[Timwi]

> But when we assess a machine, we do know everything about it based on its actions.

This is obviously false. Every developer has had hour-long debugging sessions to track down a mysterious behavior. Sometimes entire teams are stumped by a technical glitch. Until the bug is found, nobody knows everything about the machine.

[sublinear]

Yet the bug has a chance of eventually being discovered. If someone is determined to find it, they certainly will. You are not thinking clearly here.