Major Spoilers for all Expansions - Some general things I didn't understand

[Alleluia]

If we're on the topic of things we still don't understand:

1. Are Darkness and Light elements, just as Lightning, Water etc. are? If so, what's an example of Astral Light and Umbral Darkness?

2. There are three types of aether in a person, it seems: corporeal, soul, and memory. Can you create more memory aether by making more memories, thus a longer life adds more to the lifestream than it took when it dies?

2a. Could this have been how the overall amount of aether was supposed to grow and increase in the original ancients' plan to "raise up life to harvest for Zodiark"? Cus the lifestream seems to be a closed system. Since the aether present on Etherys post-final days came from Zodiark in the first place (he'd restored life to the world), where else would you get the extra you'd need to sacrifice back to him to get something new? If you aren't adding new aether somehow, then you're just shuffling the same finite amount about, and if that's it then you'd have to give up part of the planet's ability to sustain life for that second sacrifice no matter what. Cus you are just sacrificing back part of the aether he gave you to fix it in the first place. If no new aether is found or created, equivalent exchange (and thermodynamics) isn't respected and that does my head in. lol

[Eloah]

1. Are Darkness and Light elements, just as Lightning, Water etc. are? If so, what's an example of Astral Light and Umbral Darkness?

Light and Darkness are both aspects and elements simultaneously. The way I like to describe them is by comparing them to adverbs. They are modifiers, but can act as what is being modified as well.

Also, it should be noted that Light is naturally Umbral aspected, and Darkness naturally Astral aspected. A good example of the reverse, Astral Light and Umbral Darkness can be found on the First and the Thirteenth, as it was those aspects that caused their respective floods.

[Alleluia]

Light and Darkness are both aspects and elements simultaneously. The way I like to describe them is by comparing them to adverbs. They are modifiers, but can act as what is being modified as well.

Also, it should be noted that Light is naturally Umbral aspected, and Darkness naturally Astral aspected. A good example of the reverse, Astral Light and Umbral Darkness can be found on the First and the Thirteenth, as it was those aspects that caused their respective floods.

The first part, I can get behind. The second, I don't understand. The flood of light was astral and yet it left everything it touched in stasis, which we're told is the umbral quality. So... it was an astral flood of umbral light??? Same for the flood of darkness. It left everything it touched in a state of overactivity that ate away all free aether (and apparently merged the lifestream with the physical world leading to undeath). Heightened activity is astral.

Maybe there just isn't really an astral or umbral aspect of light and dark, respectively.

[Eloah]

The first part, I can get behind. The second, I don't understand. The flood of light was astral and yet it left everything it touched in stasis, which we're told is the umbral quality. So... it was an astral flood of umbral light??? Same for the flood of darkness. It left everything it touched in a state of overactivity that ate away all free aether (and apparently merged the lifestream with the physical world leading to undeath). Heightened activity is astral.

Maybe there just isn't really an astral or umbral aspect of light and dark, respectively.

I'll try to explain this as best as I can, because, while it makes sense in my head, the words always feel odd while trying to explain.

Okay, to start, most people are aware that Light and Umbral represent passivity, while Darkness and Astral represent activity. And as elements Light represents the concept of stasis while Darkness embodies change. Those concepts when polarized into either Astral or Umbral then become stability or stagnation or chaos or advancement.

But, since each element naturally aligns to one of the aspects, that means that the opposite aspect is the "bad" one. So Astral Light is stagnation and Umbral Darkness is chaos. It semi makes sense. With stagnation, you are "actively" keeping things at a standstill, preventing anything from occurring at all. With chaos it's the opposite, you are passively letting things happen without a guiding hand, which can lead to natural disasters.

Hopefully, that helps explain things a bit. Like I said, it makes sense in my head, but I'm never sure if I'm explaining it right.

[JepMZ]

The first part, I can get behind. The second, I don't understand. The flood of light was astral and yet it left everything it touched in stasis, which we're told is the umbral quality. So... it was an astral flood of umbral light??? Same for the flood of darkness. It left everything it touched in a state of overactivity that ate away all free aether (and apparently merged the lifestream with the physical world leading to undeath). Heightened activity is astral.

Maybe there just isn't really an astral or umbral aspect of light and dark, respectively.

There's some confusion here. Light is always astral. And darkness is always umbral. It's never the opposite. The devs originally stated astral is activity and darkness is passiveness, but this concept has never been brought up or mentioned in game ever before ShB. It did have me theorize the 7th umbral is light aspected. ShB gave a "plot twist", that Eorzean got the properties of light and darkness wrong all along. But it literally changes nothing of any mentions of darkness and light in the entirety of the game because they never before used polarity concept for anything. It literally doesn't matter if light is active energy or static energy before. Now we have an in-game mention for the first time that Light is passive and Darkness is activity. The "plot twist" isn't gonna be a real plot twist for most people because they wouldn't heard the devs' old explanations in the first place. It's only in ShB and forward they use polarity for in-game phenomenon.

[Cilia]

If we're on the topic of things we still don't understand:

1. Are Darkness and Light elements, just as Lightning, Water etc. are? If so, what's an example of Astral Light and Umbral Darkness?

2. There are three types of aether in a person, it seems: corporeal, soul, and memory. Can you create more memory aether by making more memories, thus a longer life adds more to the lifestream than it took when it dies?

2a. Could this have been how the overall amount of aether was supposed to grow and increase in the original ancients' plan to "raise up life to harvest for Zodiark"? Cus the lifestream seems to be a closed system. Since the aether present on Etherys post-final days came from Zodiark in the first place (he'd restored life to the world), where else would you get the extra you'd need to sacrifice back to him to get something new? If you aren't adding new aether somehow, then you're just shuffling the same finite amount about, and if that's it then you'd have to give up part of the planet's ability to sustain life for that second sacrifice no matter what. Cus you are just sacrificing back part of the aether he gave you to fix it in the first place. If no new aether is found or created, equivalent exchange (and thermodynamics) isn't respected and that does my head in. lol

I'll cover 1 down below.

2. This is just conjecture because I don't think it was ever touched on heavily by the story, but the gist of what we've been given is that every living thing has a natural expiration date (even the Ancients), and living beyond that will start to cause memory and personality degradation. This is why the unsundered Ascians needed their memory crystals; unlike their sundered pawns who use them to remember their Ancient selves, the unsundered Ascians use them to keep their memories and personality straight because their unnaturally long lives will otherwise take a toll on them that reduces their cognitive abilities. By the end only Emet-Selch is still using his, with Lahabrea having seemingly given himself over to his Hephaistos "self" and Elidibus having abandoned it to focus on his duties; and Emet is by far the most effective for it.

So to directly answer the question: theoretically but there's still a limit to how much memory individuals can hold, so a longer life won't add to the Lifestream.

2a. To my knowledge the plan had nothing to do with memories, everything to do with nurturing the planet to use some amount of its living things as blood sacrifice to restore the Ancients who sacrificed themselves. The Final Days didn't destroy the Ancients' souls as it did with the victims in our own time, and the planet was in an inhospitable (if not uninhabitable) state but it still had all of its aether. Presumably. They just had to nurture the planet to produce enough souls to sacrifice to Zodiark for what they really wanted.

Did Zodiark respect thermodynamics, and thus require more aether to produce whatever you wanted since entropy is a thing? Well that I couldn't tell you because it's magic, and magic works however the writer(s) want it to work.

The devs have stated that Light and Darkness are not a 1:1 parallel with Umbral and Astral, and act as both aspects and elements. Polarities might be a better word to use. But some people might confuse that with aspects as well. That's why I used the Adverb analogy, since I makes the most sense.

To get more specific on this...

Light and Dark(ness) roughly correspond to Umbral and Astral polarity, respectively, but they also act as mutually destructive elements in and of themselves. This is because Light is essentially non-elemental aether, while Dark is all-elemental aether. The six elements also trend toward Astral or Umbral polarity on their own (with Fire, Lightning, and Wind leaning Astral / Dark; and Earth, Ice, and Water leaning Umbral / Light) but can be shifted to the opposite polarity (Astral Lightning being a thunderbolt vs. Umbral Lightning being static electricity, f'ex).

Notably Eden Shiva (Ryne) uses primarily Ice but due to her host conflating that element with its typically strong Umbral / Light polarity is also able to transform into a bootleg Hydaelyn; and the two eldest primals use the three elements leaning toward their polarity during the Trial fights against them.

[Eloah]

To get more specific on this...

Light and Dark(ness) roughly correspond to Umbral and Astral polarity, respectively, but they also act as mutually destructive elements in and of themselves. This is because Light is essentially non-elemental aether, while Dark is all-elemental aether. The six elements also trend toward Astral or Umbral polarity on their own (with Fire, Lightning, and Wind leaning Astral / Dark; and Earth, Ice, and Water leaning Umbral / Light) but can be shifted to the opposite polarity (Astral Lightning being a thunderbolt vs. Umbral Lightning being static electricity, f'ex).

Notably Eden Shiva (Ryne) uses primarily Ice but due to her host conflating that element with its typically strong Umbral / Light polarity is also able to transform into a bootleg Hydaelyn; and the two eldest primals use the three elements leaning toward their polarity during the Trial fights against them.

This better illustrates what I was trying to say, thank you.

[Alleluia]

I'll cover 1 down below.

2. This is just conjecture because I don't think it was ever touched on heavily by the story, but the gist of what we've been given is that every living thing has a natural expiration date (even the Ancients), and living beyond that will start to cause memory and personality degradation. This is why the unsundered Ascians needed their memory crystals; unlike their sundered pawns who use them to remember their Ancient selves, the unsundered Ascians use them to keep their memories and personality straight because their unnaturally long lives will otherwise take a toll on them that reduces their cognitive abilities. By the end only Emet-Selch is still using his, with Lahabrea having seemingly given himself over to his Hephaistos "self" and Elidibus having abandoned it to focus on his duties; and Emet is by far the most effective for it.

So to directly answer the question: theoretically but there's still a limit to how much memory individuals can hold, so a longer life won't add to the Lifestream.

2a. To my knowledge the plan had nothing to do with memories, everything to do with nurturing the planet to use some amount of its living things as blood sacrifice to restore the Ancients who sacrificed themselves. The Final Days didn't destroy the Ancients' souls as it did with the victims in our own time, and the planet was in an inhospitable (if not uninhabitable) state but it still had all of its aether. Presumably. They just had to nurture the planet to produce enough souls to sacrifice to Zodiark for what they really wanted.

Did Zodiark respect thermodynamics, and thus require more aether to produce whatever you wanted since entropy is a thing? Well that I couldn't tell you because it's magic, and magic works however the writer(s) want it to work.

Can you direct me to the source that says Emet was using his crystal and that the crystals were actually given to the amaurotine officers pre-sundering? I was under the impression that crystals were something the unsundered made (with Emet doing the actual crafting) to facilitate the raising of the sundered soul shards to their seats and jumpstart the recovery of their memories. Not a pre-sundering thing the convocation regularly did. Otherwise, there wouldn't be just the Unsundered's memories of Hermes in the Fandaniel crystal, for instance, but also his predecessor's memories. Am I forgetting something in Elpis or Amaurot that touched on this?

And re: the final days -- the ancients were just stabbed/chewed to death etc, yeah. But the creations that their creation magicks made were blasphemies. It seems likely to me that that caused at least some loss of aether. The aether is used to manifest a creation which is then immediately annihilated by dynamis and turned into a blasphemy? Or perhaps the blasphemies are just a result of the dynamis reacting with a part of amaurotine's aether, but it couldn't turn the whole soul b/c of their aether density being too thick? Either way, the "aether to no aether" thing still happened. Or else the blasphemies wouldn't still look the same. Its like the dynamis attack was only able to peel off a layer of aether from them about the density of a familiar and then corrupt that. And then in modern day we all have the density of an amaurotine familiar, so it just corrupted modern people whole.

I'm still not certain whether I buy that the aether is just annihilated when confronted with dynamis, cus in an antimatter/matter annihilation reaction(which this has been oft compared to) BOTH things are annihilated. But as we saw: there was a big old monster, animated by the emotions of the person it used to be, left behind when the dynamis attack hits. So something must physically be there, and (barring some unknown third force) that something must be made of dynamis if there is no aether present, thus dynamis was not annihilated in the reaction. So, I think it makes more sense that aether and dynamis can become one another and the aether just experienced a state transference (like matter to energy transference). But this is just me rambling now. >_>

Or as you said, the writers are looking at this going "Laws of thermodynamics? In MY magic system? Ha!"

[Cilia]

snip

I specifically said "unsundered Ascians" and not Ancients for a reason - the memory crystals were made by the three unsundered Ascians (I don't remember anything about Emet-Selch being solely responsible, just that he made one for Azem despite their abdicating their seat in the wake of the Final Days made doing so taboo), but served different purposes between the Paragons and their sundered cohorts. To our knowledge none were used for that purpose during Amaurot's time, though Lahabrea sealing Hephaistos into one such crystal, Erichthonios making the one that instigated the Pandaemonium incident, and making one for Azem being taboo due to their abdication (which implies they were made for other Convocation seat holders at some point in the past) tells us the knowledge of how to make them was out there.

The Ancients' Final Days were slightly different than the one recently experienced on Etheirys. In the Ancients' time, the negative Dynamis forced their creation magicks to summon horrible monsters against their will as opposed to, well, whatever they wanted to make / summon (Emet-Selch specifically says that where prayers give rise to primals, the Final Days negative dynamis flood caused them to summon their deepest fears as Terminus Beasts / Blasphemies). Contemporary Etheirys' Final Days, due to the peoples' lower aetheric density, caused them to transform right out into Terminus Beasts / Blasphemies because they were more susceptible to dynamis-based attacks.

We know modern peoples' souls were also annihilated (or nearly so) upon transformation, but we don't know what happened to the Ancients killed by Terminus Beasts. Without anything stating to the contrary we have to assume that their souls were not annihilated and returned to the Lifestream. (The Terminus Beasts, specially powerful Blasphemies not withstanding, largely use the same model(s) as a cost saving measure. This is still an MMO, and reusing assets is far from atypical.) Besides which, as Meteion tells us in Ultima Thule, the souls of people turned into Blasphemies / Beasts (and those killed by them?) aren't annihilated per sé, just sent to her Nest so as to prevent them from being reborn. With her death (defeat?), presumably they will return to the cycle of souls.

The aether / dynamis relationship is more along the lines of matter / dark matter (or dark energy); I don't recall it ever being compared to antimatter.

... but yeah, don't think too hard about it. Magic, and they can always retcon or revise how it works to suit their story needs / interests.