The study of the origin and nature of The Universe Cosmology The study of the origin and nature of The Universe

(Space and Time included) The Big Bang Edwin Hubble observed that beyond our Local Group all things were red shifted And that the farther away they were the more they were red-shifted. That is that they are all moving away from each other. In 1931 He proposed: That originally all things (Space and Time included) were together in a single point (a singularity) that suddenly expanded and is still expanding… The Big Bang

An Experiment Hubble’s calculations showed that if he was right the radiation from the Big Bang should be found in all directions in the form of a background of micro and radio waves. For twenty years there was no confirmation and Hubble was not believed. In 1964 the cosmic background radiation was confirmed. Ironically everyone had seen it since the 1950’s… As TV “Static”

Three Possible Futures Depending on the mass of the Universe there are three possible futures for the Universe: There is a great enough amount of mass that gravity will stop and reverse the expansion resulting in The Big Crunch There is just the right amount of mass that gravity will stop the expansion but not make it collapse but stay a certain size. There is too little mass so gravity will not stop the expansion and expand forever And eventually become cold and dark, “Heat Death”

Way too little mass So Astronomers began to measure carefully both the expansion rate and the amount of mass in the Universe. The numbers didn’t come out right…the amount of observable mass was to little to account for the current expansion rate! So there must be mass that we cannot observe There must be Dark Matter!

(think than an electron) Dark Matter Dark Matter is hypothetical matter that can’t be detected by emitted radiation but who’s gravity still affects all other masses, as would anything. Dark matter is hypothetical very much in part due to its astoundingly small size. It’s particles have length scale 28 orders of magnitude smaller than the Planck length. (think than an electron) Thus they are too small to interact with light

Seeing Dark Matter We “See” Dark matter by seeing how globular clusters and dwarf galaxies orbit larger galaxies Their speed is such that there must be more mass than we can see There must be… Dark Matter