Lecture 9 Flashcards
what is the general cosmic structure
patterns of large empty regions called voids, small massive regions which are galaxies and galaxy clusters
how did the universes structure grow
initially homogeneous, same density everywhere, small variations only
over lifetime it developed into huge variations
what is the CMB
baby photo of the universe, shows cosmic structure 300k years after big bang
what is the CMB structure
hot spots are empty regions
structures visible are seeds of galaxies
still almost the same everywhere
how is the cmb measured? influence?
temp fluctuations are measured, variations in blobs of different sizes
provides measurements of contents physics and geometry of early universe
any theory of universe must confront these observations
what is the inflation part of the universes development
hypothetical period where the universe may have grown rapidly, from the size of an atom to light years across in less than a second
what energy source could have fuelled inflation
one or more energy fields going through a transition and releasing energy, nature of energy field is unknown as it is hypothetical
if real, could be happening at other points of the universe right now
what problems can inflation answer
CMB being gaussian, uniform and why the universe isn’t curved
why could the CMB be perfectly gaussian
quantum fluctuations are gaussian but small, inflation could blow these up
what is the horizon
maximum distance you can see from there, changes with time
issue with CMB temp and how inflation fixes
CMB temperature only varies a tiny amount. horizon size when cmb was formed was much smaller
how did this synchronise?
no information could travel between patches even at speed of light
inflation took a tiny region in thermal equilibrium and expanded it
what shape is the universe
flat
inflations relation to the shape of the universe
inflation forces flatness
as space enlarges quickly, it gets closer and closer to flat
pre inflation curve would be flattened and only detectable on scales larger than horizon
current status of whether inflation happened or not
not concrete but some substantial evidence
more plausible than other current descriptions of early universe
