This video series was used at William Paterson University and CUNY Hunter in online classes as well as to supplement in-person course material. Notes and links are present in the videos at the start of each lecture. 0:00:01 - Cosmic Homogeneity and Isotropy 0:32:18 - The Big Bang 1:23:44 - Why Does Cosmic Expansion Cause Redshift? 1:40:43 - The Cosmic Microwave Background. CP check. 27:38 – 28:24 2:41:44 - The First Three Minutes of the Universe 3:34:11 - Formation of Large-Scale Structure in the Universe 4:21:47 - Cosmic Inflation 5:28:37 - Dark Energy, Supernovae and the Ultimate Fate of the Universe The Universe on the largest scales is very self-similar. It looks about the same no matter which way you look, and it’s also made up of the same stuff pretty much everywhere. This leads us to the Cosmological Principle which codifies this isotropy and homogeneity, which asserts that the universe has the same physical laws everywhere. Next, we run the clock backwards in time, and we see how, using the fundamental principles of classical physics, especially thermodynamics, that the universe was smaller and hotter ago. We see exactly what we mean by the Big Bang, and what it covers and what it does not cover. The Standard Hot Big Bang basically is a story from only about the first few billionths of a second until today. It’s just amazing what exactly we can do with classical physics and elementary general relativity. Frequently, people don't understand why expansion means that light gets redshifted. Here I link the two ideas. What causes the redshift of light, how do represent it mathematically? What exactly gets stretched? Everything is a measurable, and redshift is one of those things. As part of this, we study the expansion in great detail, outlining the Robertson Walker Metric, a solution to the Einstein Field Equations of General Relativity. The discovery of the Cosmic Microwave Background is regarded as one of the most important of all science, as it is relic radiation from its early hot, dense epochs. We see that it was a key prediction of the Big Bang, which was discovered by accident by Penzias and Wilson. By studying the microwave sky in detail, the COBE, WMAP and Planck probes of NASA and ESA have shown us that the CMB is a perfect blackbody, at the temperature 2.7 Kelvin. When we study the tiny fluctuations and anisotropies away from this near-perfect spectrum, we find that we can learn what the universe was like when it was roughly 350,000 years old. We we watch atoms combine together for the first time, letting light slip free to come to us 13.6 billion years later. This observation alone is proof of the Big Bang. Overall, the segment emphasizes clear definitions, underlying geometry, and practical observing guidance so viewers can connect the concept to the real sky.