Proper focus and directing his attention to his fundament can reveal to him the massive complexities of — the fibers that make up his jeans where they're between his skin and the chair! He can't exactly sense the individual fibers and how they are woven together but there's something like that in the way they feel to him.

Accidentally perceiving things with his ass is not the kind of problem he was expecting to have yesterday! Can he do it via his hands on the chair arms?

Foam rubber padding is also pretty complicated. But the steel structure just under the paint is simple, with only a grain structure, and it just feels easy; the volume he — senses, has-in-his-mental-grasp, whatever — grows much faster than with anything else he's tried on purpose so far. He can apprehend the structural parts of the chair in a few minutes.

Okay he was going to try to scoot the chair around with his mind Professor X style but actually now that he has a metaphorical hold of this steel he has a different cool idea. He grabs a steel key off his carabiner and brain-acquires that too and tries to make it a magnet.

Doing the thing he did before makes it want to stick to his hand like the thing he did before.

It sure does and that's also great, but can he make it a literal magnet and pick up a paperclip with it?

Not by thinking 'magnet' at it. He will have to figure out what he can do with these unlabeled high-dimensional mental controls.

He does some internet research on what exactly being a magnet means on the subatomic level, then tries to get his perception as small-scale as possible.

The crystal structure of the metal is obvious, but only as a sort of texture; individual atoms, and magnetic domains, elude him.

Yeah, that was a long shot. Back to trying to scoot the chair around with him on it?

He can make the chair make creaking noises as its structure is stressed. He can push himself off the chair. If there's a “reactionless drive” mode, he hasn't found it.

He messes around with the key some more, trying to get a feel for all the things he can do on an object it's probably safe to do them on (he has a copy of the key). He can still do the thing where it sticks to his hand, so what if he tries to do the same thing backwards? He aims his hand at the wall with the key stuck to it and tries to stop doing the sticky thing all of a sudden and deliberately overcorrect. Can he yeet the key away from his hand?

The key is firmly yote! It leaves a tiny dent in the wall and falls to the floor.

Also it's still being pushed away; he can feel a force on his hand and feel it in his sense of what the key's touching, too.

Oh, that's neat, he's still interacting with it at this distance! He keeps doing the thing he's doing, or trying to anyway, and examines the sensation. How much pressure is there? Is the direction of the pressure on his hand at all related to the angle he holds it at or have Newton's laws just totally gone out to lunch?

It's not a pressure against his skin; it wants to move his entire hand like gravity, and it's directly away from wherever the key is (which correspondingly shifts against the floor a bit as he moves it around).

There is definitely some way to turn this setup into a cool-ass spaceship, assuming it's replicable and persistent and not an artifact of his having gone completely fucking bananacrackers. He needs to get a Newton meter.

What happens if he pushes gently but steadily against the pressure, trying to bring his hand closer to the key?

It increases as he gets closer to the key, but not all that much for a force that can be felt that far away, though it's enough to make the key skid along some more as he gets in arm's reach of it. Also there's maybe another sensation.

He stops to check out the new sensation. Where is it in space? Is it coming through any of his preexisting senses, or is it another new form of qualia? Is it constant with time or is it moving or changing at all?

It is broadly in his hand — and the key. It kind of feels like pressure or like warmth but not actually either of those. It seems to increase the closer his hand is to the key, and decrease away from it, and stay the same if nothing is moving.

He should make up names for all these qualia and phenomena, and write down everything he's been doing so far. Turn his screwing around into science, and whatnot. He tries to stop doing what he's been doing, in the hope that that will detach the key from his hand so he can write without dragging it around under his desk.

The thing that pulls or pushes the key is readily — erased, returned to its natural, or at least previous, state.

The pressure-warmth-sensation stops changing with distance.

Then he can take some notes, extremely detailed ones, with everything he remembers and notes on where he's more or less confident in the accuracy of his memory, the predictions he's made and how they've turned out, and made-up words for all the new sensations he can feel and actions he can take.

Then he goes back to playing with the key. Can he get it directly back into the state it was in before releasing it without picking it up first, or does he need to stick it to his hand and fling it again?

Combining what it was like to fling the key with how it felt at a distance, yes, but it's just as easy to give it a shove while it's far away, too. Apparently there is a part of the thing he is directing to happen that directly corresponds to distance.

During these attempts the unexplained additional sensation lessens somewhat.

Can the thing that directly corresponds to distance be used to get the key to hold still, say, about 20 cm from his hand in mid-air?

After some practicing he can make that happen. Setting up something that spatially precise takes a lot of care with visualizing-but-not-really the exact shape of it, the precise bend in the response curve.

This also makes it obvious that the force is not with respect to “his hand” but every part of his hand, separately — restricting the distance also fixes the key into a specific position with respect to his hand, like he replaced “key on the end of a string” with “key on the end of a beam”. Also he can't move his fingers very much now, because that would change their distance to the key.