Year: 2022

EARLY UNIVERSE. “For significant periods of time the density of the Universe is dominated by a single component. Therefore it’s instructive to initially consider the evolution of simple, single component, flat universes.” https://lnkd.in/e6ifiQMn View in LinkedIn

PHOTONS EXCEED BARYONS. “The present day photon number density is nγ,0 = 4.1×10(8) m(-3), which is roughly nine orders of magnitude greater than the present day baryon number density; the fact that there is a huge number of photons for every baryon has consequences for the thermal history of the Universe.” https://lnkd.in/e6ifiQMn View in LinkedIn

“We live in a universe which is very close to flat, the curvature density is hence small and it never dominates.” https://lnkd.in/e6ifiQMn View in LinkedIn

ALMOST FORGOTTEN. “In the upper reaches of pleasure and on the boundary of fear is a little studied emotion – awe.” https://lnkd.in/ew43YnMu View in LinkedIn

Hubble shot of giant gas and dust clouds that eventually coalesce into stars. https://lnkd.in/eWq3Y_st View in LinkedIn

“FIGURE 1: Evolution of the log of the density of the universe, ε, with the log of the scale factor, a. The universe starts off radiation dominated (red line), becomes matter dominated (blue) and then at late times is dominated by the cosmological constant (burgundy).” https://lnkd.in/e6ifiQMn View in LinkedIn

ORIGIN OF MATTER. “(Big Bang) Nucleosynthesis is the synthesis of the nuclei of the light elements (Deuterium, D, Helium-3, 3He, Helium-4, 4He, and Lithium-7, 7Li) when the Universe was seconds to minutes old.” https://lnkd.in/e6ifiQMn View in LinkedIn

Proton + Neutron. “The subsequent production of the nuclei of the light elements occurs via a chain of reactions: p+n → D, D+p → 3He, D+D → 4He.” https://lnkd.in/e6ifiQMn View in LinkedIn

Early cosmos. “The Universe is composed of nuclei and electrons, and photons scatter frequently off these charged particles. As the Universe expands and cools the energy of the photons drops and atoms form. This process is known as recombination and occurs at t ∼ 0.25 Myr.” https://lnkd.in/e6ifiQMn View in LinkedIn

A LITTLE LATER. “The Universe becomes neutral and photons stop scattering and subsequently free-stream through the Universe. This process is known as decoupling and occurs at t ∼ 0.37Myr. The resulting Cosmic Microwave Background has a black body spectrum with present day temperature.” https://lnkd.in/e6ifiQMn View in LinkedIn