Dark Energy & Its Discontents Peter Coles, University of Sussex BRLSI Friday 24 th April 2015 Notes by William Gaskell AMInstP Parsec is about 3 lightyears Calcium “doublet” signature on spectrum is marker used to measure Doppler shift with red/blue shifted light from galaxy/star indicaates relative velocity galaxy/star is moving away/towards us. Hubble’s law is: v=H 0 D Which describes how Universe is expanding but Hubble never wrote about it and he got his constant wrong by a factor of 10. Alexander Friedman took Einstein’s Theory of Relativity and developed a more comprehensive model from it “The Freedman Model” – or The Big Bang Model. Dark Energy is something that creates gravity but is not stuff – it’s like pressure that the vacuum of space exerts on matter. Dark Energy increases as space expands, as it is a constant like the Hubble constant, but space expands in order to spread out the energy density of matter evenly. Photosphere is t...
Philosophical musings on a roller-coaster ride.