For personal purposes, I'm trying to summarize the last 14 billion years. How accurate is the following? Any thoughts welcome, thanks! Most scientists believe the universe is at least 14 billion years old based on evidence about the relative movement and expansion of galaxies and other information. And further, that at that time, all the energy in the universe was concentrated in one point which exploded in a very hot Big Bang. There is no evidence for what, if anything, existed before the Big Bang, or if the initial conditions were somehow created. The theory continues that as the universe expanded from the Big Bang point, it cooled down and gravity pulled together stars into galaxies. A star is a massive ball of hydrogen and helium (both created in the Big Bang), the two most basic chemical elements. The star fuses these two elements in a process called nuclear fusion which produces heat, light, and forges other chemical elements. As the star ages, it produces more and more heat and light, until it collapses into either a dwarf or a supernovae, and in the latter case, finally a neutron star or black hole. A supernovae expels most of its contents during an explosion. It is also so hot, that it is the source of the rest of the chemical elements, and may be the source of more complex things such as the origins or building blocks of life itself – molecules. The Earth, or The World, is the third closest of eight planets to The Sun, which together make up our solar system (which is part of the Milky Way Galaxy of solar systems). The planets orbit around the sun due to its gravity. The planets were created from molecular clouds after star formation, and coalesced due to gravity. The Earth is about 4.5 billion years old. I can't philosophically describe how life is different than an inanimate object like a rock, but many scientists consider life to be a form of chemistry leading to a self-sustaining growth and reproduction process. It is believed that life on Earth started as a self-replicating molecule about 4 billion years ago. Further, about 3.5 billion years ago, DNA was formed which was an instruction set for building the proteins of a self-replicating organism. About 3 billion years ago, photosynthesis, the production of energy from light, started, with oxygen as a by-product. A cell is the basic unit of life and encapsulates the DNA, energy production, and other things. It is believed that multi-cellular life (cells that can reproduces themselves using DNA) began on Earth about 600 million years ago. The theory of evolution states that multi-cellular life evolved into different species of organisms based on mutations and natural selection. The cambrian explosion occurred about 570 million years ago and included many new animals, particularly under water. About 475 million years ago plants appeared on land. About 200 million years ago, mammals (warm-blooded vertebrae with hair, milking females, and birthing live young) appeared on land. About 65 million years ago, primates appeared (e.g. monkeys). About 2.5 million years ago, the precursor primate to humans appeared. About 200,000 years ago, homosapiens (humans) appeared, living as hunters and gatherers (a distinct but related animal, neanderthal appeared at about the same time, but was extinct by about 30,000 years ago). About 10,000 years ago, trade, agriculture, language, and technology bloomed human societies.