SEA: Space Exploration & Astronomy

Supervoids are the enormous, empty spaces between galaxy clusters and galaxy filaments. But just because they are empty, doesn't mean they can't be filled with fascinating science! They have taught us a great deal about both galaxy structures in the early universe, and how they grow in the present. And today we'll be venturing into a few of the biggest!

MUSIC:
- Long Walks [Emily A Sprague] - YouTube Audio Library
- Fairy Meeting [Emily A Sprague] - YouTube Audio Library
- A Slow Dream [Emily A Sprague] - YouTube Audio Library
- Devoid [ELPHNT] - YouTube Audio Library
- Rain Cloud Music [Emily A Sprague] - YouTube Audio Library

CHAPTERS:
00:00: Emptiness in Space
02:04: Defining a Void
03:52: Mapping Voids Around Us
04:38: How Voids Form
07:05: The Bootes Void
09:16: Voids and Dark Energy
10:33: The Cold Spot
12:10: The KBC Void

Quasars are the brightest phenomenon in the entire universe, able to outshine any type of star, and even entire galaxies containing hundreds of billions of them. They are the product of monster black holes at the centres of large galaxies, and so when we find multi-billion light year clusters of quasars dotted around the early universe, we are forced to reconsider some of our most fundamental assumptions of cosmology.

BACKGROUND MUSIC:
- Cylinder One - Chris Zabriskie
- Descent - The Tower of Light (YT Audio Library)
- Dreaming Blue - Sextile (YT Audio Library)
- Turn - The Tower of Light (YT Audio Library)
- There Are Many Different Kinds of Love - Chris Zabriskie
- Retro Dreamscape - Twin Musicom (YT Audio Library)
- Flecks of Light - The Tower of Light (YT Audio Library)
- Clouded - Public Memory (YT Audio Library)
- Trickling Up - Godmode (YT Audio Library)

Songs by Chris Zabriskie are licensed under Creative Commons 4.0 Licence:
- Artist: http://chriszabriskie.com/
- Source: http://chriszabriskie.com/cylinders/

00:00: Introduction
02:00: What is a Quasar?
09:46: The Peak Quasar Epoch
11:50: The Search for Quasars
20:39: Large Quasar Groups
22:15: Cosmic Structures & the Cosmological Principle
24:35: The Largest LQGs
27:34: Seeing Patterns In Noise

Stars come in a wide range of sizes, but how do we calculate a star's size to determine which is the largest? In this episode, we will find out how stars are measured to determine their mind-boggling sizes, and above all, which of them are the biggest of all.
PLEASE NOTE: This one is an older video of mine, back in 2021 when it was thought that the largest known star was Stephenson 2-18. It has since been reassessed as most likely not a member of the Stephenson-2 Cluster, and thus not amongst the candidates for the largest star. I plan to remake this video some time in 2026.

SOUNDTRACK:
Two songs in this video were made by Chris Zabriskie. (http://chriszabriskie.com/)
- Abandon Babylon (Album from which the songs came: https://chriszabriskie.bandcamp.com/album/abandon-babylon)Dark Fog & Ice Demon by Kevin MacLeod are both licensed under a Creative Commons Attribution 4.0 licence.
Source: http://incompetech.com/music/royalty-free/index.html?isrc=USUAN1300031 , http://incompetech.com/music/royalty-free/index.html?isrc=USUAN1200061
Artist: http://incompetech.com/
All other music provided by the YouTube Audio Library
CHAPTERS:
00:00: Introduction
01:04: What Are Stars?
05:40: How Stars Get Big
09:38: Problems with Direct Measurements
11:31: Parallax
13:01: Indirectly Measuring Stars
15:33: VY Canis Majoris
18:30: UY Scuti
22:59: Stephenson 2-18

No matter where you are, you are always moving. The Earth orbits the sun, while the sun moves round the galaxy. But what makes the galaxy move? That is the topic of our video today. Everything in our local galaxy supercluster, Laniakea, is being dragged towards a high concentration of mass obscured by the opaque clouds of our galaxy, but what is it? It has all the ingredients for an epic cosmic mystery, the mystery of the Great Attractor.

Background Songs by CO.AG Music: https://www.youtube.com/channel/UCcavSftXHgxLBWwLDm_bNvA
Transcending Ambient Chill Out Music: https://www.youtube.com/watch?v=aAp5ecwlU7MThe Deep: https://www.youtube.com/watch?v=e9TJrLeqnhw

All other tracks are from the YouTube Audio Library

CHAPTERS:
00:00: Introduction
02:13: Galaxies
04:04: Our Local Universe
06:56: The Laniakea Supercluster
09:00: The Great Attractor
10:03: The Zone of Avoidance
11:45: History of Great Attractor Observations
13:56: Surveying the Great Attractor Region
18:39: Dark Flow
20:27: The Dipole Repeller
22:16: CIZA Search
23:37: The Shapley Supercluster
26:03: The Vela Supercluster
27:30: A Mystery Solved?

How large is the universe? Where does it begin and end? How does it expand? These are some of the biggest questions of astronomy- and while humanity is so small that we may never be able to fully understand the universe's true scale, advancements in technology are helping us to look ever-deeper into space, towards the edge of our observable universe known as the Cosmic Horizon. Today, we will get to know our universe, its laws, and its awe-inspiring scale above all.

SOUNDTRACK:
Special thanks to Lombus, who allowed me to use his song Doppler Shores in the title screen:
https://lombus.bandcamp.com/track/doppler-shores

Songs by Chris Zabriskie are licensed under a Creative Commons Attribution 4.0 licence (https://creativecommons.org/licenses/by/4.0/ )
- The Theatrical Poster...: http://chriszabriskie.com/vendaface/
- Unfoldment, Revealment... http://chriszabriskie.com/reappear/
- Cylinder Five: http://chriszabriskie.com/cylinders/
- Take Off and Shoot a Zero: http://chriszabriskie.com/stuntisland/
- Oxygen Garden: http://chriszabriskie.com/divider/
Artist: http://chriszabriskie.com/
Other songs are from the YouTube Audio Library

CHAPTERS:
(00:00) Introduction
(02:23) Defining the Universe
(06:51) The Big Bang
(09:12) The Observable Universe
(10:53) The Hubble Telescope
(11:46) The Hubble Deep Field
(16:49) Cosmic Expansion
(19:40) Redshift
(21:48) The Cosmic Horizon and the Unobservable Universe
(25:36) Accelerating Expansion
(28:29) Dark Energy
(30:14) The End of the Universe