We have no idea. I would assume the Traveler would be able to do so, given the power of paracausality over the Vex, we just never had a chance to see it in action. All of the machine worlds in existence right now are when the Traveler isn’t really capable of doing much at all, and hasn’t been since they were converted, and had other pressing matters than to zip around the system reverting the damage done.

But I’m assuming if it were back in action and had the freedom to do whatever, it could probably change it all back. It may possibly depend on the damage done though. Like, I have no clue the extent of the Traveler’s terraforming powers that would be needed to unfuck what happened to Mercury - completely converted on the surface, and completely hollowed out, and also nearly destroyed by the Almighty. Could the Traveler, even at its prime power, completely revert all of that? No idea. But I (Mercury Nine) sure did show us a vision of us exhumed while holding a “pale trowel,” a line that’s keeping me up every night, so you understand the kind of stress I’m under. What do you mean bestie? You want someone to come gardening again?

Really impossible to say definitively. There’s a lot of little details about the Traveler and the Light and how many different species referred to it, as well as the fact that the Witness and its servants have been chasing it across the universe so it may as well be the same entity. But given that the Winnower does not appear to be a physical being, but rather a “concept,” the same may apply to the Gardener. In which case, the Traveler would be the closest to it, but not really it.

Then again, we have the whole Unveiling thing and the Gardener “inserting itself into the game” which to me implies that it did so as the Traveler. However, the nature of Unveiling is that it’s essentially a religious text. So a hundred people will interpret it in a hundred different ways, and that’s on purpose.

Personally for me, probably the strongest piece of evidence or at least something that’s very peculiar is the fact that when the Red War happened and the Traveler was caged, the Light got shut down across the universe (proven by the Drifter being outside of the solar system when it happened), and similarly when the Traveler woke up at the end and sent the blast of Light, the blast of Light travelled far and wide. That makes the Traveler the only, or at least strongest possible, source of Light in the universe which is quite interesting when it comes to this question. Is the Traveler the Gardener itself then, or is the Traveler just something the Gardener created to bring Light into the universe, but it’s not the same entity?

I do think there’s a strong link between the Gardener and the Traveler, and that there is a possibility they’re the same, but there is no direct and undeniable proof of this, and there likely never will be. If anything, the Traveler is the closest to the Gardener as it was described in Unveiling, for sure, and basically enacts its philosophy and power in the universe. Until either the Traveler or the Gardener speak directly to us to say something about this, I don’t think this will ever be answered conclusively.

It was never answered directly in simple terms, but we have a vague idea that it had something to do with whatever happened at the end of the Collapse which resulted in the Black Fleet being pushed out of the Solar system. This involved the Traveler doing something which ended up leaving it heavily damaged and also dormant, as well as Savathun tricking the Witness, stealing the Veil and hiding it away. With the Veil gone and the Traveler “asleep,” the Black Fleet was driven away and had no reason to reactivate because the keys to the Witness’ plans (the Traveler and the Veil) were in some way removed and disabled. Kinda like, there’s nothing to do with the Veil gone and the Traveler metaphorically dead.

The Pyramids reactivated when the Traveler sent out the pulse when it awakened at the end of the Red War because it essentially signalled its position and its status as alive. This basically told the Witness “Hey one part of the equation is ready, we just have to find the Veil now. Worth taking a look.”

Difficult to say! I think it’s intended to be that way primarily because of how more or less everyone speaks of it and calls it Gardener, as well as some other details mainly from the Traveler’s POV, including the way it describes Light itself as its blood (and again in Ergo Sum). Also the way the Traveler itself is described as:

It feels like lead and neutronium and electroweak matter fashioned into a moon-sized ball that you must carry as you move.

Aka it feels like the Traveler itself was created to be a physical entity in the universe; the Gardener created a “moon-sized ball” that it must carry around as it moves. This is interesting in the context of what we’ve seen in the cutscene for the creation of the Witness, and also interesting in the context of Unveiling and the way this is described as the Gardener “inserting itself” into the game to change the rules.

But stuff like this can have multiple interpretations, and intentionally so. At the end of the day, we don’t truly know the scope and scale of the Traveler and its origin, even with everything we’ve seen and established. It’s possible that the truth is somewhere in between; aka the Traveler is considered to be the Gardener because it’s the closest to our concept of it. It’s possible that the Traveler and the Gardener are two entirely different concepts, as well as that they’re one and the same.

It’s also possible that “Gardener” is one of those nebulous/religious ideas that the people in the setting have to try and explain paracausal forces and the origin of the universe; maybe they ascribe the term “Gardener” to the Traveler because it’s the easiest way to understand it. And maybe the Gardener is some force that exists somewhere in a non-physical state beyond the universe. Maybe it’s just a concept (much like the Winnower described itself as a concept).

Personally, I think it makes sense that the Gardener = Traveler, given the physical nature of the Light, as a contrast to everything Darkness. So the Gardener and the Light physically exist with us. But ultimately we don’t really know for sure. It’s one of those things that are too grand in scale in cosmology to ever be fully answered directly. Or at least it makes more sense that way.