The Speculist

Reality's Flashlight

Let’s draw a map of i Space.

As I noted last time, there aren't really any boundaries within i Space. However, we can add boundaries to help us begin making sense of what we find there. In fact, we drew one set of arbitrary boundaries last time when we introduced the regions of the Exhaustive Past, the Exhaustive Present, and the Exhaustive Future.

This time, we're going to draw a different boundary. It will be more useful for us in the pursuit of practical time travel.

The boundary we’re going to draw is between the real and the not-real. Immediately we run into a problem. Where do we draw the line? Let's assume for simplicity's sake that the universe we know is the only universe that exists. Even if other universes are real, we aren't going to count them. We currently have no way of observing them, so we'll just say that anything that really exists within them doesn't count as being real.

Here’s one way to draw it. Reality is an island in i Space’s ocean of unreality.

To return to our examples from last time: the Battle of Gettysburg in which the Union Army controlled Little Round Top, won the battle, and went on to win the Civil War is in the little gold box; the Battle of Gettysburg in which the Confederate Army took the day is out there floating in that sea of black. Bobbing along on the waves of unreality with the triumphant Confederate Army are the Neanderthals who won the evolutionary competition, the Chinese explorers who settled North America, and the sentient froglike beings who might have evolved as the dominant species on this planet had that big ball of methane never erupted.

Everything that never happened is out there in the ocean.

Accompanying the triumphant Union Army on our island of reality is everything that ever really did happen, including you and your life. It’s easy to place items from the past within i Space. In 1969, Neil Armstrong was the first man to walk on the moon. Yuri Gagarin was not. So Armstrong’s moonwalk goes on the island, Gagarin’s belongs out in the ocean.

It’s also easy to place items in the present. Right now I’m wearing a blue shirt. I’m not wearing a green one. Me in a blue shirt is in the little gold box; me in a greenshirt is in the larger black area

But how do we draw the line in the future?

The easy way would be to simply close the boundary off, and declare the future not-real. But I think that’s wrong. Right now the tomorrow in which I’m wearing a green shirt is real in the way that my wearing one right this instant can’t be. There are many possible versions of tomorrow (or even five minutes from now) in which I’m wearing a green shirt. Maybe these versions aren’t real in the same way that this moment is real, but they also aren’t unreal in the same way the Confederate victory at Gettysburg is unreal.

Here’s my map of i Space showing the boundary between the real and the not-real. The not-real surrounds the real on every side except for in the direction that time is moving. At the present, the boundaries of the unreal slope sharply away. As we move away from the present in the direction of the future, fewer and fewer possibilities within i Space are excluded.

You’ll note that reality is shaped like a flashlight. The handle of the flashlight is the past, the light bulb is the present, and the beam of light shooting out ahead is the future. Anywhere the light doesn’t touch is the future that will never happen. For example, the future day in which I recover the $10 million I buried in my back yard last winter is outside the beams. I never did that. And even if I get $10 million and bury it in my backyard tomorrow, it won’t be the $10 million I buried last winter. So that’s a future that will truly never happen.

Inside the beam is everything that could happen. What's within that beam of light is what I call Possibility Space. We'll take a closer look at it next time.

Posted by Phil at September 22, 2003 03:41 PM | TrackBack