Scissors NOT Gate [video]

Well, if you join just two L shaped bits at their vertices using a hinge/rivet (like the middle section in this video) you essentially get the same "NOT" gate inversion

Much simpler ... a clothes clip is also same: press the legs together on one end and the other end opens up in inversion, and let go for reverse

and its length doesn't change much at all -- which answers the question posed at the end of the video.

I am failing to grasp the deep computational theory implications of this though

One often overlooked interesting property that comes naturally with many mechanical computers (and also applies in this instance) is reversibility [1]. Meaning that not only the input can influence the outputs but also vise versa. Furthermore, this means that no information is erased and it could therefore theoretically perform computation without consuming any energy at all [2].

[1]: https://en.wikipedia.org/wiki/Reversible_computing [2]: https://en.wikipedia.org/wiki/Landauer%27s_principle

I've been looking for ways to create gates with real life objects, and this one is quite novel! I think for linking gates though, you'd need some sort of connector system in between, like a longer metal piece from the ends. It's bizarre how easy a full adder computation is when you break it down.

The issue with making an AND gate is you need a mechanical nonlinearity of some sort.

Electrically if you define 1 as true and -1 as false (even though this isn't the traditional definition), a NOT gate is just a flipped wire pair, but an AND gate would require a semiconductor.

This guys channel is awesome. Been following him for years.