i think that the definition of 'illusion' needs to be explored as the word illusion implies that there is something there but we can't see the truth. if time is an illusion then what is it hiding? time isn't a hallucination but a distortion of something that actually exists. if time is related to mass (time appears to speed up to objects the closer they get to the mass of a black hole etc) then what is mass? if energy is mass times the speed of light squared what exactly is energy? man, this is a total rabbit hole!