Observational cosmology
The science of physical cosmology as it is practiced today had its subject material defined in the years following the Shapley-Curtis debate when it was determined that the universe had a larger scale than the Milky Way galaxy.
This was precipitated by observations that established the size and the dynamics of the cosmos that could be explained by Albert Einstein's General Theory of Relativity.
The publication of the observations by Slipher, Wirtz, Hubble and their colleagues and the acceptance by the theorists of their theoretical implications in light of Einstein's General theory of relativity is considered the beginning of the modern science of cosmology.
Their prediction was rediscovered by Robert Dicke and Yakov Zel'dovich in the early 1960s with the first published recognition of the CMB radiation as a detectable phenomenon appeared in a brief paper by Soviet astrophysicists A. G. Doroshkevich and Igor Novikov, in the spring of 1964.
[16] In 1965, Arno Penzias and Robert Woodrow Wilson at the Crawford Hill location of Bell Telephone Laboratories in nearby Holmdel Township, New Jersey had built a Dicke radiometer that they intended to use for radio astronomy and satellite communication experiments.
"[17] A meeting between the Princeton and Crawford Hill groups determined that the antenna temperature was indeed due to the microwave background.
For example, the observational evidence for dark matter has heavily influenced theoretical modeling of structure and galaxy formation.
When trying to calibrate the Hubble diagram with accurate supernova standard candles, observational evidence for dark energy was obtained in the late 1990s.
These observations have been incorporated into a six-parameter framework known as the Lambda-CDM model which explains the evolution of the universe in terms of its constituent material.
With the advent of automated telescopes and improvements in spectroscopes, a number of collaborations have been made to map the universe in redshift space.
The Great Wall, a vast supercluster of galaxies over 500 million light-years wide, provides a dramatic example of a large-scale structure that redshift surveys can detect.
Another notable investigation, the Sloan Digital Sky Survey (SDSS), is ongoing as of 2011[update] and aims to obtain measurements on around 100 million objects.
[33]: 8.5.1 After a lull in the 1970s caused in part by the many experimental difficulties in measuring CMB at high precision,[33]: 8.5.1 increasingly stringent limits on the anisotropy of the cosmic microwave background were set by ground-based experiments during the 1980s.
This theory of rapid spatial expansion gave an explanation for large-scale isotropy by allowing causal connection just before the epoch of last scattering.
Inspired by the initial COBE results of an extremely isotropic and homogeneous background, a series of ground- and balloon-based experiments quantified CMB anisotropies on smaller angular scales over the next decade.
