Do you know the "brain in a vat" hypothesis?
"A man (let's say it's you) was operated on by evil scientists. His brain was cut off from his body and placed in a vat containing a nutrient solution that kept the brain alive.
The nerve endings of the brain are connected to a computer, and the computer transmits information to the brain according to the program, so that he can maintain the illusion that everything is completely normal.
For him, it seems that people, objects, and the sky still exist, and his own movements and body sensations can all be input. This brain can also have memories input or intercepted (the memory of brain surgery is intercepted, and then the various environments and daily life he may have experienced are input). He can even be entered into a code and 'feel' that he himself is here reading a funny and absurd text. "
Human vision, hearing, smell, taste, and feelings are all formed in the cerebral cortex, and the brain tells us everything about the outside world. When the brain can be controlled, how do you prove that the world you live in is real?