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Ch 24: The Universe: Key Concepts & Theories

About This Chapter

Watch enlightening video lessons to learn more about the basic theories and concepts related to our universe. The short quizzes that accompany each lesson give immediate feedback about your progress.

The Universe: Key Concepts & Theories - Chapter Summary and Learning Objectives

Sometimes the terms galaxy, solar system and universe are interchanged incorrectly. This chapter clears that up for you and leads into a discussion of various models and theories that could explain our universe. Differences between the observable universe and the entire universe will also be explained.

So many considerations exist, such as various models, the age and the acceleration of the universe. Knowledgeable instructors present all of this fascinating information in short, animated video lessons to make learning fun. By the time you finish this chapter, you should feel comfortable with discussions of the following:

  • The beginnings of the universe
  • Non-baryonic matter
  • Universe expansion
  • Edge-center problem

Video Objective
Solar System, Galaxy, & Universe: Definitions & Difference Explain the differences between universe, galaxy and solar system.
Origins of the Universe: The Big Bang and Expanding & Contracting Universes Discuss the Big Bang Theory.
Evidence for the Big Bang Theory: Background Radiation, Red-Shift and Expansion Outline the evidence in support of the Big Bang Theory.
The Steady State Theory vs. the Big Bang Theory Compare the Big Bang and Steady State models of our universe.
Olbers' Paradox & Cosmic Expansion: Nature of the Universe Explain the edge-center problem, Olbers' paradox and cosmic expansion.
The Observable Universe vs. the Entire Universe Explore the differences between the entire universe and the observable universe. Understand why the entire universe can't be seen.
Photons, Particle Soup & Nucleosynthesis Explain particle soup, photons and nucleosynthesis.
The Evolution of the Early Universe Reveal the events that may have occurred as the early universe evolved.
The Cosmological Principle Explain why the Cosmological Principle is essential to our current understanding of the universe.
Three Models of the Universe: Flat, Open & Closed Detail the three existing models of our universe.
Hot & Cold Dark Matter & WIMPs Address non-baryonic matter, WIMPs, cold dark matter and hot dark matter.
Cosmic Inflation: Solving the Flatness & Horizon Problems Explain flatness and horizon problems in relation to the universe and tell how dark energy relates to each.
The Acceleration of the Universe Show how acceleration of the universe is related to scientific observations of expansion.
How to Calculate the Age of the Universe Detail how the universe began and what it looked like. Use the formula to calculate the age of the universe.
The Universe's Curvature, Age & Fate Tell how age, curvature and fate relate to our universe.

15 Lessons in Chapter 24: The Universe: Key Concepts & Theories
Solar System, Galaxy, & Universe: Definitions & Difference

1. Solar System, Galaxy, & Universe: Definitions & Difference

Want to learn what the universe, galaxy, and solar system are as well as some cool facts about each one? This lesson will give you an overview of what these three things are in a relatable fashion.

Origins of the Universe: The Big Bang and Expanding & Contracting Universes

2. Origins of the Universe: The Big Bang and Expanding & Contracting Universes

Students will learn the origins of the universe, the Big Bang theory, the timeline of the universe, how the universe is still expanding to this day, and what astronomers expect the universe to look like in the future.

Olbers' Paradox & Cosmic Expansion: Nature of the Universe

3. Olbers' Paradox & Cosmic Expansion: Nature of the Universe

Why is the night sky dark if there are so many stars in the universe? It used to be thought our universe had several properties that we now know not to be true. This lesson will explain what all that means and why the night sky isn't as bright as the sun.

The Observable Universe vs. the Entire Universe

4. The Observable Universe vs. the Entire Universe

This lesson will tie in the concepts of our observable universe, redshift, and the cosmic light horizon to explain why we cannot see the entire universe.

The Steady State Theory vs. the Big Bang Theory

5. The Steady State Theory vs. the Big Bang Theory

Did you know that the Big Bang wasn't always a well-accepted theory of our universe? There was a competing theory called the Steady State theory. Find out what it was all about and why its proponent actually helped name the Big Bang theory.

Evidence for the Big Bang Theory: Background Radiation, Red-Shift and Expansion

6. Evidence for the Big Bang Theory: Background Radiation, Red-Shift and Expansion

Discover what evidence exists to support the Big Bang theory of the birth of the universe. Learn how cosmic background radiation, the red shift of light and the ongoing expansion of the universe led scientists to believe that the universe was started with the Big Bang.

Photons, Particle Soup & Nucleosynthesis

7. Photons, Particle Soup & Nucleosynthesis

This lesson will explore what happened in the fractions of a second and minutes after the Big Bang occurred. You'll learn about matter, antimatter, photons, deuterons, positrons, and a lot more!

The Evolution of the Early Universe

8. The Evolution of the Early Universe

This lesson will describe four important stages of development in the early universe, the radiation era, recombination (decoupling) epoch, the dark age, and reionization era.

The Cosmological Principle

9. The Cosmological Principle

This lesson will dive into the famous cosmological principle by defining and explaining isotropy and homogeneity as well as their important implications for our universe.

Three Models of the Universe: Flat, Open & Closed

10. Three Models of the Universe: Flat, Open & Closed

This lesson will describe three models of the universe, including closed, open, and flat, as well as critical density and which model is most likely the correct one.

Hot & Cold Dark Matter & WIMPs

11. Hot & Cold Dark Matter & WIMPs

Neutrinos, neutralinos, axinos, gravitinos, and what the inos! Dark matter is a crazy thing and there are many different kinds of dark matter. This lesson will go over what they are and what they might be made of.

Cosmic Inflation: Solving the Flatness & Horizon Problems

12. Cosmic Inflation: Solving the Flatness & Horizon Problems

The standard Big Bang theory doesn't explain everything in our universe, namely the horizon problem and flatness problems. This lesson will explain what does, inflation, and how so.

The Acceleration of the Universe

13. The Acceleration of the Universe

The acceleration of our universe is driven by a mysterious dark energy, which can take more than one form. This dark energy helps to explain why our universe is flat.

How To Calculate the Age of the Universe

14. How To Calculate the Age of the Universe

This lesson will explain to you how old our universe is and how we calculate it thanks to the Hubble law and Hubble constant as well as one other simple equation.

The Universe's Curvature, Age & Fate

15. The Universe's Curvature, Age & Fate

What is the age of our universe? What shape does it take? What determines the fate of our universe and what is this fate? This lesson will tell you all of this and more!

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