AST 105 1st Edition Lecture 22 Outline of Previous Lecture (#22 from 4/9)I. Cosmology II. Cosmological Red Shift III. Age of the UniverseOutline of Current Lecture (#23 from 4/14)Topic: Big Bang TheoryI. EvidenceII. Original Theory’s Problem a. “the horizon problem”III. Inflation Big Bang Theory - If we go back about 14 billion years, the universe began as a small, dense region, of compressed energy - The outward explosion is known as the Big Bang.Evidence for the Big Bang Theory - About a second after the big bang, space was filled w/ electromagnetic radiation The dominant wave length was about 10-14 meters (gamma rays)- Universe was at a temp. of about 1012 K- For the past 14 billion years the universe has been expanding Thus radiation (EM, gamma rays) has been cosmologically red shifted to a wavelength of about 1 mm (microwaves)- 1965- Penzias and Wilson detected this 1 mm signal cosmic microwave background radiation (CMBR) first piece of evidence in support of Big Bang Theory The Problem of the Original Big Bang Theory - the CMBR is perfectly isotropic the intensity is the same in all directions o this was a problem because “How can locations that are not causally (have same temp) connected have the same temperature? These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- The original Big Bang Theory predicted that when the CMBR was emitted, the universe was suchthat the cosmic horizon distance was less than the distance across the universe. - “Regions A and B the same temp., but never could’ve been.” the horizon problem - CHD defines volume of causally connected locations Inflation - The horizon problem was solved by Alan Guth in the late 1980’s: inflation period Universe in very rapid expansion o Rapid expansion Big Bang Inflation - A and B are causally connected same temp.- Today, the Big Bang Theory includes inflation. The inflation aspect now built in with horizon problem
View Full Document
Unlocking...