haha, you will likely discover the answer to this question and many others that concern you..However, there's only way...
take the plunge and try DMT
I can see why they're convinced the worlds are real...the brain knows no difference. In fact, much of what we imagine has a similar affect on us as if it actually happened. Where people are mistaken is that they go through their entire lives imagining everything
they don't want to happen. They should be imagining
what they want. To a degree it's as if the things you imagine actually happened to you physically and those are the signals we send to our bodies. In each moment in life, you either grow or shrivel away in fear. It
does impact you physically; the signals stream through your body and modify your DNA. Eisenherz knows what I'm talking about.
Now about the other worlds... I can understand why they think they're real. They are probably more real than reality as we consider it because sensation will be more enhanced than it is in the "reality" we believe in... BUT it is possible other dimensions do exist and therefore these other worlds may exist in realities we tend not to perceive in this form, as James mentioned. So, they may exist, just not in our current method of perception. Maybe it is a shift in the
method of perception that enables us to now become aware of the other worlds and therefore enables us to now exist in them?