The Big Bang Theory: Explanation and Evidence

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  • 0:04 The Beginning of Time
  • 0:56 Hubble's Law
  • 2:03 The Big Bang
  • 2:51 Quantum Physics
  • 3:35 Lesson Summary
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Lesson Transcript
Instructor: Lisa Roundy

Lisa has taught at all levels from kindergarten to college and has a master's degree in human relations.

A popular scientific theory is that our universe originated with what is known as the Big Bang. This lesson explains what the Big Bang is and the evidence that supports it. Following the lesson, you can test your newfound knowledge with a quiz!

The Beginning of Time

When we look around at our surroundings as kids, many of us wonder how everything around us came into being. Trust me: this continues on all throughout adulthood and is why we have certain scientific fields!

Rarely the knowledge of what exists is enough to satisfy us, and we want to know how and why everything exists. These aren't easy questions to answer, and we may never know the answers with absolute certainty. However, we've learned a lot about the laws of nature in our quest for this knowledge. The laws of nature govern all things in the universe from the direction and speed a ball bounces to the way the planets move in their orbits. Our increased understanding of these laws over time eventually led us to describe an event known as the Big Bang, which is the idea that the universe began at a single moment in time with an intense burst of energy.

Hubble's Law

In order to understand the Big Bang, we need to begin with the discovery that started it all. The name Edwin Hubble may sound familiar to you, probably because of the famous Hubble telescope. Hubble didn't build the telescope, but it was named after him. One thing you may not know is that the foundation for the concept of the Big Bang theory comes from one of Hubble's discoveries: Hubble found that galaxies are moving away from us! He also found that this appears to occur at speeds proportional to their distance and that it's occurring in all directions. In other words, he observed that the universe is experiencing an ongoing process of expansion. This observation has come to be known as Hubble's Law.

The idea of expansion as explained by Hubble's Law supports the idea that the universe was once compressed into a much smaller space. Hubble's Law was used to develop a new theory of the creation and expansion of the universe that eventually came to be known as the Big Bang. Over time, the Big Bang theory has been modified and adapted, and the future will likely hold more adaptations as our understanding of the universe increases.

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