A really brief history of time

   The Big Bang is a theory about the creation of the Universe. The word theory does not imply that it's something Steven Spielberg thought of one lazy afternoon, but a collection of many ideas that scientists have been working on since ancient Greece... and while some things are still far from settled, it's generally considered a pretty awesome approximation of our Universe.

   The idea is that the Universe has expanded from a primordial hot and dense initial condition about 14 billion years ago. This cataclysmic expansion created all space, matter and time that we see in the universe today. A millionth of a second later (!), the universe was less dense and less hot, so the forces of nature become distinct (gravity, strong nuclear force, electromagnetism and weak nuclear force).

   One second later, elementary particles start to form (electrons, quarks, photons, etc.) and they smash together to produce protons and neutrons which come together to form hydrogen and helium... the simplest elements.

   Fast forward to 5 billion years ago, a small corner in our galaxy is filled with gas, dust and rocks which comes together by the force of gravity, getting increasingly hotter and denser until the pressure in the center is so extreme that hydrogen atoms fuse together, releasing huge amounts of energy and creating a star (our Sun). The dust and rocks that were further out eventually clump together with gravity and form planets.

   The earth finally cools and 3.8 billion years ago, microscopic life begins to evolve. For almost 3 billion years, all life is made up of single celled organisms, but suddenly multi-cellular structures appear that form complex organisms (algae, jelly fish, giant scorpion things etc).

   The first mammals evolve 200 million years ago, probably from reptiles... but they keep a pretty low profile until a 10km-wide asteroid (or comet) traveling at around 24000km/h slams into earth and kills all dinosaur species apart from birds. Mammals start evolving into a wide variety of families, like the primates, the family from which Homo Sapiens (yes you!) finally evolves around 600,000 years ago.

   Well.. squeezing 14 billion years of history in this blog article was fun. I would be glad to answer any questions you have, but if you have some time to spare I recommend watching Beyond the Big Bang, a documentary from the series The Universe, which not only explains the big bang model but also how great scientists built this theory piece by piece throughout the ages. It's a playlist on youtube so you can just autoplay all and chill!