[hinkley]

Pockets are power.

If I have an artificial limb, I'd like to have more storage space. Human bodies try to keep crevices to a minimum since they are points of attack by pathogens and parasites. An artificial limb doesn't have to survive to see my grandkids.

There's also no reason a prosthetic limb has to constrain itself to human standard dimensions. Oh I'm sure for propriety and interpersonal dynamics they need a default mode that looks quite similar, but an arm could telescope to give you a few extra inches of reach.

And I've already seen science fiction where a prosthetic hand has nine, ten fingers instead of 5, to facilitate human computer interaction. Though one does wonder, if the brain is capable of controlling a machine hand with higher numbers of digits, can we not skip over the two middle steps in brain-computer-input-computer translation and simply imagine you're typing on a 150 key keyboard that isn't really there? Or at least switch to a virtual hand that the computer uses to intercept the motor commands to the physical hand.

[crooked-v]

> can we not skip over the two middle steps in brain-computer-input-computer translation

Well, if we're talking Ghost in the Shell (the most iconic case of robot-hand super-typing I can think of), having that disconnect is entirely on purpose, to airgap the operators' brains (enhanced, but self-contained) from any external connections.

[hinkley]

I've seen it elsewhere but it's also possible those other cases were an homage to GitS.

I think there's still an airgap if the human brain is not feeding to or reading directly from the external computer. To be clear, we are both treating the prosthetic as 'me' in this exercise, and the system we are communicating with as Other, which we cannot implicitly trust.

The brain-hand interface could act as an input device, then you can still use your motor cortex to tell the hand to type a SHIFT-a, and the interface interprets it directly as an A instead of the movement for A. You can airgap an output device and still use it. There are some precedents for that in avionics I'm told, which are the moral equivalent of optical isolators meant to keep power spikes from frying the more delicate parts of an electrical circuit.

Which I agree is a hell of a lot safer than directly telling your brain you see a virtual terminal, and that now is a good time to have a seizure.

[LtWorf]

You want to keep heavy stuff close to the centre of mass. Heavy stuff flailing around isn't that good to keep balance and do precise movements.

[hinkley]

My arm is full of oxygen delivery and self-repair equipment. It also contains several parts of my immune system.

A prosthetic arm within my lifetime will likely be lighter than my real one. Carrying around a flashlight or a multi tool embedded in a void in it wouldn't be that weird, and wouldn't upset your balance.

Those running legs are already much lighter, but they don't fulfill the full range of features provided by a lower leg.

[LtWorf]

> If I have an artificial limb, I'd like to have more storage space.

Importantly, the internal parts of your arm don't move around and don't change. Unlike stuff stored in a box.