"Physics simplifies in higher dimensions, yet we do not experience higher dimensions."
"We"? I have experienced higher dimensions. I claim you have, when very young; you must have forgotten!
"Feymann's QED solution requires virtual positrons coming back from the future, yet we do not experience the future."
"We?" I have experienced a glimpse of the non-hyperspace future. Consistent with hyperspace theory; this glimpse occured when my "hyperspace clock" froze and I collapsed a higher dimension of myself (as a newborn baby who found nobody could see the higher dimension me (other than my twin).
Scientists have recently carried out this experiment: Subject's brain was wired up so as to give read-out of brain-wave patterns on a screen. Scientists documented which patterns occured as various playing-cards are shown on a screen to subject.
Each playing card gave a distinctive brain-wave pattern. Now the amazing bit: the scientists discovered that when the computer chose a card and displayed it to the subject; the brain-wave pattern for that card occured in the subject BEFORE they had seen the card!
So direct evidence that a person's brain can detect short-term future events even though the subject was not accessing this future-detection that occured sub-consciously in their brain.
Roger Penrose was involved with the TV program presentation of that discovery.
Socrates suggested that "All Knowledge Is Remembrance". My theory is: we are higher dimensional beings than many realise. Humans celebrate Christmas each year; yet seem slow to take the hint: that maybe THEY KNEW how it all basically works when they were newborn babies, but have repressed this knowledge in a dangerous world to babies.