I remember that the first question he asked in that philosophy circle was: Imagine we were to replace all the carbon atoms in the protein molecules of the human body with silicon atoms - would it still be the same human being or not? We, physicists, without much thought, answered unanimously: Yes, of course, the same, because silicon and carbon have the same valence. Then Avenir Ivanovich suggested thinking about whether, for example, the mass of silicon man and his

sensitivity to environmental temperature would change. Yes, of course, they will change, we replied. Avenir Ivanovich then asked if his perception of the environment would then also change. I went into myself for a moment and realised that his perception of the environment would indeed change and that a silicon man would therefore be different from a carbon man!