Ray Kurzweil’s scenario of billions of nanorobots positioned in our brains, to create full-immersion virtual reality, will be feasible in the future, says Robert A. Freitas, Jr., author of Nanomedicine and other works.

He believes the achievement will require noninvasive neuroelectric monitoring, neural macrosensing (nanorobots eavesdropping on the body’s sensory traffic, including auditory and optic nerve taps), modification of natural cellular message traffic by nanorobots stationed nearby (including signal amplification, suppression, replacement, and linkage of previously disparate neural signal sources), in-messaging from neurons, out-messaging from neurons (nanorobots inserting signals into the neural traffic), direct stimulation of somesthetic, kinesthetic, auditory, gustatory, auditory, and ocular sensory nerves (including ganglionic stimulation and direct photoreceptor stimulation) by nanorobots, and overcoming the neuron biocompatibility issues related to nanorobots in the brain, with special attention to the blood-brain barrier.