PHYSICS S6 UNIT 14: COSMOLOGY, GALAXIES AND EXPANSION OF UNIVERSE.
About Course
The course Unit 14: Cosmology, Galaxies, and Expansion of the Universe is a capstone unit in astrophysics that explores the largest structures in the cosmos—galaxies—and the ultimate history, structure, and fate of the entire Universe.
You will learn about the observational evidence that supports the Big Bang Theory and the fundamental physical laws governing the Universe’s evolution.
- The Expanding Universe and Cosmology
This section deals with the global properties of the Universe and its origins.
- The Big Bang Theory: You’ll study the evidence and timeline of the Big Bang, starting from the earliest moments and tracing the evolution of the Universe.
- Hubble’s Law and Expansion: You will learn about Edwin Hubble’s foundational discovery that galaxies are moving away from us at a speed proportional to their distance. This relationship, Hubble’s Law, is the primary evidence for the expansion of space itself:
v = H0d
where v is the recession velocity, d is the distance, and H0 is the Hubble constant.
- Cosmological Redshift: You’ll understand how the expansion of space stretches light waves, causing light from distant galaxies to be shifted toward the red end of the spectrum (redshift). You’ll distinguish this from the local Doppler effect.
- Cosmic Microwave Background (CMB): This is a crucial piece of evidence. You will study the CMB as the faint, uniform afterglow radiation from the hot, early Universe, and learn how its slight temperature fluctuations provide seeds for later structure formation.
- The Content and Structure of the Universe
You will delve into the major constituents of the cosmos that determine its fate.
- The Universe’s Composition: You will learn that the observable Universe is composed of only about 5% normal matter. The remaining majority consists of mysterious components:
- Dark Matter: Evidence for this unseen matter comes from galaxy rotation curves and galaxy clusters. You will explore its role in providing the gravitational scaffolding for large-scale structure formation.
- Dark Energy: This is the mysterious force responsible for the accelerating expansion of the Universe, a discovery made through observations of distant supernovae.
- Large-Scale Structure: You will learn how gravity organized matter into the cosmic web—a massive structure of filaments, sheets, and voids—which contains galaxy clusters and superclusters.
III. Galaxies: Classification and Our Place
This section focuses on the structure and evolution of the star-filled building blocks of the cosmos.
- Galaxy Types: You’ll learn the Hubble Classification System (the “tuning fork” diagram) and classify galaxies based on their morphology:
- Spiral Galaxies (like the Milky Way)
- Elliptical Galaxies
- Irregular Galaxies
- The Milky Way: You will study the structure of our own galaxy, including its central bulge, disk, halo, and the location of our Solar System within it.
- Galaxy Evolution: You will learn about how galaxies form and evolve, including processes like galaxy mergers and the role of supermassive black holes found at the center of most massive galaxies (including our own).
Course Content
GALAXIES AND CLUSTERS.
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The structure of the Milky Way Galaxy
22:14 -
Types of galaxies
11:48 -
Checking my Progress
33:13
COSMOLOGY
END OF UNIT ASSESSMENT
GENERAL TEST UNIT. PASSMARK 80%
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