Question: “In Sri Nisargadatta’s talks the world is only in the perceiver’s mind. So would the person I am perceiving also be aware of me perceiving him?”
Answer: The question, as far as enquiry goes, is, “Who is the ‘me’ perceiving him or anything else?”
The “me”, like the world, is in the perceiver’s mind.
If it should become seen that the world is in the mind, then the questions of “me” and “him” dissolve in that seeing. There is only what is arising now and it is what it is.
All things are made of the same “stuff”, yet all things appear individualistic. The question of how things interact becomes moot at the point of seeing that all is exactly what it is in this instant. All questions dissolve in that moment.
Still, from the point of view of parapsychology and quantum theory and other disciplines, it is an interesting question about how perceivers are aware of each other. I don’t have all the theories and studies at hand to relate or summarize, nor are they the point of this response.
There is the day to day way of addressing questions, in this case by talking about parapsychology and quantum theory. And there is also the absolute way of addressing questions, in which questions are revealed to dissolve into that out of which they arose, like a wave out of the ocean.
Nisargadatta is sometimes “day to day” and sometimes absolute in his responses. Questions dissolve into the Absolute and get addressed at the day to day level, both.
The answer to the question is that there is no question, no “me” asking the question, and, at the very same time, there is an interaction between perceived and perceiver that quantum theory, parapsychology, psychology, physics, sociology, and other disciplines study and address.
There is no answer and there is an answer. Discussions about nonduality are presentations of paradox. Where the materialist (you and me?) calls out, “Show me the money!”, the nondualist gets on the phone and shouts, “Show me the paradox!”