I would say, absolutely ... in whatever density they may take shape, I think thoughts have 'mass' ... particle science and physics indicate other dimensions than the 4 we find obvious (height, width, length, time), even the Bible describes the 'principalities and powers' that are unseen around us ... beyond the forms of matter ( solid, plasma, liquid, gas), (plasma was 'recently' added), perhaps someday scientists will include 'ideas') ... seems like the brain would have to form the 'idea', before it can form the 'picture' , and then, experience the physical 'object matter' ... but, that's just my thoughts, and I'm admittedly twisted (60's veteran )