Monday, September 18, 2006

Time Travel

I was watching "Back to the Future" for the umpteenth number of times the other day and I happily pontificated on what I would do if I had a time machine, which led me to consider the possibilities of such a journey, for which I decided that Marty McFly would be the harbinger of doom for all of mankind if he ever set foot outside his space/time continuum. After such thoughts, much to my disappointment, as I have always been a fan of fantasy and “what if” scenarios, I’ve finally given in and agreed with everyone else in the world in saying that time traveling into the past is virtually impossible… for two distinct reasons:

Reason Number One: You’d kill everybody. Hands down, no question about it, you’d be the new Bloody Mary (unless you went back to the time before she was born and then you'd just be Bloody...whatever your name is), so much so that you would probably fade out of existence seconds after you take your first breath in another era because you’d unwittingly kill your own ancestors. Consider this: Part of history that they don’t bother to teach you in school is that when the pilgrims and the Old World tourists made tracks to the New World and met all of the really interesting red-skinned fellows, they suddenly started dying. America wasn’t conquered by force, but by germs, as the Europeans brought with them vicious little creepy-crawlies the Indians hadn’t run up against yet and their immune systems couldn’t handle it.

Well, image yourself, today, stepping into your flying DeLorean and going back in time to the Middle Ages… or “to witness the birth of Christ” (as Doc Brown so suggests), and you’re standing there peering over the Three Wise Men at Mary struggling through her Lamaze breathing and Joseph is wringing his hands wishing he could have sprung for a motel… and you sneeze. I don’t know. Maybe you have a cold, or maybe the hay in the manger is tripping your allergies, but you sneeze all over the shoulders of the Magi who disregarded the five-dollar gift limit and brought the gold (makes those frankincense and myrrh guys look cheap). All of these nasty little viruses, germs and bacteria that you are playing host to are released on an unsuspecting population.

Everyone gets sick and Pontius Pilot ends up putting the guy who started Mormonism on the cross instead. Let me tell you, a billion or so Christians would be pretty disappointed (no, not that Joseph Smith would be crucified, but that Christianity was thwarted by your looky-looing through time).

Reason Number Two: Where is everybody? Over a year ago, two such conventions were held, welcoming potential time travelers from the future to the present. One was at a convention center at MIT Here and the other was down in Australia Here. At both events, not a single time traveler attended; however, it could be argued that some did and by some future time traveling law or guideline, they are forbidden to talk to anyone, but it is highly unlikely.

Perhaps the second reason isn’t as concrete as I had initially hoped, and maybe the dawn of the 21 Century isn’t that great of a place to visit if you’re from somewhere as exotic as the 36th Century. I mean, really, what if anything monumental has occurred in the past few years to make it pertinent for a time traveler to waste his plutonium on a visit here and now? I honestly can’t think of anything worth seeing again from a historical point of view that can’t be glossed over by more important events… then again, maybe the events in the 25th Century are gaining all of the time travel attention.

I mean, that’s where Buck Rogers went when he traveled through time. Ah, yes, Buck Rogers, and this leads us to our final point of the evening. Time travel is possible, most certainly, but just not in the direction everyone is interested in going. Consider the future, as it is most possible to skip though a few hundred years in the time of a couple.

Let’s ask Einstein. In not so many terms, he suggested a riddle: You’re on a train that’s moving at 50mph and you throw a ball in the same direction the train is moving. The ball leaves your hand traveling at 20mph. From the point of view of someone standing alongside the tracks, how fast is the ball moving?

Easy concept to grasp, isn’t it. The ball, from the point of view of the guy along side the tracks, is traveling at 70mph. Okay, here’s one that’s a little more difficult. You’re on a train again, but this time, it’s going a little faster, say half the speed of light, which would be 93,000 miles per second. You turn on a flashlight, and since light travels at 186,000 miles per second, how fast is the light leaving the flashlight according to the guy along side the tracks?

Did you say 279,000 miles per second? Well, sorry, you’re wrong. According to experiments conducted by James Clerk Maxwell, he discovered that light always traveled at the same speed regardless of its source or its relationship to any observer. It doesn’t matter who was moving and how fast they were moving; the speed of light does not change. That’s a proven fact.

We all know about the simple formula for calculating speed, right? Rate x Time = Distance. For the first question, it is easy to see that the numbers fit this formula nicely. In order for something to travel 50 miles in two hours, it has to be going 25mph. See? Well, when the speed of light is plugged into the equation, there’s a problem because the Rate always has to remain the same, no matter what. Therefore, you have to conclude that either Time or Distance must change. That’s the Theory of Relativity, courtesy of Einstein (who was 16 when he first thought about it…what were you doing when you were 16?).

In our train examples, the speed of light turns out to be exactly the same for both you and the observer standing along the tracks because time, as measured by your watch on the train, ticked along at a slower pace than time measured by the guy along the tracks. Not only that, distance changed, too. For the observer, a one-foot ruler whizzing by on the train would have measured less than a foot. The weird thing is that, for you on the train, time wouldn't seem to be moving slower and your ruler wouldn't be shorter at all—in fact, all would appear completely normal.

Now let's do some time traveling. Go on, board a spaceship and take off for deep space.

As the ship approaches the speed of light, time for you seems to pass as it always has, 60 seconds in a minute, 60 minutes in an hour and so on through the day. It takes you about five seconds to tie your shoe, but to someone on Earth (assuming they could watch you while you’re in space), you are moving at a snail's pace; it takes hours to tie your shoe. Anyway, you continue on your journey with your shoes nicely tied. You slow down, come to a stop, buy a Moon Pie and some cosmic dust and zip back to Earth at nearly the speed of light. You arrive home, grab a cab to your apartment, unpack, wearily go through your mail, as you’ve noticed it’s piled up quite a bit since you left… in fact, you received in the mail over 200 Happy Birthday cards from your mother. That’s funny; you only aged two years during your flight, but, remember, you were time traveling. Two hundred years have passed on Earth since you were gone.

Congrats! You have successfully traveled forward through time. Now you want to go back? Sorry. According to Relativity, you can only move through time in one direction.

That’s it. That’s how you travel through time. If only we could go the speed of light, but the fastest man-made object so far, the Voyager probe which is somewhere just outside the Solar System, isn’t nearly quick enough. It would have to accelerate 318 times its current speed of 35,000mph to go the speed of light.

The only time traveling we can do now is one day at a time.

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