Bill and I were talking about time travel the other day. I said it would be impossible to go back to the past, because it would set off a ripple effect that would change ALL of history. "Let's say your body has three billion molecules - give or take - when you land, you will displace three billion molecues at random. They will bump into other molecules that will set off a chain reaction of global proportions."
"Not really," Bill said. "Not if you just pop in for a visit, and then leave right away."
"But you will still displace the molecules, even if you don't move," I responded. "You can't just 'visit' without having an effect."
Then Bill whipped out the old analogy of sticking your hand in a bucket of water. "After you pull your hand out, the water resumes its original form, and all is good."
"Well, not if there is a fly caught on the top of the water. When you stick your hand in, the water level rises to the top of the bucket, the fly swims over to the rim, goes over the top, and flys away. In the original time line, the fly died.
"That's assuming their is a fly in the bucket," Bill said. "It would be perfectly plausible if I landed on the side of a mountain, observed, and then left."
"You would still disturb some pebbles and they would roll down the hillside. Better make sure you don't start an avalanche!"
We both smiled.
"But here is the thing," I responded. "If you land in the middle of Main and Elm Streets, your sudden appearance will cause a car or a bicycle rider to swerve, setting off all kinds of chaos. If you land at any place their are people, or animals, or birds - whatever - you are going to have an effect."
"Ah, but I will make sure I DON'T land in the middle of the street. For example, what if I settle myself down on a hill by the crucifixion of Jesus. Yes, I might make an indentation in the ground, but so what? I quietly leave - no harm, no foul."
Bill got me to thinking. The margin of error would be absolutely critical - hypercritical - but maybe, just maybe, we could travel back in time for a very descrete visit. We would have to be very sure we did not touch anyone or anything, or we would set off the inevitable conundrum of time travel - you would not be born! For that matter, neither would Hitler, nor Lenin, nor JFK, nor. . . . . . The point is, just changing one historical event, no matter how small, changes all of history.
So, let's assume we can "pop in" to any event in the past. Where would I go? How about the moment my mother either fell out of bed, or was pushed out by poltergeists. She lived in the most haunted hosue in England for five years, and at one point, her bed may have been turned over by ghosts. It would be great to check that out.
Or, going back just a few years earlier - same house - I'd be on the lawn during the late afternoon of July 28, 1900. That's when four sisters saw a ghostly nun walk past. I could prove or disprove the legend of Borley Rectory with one simple visit. How fun.
As for visiting the future? Bill and I didn't have time to figure out that one.