Whats an unethical or dangerous experiment that you would like to see performed or perform (if it werent for the ethics/danger)
For me "How long could I get away with driving like an ABSOLUTE ASSHOLE all the time before I lost my licence or had an accident." Speed limits, red lights, stop signs... forget them all. Every day I have to drive sensibly and obey the law because without my licence I dont have a job, and every day I see at least one person driving like an absolute moron and I wonder...
It may not be possible, but I want to gradually replace a person's brain piece-by-piece with the same areas from other brains and see if they retain their sense of self when none of the original brain remains.
We can satisfy this curiosity with a fair amount of scientific evidence.
Of course, most regions of the brain are so densely and variably interconnected that the technical difficulty of “replacing parts” precedes the ethical consideration by many, many years. But we do have a great deal of evidence for how our subjective sense of self is affected by “losing/removing parts” of the brain. Patients are often unaware of change unless evidence for it is overwhelming, and even then are adept at healing/reconciling instinctively. It appears that this is just something brains have evolved to do.
So while the technology (and sheer artistry) required to match and “stitch” these networks is quite staggering, basically magic, it is theoretically possible that a patient could have every part replaced without recognizing any continuity errors in the chimeric stages, until one day they wake up as a completely different person.