Do the books go more into detail of the past? Like the science fiction part? That shit was like some weird, intriguing kind of timeline. Floating fucking death star up above, peasants harvesting down below. Then what was that? A tear in the veil? The veil to what? What was on the other side of that "thin" part or whatever tf they were talking about. The show has been watchable background noise, but that part of the time travel shit really got my attention.
The books go into more details, but overall you only learn very little about the Age of Legends and the ages even before that. It becomes clear as you read through the story that the world this story takes place in is our world in the far far future, the Age of Legends being our far future itself. Ancient lore that survived to the current era mention "giants fighting across the world, throwing spears of fire at one another", their names being "Merk" and "Rusk" or something, which references our age's Cold War (that might have ended differently in that spin of the Wheel).
The Age of Legends is an age of both technological and magical wonder, the Aes Sedai of the time have a mastery over weaving saidar, saidin, or both combined when working together, that can only be dreamed of by the Aes Sedai of the current era.
The floating sphere, known as the Sharom, for instance is not floating due to the One Power but with technology that uses magnetic fields. They could have used the One Power to do it, but went for science "because they could".
It is a laboratory for Mierin Sedai/future Lanfear and her colleagues to study the Pattern, which is basically the fabric of the universe. Through her experiments and studies, Mierin has discovered that this particular area is where the pattern is at its thinnest, and they have detected a "source of power" beyond. What they don't know yet is that that power is the Dark One's own, which exists in parallel to the male One Power (Saidin) and the female One Power (Saidar). The Dark One's power can be used by either sex and is known as the True Power (though it comes at a price, corrupting the body overtime).
What you see in the episode is the Aes Sedai "scientists" accidently rupturing the Pattern at that spot, effectively creating what will be known as "The Bore" which is a fissure into the Dark One's prison, where He was imprisoned, supposedly for all time, by The Creator.
This begins an era called The Downfall where many Aes Sedai are seduced by the Dark One's promises of immortality and great power, and eventually to the War of Shadow which takes place around 90 years after the accidental creation of The Bore.
At the end of the War of Shadow, the Dragon, Lews Therin Thelamon, takes a hundred male Aes Sedai, known as The Hundred Companions, to Shayol Ghul (the area where The Bore is) and attempts to seal the Dark One's prison again. It kind of works, but not entirely. The Dark One lashes back against the channelers and saidin, the male One Power, and corrupts it so it renders males mad when they channel (those become instantly insane, probably because they were channeling a lot at the time, or because they were so close to the impact).
The Chosen/Forsaken, the Dark One's strongest Aes Sedai lieutenants, are also imprisoned around The Bore, in a stasis. Some are closer to the surface and can actually barely interact with the world, while some are deeper and completely dormant. The prison's integrity is maintained by seals made of a virtually unbreakable material known as cuendillar.
The female Aes Sedai, led at the time by Latra (the one who ends up in Rhuidean creating the glass columns in the episode), refused to accompany the male Aes Sedai at Shayol Ghul, prefering other plans and a less direct approach.
The taint of saidin in turn leads to the Breaking of the World, where insane male Aes Sedai are rampant and wreaking havoc on entire countries, while the female Aes Sedai (those not corrupted) attempt to capture and gentle them or destroy them. The Dragon himself kills his family and household in his madness, and Ishamael (the Forsaken nearest to the surface and who can continue to interact with the world) briefly visits him to taunt him and gives him back his sanity so he can see what has has done. This leads to the Dragon's rage overwhelming him and effectively destroying him in a tremendous cataclysm that raises the tallest mountain in the world, Dragonmount, where Rand will be born millenia later to become the Dragon Reborn.
