L12 the dark sector/dark energy

fate of the universe depends on

abundances of matter and dark energy

if the universe has more dark matter than we currently think, its estimated age would be

smaller

if the universe has more dark energy than we currently think, its estimated age would be

larger

standard candle

a type 1a; it always explodes in the same way, so we can figure out how far away it is or the surface area of its surrounding sphere by measuring its apparent brightness

cosmological redshift

direct measure of space’s growth in the time since light was emitted - apparent wavelength vs known wavelength from a long time ago

we can measure expansion history of universe using

supernovae 1a and the redshifted wavelengths of their known emission lines

plotting supernovae data of the growth of space time fits the 

accelerating model best

since measurement of CMB indicate that the universe has a flat geometry, the remaining mass-energy needs to be filled out by

dark energy

while gravity is an attractive force and resists the universe’s expansion, dark energy

is repulsive and speeds it up; it dominates now