Astronomy 1021 Lecture Notes - Lecture 21: Nuclear Fusion, Horizon Problem, Fundamental Interaction

• School: Western University
• Department: Astronomy
• Course: Astronomy 1021
• Professor: Robert Cockcroft

Document Summary

Prior to ~1926, scientific consensus was that the milky way galaxy was the entire universe. Hubble showed that the nebulae were actually galaxies external to the milky way. Galaxies all look to be moving away from us. Expanding universe leads to idea of big bang. Big bang was not at a specific point in space. The scientific theory that the entire universe started from an incredibly tuny, hot and dense collection of matter and radiation that evolved following well- known and tested laws of physics. Proposed "hypothesis of the primeval atom or the cosmic egg. Predicted the proportions of elements in the universe. The cmb radiation"s "surface of last scattering" is analogous to the light coming through the clouds to out eye on a cloudy day. Early universe was full of particles and radiation. Even earlier: so hot that matter could transform into light and vice verse via. However, antimatter only observed naturally in small quantities.