big bang

Our galaxy is a small part of this vast universe. But have you ever wondered how this universe came into existence?

The origin of the universe is the origin of everything. Multiple scientific theories plus creation myths from around the world have tried to explain its mysterious genesis. However, the most widely accepted explanation is the Big Bang theory.

Most astronomers believe the Universe began in a Big Bang about 14 billion years ago. At that time, the entire Universe was inside a very tiny hot point that was thousands of times smaller than a pinhead. It was hotter and denser than anything we can imagine. This point slowly burst to create the universe.  

Time, space, and matter all began with the Big Bang. Under conditions of extreme heat, all the matter, and energy that make up the universe spread out to create space. And it kept on growing at a fantastic rate. It is still expanding today. As the Universe expanded and cooled, the energy changed into particles of matter and antimatter. These two opposite types of particles largely destroyed each other. But some matter survived. More stable particles called protons and neutrons started to form when the Universe was one second old.

Over the next three minutes, the temperature dropped below 1 billion degrees Celsius. It was now cool enough for the protons and neutrons to come together, forming hydrogen and helium nuclei. Atomic nuclei could finally capture electrons to form atoms. The Universe filled with clouds of hydrogen and helium gas. Those atoms later formed stars, which led to the creation of planets.

Big Bang events occurred in the following order: 

1. Big Bang beginning – universe began with a singularity — a point of infinite density and temperature.
2. Planck Era - initial energy (all four forces gravity, nuclear strong force, nuclear weak force, and electromagnetic force are unified)
3. Elementary Particles – photons create particles and antiparticles 
4. Inflation of the Universe 
5. Four Forces become distinct (strong, weak, electromagnetic, and gravity) 
6. Protons, Neutrons, Electrons formed.  
7. Hydrogen ions fusion into helium ions 
8. Stable, Neutral Atoms formed
9. Stars, stellar systems, galaxies formed
10. Life, Humans, today

What evidence is there to support the Big Bang theory?

Two major scientific discoveries provide strong support for the Big Bang theory:

• Hubble’s discovery in the 1920s of a relationship between a galaxy’s distance from Earth and its speed. Hubble’s law allowed astronomers to calculate how long ago galaxies started moving apart, which provides an estimate of when the Big Bang occurred and how old the Universe is.
• The discovery in the 1960s of cosmic microwave background radiation. The cosmic microwave background (CMB) is thought to be leftover radiation from the Big bang or the time when the universe began. When the universe was born it underwent rapid inflation and expansion, the CMB represents the heat leftover from the Big Bang.