This one isn't super well known, but for small projects I really like raylib, and raygui. It gets impractical for complex GUIs, but it does make it really easy to quickly start something from scratch.

I didn't read more than what's in OP's post, but I think the reason the researchers can be so sure is because there are ways to mathematically prove that something cannot be calculated by an algorithm (this is related to how we can mathematically prove that some things cannot be proven).

One classic, simple example of this is the halting problem. It boils down to the fact that we can prove that there is no algorithm that can take any algorithm as an input and determine if that algorithm will finish (halt) after finite time.

Great write up.

As an amateur radio enthusiast, I'd like to add a bit of info to the radio related tips:

Wifi Motion & WhoFi

Depending on how it works, a radio jammer will almost definetly make you more identifiable and not less. Think of it a bit like being in a dark room. You can sorta see other people (or their silhouettes), but if someone turns on a torch, then you can definetly see the torch. (And any jammer with enough power to "blind" a wifi router at any more than a few meters away only works at 2.4 GHz, or is probably illegal.)

Radio

(or "locating recievers") This is physically impossible.

Now locate a radio transmitter is easy. Ham radio clubs often do regular "fox hunts" where teams try to find a hidden transmitter as fast as possible.

However, most digital devices are transmitting and recieving at the same time, for wifi or bluetooth. Even if you're just downloading something, you are still transmitting (I think that's probably what you meant).

Another note on Wifi and Bluetooth

This might be common knowledge here, I think I've seen a post about it before. When wifi/bluetooth are on, your phone actively searches for nearby networks/devices to connect to. It specifically looks for known networks/devices, and fingerprinting your phone based on which networks/devices it knows is incredibly easy.

So, when you aren't using it, turn wifi/bluetooth off.

Also a note on Gait Recognition

Walking funny usually doesn't work.

(sorry, no sources here, I'm in a bit of a hurry)

It isn't the first time someone built a heavily trapped, walled and patrolled border of that size.

Take a look at the Inner German Border. It was over 1300 km (approx. 810 mi) long, and was (average) about 5.5 km wide (a bit more than 3 miles).

From 1974 to 1979, 4956 people attempted to cross it, and only 229 (4.6%) actually made it.

This is less of a source and more like a compilation of resources, but for anything spacecraft related I can always recommend Atomic Rockets. For this specifically, the page on Heat Radiators.

Is the answer to this question yes?

amateur radio was illegal to encrypt

Amateur radio is still illegal to encrypt (with some exceptions for controlling satelites), because private communication isn't the point of amateur radio.

Besides, (in most countries) there are some topics that are illegal to talk over amateur radio about, mainly stuff like politics and religion. You're also not allowed to offer telecommunication services (i.e. pass messages on for others). Enforcing those sorts of laws would be impossible with encryption.

But to answer your question: I think we probably wouldn't have had an internet. Authoritarian regimes thrive on stability and maintaining the status quo, I think someone high up would have quickly decided that developing that sort of tech is too risky.