neutrino backgrounds are hot relics. The dark matter may be a cold relic.
