The Big Bang Theory



The Big Bang Theory

The Big Bang Theory is the current scientific theory that explains how the universe formed and its evolution (its change over time). Below is a brief explanation of the theory.

14 billion years ago, all matter and energy was contained in a dense,hot sphere in space. This sphere became unstable, blew up, and the contents of the sphere violently expanded outward into space. When this happened, the different types of energy formed. Also, the universal force separated into the four forces: strong nuclear, weak nuclear, electromagnetic, and gravitational.

At the same time, the smallest particles of matter formed. These particles were electrons and quarks. The force of gravity started pulling these quark particles together to form the sub-atomic particles, protons and neutrons. Each proton and neutron is made of three quarks.

Next, gravity pulled the sub-atomic particles (protons, neutrons, and electrons) together to form the first atoms. The first atoms were unstable Hydrogen and Helium atoms (the first two elements on the periodic table.) These atoms were pulled together and formed clouds of atoms called nebulae. Some of these atom clouds were unstable and exploded. Other atom clouds (nebulae) condensed, forming the first stars. The hydrogen atoms making up the stars began to fuse. When they fused, the nuclear reaction (called fusion) gave off huge amounts of heat, light, and other energy, and the stars burned bright, like our sun. The Hydrogen atoms became Helium atoms during the fusion reaction.

Over time, the first stars became old and unstable. When stars get old, they blow up in an event called a supernova. Huge amounts of energy are given off, and atoms, and sub-atomic particles are blown outward into space. Gravity pulls on the atoms and parts of atoms, and energy acts on these atoms. The result is atoms of new elements. This is how all of the elements formed, like Carbon, Boron, Sodium, Lead, etc. (FYI: The smallest particle of an element is an atom.)

These atoms were again pulled together by gravity. Atom clouds (nebulae) formed, and as the nebulae condensed, new stars, planets, and even galaxies formed. Smaller nebulae formed stars and planets. Our sun formed about 5.5 billion years ago, and our Earth formed 4.5 billion years ago, both from nebulae. Really big nebulae formed into galaxies. Remember, billions of stars and planets make up just one galaxy.

Our galaxy is the Milky Way galaxy. It has a diameter of 100,000 light years and is about 30,000 light years from top to bottom. A light year is the distance light travels at a speed of 300,000 m/s for one year. In other words, if you turned on a flashlight at one end of the Milky Way and then immediately turned it off, the light emitted would begin traveling at a speed of 300,000 m/s. It would travel 70,000 years to make it to the other end of the galaxy. Crazy, huh? And, billions of galaxies, some even bigger than the Milky Way, make up today’s universe.

Today, our sun and other stars burn because of the fusion reaction. Stars get old and blow up, and then the atoms released get recycled to form new atoms, stars, and planets. The universe is still expanding and cooling down today, and galaxies get further apart every day.

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