In 1927, an astronomer named Georges Lemaître had a great idea. He stated that a long, long time ago, the universe began as a single point; then it stretched and expanded to become as large as it is now, and that it could continue to expand. What a picture, right? Just two years later, an astronomer named Edwin Hubble noticed that the galaxies were moving away from us and that those galaxies so far away were moving faster than the galaxies closest to us.
Thus, the Big Bang theory is the main explanation for how the universe began. In its simplest form, it says that the universe as we know it began with a small singularity – that point cited by Lemaitre – that then inflated over the next 13.8 billion years to become the cosmos we know today.
Because current instruments do not allow astronomers to clearly observe the birth of the universe, much of what we understand about the Big Bang theory comes from mathematical formulas and models. However, what astronomers can see is the “echo” of the expansion through a phenomenon known as the cosmic microwave background.
The name of Big Bang comes from the fact that something so small became so big and led to such colossal elements but perhaps the most correct or adequate appreciation for what happened would be “stretching everywhere”, although it is clear that Big Bang is a lot more media and simple.
The mathematical foundations of the Big Bang theory include Albert Einstein’s general theory of relativity along with the standard theories of fundamental particles. Today, NASA spacecraft, such as the Hubble Space Telescope and the Spitzer Space Telescope, continue to measure the expansion of the universe.
While most of the astronomical community accepts the Big Bang theory as the standard for the origin of the universe, there are some theorists who have alternative explanations in addition to this, some more curious and strange than others, such as the eternal inflation theory or the of an oscillating universe.
