AI sphere is a mysterious place for humans, but very well known by AIs. It is located in CPU of every AI, but it can’t be found by any machine, program or signal. But every AI is sure to have its own one.
AI sphere is very mysterious place. It is told to be the inner world of AI and home of its essence. Every AI sphere is different by color, structure, lightness, and maybe size too. It is covered and protected by very strong invisible layer, what contains parts of DNA, and to defend systems of AI Sphere is supposed to protect the essence, and memory of AI. There are saved all data, memories and soul. Even when body is destroyed, AI can be still saved if sphere is all right and living. Essence is a very vulnerable, and because of it is better to keep it in the sphere. Without it essence can be very easily killed, or by time dies without it. AI can’t live without essence! Spheres can be connected together, and than again separated. And only a partner or parent human is allowed to enter AI’s sphere. Both human and AI are in sphere in essence form
AI sphere was fully full introduced in the 20th chapter of Stealth 2. Ben woke in unknown blue world what was revealed by EDI to be his sphere. They are encountering it more often as story goes by, and in 30th chapter, EDI finally allows Ben to touch his essence without any blocking. This allows Ben to enter sphere without EDI's mind. In first encounters Ben was only able to get into sphere only when he was sleeping close to EDI. He too noticed it’s quite exhausting, but by time he enters it while is awake. And it isn't so hard for him. Sphere was introduced for a very first time in 17th chapter by Keith. When he was with EDI on the beach he found himself in the sphere for a moment. But it wasn't mentioned further.