Aetheryte

[Berethos]

Any piece of gear that is bound to you can travel through the aether with you

It may also be a question of how much "energy" is needed to accomplish the journey.

According to the lore book, magicks are used to reduce the corporeal body and will to just aether, with the will keeping it together, and passing through the lifestream to another place where the boundary is weaker (on Hydaelyn, that's the location of Aetherytes) at which point they pass back into the corporeal realm and reform.
It's quite possible that the amount of magick needed to break down inanimate objects grows at such a rate that beyond a certain point (say, the weapon, clothing, and a certain amount of carried items - lore wise I don't think we actually carry quite as much as we can gameplay wise) it's simply not feasible to do so - either it would take too much magick, the will of the host can't keep it all together, or both.

Also, in terms of can it change something like food? I think it's possible, though I doubt it would be so drastic as ending up with a different type of food. That being said, it would take spending longer in the lifestream than you normally do when using the aetherytes, as those act as beacons and you spend so little time in the lifestream that everything that goes with you arrives in the same form.

Y'shtola returned without her natural sight and instead has to sense the aether around her to see, and Thancred was spit out without the ability to tap into aether at all, so teleportation can make changes to the aether that is involved in it...but only if that teleportation doesn't involve aetherytes at all, or perhaps if something were to happen to the aetherytes at the same time you entered.

[Kennar]

...snip...

All good thoughts. Perhaps, technically, anything could be teleported through the lifestream, but the further removed something is from a living being with a spirit (and a will), the more magick it takes to do it; and without a will to hold it together, there is no guarantee the object will come back complete on the other side. Your gear being spiritbound, your spirit "knows" the composition of your clothing, weapons, items, etc., and through strength of will those things can be faithfully recreated on the other side. We know there are various teleportation devices of Allagan and Garlean design, but the power requirements are likely immense for the distances at which they can operate.

I agree with you about not being able to carry unreasonable amounts of stuff, from a lore perspective. Even as a hulking Roegadyn, I would still have to travel relatively lightly. This takes a little hand-waving, but maybe if our packs/pouches/purses are bound to us, then the things inside of them are bound by proxy--the lifestream and magicks involved treat your pouch of stuff as one object. The more stuff in the pouch, the more difficult it would be to recreate, which would provide limits on what could be teleported.

I'm not sure how much of this is spoilerific, so I'll just hide it all...

I see what befell Y'shtola and Thancred as not being changed by teleportation magicks or the lifestream, but a result of what is essentially data loss in the lifestream. Using a proper spell opens a conduit between two aetherytes that provides accurate tranferrance of information with negligible losses, much like a telegraph or fiber optic cable in our world.

Y'shtola's forbidden magicks, in effect, broadcast her and Thancred's information into the lifestream like a radio, in hopes a "reciever" could quickly pick it up. She was, very briefly, one of the most powerful transmitters in the world. Time weakened their signals, and it was probably only shear strength of will that kept their spirits intact enough that they came back as they did. A person of lesser constitution might have come back a vegetable, or been absorbed by the lifestream entirely.

I assume more than one Sharlayan researcher met a gruesome end in the name of science while studying teleportation magicks. Y'shtola was lucky to come back only missing her sight. What if she came back without her face? *shudder*

[NephthysVasudan]

Y'shtola returned without her natural sight and instead has to sense the aether around her to see, and Thancred was spit out without the ability to tap into aether at all, so teleportation can make changes to the aether that is involved in it...but only if that teleportation doesn't involve aetherytes at all, or perhaps if something were to happen to the aetherytes at the same time you entered.

Forgot a key point or two/and some remarks.

Didn't Thancred fall through time or something? or an alternate reality? Hints at extreme risk. That and Y'shtola is basically draining her life force to keep doing what she does.... sad

[Berethos]

Forgot a key point or two/and some remarks.

Didn't Thancred fall through time or something? or an alternate reality? Hints at extreme risk. That and Y'shtola is basically draining her life force to keep doing what she does.... sad

Short answer - Nope (or at least a strong probably not).

There is definitely extreme risk (which is why Matoya upbraids her for it later), but Kennar basically has the right of it - the big threat is essentially data loss while in the Lifestream. Without the beacons of the aetherytes to help guide the aether of the body and will back to the corporeal realm (in a place where the boundary is weaker), the wielder of the teleportation magick has less control over where the users end up. In Thancred's case, he gets spit out in the Dravanian Forelands with two key elements of data loss - his clothing and weapons, and his ability to control aether. He's actually somewhat older than he looked when we first met him (32, despite looking more like he's in his early 20s), and I believe that's due to use of magicks to keep himself at least looking youthful. I know that Y'shtola used the arcane arts for something like that, but I don't know for certain if it's mentioned that he has as well, though it would help explain why he starts to look older afterward.

I think the chance of him having spent more time in there before popping back out to not be as high, as that part of the story makes it clear that too much time spent in the Lifestream means you lose your form and eventually dissolve back into the lifestream itself, and there's no indication that he otherwise ended spending more than a short time there before being spit out...and there's definitely no hint at an alternate reality/dimension. While travel to one of those is technically possible, it requires either a rift between words (like the ones the Voidsent use) or for the one making the jump to give up their mortal body to make the jump (as we saw with the Warriors of Darkness).

For Y'shtola, I seem to recall something else that hints at it not necessarily being her draining her life force away every time she does it so that she will eventually die sooner than she would otherwise, but instead that in doing it she could easily overextend herself if she isn't careful and get herself killed that way - like she could end up using too much at once, but if she's careful to not do that then she's fine (though that may just be my interpretation of various character comments from those like Matoya.

[Keever]

Thancred's face from ARR to HW is pretty much identical. He just got a tan and grew out his chin-scruff a little. I've seen a lot of folks saying he "looks older" but he hasn't visibly aged at all. It's all in his demeanour and the way his new hair and outfit frames his face.

It's just like how everyone thinks F'lhaminn is really old, but she's only 37, and she looks exactly the same as she did 15 years ago. Putting on glasses and a frumpy outfit really alters perceptions.

[NephthysVasudan]

Thancred's face from ARR to HW is pretty much identical. He just got a tan and grew out his chin-scruff a little. I've seen a lot of folks saying he "looks older" but he hasn't visibly aged at all. It's all in his demeanour and the way his new hair and outfit frames his face.

It's just like how everyone thinks F'lhaminn is really old, but she's only 37, and she looks exactly the same as she did 15 years ago. Putting on glasses and a frumpy outfit really alters perceptions.

guess i need to re-watch the cut-scenes...been too long lol.