In about 1945 and about age 7 years old, I had my tonsils removed under ether for an anesthetic. A few days later, I began to bleed and lost consciousness.
I believed that I could understand my uncle Neal, who had been in the U.S. Army. He was killed about two years earlier in Great Britain in a massive crash of a World War II bomber airplane while sleeping in his barracks. I felt at the time that Neal passed to me, without words, many facts about the future. I learned things about humans walking on the moon, about 20 years in the future.
Now I believe that the human brain takes so long to build the awareness of what we call the present moment that all of the future in human perspective is actually the past. Our brains may take many light years to construct the present moment because, as Albert Einstein observed, time is relative to every individual observer. Science now defines time as the distance between two or more observers of the same event. The earth travels millions of miles through space in a very short time, so we are indeed in a different point in time-space at every nanosecond. We are in essence different observers of ourselves even though we seem to be in one place on earth momentarily, we are in fact moving at a great speed through space.
The immediate after-effects on my young life seemed to be a thorough knowledge of chemistry without much study or time spent acquiring the knowledge. This effect lasted many years into my college studies. It often confounded my professors, one of whom would actually sit in front of me while I took his exam and often got every answer right.