Trying to Understand Relativity (part 8)

In the Principia Mathematica, Issac Newton laid out his revolutionary theory of gravity.  He laid out with incredible precision exactly how gravity worked.  His formulas were used to calculate the exact orbits of the planets with an accuracy that stood for hundreds of years.  Say the word "gravity" and Newton's name is probably the first to come to mind.  His work is a milestone in the history of physics.  But although Newton literally wrote the book on gravity, he left out one little piece of information.  He never made a clear statement of exactly what gravity is.  Sure, he demonstrated how it worked in complex, intricate, mathematical detail, but he never really delved into what it was, beyond the idea that it was a force of attraction between objects that depended on mass and distance.  But what was this force?  How did the sun reach across the millions of miles of empty space and hold the Earth in it's place?  It was like a puppet master moving a puppet, but no one could find the strings.  Newton provided precise calculations of how the puppet master's hands control the puppet, and he basically left it to someone else to figure out the nature of the strings.

The someone else was Albert Einstein.  With his theory of General Relativity, Einstein showed that gravity was caused by the fabric of space-time being warped by the mass of an object.  The heavier the mass of an object the bigger and deeper the warp it caused in the fabric.  Imagine you have a blanket stretched out tight in the air.  If someone sets a baseball on it, it causes a dip around it in the blanket.  If someone sets a bowling ball on it, it causes a wider, deeper dip.  If you bring the baseball close enough to the bowling ball, it will fall into the bowling ball's dip and hit it.  This is what causes gravity.  This concept corresponds exactly with Newton's calculations of his "force" which varied according to mass and distance, but in a way he probably never imagined.

After spending the past month discussing time and time travel, it's got me wondering if there isn't a point at which Einstein's theory runs up against the same sort of wall that Newton did.  In case you missed it, I added a rather long edit to the last relativity post.  It starts about halfway down with the word "EDIT".  If you're actually making a serious attempt to follow this mess, then I suggest going back and looking it over.  I start with an explanation of the concept of relative motion, and then the constancy of the speed of light, and then I get into a thought experiment demonstrating how the time distortion effect can be inferred from these facts.  It's a rudimentary explanation of Special Relativity, and it's about as far as I've gotten at this point.  

Now, I'm told that I need to bring General Relativity into the picture to solve our Bob and Ann problem, but I'm not quite done with Special Relativity.  For one thing, I feel like I've barely got a finger hold on the idea.  I certainly don't feel confident that I have my mind completely wrapped around it, and I'm not ready to move on just yet.  But something else bothers me as well.  I kind of get how you look at the constant speed of light and you're forced to draw the conclusion that time distorts to compensate, but I'm not quite sure what this tells us about the nature of time.  This is where I feel like Relativity begins to run into that Newtonian wall.  Maybe it's my own limited understanding.  I spent some time yesterday, looking up "space-time" and "Minkowski space" and found a lot of equations that might as well have been written in ancient Sanskrit, for all that I was able to understand them.  But yet, I couldn't quite find what I was looking for.

I get the sense that Relativity looks at relative velocity and the constant speed of light, and then simply demonstrates the mathematical fact of time dilation, in the same way Newtonian physics looks at mass, motion, and attraction and then demonstrates the mathematical fact of gravity.  It's like, you point to where they show up in the calculations, but you're not really explaining them beyond the math.  Perhaps I'm being presumptuous.  Maybe the answer has just gone completely over my head.  Still, I can't help but wonder:  What is the significance of the fact that time can be distorted?  Why are mass and velocity the defining factors in this distortion?  What does this tell us about the nature of time?  Suppose time is the "dynamic flux", the constant change and motion of all matter in the universe that I proposed earlier.  Then, what does it mean that an observer can see this flux slow at high velocity?  If anyone has any answers, feel free to speak up.

It's like "dark matter", which is a theoretical construct that scientists use to make the calculations work in astrophysics.  They really have no idea what it is.  It's just something that shows up in the calculations.  Or consider the puzzling results of the double slit experiment that show up in quantum physics.  There is an old fable about three blind men stumbling across an elephant.  One of them grabs the trunk, and declares that the elephant is like a long snake.  Another grabs the leg, and declares that the elephant is like a thick tree trunk.  Still another feels the side of the animal, and declares that the elephant is like a wall.  I get the sense that these scientists are like these blind men.  There's something there.  It reveals its presence in the equations, but what it is remains a mystery, seen through a formula darkly.  I don't mean this to be derogatory to scientists, by the way.  They'd be the first to admit to being mystified.

The philosopher Immanuel Kant proposed that time and space were simply products of the mind, concepts that we filter reality through to make sense of it.  Frankly, I've always been appalled by this idea.  If time and space aren't objectively "real", then how can we hope to establish any sort of solid reality beyond ourselves?  The slightest flirtation with this idea and it feels as though the vast universe is about to collapse into my brain and become some sort of flat non-entity, like an image on paper with no depth.  It's likely that my understanding of Kant is as flawed as my understanding of Einstein.  But this idea that the speed of time's passing is relative to the speed of the observer forces me to at least consider if there isn't an element of perception involved in the nature of time.

And on that confusing note, I bring my contribution to "Time Travel Month" to an end.  I hope you've all had fun.  I enjoyed it, but I feel like I could go another ten years without talking about time travel and its strange paradoxes again.  It's been a little exhausting.  Oh...And hey, Doug, if you followed the link here from the first post of the month and you're reading this on February 1st, don't forget to mention something about the timetravelfund.com in the comments below that first post.  I don't want to waste any time getting on the ground floor of that amazing opportunity.  I'll thank you for it later.

(This post also available in extra cheesy version.) 

Grant Me the Serenity

We all have memories that are special to us.  Sometimes we wish that we could crawl back into these memories and somehow live inside them all over again, not to change things, but just to be there again, to feel the way the air felt different then, to look into the eyes of someone who has long since slipped away, to really savor and appreciate those moments in a way that was impossible the first time around when we had no idea how fragile and transient they were.  But the wave of time pushes us farther and father away from these memories.  We struggle against the sweep of the wave, straining to reach back and grab a hold of these things.  But the wave says, "No.  We have to keep going."

We've all had our share of regrets.  We turned right when we should have turned left.  We gave in to temptations that we knew we should have resisted, and we eventually had to face the consequences.  We acted on what we knew then, instead of what we know now.  We let opportunities slip through our hands, thinking that another one would be right around the corner.  We've all had moments when we finally realized it was too late to fix a mistake, and we clinched our fists and cursed our inability to undo our own stupidity.  We've all held something priceless in our hands, and we've stumbled and faltered, and before we even knew what had happened, we watched the thing shatter on the ground.  These shattered pieces are the wave of time.  One moment the thing is whole, and in the next it's laying there, broken forever.

But it's not only our own regrets.  We watch as the whole world moves and changes, evolving and transforming beyond our control.  We watch our old elementary school being torn to the ground.  We watch them build a shopping center in it's place.  We watch as stars fade out and things rust and rot away.  We carve our names into a tree, as though preserving it in stone, only to see that same tree chopped down and cut into firewood and then burned away.  We see the people around us passing one by one.  The wave keeps advancing, carry some forward, and leaving some behind.

But the wave sweeps on, and eventually we all succumb to the great equalizer.  Our bodies age and whither, until they're finally broken by the wave, scattered in pieces or laid in the ground.  New life is born in our place, and it grows and changes and undergoes the same processes along the crest of the wave.  Even the sun itself will die out and the galaxies will collide, and all the intricate traces that we've made in the sand will be smoothed out and erased by the relentlessess, unstoppable sweep of the wave.  But another star will be born in it's place, and again the process will go on, on a larger scale, until even all the stars and galaxies themselves are no more.  Eventually the wave will wash the entire slate clean and there will be nothing but darkness and emptiness and vast silence.  Then the universe will collapse in on itself, and maybe the result will be another Big Bang, and rebirth will happen once again on the largest scale of all.  And the wave will press on.

I know that time travel isn't a subject for everyone.  I knew that going into this.  Some people are fascinated by it's puzzles and possibilities, while others see nothing but confusing nonsense.  Nevertheless, I think time itself is something that we all care about.  It is one of the fundamental aspects of our existence.  In some form or another, it is a dimension of nearly every thought we have.  We think of it thousands of times a day, even now as you think of how many times you think of time.  It can seem cruel and relentless.  It can seem like a road of opportunities, waiting ahead.  Perhaps the true power over time comes not in looking for ways to manipulate it or alter its course, but to accept it as it moves us along to the next thing that's just about to happen...now.

(This posts is also available in extra cheesy version and chaos flavor and full-blown neurosis.)

If I Had a Time Machine

If I had a time machine,

made from a stellar implosion and a quantum string,

I'd travel back to ancient Rome,

where I must have dropped the first cell phone.

I'd visit the future once or twice.

I'd invent the Antikythera device.

The Voynich Manuscript, that was also me.

It's actually a chicken recipe.

I'd have all of history at my disposal,

from Alexander the Great to Karl von Cosel.

First, I'd take a few snapshots of the dinosaurs,

then I'd pelt Issac Newton with some apple cores.

Drop in on Hemingway to shoot the breeze,

but I'd pass on that drink with Socrates.
I could wait in Roswell for the aliens to land,
or learn the identity of The Somerton Man.

Killing Hitler, you'd think I'd have that one nailed,

but Operation Valkyrie has already failed.

This time travel stuff is a little confusing.

Cause and effect, nuclear headache inducing.

It could all turn out I'm my own great grand pa,

but then how did I get here after all?

Well, at least I'd be here and able to dream,

if I had a time machine.    

 I suppose I could have hyperlinked some of the obscure references here, but I didn't want the whole thing to be a minefield of blue words.  So, instead, I figured that I'd make it like a scavenger hunt and turn this into a contest.  I figure that there are about...oh, a dozen or so different references, some familiar, some obscure.  The first person to find at least five of them and post descriptions of each in a comment below will be the first recipient of the soon-to-be-coveted "Fountain of Useless Knowledge Award"  Feel free to use Google or Wikipedia, or whatever.  Consider it an open book test.  If more than one person submits the answers before I get around to approving the comments, I have no problem giving out multiple awards.  I have an infinite pile of these things.

(This post is also available in extra cheesy version and chaos flavor.)

Of Fortune Tellers & Predestination

You'll recall that early on in our little adventure in time here, I made the point that temporal paradoxes were, by definition, impossible.  I concluded that if a concept of time travel could not be conceived that didn't run into these paradoxes, then you would be forced to conclude that time travel itself is impossible.  Well, the inverse of this is also true.  If someone were to suddenly appear out of the blue and toss you the keys to a time machine, then you would be forced to conclude that temporal paradoxes are apparently not a problem.  You may not be able to wrap your mind around how that could be possible, but nevertheless, you would be holding the proof in your hands.  The constant factor is that paradoxes can not happen in reality.  At this point, the simple solution would be to declare time travel impossible.  Being presented with the reality of time machine would force you to cast about for another explanation, but the principle would remain the same.  Well, it appears that there's a very old and familiar phenomenon that raises the issue of a temporal paradox, and you don't even have to bring a time machine into the equation.  All you need is a call to a psychic hot line, and the power to believe.  Whooo Ooooo.

The paradox in question is called the predestination paradox.  I mentioned briefly, while discussing the ontological paradox, that the two were close cousins.  In fact, many of these paradox scenarios involve a combination of the two.  The ontological paradox is where a thing causes itself to exist, whether that thing is a physical object or merely a piece of information.  The predestination paradox is where an event causes itself.  The ontological paradox is like a domino coming into existence out of nowhere, while the predestination paradox is like a domino knocking over the same ring of dominoes that knocked it over in the first place.  It's a bit more subtle and harder to see, because there isn't a tangible object to focus the imagination on like there is with the ontological paradox.  But once you see it, it's a lot easier to understand how one could happen in a time travel scenario.

Let's say, for instance, that when you were little, your grandfather told you a story about a time traveler that appeared out of thin air in his yard one day when he was a kid.  As you grew older, you doubted the literal truth of this story, but it still stuck with you and held a special place in your imagination.  It inspired you to dedicate your life to discovering how to travel in time.  Finally, one day, you succeed.  You travel back to the day that grandfather told you about, hoping to shake hands with the fellow time traveler that inspired you, only to arrive and find no one else there.  It's just you and little grandpa.  Then it dawns on you.  You were the time traveler that appeared to your grandfather that day.  But...then that means that the event that inspired you to travel in time was caused by the event that inspired you to travel in time.  You begin to see how cause and effect become like a run of dominoes looping back on themselves?  Like the pocket watch, the event is self-generated.

Like I said, it's a little harder to see.  Try this one: Let's say that your dog runs out and gets hit by a car.  You're very upset about this, but you just happened to have a time machine and you believe it grants you ability to change the past.  You believe that you can go back and save your dog.  So you hop in your time machine and travel back to that fateful day.  You speed to the scene, hoping to get there before the accident happens again.  You remember the exact time.  You look down at your watch.  Oh no, it's only seconds away!  You look up just in time to see the dog run out in front of your car.  It's too late.  Again, you have the event causing itself.  Your hitting the dog is what makes you go back and hit the dog.  (Sorry about that.  Feel free to take a few seconds to go pet your dog if you have one.)

In most of these predestination scenarios there usually seems to be an element of ignorance and good intentions gone awry.  You don't know that trying to save the dog is what actually resulted in its death.  You don't know that your grandfather was talking about you.  And so on.  Only in completing the circle of events does the twisting turn of fate dawn on you, dun dun dunnnn!  It might be easy to conclude that the predestination paradox is limited to such cases.  The problem is actually far more insidious.  You'll recall that I said that the grandfather paradox could apply to any successful attempt to change the time line.  Well, the predestination paradox could possibly apply to any interaction with the past whatsoever.

Causality is a funny thing.  Every event from the Big Bang up until this present moment is intimately interconnected.  Everything that happens is caused by something else that happens which in turn was caused by something before that.  It's a vast and intricate network of interlocking chains.  It's too big and complex for any one person to see how it all fits together.  Once you grant the premise that a time traveler was always present in the past, that things always happened the way they did, then any action that the time traveler takes, no matter how small, becomes a pre-existing part of this network.  There's really no way of telling how their actions might have affected the intricate chain of events that led them to be there to be there to affect the chain of events.

Suppose you travel back to 1955.  You're walking down a street and you briefly brush against a woman's shoulder.  She stops and looks back, you apologize, and she continues on her way.  It's a small, momentary incident, lasting only seconds.  But that brief delay causes the woman to be a few seconds late getting home, and she misses the woman her husband has been having an affair with leaving the house.  Their marriage endures, instead of ending that day.  The husband keeps his assets instead of dividing them in the divorce.  He has those assets invested in stocks that increase in value.  He leaves a fortune to his grandson who starts his own company.  The company funds various research projects, including your ground-breaking time travel device.  So again, you caused the chain of events that caused you to be there to cause those chain of events.  And that's an easy one.  There's always a chance that the traveler's actions could somehow be connected to what eventually leads him there, no matter how long and complicated the chain.  Once you move cause and effect out of its chronological place in the network, the problem is nearly inevitable.

So where does this psychic hot line come into all this?  Well, so far we've only discussed ways that a traveler returning to the past can create a self-caused event.  The problem can also work in the other direction.  In fact, the name "predestination paradox" implies a future destiny that fulfills itself.  If you learn of a future event and you knowledge of that event is what causes it to happen, then you're faced with a predestination paradox.  It's an identical situation.  Let's say that instead of owning a time machine, a psychic tells you that at 3:15 tomorrow your dog is going to get hit by a car.  So, tomorrow you leave work early, and rush home trying to stop this tragedy from happening.  You're almost home.  You look at your watch.  It's almost 3:15.  You look up just in time to see the dog run out in front of your car.  It's the exact same thing, except this time the psychic is the time machine, receiving information from the future.  (Go pet the dog again.)

You've probably heard of the term "self-fulfilling prophesy".  Taken literally, this is basically the same thing as the predestination paradox.  Fictional accounts of this particular time paradox are far older than The Terminator or 12 Monkeys; they go all the way back to Ancient Greece.  In the famous story of Oedipus, Oedipus is warned by an oracle that he will one day kill his father and marry his mother.  Horrified by this idea, he flees home and gets as far away from his parents as he can.  Well, it turns out that those weren't his real parents.  They live in the kingdom that he flees do.  He kills a man on the road, his father.  Then he marries his widow, which turns out to be his mother.  Rather than post their escapades on the internet, he stabs his eyes out instead.  (It was a different time.)  So the oracles prophesy is what causes the very thing that the oracle prophesied.  Predestination paradox.

So, you see, this issue of paradoxes don't just raise the question of whether time travel is possible.  They also raise the question of whether any kind intuition of the future is even possible.  This recent study seems to suggest that it may be possible.  So where does that leave us?  What do you think?  What do you believe?

(This post is also available in extra cheesy version.)         

Possible Methods

You'll remember that at the beginning of the month I posted all the titles for all the posts I would be writing this month.  You may be wondering how this was possible.  Well, there's a funny and completely fabricated story behind that.  What I'm about to tell you may be a little shocking.  You see, I've invented a machine that allows me to have very brief glimpses of the future.  I made it out of a wooden board and some parts from an old lamp that I found in the spare room.  It works like this: the wires are mounted on the wooden board, stripped at the ends, and placed about a foot and a half apart.  Then the cord is plugged into the wall socket.  Normally, the wires would be too far apart for the electrical charge to cover the distance between the wires.  That's where the magnet comes in.  It's mounted to the board between the wires.  It spins at a variable speed, creating a magnetic field that allows that electrical circuit to be completed.  The speed that the magnet spins is controlled by a dial on the control pad.  So what powers the spinning magnet?  That's the interesting part.  It's powered by the electricity traveling between the wires.  You see, the spinning magnet allows the electrical circuit to complete and the completed circuit powers the spinning magnet.  This results in a variable closed time-like curve.  This creates a "time field" between the wires.  The time curve advances into the future, constantly trying to overcome itself.  The faster the magnet spins, the faster it advances into the future.

Patent Pending (Around 2015 from what I've seen.)

Now, having created this device, I placed my head into the time field, so that the electrical feeds were lined up with my temples.  It was extremely painful, but I was able to get a flash of the future.  It was very brief.  Believe me, you can't hold your head in that thing for very long, and if you use it too many times, I'm pretty sure you'll get brain cancer.  Anyway, in this brief flash, I saw my computer screen.  It was just as I had published my last post of the month.  Along the right side I saw the titles of all the archived posts.  I made a quick note of them and then pulled my head out of the time field.  Smoke was pouring from my temples and my brain was throbbing, but I quickly grabbed a pen and paper and wrote down all of the post titles.  Then I think I blacked out. 

So, I knew the titles, but I didn't know anything about the content of the posts, which brings me to this post.  You see, I just assumed that "possible methods" referred to possible methods which physicists had proposed for traveling in time.  After all, this was Time Travel Month, right?  So, I set out to write a post about that.  Well, it wasn't going well.  I was knee deep in relativity, worm holes, the Casimir effect, and rotating lasers.  It wasn't making sense to me at all.  Even worse, I had the weirdest feeling that I wasn't writing the post I was supposed to write.  Something just felt...off.

Then I come to find out that Chanel over at Fabulously Neurotic had given me The Stylish Blogger Award.  I certainly appreciated the thought on her part, but I wasn't sure how I was going to fit it in with my time travel themed schedule.  I had seen the titles unmistakably.  There had been nothing about any awards.  There was no doubt about it.  I had to stick with the titles I had seen.  How was I possibly going to do this?  I was going to have to devise some method of fitting it in.  And then it hit me.  The title didn't refer to the "possible methods" of time travel.  The title was referring to the possible methods that I could come up with to accept this award and not disrupt my time travel theme.  These were my options:

1. I could just wait till next month to deal with this award.
2. I could continue to write my post that was going nowhere and then tack the award thing on at the end.
3. I could just make up a bunch of crap.

Well, it seems like option 3 is always my go-to move when I get stumped, so here I am, at it again.  On to the award:

It appears that there are some rules that go along with accepting this award:

1. Link back to the person that gave you the award (check)

2. Share seven things about myself.

3. Pass it on to ten blogs I'm following

4. Tell them I gave them the award (You know what; I'm going to pass on this last part.  Consider this a little experiment to separate the wheat from the chaff.  I lost a follower the other day.  Apparently someone had something better to do that read my uneducated ramblings.  Can you imagine?  So, consider this a test.  If you want this award you're going to have to come here and read this nonsense.  I'll know who reads, by who knows that they got the award.  Yeah!)

Okay, so seven things about me, hmmm:

1. I have a circular spot on the side of my head where hair has never grown.  I don't know why.  Seriously.

2. I have three cats, a dog, and wayyyy too much hair around my house.

3. But I don't have enough hair on my head.

4. I thought the Transformers was like the greatest thing when I was kid.  Now, I have no idea why I thought that.

5. Supposedly, I have an I.Q. of 142.  (Hey, you asked.)

6. I have a memory from when I was two weeks old.  I was born with some kind of rare intestinal defect where my muscle was knotted around my intestine or something.  I was throwing up almost all the food I was given, I guess.  One day when I was 2 weeks old, I was choking on my food and had to be rushed to the hospital.  I remember being on the couch and my mother running into the kitchen to use the phone on the wall.  I remember another baby that was in the room with me that had all these tubes and wires attached to it.  It seemed like there was a glow around it.  I remember everyone feeling sorry for this baby.  No one believes that I remember these things, but I do.

7. I did briefly attend college.  I majored in psychology.

Okay, so who am I going to give this too that doesn't already have it?

Vincent @ Wayfarer's Notes.  He's got an awesome blog, full of all kinds of deep musings.


Darv2005@Attitude and Pepper Spray.  An insider look at our penal system.


Rachel Hoyt@Rhyme Me a Smile. She's rhymes at all times.


Deanne@Some Days or Now. I really like her perspective on things.  And she's never afraid to disagree with me.


Tommy Douglas@Notes on Living.  We still don't know what happens when you strap buttered bread to a cat, and we only pray the world never finds out.


Martin Redford@The Perfect Male Blog.  By definition, trying to help me become a better person.


Doug Stevens@I Like Cheese.  Who doesn't like Cheese?


Patricia Lynne@My Journey Through the Pages.  Some nice honest thoughts about the writing a publishing process.


Asha Coleman@Random Ramblings of an Agnostic Mom.  She's just hilarious and clever, and my dreams make more sense to her than they do to me.


Lea White@My Writing Journey.  She's my daughter and she almost never reads this.  Actually, she'll probably be the only person on this list that doesn't realize she got the award.  Serves her right.


So there you go.  They said it couldn't be done, and I did it.  Actually, I said it couldn't be done.  That'll show me.


(This post is also available in extra cheesy version.)

The Infinite Pocket Watch

Consider the following story.  On your eighth birthday your grandfather gives you a gift.  You unwrap it and find an antique pocket watch.  It hangs from a silver chain, and it has a beautiful carving of a clipper ship on the lid.  The back is engraved with the words, "The Best of Times."  It's a nice gift, but you're eight.  You wanted a toy truck.  From that day forward you vow revenge on this old coot.  If it takes you the rest of your life, you're going to crack the secret of time travel and then travel back and give him a present when he was eight, a bullet to the head.  Sure it's little extreme, and sure you might be nullifying your own existence, but to hell with the consequences!  You were really counting on getting that truck.  So, you tinker away in your basement on your time machine, plotting your revenge, and you carry the watch for thirty years, as a reminder of your vow.  Finally, everything is ready.  You travel back sixty years to the day your grandfather turned eight.  You find him playing in the dirt in his front yard, playing with a toy truck of all things, what nerve!  You walk up to him and throw the pocket watch in his face and yell, "Happy birthday Jerk!", as you raise the gun to fire.  Just then, a meteor falls from the sky and lands right on top of you.  Your eight year old grandfather blinks in surprise at the giant smoking rock in his front yard.  Then he notices the pocket watch laying in the dirt beside his truck.  He picks it up and dusts it off.  He holds on to this watch for the rest of his life, as a memento of this strange incident.  On his grandchild's own eighth birthday, he presents it to you as a gift.

So now you see the new can of worms we've opened.  We've disposed of the grandfather paradox with the idea that whatever happened in the past, already happened and can't be changed.  You can't kill your grandfather because you already tried and you ended up getting flattened by a meteor.  That's what happened.  But now we have a new problem.  In the process of your assassination attempt, you gave your grandfather a pocket watch, the same pocket watch he gave you.  So this raises the obvious question: where the heck did this pocket watch come from?

This is what is known as the ontological paradox.  This is where information or objects loop through time without a clear origin.  The ontological paradox and its close cousin, the predestination paradox are the result of the theory where the time traveler was always in the past.  The grandfather paradox arises from an inconsistency between cause and effect which results from a change in the time line.  The effect cancels out the cause.  With these new paradoxes you have the opposite problem.  In the predestination paradox, you have the effect causing itself.  In the ontological paradox, you have an object or information originating with itself.  In both cases, you have a closed loop where the past is fulfilled by the future that has resulted from it.  The constant and unchangeable nature of time, which was once the handy solution, has now become the problem.  Sure, it's already happened, that's why it's going to happen.

Now, my first, intuitive reaction to the ontological paradox is simply to dismiss it as a cute little trick of fiction.  Yeah, it's neat and everything that the grandfather gives you the watch he got from you, but is this really a legitimate concern?  Could it actually happen in the scenario?  Well, remember the "links" I put in the post at the beginning of the month?  Suppose I had been able to read the posts before I wrote them.  I'd know what I was going to write, and then I could have just gone back and written it based on what I read.  But then, where would the words and ideas have actually come from?  They would loop around through time, originating with themselves.  I would just be copying from myself what I had already copied from myself, without ever actually writing the original material.

Okay, so that covers information, but what about an object.  Well, suppose you stole the Mona Lisa from the Louvre.  Then you take it back in time and leave it on Leonardo Da Vinci's  doorstep.  Now, Leonardo could preserve his integrity and simply throw the thing away, but even so, he couldn't forget what he saw.  The Mona Lisa would inevitably influence his painting of the Mona Lisa, perhaps even giving him the idea.  So, at the very least, you'd still have information running in a loop.  But what if Leonardo wasn't so scrupulous?  What if he just looked this way and that, took the painting inside, and then eventually passed it off as his own?  Now you've got a solid object, paint and canvas, looping around through time, and God only knows where it came from.  So yes, the ontological paradox is definitely a real problem.  All it would take is setting the Mona Lisa on Da Vinci's doorstep.

If you look closely, you'll notice a mathematical problem that arises from this as well.  Take a look at our pocket watch again.  Between the day your grandfather picks it up and the day you take it back in time with you, sixty years elapses.  The hour hand has made 43, 800 rotations around its face.  So that means that the watch is at least sixty years old when you throw it at your grandfather.  So it was already sixty years old when he picked up, then  it was carried around for another sixty years before it was taken back in time.  Okay, so the hour hand has made 87,600 rotations and the watch was at least 120 years old when your grandfather picked it up.  But then it was carried for another sixty years, so it was really 180 years old.  Round and round it goes until you're forced to conclude that the hour hand has made an infinite amount of rotations around the face.  Not even the best made watch could last forever, let alone one that wasn't made in the first place. 

The problem here is that you have no starting point to calculate the watch's age from.  It's not that the loop itself keeps repeating.  The events only happen once, but yet the numbers keep piling up.  You can never establish exactly how old the watch is at any one point, so you're forced to keep compounding the time it traveled around the loop.  So, not only does this watch have no beginning; it has no ending either.  It exists for eternity in an isolated circle of events.

Or how about this: Let's say you work as a scientist in a lab.  You come in on Monday and find a mysterious petri dish on the table.  You take the dish back to Sunday and leave it on the table for yourself to find on Monday and bring back to Sunday.  The microbes in this dish double once a day.  So, if there were at least two microbes on Sunday, then there were four by Monday, which means there were at least four on Sunday, which means there were eight on Monday, which means there were at least eight on Sunday, which means there were 16 on Monday, which means....Yes, quite a can of worms indeed.

I wish I had a solution to offer for this, but honestly, I'm stumped this time.  I have no ideas or theories at the moment.  Even the multiverse won't save us this time.  We can't skip over to the universe next door, because we aren't changing anything.  And yet, solve it we must, for one could argue that our entire existence is the ultimate ontological paradox.  You know the old conundrum: what caused the thing that caused the thing that caused The Big Bang?  Where did the stuff come from, that all this...stuff came from?  You could go around with it forever, but here we are, the most infinite pocket watch of all.  So, the solution is out there.  Maybe I'll find a note on my refrigerator tomorrow morning, explaining it all.  After I read it the next day, I just have to remember to travel back to yesterday and leave it on the refrigerator.

(This post is also available in extra cheesy version.)                   

Correspondence with My Future Self

Some of you may be wondering if I have the slightest idea what I'm talking about with all this time business.  You may be wondering, who died and made him the king of time travel?  Where is his proof?  Where is his time traveling sports car?  Where are all his degrees and important science awards and...stuff?  Why is he so impossibly good looking?  Okay, maybe not that last one.  I figured I'd try to slip that one in there.  But let me ask you this: How many of you have tried to actually test the possibility of time travel?  Well, I have.

As I've said on more than one occasion, I was very interested in time travel when I was a kid.  When I was twelve, I began to wonder if this obsession of mine would ever yield any results.  I wondered if I would ever find myself traveling in time some day.  What can I say?  I was a weird kid.  Anyway, it occurred to me that there might be a way of finding this out without learning the virtue of patience.  I decided that I would try to write myself a letter, my future self.  I would give my future self instructions to meet at an exact time and place.  I'm not sure why I thought my future self would be at the beck and call of a twelve year old kid, but I figured that he was probably a pretty cool guy.  So I wrote myself a short note and included the time and date: September 6, 1988 at 6:35pm (see kid, I remember) and the location where I'd be.  Then I put a note on the envelope specifying that it wasn't to be opened until 2010.  2010 sounded like it was way, way in the future.  Certainly there would be time travel by then.  So I took this letter down to the mailbox, dropped it in and waited...and waited.  Nothing.  Well, I wasn't giving up.  I wrote another letter.  This time I said to meet at 7:05pm and left a note on the envelope saying not to open it until 2015.  I dropped it in and...again, nothing.

I learned something about my future that day.  I didn't learn who I was going to marry.  I didn't learn if I was ever going to be rich.  I didn't learn if I where I was going to live.  Technically, I didn't even learn whether I was actually ever going to be able to travel in time.  I learned one, simple thing.  I learned that I was never, ever, under any circumstances, going to travel back in time to meet that twelve year old boy standing by that mailbox.  If it was going to happen, it would have happened.  In this case, I was the silver jumpsuit guy, and I never showed up.  I know; pretty rude.  But suppose it was possible now, and I decided to go back there.  Well, then why don't I remember it?  If I did go back there, and the whole "multiverse" thing was true, I guess I would be meeting a me from a parallel universe then.  I don't want to meet some me that isn't me, some Asimovian construct that goes through the robotic motions of being me.  Why should he get to have all the fun?  What a weirdo.  But this isn't what you really want to know, right?  You want to know where the hell I sent those letters.

Well, I was living in Ohio then.  My parents had divorced years ago, and my father had ended up moving out to Arizona a few years later.  So I sent the letters to his address, but with my name on them.  I figured that he would stick them in a drawer and save them for me for the next twenty years or so.  Well, I was never much of a letter writer, so he was quite surprised to get something in the mail from me.  He completely ignored the notes on the envelopes and opened them.  I probably could have brought him up on federal charges for opening my mail, even if it was in his mailbox.  He got a big kick out of the whole thing.  He probably either thought it was very clever or that his son was slightly autistic.  Either way, he told this story to everyone in my family way, way more times than I cared to hear it.  It's only because I have twenty three years on that kid now, that I can even rationalize my own embarrassment  enough to talk about it here.

The future is a funny thing.  You never know how it's going to turn out.  My dad died in 2008.  How could either of us have known that I was giving him letters to deliver beyond the grave?  You never think of these things when you're twelve.  You think people are always going to be around in the years to come.  They'll be there to deliver your letters.  You think you'll have it all figured out.  You never see anything bad coming your way.  So yeah, I'm glad he opened the letters.  I'm glad they didn't just sit in a drawer as a mystery that he'd never know the answer to.  I'm glad he got a kick out of the whole thing.  I'm glad I can look back on it all with a smile.  When it's all said and done, that's more important to me than shaking hands with myself beside a mailbox.  Now, if I could only tell that kid that. 

(This post is also available in extra cheesy version.)        

12 Monkeys: Mental Divergence

The Path of the Virus

I love a good time travel story.  I have seen all three of the Back to the Future movies more times than I can remember.  I could tell you precisely how the time travel rules change from one Terminator movie to the next.  I even sat through The Time Traveler's Wife, God help me.  But, my all time favorite has to be 12 Monkeys.  It faithfully follows the principle that the past can not be changed and then takes that principle to the point of absurdity as causality circles back on itself like the monkeys chasing each other's tails round and round, representing the twelve hours on the face of a clock.  The funny thing is, though, in a certain sense 12 Monkeys isn't about time travel at all.  It's about mental illness.  It's about the fine line between insanity and what we're willing to believe.

In the late 19th century a man named Daniel Schreber was treated from what was then known as dementia preacox, a illness which we now call schizophrenia.  He believed that God and his psychiatrist were trying to turn him into a woman.  He believed that God was trying to penetrate his skull with "rays of sperm".  At one point, he became convinced that the outside world had ended and that the people and doctors that visited him were only mere facsimiles of the people they represented.  In 12 Monkeys, James Cole is locked in a mental institution in 1990 following a violent outburst.  He believes he is from the future.  He believes that billions will die in 1996 from a deadly virus.  He believes that he has been sent to the past to collect information, and that the people around him are already dead from his perspective, ghosts of the past living in a world that has long since been abandoned and reclaimed by the animals.  He believes that there is a transmitter in his tooth that transmits his location to the people in the future.  He often hears a disembodied voice when calls him "Bob."  Much like Schreber's doctors, Cole's doctors consider him to be insane.  The difference in 12 Monkeys is that it's all treated as if it's completely true.

There's a statement at the beginning of the film that suggests that Cole's story is based on a real patient's delusion.  The issue the film raises is how do we know what's true and what isn't?  How do we know if a man who claims to be from the future is insane or telling the truth?  We hear all the time from people who claim to have been abducted by aliens, people who claim to be channeling the dead souls of Egyptian pharaohs, and yes, even people who claim to be from the future.  It's easy to be dismissive and declare that these people are either "crazy" or lying to get attention.  But how can we really be sure?  Maybe aliens really are secretly communicating with certain chosen people via their television sets.  When it comes to committing someone to an institution where do you draw the line between someone who needs help and someone who claims something that you "know" is impossible?

Having seen a few cases of schizophrenia for myself, I believe that the defining feature of the illness is the lack of internal logic.  It's one thing to have someone tell you that they've seen a UFO.  It's another thing to have someone show you a jar of chunky peanut butter as proof that Jesus controlled an army of robot spiders.  If you've ever been there, you know the difference.  I'm not saying that you necessarily believe every person that tells you they've seen a UFO.  I'm just saying that don't just dismiss them as insane because you don't believe in UFO's.  If it sounds like it makes sense if you granted the premise that it was true, then you can at least give them the benefit of the doubt, and agree to disagree and remain skeptical until you see some proof for yourself.  

Following the recent shooting in Tuscon, one of my cousins in Arizona posted links to some Youtube videos that this Jared Loughner kid had made a few months earlier.  Most of them feature little blocks of text talking about "conscience dreaming" and "a new currency".  I've watched these videos, and I really don't see the slightest possibility of making any kind of sense out of anything he's saying.  Obviously, I don't need to tell you that I'm not a doctor, and I don't know the kid.  It's hard to make a determination based on a few words taken out of context in an online video.  Is it possible that he has some valid theories about the true nature of reality?  I suppose.  But strictly on the basis of what I've seen, and with my extremely limited qualifications, I think there are definite signs of metal illness.  In any case, I can't quite imagine any insight into the nature of reality that he might have had that would justify the actions he took.

12 Monkeys presents a very extreme case.  True though it is, Cole's story sounds every bit as much like dementia as any story could.  Is the movie simply trying to present a concrete dramatization of a schizoid delusion, or is it just doing everything it can to push the boundary between the possible and the insane?  It's hard to say.  At one point he vanishes from a tiny locked room where he was sedated and restrained to the floor.  One of the doctors speculates that Cole must have slipped the restraints, climbed the high, smooth walls, and escaped through an extremely small vent in the ceiling.  Given what he believes, this is the only logical explanation that he can come up with...and it's just as crazy as anything else in the movie.

(This post is also available in extra cheesy version.)

John Titor

There's a little bit of everything on the internet these days.  There are probably forums where people discuss their collection of silly straws, and youtube videos featuring stop-action animation of little stick figures someone has made from their fingernail clippings.  There are probably sites dedicated exclusively to photos of pregnant Siamese twins soaking their feet in yogurt, if you're in to that sort of thing.  Heck, you can probably find a separate site if you insist on the yogurt being non-fat.  It's a real human carnival.  So, it's probably inevitable that sooner or later a time traveler was going to stop by for a visit.

His name is John Titor, and in January 2001 he claimed to be from the year 2036.  He claimed that a third world war will break out in 2015, killing billions of people.  He claimed that he traveled back to 1975 to find an IBM 5100 computer, which they apparently will need in the future to fix some sort of computer problem that's due to crop up in 2038 that's similar to the Y2K problem.  I guess his time flight had a layover in the early 2000's, so he made a pit stop here and shared his story with the world via the internet and the Art Bell radio program.  He even saw no danger in sharing the colonel's secret recipe for time travel. (You'll be happy to know, Doug, he claimed that the multiverse theory is correct.  So, you have at least one possible authority in your corner.)

Do I believe any of this?  Is this the silver jumpsuit guy?  Well, while it would be a tragedy to be dismissive of anyone claiming to be a time traveler, and thereby missing the opportunity to appreciate having one right in front of us, I'm definitely a little skeptical...to say the least.  The story is a little Terminatoresque, don't you think?  Plus, 2036 seems like a fairly ambitious deadline for cracking the secret of time travel, even without a third world war and the death of billions providing a bit of a distraction.  With the struggle to survive and the effort to dig the bodies of loved ones out of rubble, you wouldn't think there would be a lot of time on their hands to figure out how to manipulate the space-time continuum.  After all, there's a reason they weren't splitting the atom back in the dark ages.  Also, since he ascribed to the "multiverse" theory, you'd think he'd be trying to stop this coming world war, instead of mooing about mad cow disease.  At the very least, he could have warned us about 9/11.  I'm just scratching the surface.  These are just a few problems I see at a glance. 

There are plenty of people who do believe him, though.  Of course, there are always people out there that will believe in anything, no matter how crazy it is.  I'm sure there are people that would believe it if someone told them that shoving pyramid shaped sugar cubes into their rectum was the secret to immortality.  You'd think that the fact that the things he's predicted up to this point haven't happened would lay the whole thing to rest, but we live in a society where people are led to believe that it's a virtue to hold fast to your stupidity...errr, I mean faith in the face of reason.  So, really, is it any wonder that some refuse to let it go?

The Titor Time Line

He predicted that the 2004 election would lead to "civil unrest" that would erupt in 2008.  I suppose that all depends on what you call, "civil unrest".  Are people pissed off?  Sure.  Is there war in the streets?  Ehhh.  He claims that he was a soldier in the "Fighting Diamondbacks" when he was 13 in 2011.  Well, the year is still young, but most of the 13 year-old boys I see are still playing their Xbox.  Maybe he was referring to a new Halo game.   He predicted that mad cow would be a "pandemic."  I just ate a hamburger this morning, and I'm not too worried.  He predicted that the U.S. would split into five different territories, but I'm not sure when this is suppose to happen.  Apparently some time before 2015.

At any rate, if it's a hoax, it's a pretty good one.  As a part time fiction writer, I can always appreciate the imagination that goes into a good lie.  I just wish I would have thought of it first. 

(This Post is also available in extra cheesy version.)

Superman & The Wave Model

If you've ever seen the 1978 film Superman, then you may recall a very memorable scene that happens near the end of the movie.  It's been awhile since I've seen it, so you'll forgive me if I'm a little hazy on the details.  Okay, so, Lex Luther had just activated some sort of earthquake-causing machine along the San Andreas fault line as part of the world's most bizzare real estate scam.  A big crack opens up in the earth, spreading across the land.  Lois Lane is driving down the road when it splits open in front of her, and then her car falls into the spreading crevise and she dies.  By the time Superman reaches her, it's too late to save her.  Or is it?  He flies out into space and begins to circle the Earth counter to its rotation.  He flies faster and faster, and as he does, we see the Earth slow to a stop and then start to spin the other away.  As he continues to circle the Earth, we are treated to cutaway shots of everything on Earth happening in reverse.  We see Lois' car fly back up out of the crack, the crack seals back up and recedes from the direction it came, ect.  These cutaway shots establish an important distiction.  Superman is not traveling back in time to save Lois.  He's turning back time itself to before she died.  Naturally, this is a ridiculously implausible concept, and it may seem as though I'm splitting hairs with the distinction I'm making.  But would you believe me if I told that our entire concept of time might hang on this difference? 

In my previous post, I formulated my position on the grandfather paradox by saying, "It would be impossible for a time traveler to change the past."  I knew that I had to choose my words carefully, because I knew where I was going with this.  I needed to keep the statement simple and absolute, without a lot of provisions and qualifications, but it also had to be precise.  I couldn't quite say, "It's impossible to change the past.", because, oddly enough, if you take the time traveler out of the equation, then it MIGHT be possible to do just that...at least in principle and on paper.

Time travel, as we typically understand it, would only work in a certain model of time.  I'll refer to this as the "linear model", because in this model time is...well, like a line.  In order from someone to travel freely on this line, the line itself would have to exist in a completed, static state.  Consider this: Picture time in this model as a long, straight country road.  As you drive along this road, this represents the way you experience time.  You experience the section of the road you cover as a succession of moments that you call "the present".  There is no special point on the road itself designated as the present, rather the present is just your perspective of the road as you drive over it.  Now, if it were possible to pick up your car and move it back to a section of the road behind you, then that section of the road would have to still exist back there in some sense.  If it were possible to skip ahead to a section of the road far ahead of you,  then that section of the road would have to already exist up there in some sense.  If, in all this skipping around, you encountered other cars on the road, they would consider the section of the road they're covering as the present, and you would be forced to conclude that the section of the road that you consider the present isn't a unique perspective.  You would be forced to conclude that there are just different cars driving on different sections of the road.  

In other words, for it to be possible to be able to pick your car up and move it around freely to any point on the road, then the road itself has to be finished product, fixed and complete.  That would mean that past, present, and future have all already happened and we are just experiencing our position on the road from our own subjective point of view.  That would mean that any time traveling that anyone is going to do, they've already done, and if they're going to go to what we consider the past, then they're already been there, and they've already done whatever they did.  This is why a time traveler can not change the past.

If there's a part of you that rebels at this idea, if there's a part of you that's uncomfortable with the notion that the future ahead of you has already happened and that it's as inevitable and unchangable as the past, if there's a part of you doesn't like feeling the stranglehold of fate slipping its icy fingers around you restricting your freedom to make your own choices, then don't worry.  I feel the same way.  There's a way out of all this.  We just have to ditch the time traveler.

We've been looking at time on the linear model.  But what if time isn't like a "line" at all?  What if time isn't a fixed thing that we move on?  What if it's time itself that's moving, sweeping us along like a wave?  In this model, the present is no longer just a matter of perspective; it's no longer a subjective point on a quiet eternal road.  In this model, the present is right now, right here along the cutting edge of the wave.  The crest of this wave is composed of the dynamic flux of everything in the universe, galaxies colliding, mountains crumbling, a ball as it flies through the air.  It's composed of the motion, the evolution, the degeneration, the growth, and the changing of all matter and energy and even consciousness.   In this model, the present is...everything.  It's the advance of the wave.  The past doesn't "exist" somewhere behind it, but rather the past is just a way of describing a prior state of the flux.  The future doesn't "exist" out there ahead of the wave.  The wave is just moving in that direction and things are just happening, moving, changing along the crest.  Now, honestly, doesn't this sound a little bit more like time as we know it?

In this "wave model" you can't travel back and see Ben Franklin fly his kite, because he isn't back there anymore.  The wave has long since swept over him and his kite, and along the crest he grew old and died and men dug a hole and buried him, and still the wave swept on until what was left of his body crumbled away into dust, and then the wave moved on without him.  In the "wave model" you'll never get a knock at your door from a guy in silver jumpsuit from the year 2598.  There's nothing but emptiness out in front of the wave, nothing but the potential of what the flux might become.  There is no man in a silver jumpsuit.  There is no 2598...at least, not yet.

Take a look at our old friend Relativity, which remains our best and only hope for manipulating time in the real world.  If you look carefully, you'll notice that Relativity suggests nothing about people occupying seperate points in time.  Relativity only suggests that someone could observe time running at a different rate in a different frame of reference.  The twin on Earth sees time run slower aboard his brother's ship, but yet they're both still contemporaries.  They can maintain eye contact, even as one grows old and the other stays young.  They still agree on what "now" is, even though their clocks disagree about the speed of its passing.  If anything, this only gives further evidence that time is not a fixed and rigid line, but rather something fluid and dynamic.  This may not be useful information to Dr. Stumblebum puttering around in his basement, but it can be useful to us.  It tells us that the sweep of this wave is not constant and relentless.  It tells us that the wave is flexible.  All you need is a lot of speed and a lot of gravity.  As to why that is....well, what do think I've been trying to figure out?

So that leads me back to my original point.  I said that it might be possible in principle to change the past, if you took the time traveler out of the equation.  What exactly did I mean by that?  Well, suppose it were possible to push the wave itself back, so that the motion in the universe's dynamic flux moved in reverse, so that everything that has happened up to a certain point can be made to unhappen.  What if, instead of traveling back to yesterday, it were possible to push time itself back so that today never happened, or rather could be made to have unhappened, and every change in the flux reversed?  This is why I say "in principle".  Clearly, the magnitude of such a thing is unthinkable at this point.  But hypothetically, suppose it were possible.  First of all, the mere act of pushing the wave back, as momumental an undertaking as it would be, wouldn't be enough to cause a change.  Without introducing some new element, some new factor or piece of information, the dynamic flux would simply repeat the same motions once you released the wave and allowed it to run forward again.  Yesterday would play out the same way it did before and we'd be right back here all over again.  There would have to be some way of carrying back on the wave some kind of premonition of what the flux was going to do once it ran forward again.  Only then could someone act on this information and change the outcome.  In effect, they would be changing the past, even though they might not realize it.  Would the grandfather paradox still be an issue?  Would any paradox be an issue?  I don't know.  I've taken this line of thought as far as I'm going to today.

Does this mean that the linear model is dead?  Not necessarily.  Personally, I prefer the wave model.  I think it makes more sense, but I'm in no position to make any solid claims.  As far as  time goes, we are all like the citizens of Flatland.  Without any freedom of movement or control over the 4th dimension, it becomes difficult to be certain of its true nature.  I present this "wave model" hypothesis simply for your consideration, just as means of showing you the different possible ways of looking at time.  The silver jumpsuit guy could still concievably show up at my door any day now, and we still have the rest of the month to consider the possibilities.  

(This post is also available in extra cheesy version.)

Stop Trying to Kill Your Grandfather

If you're familiar at all with the concept of time travel, then chances are good that you're also familiar with the concept of the temporal paradox.  This is where a time travel scenario leads to a situation which violates the rules of logic and the laws of causality.  In spite of what you may have read in books, seen in movies, or been told by a certain goofy, bearded blogger in his last post, the problem with these paradoxes is not that a time traveler might inadvertently cause one, threatening the integrity of the space-time continuum or the existence of the universe.  By its very definition, it's impossible for a temporal paradox to happen.  There's about as much danger of you causing a paradox, as there is of you eating your own head.  It just can't happen.  Paradoxes do pose a legitimate problem for time travel, however.  As long as it can be demonstrated in any conceivable way that time travel could potentially lead to a paradox, then either the issue has to be resolved, or you're forced to reach the inescapable conclusion that time travel is impossible.  The problem is solved at the source.  It would be like someone trying to build a house from an M.C. Escher drawing.  The problem isn't that the staircases that loop back on themselves or the support beams that connect this corner of the floor to the far corner of the ceiling would destroy the universe if you built the house.  The problem is simply that the house can't be built.  So, before you go packing your extra plutonium, these paradoxes have to be addressed.

There are three basic types of temporal paradoxes: the predestination paradox, the ontological paradox, and the grandfather paradox.  As the title suggests, it's primarily the grandfather paradox that I want to deal with in this post, because it's based on a very common misconception about time travel.  Once the misconception is laid to rest, it should take the grandfather paradox into the ground with it, leaving no ghost to haunt us.  Unfortunately, it's the resolution of the grandfather paradox that makes the other two paradoxes an issue.  Those two are a little trickier to deal with, and quite honestly, at this point I'm not sure that they can be resolved.  We'll just have to see where we're at when we get to them.

So anyhow, the grandfather paradox is the basically the idea that a time traveler changes the past in such a way that it negates the cause of the change.  The most famous example, and the one from which the paradox gets its name, is a scenario where a time traveler goes back in time and kills their own grandfather when he's a baby.  I'm not sure why someone would ever want to do this, but hypothetically, if they did, it would mean that the time traveler had just canceled out his own existence since without his grandfather he never would have been born.  This would mean that he would never have been around to kill his grandfather, which means he couldn't have canceled out his own existence, which means that he would have been around to kill his grandfather, which means...Well, I'm sure you can appreciate the can of worms this opens.  Although this grandfather murdering scenario is one of the more drastic versions of the paradox, it's hardly the only one.  Once you introduce the concept of changing the past, it becomes practically inevitable.  One could even make the argument that any successful journey to the past with the deliberate intention of changing anything at all, would automatically result in a grandfather paradox.  After all, why make that trip back in time to stop Kennedy from being shot if he's already alive and well this time around, thanks to you?

Some people have tried to solve this paradox by postulating the existence of separate parallel universes for every possible outcome of every event since the beginning of time.  Then they cast our grandfather murdering scenario with a couple of different actors from different universes to play the part of our time traveler and voila', paradox solved.  Yeah, nice try.  Not only does this messy idea have more holes in it than a slice of Swiss cheese, but the actual solution is so much simpler, and we don't need to resort to an absurd multiplicity of countless universes for all the infinite places where I could have set my glass on a table or all the infinite ways I could have put my socks on this morning.  To be consistent, every slightest fraction of a micrometer difference would have to be accounted for by these continuously spawning universes.  Luckily, we can ditch all of this tedious redundancy once and for all.  These parallel universes were brought into the picture to solve a problem that doesn't exist, because, you see, it would be impossible for a time traveler to change the past.

Now, I'm certainly not the first person to realize this.  I'm just here to explain it, so buckle up.  The first thing that you need to understand is for a time traveler to change even as much as the position of a blade of grass in the past, it would be necessary to assume the existence of two separate time lines: one in which the traveler visited the past, and one in which he did not; one in which he touched the blade of grass, and one in which he did not.  This concept is usually presented to us in such a way that the problem with it escapes our attention.  First, we have history running its natural course.  The cavemen draw some bison on a wall...fast forward...Julius Caesar rules over Rome...fast forward...Benjamin Franklin flies his kite...fast forward...Hitler kills a lot of people...fast forward...We land on the moon, etc.  Then one day Dr. Stumblebum builds a time machine in his basement, and he decides to go mucking around in history.  He knocks into Ben Franklin, ruining the whole moment with the lightening and the key and forever changing one of our treasured moments of history.  See, did you catch the problem?  Probably not.

Again, we have two versions of the time line.  We have the original version, where Franklin flies his kite in peace.  Then we have the "new" version where Dr. Stumblebum shows up and ruins the whole thing.  Here's the question, though: When was this new version created?  Well, that's easy enough to answer, right?  It was created the day Dr. Stumblebum decided to load his clumsy ass into his time machine and travel to the past.  It makes sense, or at least it seems to as long as we keep looking at everything from Dr. Stumblebum's point of view. 

Let's try instead to look at from Ben Franklin's point of view.  It's a cloudy day, somewhere in the middle of the 18th century.  Storm clouds are rolling in, and Ben decides this would be a great time to fly his kite.  From his point of view, the day is today.  What else would he ever consider it?  Anyway, he grabs his kite and heads out.  Lightening hits the key, Ben craps his pants, and all is right with the world.  But, wait a minute?  Where was Dr. Stumblebum?  Well, that was a different time line, and it doesn't get created for another 200 years or so.  Oh, okay then.  Wait, hold on.  I've got another question.  Exactly when is that day he flew his kite ever going to be 200 years in the past from Franklin's point of view?  I guess Dr. Stumblebum can't show up from the future until the future happens.  When's that going to be?  I don't know, but I have a feeling Ben's going to be waiting for a long time.

Still not seeing it, huh?  What does Ben Franklin know, right?  He's too stupid to even know that it's really 2011 and he's been dead for hundreds of years.  So, let's try a different example.  Let's say that there's a knock at your door right now.  You can go get it.  I'll wait.  You open the door and a guy in a shiny silver jumpsuit gives you the Vulcan hand sign and tells you he's from the year 2598.  What the hell?  I guess that must mean it's really 2598, because this new time line couldn't have existed until then, right?  But then, where were you when it was really 2011?  How did you miss it?  Did you oversleep?  I tell you, you have one extra White Russian and you wake up and find that it's six hundred years in the future and you're living six hundred years in the past.  Ain't that a bitch?

If all this seems just a little too confusing, don't worry.  It's not supposed to make the slightest bit of sense.  That's the point.  You see, once you put time travel on the table, the "present" is no longer a privileged, objective position.  It becomes entirely a matter of perspective.  To Ben Franklin, the day he flew his kite is the present.  To you, as you're reading this and rubbing your temples it's the present.  To our silver jumpsuit guy, 2598 is the present.  None of us are in a position to prove the others wrong.  So, when the silver jumpsuit guy shows up at your door, it's not a new version of today, six hundred years in the making.  It's just the same old today it always was and everything's going to turn out the same way it always did.  On Feb. 2, 2011 a man from the 26th century showed up at your door.  It may be ancient history to him.  It may be the present for you.  It may be the future for Ben Franklin.  But no matter who's point of view you look at it from, it's still the one and only version of this day that it's ever going to be.   

There is no new time line.  There is only one time line, and it happened the same way it always did, and it can not be changed.  If Dr. Stumblebum gets into his time machine and travels back to the day when Benjamin Franklin flew his kite, then he was always there that day.  He can't ruin Franklin's experiment, because he didn't ruin it.  The kite flew just like it was supposed to, and we all read about it when we were kids.  For some kind of change to take place in the time line, it would have to happen from some point in time that the universe itself considers the present, and I get the feeling that the universe is staying out of this one.

So does that mean that this isn't really, really the present?  Not necessarily, and in fact, we'll be considering that very thing in the next post.  For the moment, what this means is that once you grant the premise that someone can move around in time, backwards and forwards, then time has to be viewed as a line that one can travel on, and the position that we call the present is only one possible point on that line.  If you can land in the 18th century and meet a man that thinks the date is today, or land in the 26th century and meet another man that thinks that date is today, then the mere fact that you're the one with the time machine hardly puts you in a position to argue with them.  When in Rome, it's today in Rome.  As for your grandfather, you can't kill him because you didn't kill him.  The day you tried only happened once, and you clearly failed.  If you can figure out when you'll ever be able to make a new version of that day, be sure to let me know. 

(This post is also available in extra cheesy version.)