What is a 'dream'?
It is a dream you see while sleeping at night. I'm not actually watching because I have my eyes closed. But while we are dreaming, we certainly see the scene. It may be a virtual space created by memories in the brain. But then, why does the memory become ambiguous over time after waking up from a dream?
The most mysterious thing is the volatile nature of dreams. Although it is remembered in pieces, details are erased from memory.
From these trends, I speculate that the human brain is a hybrid. Every day, the awake brain can remember like an HDD. However, during sleep, it behaves like DDR memory and clears the contents when you wake up. In other words, a dream may be the ancestor of private browsing.
I hope that
@venustus will solve the mysteries of dreams using esoteric formulas.