So a sprinter that uses artificial legs was just ruled ineligible to run in the Olympics. The hangup: A normal foot is 60% efficient, but the runner’s artificial legs are 90% efficient—meaning that running at any given speed takes 25% less energy.

Not to get all William Gibson on you, but here’s my point…

What’s the threshold efficiency at which a normal person will decide to replace a normal limb with an artificial one? Cause honestly, if I could run at 60 mph with minimal effort, I’m getting fake legs. These sorts of questions can only become more pressing, because prosthetics will only get better while people will only stay the same. Ergo: There should be a futuristic sounding name for that changeover threshold, if there isn’t one already. That limit is of vital interest both to engineers and couch potatoes.

I already know that some of you are saying: Efficiency isn’t the point; No one wants to look like a freak if they don’t have to. But look, robotic limbs will eventually look normal or even better than normal. And those new fangled limbs will have Halo 7 built into them, with an automatic popcorn popper. What do you say then?

Sidenote: Here’s a rocket-powered arm.