Often mislabelled as simply "A Photo Of The Universe", this video investigates and explains the deeper meaning behind one of the most important images in fundamental physics and cosmology.

Discovered over 50 years ago, the Cosmic Microwave Background (CMB) radiation spectrum can be detected in every portion of space. Its presence acts as evidence in favour of the Big Bang theory and model of the origins of the Universe and effectively ended discussion on other models. The CMB is the last scattering surface of an early and opaque universe. Its inception marks the beginning of the photon epoch which leads up to present day. Before the CMB were the lepton and quark epochs, where particles behaved relativistically (travelled close to light speed) and Big Bang Nucleosynthesis (BBN) was constantly producing new particle-antiparticle pairs due to how hot and energetic the early Universe was.

The CMB acts as a cover preventing us from seeing these early times, however it also acts as a useful probe to allow scientists to test models for the composition and evolution of the Universe including Dark Energy, Dark Matter, Expansion Rate and Curvature (Geometry). It shows the Universe to be mostly homogeneous and isotropic over large scales. Its discovery led to a Nobel prize in physics and so has the work which has been conducted from analysing its properties.

0:00 - The Cosmic Microwave Background Planck Satellite Image
0:35 - History of the Discovery of the CMB
1:15 - Physical meaning, the Early Universe and Recombination
3:40 - Analogy of the Last Scattering Surface
4:31 - Redshift and Electromagnetic Microwaves
4:56 - Image Processing (Milky way interference)
5:52 - Temperature Anisotropy, Power Spectra and Universe modelling
7:10 - Review and Summary