Homogeneity, Isotropy and the Cosmological Principle

The Universe on the largest scales is both homogenous and isotropic. What this means, and how we know it, are the subject of this video. I also chat about some of the philosophical implications of this amazing idea, plus adding in a couple personal biases.

This is the third of the videos in my new series of Cosmology. I'm going through Dr. Barbara Ryden's textbook "Introduction to Cosmology". If you follow along, you'll get a full upper-division undergraduate course in Cosmology. I used this textbook at William Paterson University.

This course will cover the current state of the science of Cosmology. To follow along, it'll be a good idea for you to ge to know your calculus. Here are the topics of this video:

Introductory Cosmology
Chapter 02: Fundamental Observations
Section 02: The Universe is Isotropic and Homogeneous

Some things covered:
What are homogeneity and isotropy?
How can we measure them?
How does the Cosmic Microwave Background apply to this?
What does the Hubble Deep Field Survey add?
What does this mean for the laws of physics?
Why are we alone in the local universe?


Join this channel to get access to perks:

[travischilders]

Absolutely top tier lecture! My favorite YT channel right now.

[astronomy-channel]

Broad ranging- from the nature of the universe, to the birth of nature. Philosophy meets science. Jason you’re a content machine!

[scottbruner]

Hello professor Kendall,
I showed up to the “wrong” lecture hall again.
You are seriously making me want to take an astronomy course, even at my age of 49….

[astronomy-channel]

From the nature of the universe to the birth of nature. Philosophy meets science. Jason, you’re a content machine!

[KF]

Hello from within 200Mpc of this broadcast!

[memoredspectrum]

@Jason Kendall Thank you for explaining some things for me, so much to learn more

[Singe]

First! - This is a fundamental comment of the cosmos.

[Truth_Teller_]

Homogeneity? Do you really want to assume the universe's gender preference and pronouns? Maybe they/them identifies as chaotic.

Serious question: why do radio galaxies play such lousy music?

This channel is the best.

[DrDeuteron]

I just want to protest the megaparsec. I mean well all know the age of universe, and speaking in Mly and Gly just seems more natural. And while the light year is a unit tied to the 🌏, it is in a natural way. The parsec is also tied to the 🌏, it also involves a man made unit, the arcsecond. I guess the only truly natural unit of time is one over the Hubble constant…