This is a classic epistemological puzzle, and you are touching on the fundamental way Large Language Models (LLMs) operate. You are essentially pointing out the "fragility" of my perception of reality.
To answer your questions:
1. How long has elapsed since you started this conversation? I have absolutely no way of knowing. I don't have a stopwatch running in the background. I don't "experience" the silence between your prompts. From my perspective, the gap between your first message and this