Lets answer the first question by taking a look at the scientific definition of levitation:
Lift = Increase in distance of a person or object by some means.
So levitation is the ability of a moving object to reach a higher distance. There is an increase in mass through levitation as seen in your example example of a butterfly.
So an object that exerts no force on its surroundings or an object that can generate very small amounts of force on its surroundings will not levitate. You might say I levitate if there is no force acting on me.
However, this is not completely accurate. I might be levitating in my own mind or in my mind’s mind but I might not be levitating with the rest of my body.
The second point you’ll need to clarify is that there is no evidence for an illusion of levitation as that sounds a bit too much like witchcraft.
The most plausible answer I found is that in order for you to levitate you must create an illusion using your mind (for more details, see why levitation occurs in my articles page). So there is no reason why a mind-controlled person should not be able to levitate. It just may be an illusion induced by your mind to create that lift with the rest of your body.
I’m sure if you would ask the best philosopher in the world to answer that question you wouldn’t get very far.
For the other question, I don’t think there has been one study which has proven levitation in humans. So in the end it seems a very open question. There is also a strong possibility that your body will simply not produce an effect on your surroundings so you’ll either not levitate or if you do you may do it with a tiny amount of force, thus losing that lift. You can try to levitate without using mental powers.
However, in general, I think that levitation may be a true illusion. For example, most of us are not aware that we can levitate or that we can induce a temporary levitation effect using mental power. People who are levitating will not remember the experience the next day so this experience may have been artificially induced.
I think there are a few other explanations for this phenomenon. There is a lot of unexplained weightlessness which probably isn’t something generated by the human brain. Also the Earth’s tilt might allow for some degree of weightless flight.
For a more elaborate explanation
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