I wish to thank Vazor for his kind words about my site, and for alerting me to the posting on his. I hope I can answer at least some of the points he raises. I warn, though, that I am not noted for brevity.
I will also be making references to pages on the M. J. Young Net site, particularly the Temporal Anomalies in Popular Time Travel Movies section, and including links to those pages. I do this in part so that I will not have to repeat too much of what I have written elsewhere. The Temporal Anomalies site has existed for a decade now, and has grown significantly in that time, so there is a great deal of material covered by it. Vazor clearly has read much of it, but for the guest reader I would encourage attention to the original pages.
Vazor references the Primer on Time. This is probably the oldest of the pages in the theory section of the site, but apparently it holds up well, as he has most of the essentials clear. I am, however, concerned about this: he wrote:
I'm not clear on what the theory says will happen if the new timeline ends up destroying the time machine or making no traveler go back in time....I am surprised because I would have thought that the most obvious aspect of the theory; however, let me give a brief background which might help.
One of the essential principles of science is the chain of cause and effect. Everything which happens is caused by something which happens before it in the chain. The water in the pot boils because heat from the flame is transferred through the metal into the water. My wife gets angry because I annoy her when she does not feel well. Without the heat from the burner or the annoyance from me, we would not have in the one case agitated water and in the other an agitated woman. We say that causes precede effects, that is, the cause must happen prior to the effect. Because for us time is always moving in one direction, what we mean by that is not as clear as it might be.
What time travel does is move effects temporally before causes; they still must occur after them in a sequential sense. That is, the cause of a time traveler arriving in 2000 is the departure of that time traveler from 2010, which from the perspective of the sequence of events happened first--the time traveler left 2010 and then, subsequently from the perspective of the causal chain, arrived in 2000. However, if you eliminate the cause, you logically also eliminate the effect.
Let's use a popular time travel trope to illustrate this: someone travels back in time to kill Hitler before he becomes a problem. It is arguable whether this would eliminate World War II or the Holocaust (there were other forces pushing Germany toward the strong nationalist fervor which led to both), but those who would argue for killing Hitler would claim that this would eliminate the cause of those two horrors. We grant that, because we recognize the effect of the causal chain, that if you eliminate the cause--in this case, Hitler--you also eliminate the effects--in this case, the war and the massacre. We will even recognize that it might not stop there. Without the threat of World War II, it is doubtful that the United States, or any other power, would have pursued the development of an atomic bomb, at least so soon; without the atomic bomb, the Cold War would not have been so cold, as it was undoubtedly Mutually Assured Destruction that kept both sides from allowing the various conflicts in which they engaged to escalate. The elimination of this one significant person will alter history in significant ways.
What most people fail to recognize, however, is that it will also alter one more very critical piece in the chain of cause and effect: there is now no reason for anyone to want to assassinate Hitler, an insignificant politician who died before achieving anything of note. Thus our time traveler is now not going to leave the future on that mission. However, if he does not leave the future, he cannot arrive in the past--the same causal chain that prevents the events we wish to erase also prevents the event which prevents them. That means that our time traveler will not make the trip to the past, the causal chain is broken, Hitler is never killed, and the events of the twentieth century play as we in our history know them. Yet it has already been established as part of the premise that if our history plays as we know it someone will decide to travel to the past to kill Hitler, and that person will succeed, creating the alternate history in which he will not make that decision. We have two distinct and incompatible histories; time is alternating between them.
Thus if for any reason a time traveler is prevented from making the trip at the end of the altered history which he made at the end of the original history, an infinity loop occurs. It does not matter that the change in history is not so drastic as whether or not Hitler dies; what matters is that history is different in any way, and cannot stabilize into a repeat of the same events.
Next, citing the aforementioned Primer on Time, Vazor writes:
Why in an N-jump does the future get destroyed? Don't all those people that the Traveler leaves behind still have their own free wills and their own timelines?A lot of people get stuck on this point. The simplest way I can say it is that it has nothing to do with people having their own free wills. It has to do with the fact that there is only one history of the world.
Let us suggest that in 2005 there is a bank robbery, in which Mark is killed but Bob escapes unscathed. In 2010 someone with no connection to Bob or Mark makes a journey back to 2000. Something that he does changes the situation at the bank in 2005 such that it is Bob who is fatally shot and Mark survives. When 2011 arrives, Bob will be dead, because he was shot in 2005, not because someone left on a time travel journey in 2010.
Imagine for a moment that all of time is like a giant domino knockdown, in which each domino knocks over the next, or sometimes the next several. Time starts with the fall of the first domino, and dominoes continue to fall in sequence. Now imagine that at some point before all the dominoes have fallen, while they are falling, it is possible for someone to reverse the process briefly, to have the dominoes stand back up so that they return to a position they had a while back, and then this person is able to move some of the dominoes that are standing and let the process continue again. That is effectively what time travel does: it backs up the process to an earlier position in time and allows us to make changes. However, in doing so, we eliminate all that would have happened in the original fall of the dominoes. Bob is dead and Mark is alive because the dominoes were moved, and this is the result of the dominoes having moved. If it is possible that killing Hitler would prevent all that resulted from his rise to power, then it is just as possible that changing something in 2000 will result in Mark living and Bob dying. You cannot have it both ways: either you can change history or you cannot. If you can, then whatever changes you make will affect everyone; if you cannot, then either the fixed time theorists are correct and you cannot actually change anything at any time (because the future is not different from the past, it is only unknown to us), or time travel is impossible.
Vazor then addresses my page The Two Brothers: Why Parallel Dimension Theory Is Not Time Travel, writing:
Why couldn't the time machine take you to a future you created but with yourself replacing the self that supposedly would have lived all those years?I find this difficult in the extreme, and far more egregious than any complaint that my theory destroys the future. However, perhaps it just requires that we look at what it is actually saying.
In the page in question, which is intended to show some of the problems with parallel dimension theory, I postulate the existence of a young man in high school whose brother dies of an incurable disease. Let us put some numbers to it: the young man graduates from high school in 1973. His brother is already sick and expected to die from this debilitating disease after suffering for years. Our hero dabbled in music in high school, but he gets serious about saving his brother, graduating from college in 1977 and getting an advanced degree in pharmacological research in 1980. Building on his dissertation, he has a drug prototype ready by 1985--but his brother died in 1982. Undaunted, our hero goes back to school and completes a Ph.D. in Physics, in Temporal Mechanics, by 1989, and in 1990, when he is forty-five years old, he leaves for the past, arriving in 1950 so that he can introduce his medical discovery through proper channels in plenty of time for it to be available to save his brother in 1970 It takes five years for him to do this, so in 1955--the year in which he will be born--he leaves.
Vazor wants our hero to travel to the year it would be for him to be his present age; he is now fifty, so he must travel to 1995. Vazor maintains that this is still him, still the medical researcher and physicist who developed the time machine. He is to replace himself. But what has happened in those fifty years that he skipped? According to the example, in 1955 our young hero was born. In 1970 his brother gets sick, but there is already a cure so this is not a significant problem. While his brother is taking the wonder medicine, the young man pursues his interest in music, majoring in music in college and then going on the road with a rock band which becomes one of the sensations of the late seventies and early eighties. By 1995 he is living off his royalties and making reality television shows for MTV Networks.
At what point do we eliminate this person's existence? Was he never born? There is no logic to the suggestion that our time traveler prevented his own birth in what he did. There is no logic to the proposition that he became that same research scientist without the sole motivating factor of his sick brother. Yet if Vazor's suggestion holds, suddenly in 1995 the famous rock musician with the reality television show vanishes and is replaced by a perfect duplicate who has absolutely no knowledge of anything that has happened in the only fifty year history of his life in this world, who does not know any of his hits or his own albums or television shows, nor any of the people who have surrounded him for the past thirty years, but who suddenly has extensive knowledge of the disease his brother suffered and of the cure which saved him, and of time travel mechanics. If this scientist brother replaced the rock musician brother, where is the rock musician brother?
Sure, you could design a machine that would pull the "real" brother out of time and discard him into the temporal void. That is not time travel, and someone would realize pretty quickly that you are not the right guy. Vazor is talking about murdering the other brother and replacing him. He doesn't recognize that this is what he is saying, because he imagines that divergent versions of yourself would be interchangeable. The point of the Two Brothers illustration is that they are not, and in this particular circumstance they could not possibly be so.
In connection with this, he writes:
...it could even just move you to a future where the time in-between didn't even have to happen- everything just jumped forward and is only left in your mind as a history that you erased.You could accept that if you are willing to discard cause-and-effect as having any reality. Unfortunately, since science is built on the foundation of cause and effect, it would be very difficult to do any kind of science in a universe where cause and effect were not real.
He further writes:
if you subscribe to the parallel dimension theory then you easily answer the problem of scientists never getting results by supposing that the time machine (or perhaps more accurately parallel dimension traveling/jumping machine) could easily send the cube to a dimension where we are all the same and the scientists receive the cube and make the recordings and travel down the series of parallel universes in which the scientists will send the cube back to themselves and then life goes on- having infinite parallel dimensions at your disposal means you can have as successful or as unsuccessful an experiment as you could ever imagine- no matter what type it is or what kind of travel it may be trying to do.A lot of what is suggested for parallel dimensions is confusing, sometimes contradictory. Let us clarify two distinct types of parallel/divergent dimension theory.
One theory maintains that the alternate dimension is created by the time travel event itself. That is, Traveler leaves from point B in universe 1 and arrives at point A; to him it is universe 1 and it is exactly as universe 1 was at point A. However, his presence alters it; it is now universe 2, a distinct universe brought into existence by the change in events, that the time traveler has arrived.
It should be apparent in this that even though time travelers can depart from the universes that have diverged, they cannot arrive in any universe which is not diverging. That is, the time traveler cannot arrive in the past of universe 1 because the theory maintains that his arrival in the past creates universe 2. Since universe 1 already exists, no time traveler can arrive in its past, because arriving in the past always creates a new universe, and never alters an existing one. In this explanation, there will never be two successful time travel experiments in the same universe; every experiment will create one universe in which time travel did not work this time, and another in which it did work.
The alternative is to propose that all the universes already exist. If so, the time traveler merely moves to another pre-existing parallel universe where everything is the same to the moment he arrives. How, though, do we know to which universe he moves? Either the move is random or it is ordered.
If it is random, then anyone who understands genuine randomness will recognize that there is no chance even for a vast, never mind infinite, number of universes that every universe will be the recipient of exactly one time traveler. Let me make it simple. Being also a professional game designer I have dice on my desk. I will postulate that there are exactly ten universes, and I will list them as universe numbers one through ten, and then for each I will roll one ten sided die to determine in which universe the traveler leaving that universe arrives. Since it is agreed that no traveler will arrive in the universe he left, I will re-roll all such rolls. Here is the list:
Let us then assume that it is ordered: travelers departing from universe 1 always arrive in universe 2, and those departing from universe 2 arrive in universe 3. The problem is, who arrives in universe 1?
Vazor wants to escape this by throwing around the word "infinite". I try not to use that word without being very certain that it applies. In this case, if there are an infinite number of universes, he has prevented the possibility that there should ever be anyone arriving in universe 1: from no matter what universe N a traveler departs, there will always be a universe N+1 in which he will arrive, and there being no universe N=0, there can be no universe from which someone will arrive in universe 1.
This may seem a small problem, given there are an infinite number of universes in only one of which no one will arrive; but the problem grows because of that. Universe 1 will send a time traveler on the first experiment, who will arrive in universe 2, while their traveler meanwhile will arrive in universe 3. However, since no time traveler ever arrived in universe 1, there will not be a second time travel experiment in that universe, so on the second experiment in universe 2 no time traveler will arrive from universe 1, and that will create two universes in which time travel does not work. This will grow linearly with every experiment.
This, though, assumes that whatever the time traveler arriving in universe 2 does, he does not prevent the time travel experiment. Given that he is arriving in their time before they send anyone, there is a good chance that he will derail the sending of a time traveler in this universe. That means no one will arrive in universe 3, which will send someone to universe 4, which will not send anyone to universe 5, and so our infinite number of universes will immediately diverge into two distinct groups, one from which a time traveler was sent and another in which such a traveler arrived. By any standard, that will wreak havoc with parallel dimension theory; it also will very clearly make it so that any future dimension travelers will arrive in a world that is distinctly different from the one from which they departed: someone arrived here but was never sent, or someone was sent from here and never arrived. One minor glitch on such an experiment, and the homogeneity of the infinite universes is undone forever.
Vazor probably wants us to accept that the traveler sent from the last universe arrives in the first. This eliminates the possibility that there could be an infinite number of universes. It also erases any advantage that might have been gained by using parallel dimension theory: by linking the events of multiple universes, you link their timelines through sequential causation.
Traveler 1 leaves Universe 1 from 2010 traveling to Universe 2 in 2000. Parallel dimension theory says that it's fine for him to make changes, because this is not his world so he cannot affect himself. He has arrived in Universe 2 at a point in their timeline temporally before he departs, but since he does not depart from this universe it does not matter. Now, Vazor would add a huge number of other universes into the mix, but the result is not different for the number of intervening universes: whether events in Universe 2 directly impact events in Universe 1, or whether they impact events in Universe 3, through that to 4, and on to Universe 1*10^33 (one times ten to the one decillionth) which then impacts events in Universe 1, we still have an intact causal chain. Thus to simplify understanding, we have Traveler 2 leaving Universe 2 in 2010 and traveling to Universe 1 in 2000. He has left temporally after Traveler 1 arrived, and arrived temporally before Traveler 1 left, but we see no problem there because time in the two universes can be completely independent. What is not, however, independent is causal sequence. We now have a chain in which sequentially Traveler 1 departed before he arrived and arrived before Traveler 2 departed, who in turn arrived before Traveler 1 departed--speaking sequentially. Thus before Traveler 1 departs, Traveler 2 must arrive, and before Traveler 2 arrives he must depart, and before he departs Traveler 1 must arrive, and before Traveler 1 arrives he must depart, which he cannot do until Traveler 2 arrives, who cannot arrive until Traveler 1 arrives--you have created an infinitely blocked loop, that neither traveler can depart before the other arrives. Adding more universes, even infinitely more universes, only increases the number of events that are dependent on other events in other universes. The sequential dependency will lock up time in every universe, as nothing can happen unless it happens in an order that requires it to happen before something else happens which must happen before it.
I know that was confusing, but that is the problem. When you tie parallel universes together like that, you eliminate all advantage you were hoping to gain from making them independent. When you make them independent, you prevent them from being homogenous. Parallel dimension travel is not time travel, and cannot be time travel.
If there are so many cool parallel dimensions.. why hasn't any of them tried to contact us?I am not certain whether this is a misunderstanding of my theory or an attack on parallel dimension theory independent of mine. Let me just state that under the replacement theory there are no parallel dimensions; there is only one universe, one history of the world. What matters is that we can change it, replacing the old history of the world with a new history of the world by undoing what was. At any given moment there is only the present moment. The past and the future in some sense exist (or time travel would not work at all), but when the clock strikes 10:00 tonight there is only one set of events for 10:00 tonight in existence. If there ever was a different set of events, it has been erased, and no longer ever existed in any real or historic sense.
He also says:
There are entrance points and exit points and you can start forming double loops and complex knots and everything. If you want to just focus on one loop, fine, but there's no reason that things outside the loop can't have stuff happen to them as well.Certainly it is possible for someone beyond the endpoint of an anomaly to send someone back into the heart of the anomaly. The Terminator films are particularly good examples of this (although that is the earliest movie analysis on the site, and might be a bit less clear than some of the more recent ones). The problem that arises is, from what future does someone come? If we have an N-jump, then we have a single future. If we do not have an N-jump, we do not have a future.
Going back to the bank heist, let us assume a new wrinkle: somehow not only does the time traveler alter history such that Bob is killed and Mark survives, he also alters history such that he will not be able to make that trip. Perhaps it is the flux capacitor that Bob invents in 2006 which makes time travel possible, and without Bob there will be no flux capacitor and no time travel. That means that no time traveler will interfere in a way that changes the situation at the bank, and it will be Mark who is killed, with Bob surviving to write his time travel paper. However, in 2011, who is alive, and does he have a time machine? If Bob survived, then the time machine was invented; but in that case Bob was killed in the bank heist and the time machine was not invented. However, if Mark survived, then no time machine was built, no one meddled with history, and he, not Bob, was killed.
When we hit 2010, the moment of the time travel experiment, we have built a decade of history on the events of 2000. When we reach that moment, though, we automatically hit the reset button: whether or not the time travel event "occurs", 2000 changes. Once 2000 changes, 2001 changes, and so through 2005 when the critical events of the bank robbery are reversed, and so too we change what happens in 2010 in a way that once more hits the reset button, sending us back to 2000. We have at any given moment in time only one history, in which all causes and effects must be contained. The decade between 2000 and 2010 must stabilize into one history before anyone can awaken in 2011 and know what happened last year--before we can know whether Mark or Bob is alive. There can be only one consistent history of the universe.
We want to ask where the cause originally came from, but what if it is just that it came from nowhere? Maybe rules like conservation of matter can be broken, and rules like cause and effect can be bent. We can still travel through a nice and orderly sequence of causes and effects with something being introduced that seemingly has no cause (it just is), or has its cause in the future. That being said, I can see it from your point of view. Your opinion that "uncaused events just cannot happen, that's not the way it works" is definitely plausible. But the idea that "the ball reentering the hole in a different way just cannot happen, that's not the way it works" seems just as plausible as well.This is citing material from The Uncaused Cause: Failure of Fixed Time Stories, in which I show the concept of a causal loop and argue that it is logically impossible. What Vazor appears to be saying is that even if it is logically impossible, it might happen anyway.
That is not intended as a criticism. There are many people who believe that logically impossible things happen. Some believe this because of a belief in the supernatural (and I hasten to add that a supernatural is not itself logically impossible, nor that miracles are, but only that some people believe in the supernatural as a cause of logically impossible events). Some believe this because of what might be called a limits of rationality theory, that our logic is good for some things but is not entirely reliable in areas for which it has no experience. I cannot and will not say that a belief in logically impossible events is foolish or crazy; it is a choice.
What I can say, though, is that if one will assert that logically impossible events can occur, then one can end all discussion of what might happen right here. The glass of water I leave on my desk might crystalize into diamonds overnight. It is logically impossible for that to happen, but that does not make it impossible in actuality. We join Douglas Adams in the search for the Infinite Improbability Drive, knowing that absurdities are the norm once we dispose of logic.
To simplify the argument against an event causing itself, what we have in one direction is, this event can only happen if it happens; that means, stated a different way, this event cannot happen unless it happens. I assert that an event that is dependent on itself as its own cause cannot happen, because it will never happen unless and until it happens.
It is possible that the cause of an event is outside the realm of what we know. Miracles are not illogical, any more than saying that a pool ball hit directly at the pocket will not sink into the pocket if someone in the pool hall grabs it off the table. There might be causes outside our knowledge. The Replacement Theory of Time maintains that such apparent causal loops had a cause outside themselves which has since been erased and replaced by a self-sustaining causal loop. The Fixed Time Theory's notion of the uncaused cause, however, is not reliant on some external cause. It is reliant on the notion that as long as everything in the loop is caused by something in the loop, it is self-sustaining and therefore possible. What it fails to explain is what has caused the loop: why has any of this happened at all? That is what I find objectionable.
Occam's Razor maintains that the simplest explanation for any event ought to be preferred. It strikes me as much simpler to suppose that there was some cause of these events which has been erased by the repetition of time than to suppose that the causal loop itself has no cause. If once we allow that, we might as well get rid of the causal chain within the loop: the logic of cause and effect no longer applies, and so is no longer necessary. The kettle boiled because it was time for the kettle to boil, and the fact that no one remembered to turn on the heat was a minor flaw that was not going to prevent the effect from occuring absent the cause.
Nearing the conclusion of this part of the discussion, he adds:
Your opinion that "uncaused events just cannot happen, that's not the way it works" is definitely plausible. But the idea that "the ball reentering the hole in a different way just cannot happen, that's not the way it works" seems just as plausible as well.If I understand aright, he is taking issue with my statement that the ball might enter the wormhole at a different angle and still come out the same way is not plausible. This is not an opinion; this is simple billiard ball physics. Given a ball colliding with another ball which is moving at a ninety degree angle to it, and given that both balls are moving at the same velocity with the same mass, the collision will result in the second ball moving at a trajectory of forty-five degrees from its original path, one hundred thirty five degrees from the path of the first ball. If it now enters a wormhole and emerges as the first ball, it would have to be moving at the same angle as the first ball, ninety degrees from its original path, at the same velocity, in order to have the same impact on the new second ball. If it does not match the original impact precisely in every detail, it will not have the same effect on impact.
The problem is that absent the original impact, the original ball would not have entered the hole at all. It cannot be both that had it not been impacted it would have entered the wormhole and emerged on a ninety degree trajectory and that having been impacted by itself at a ninety degree trajectory it entered the wormhole and emerged on a ninety degree trajectory. If it would not have hit the wormhole absent that impact, it will never come out of that wormhole; if it would have entered the wormhole without the impact, the impact will alter its course such that it will not enter the wormhole, or at the very least such that it will emerge on a different trajectory.
I accuse at least some fixed time theorists of using the word Nature in a way that requires an omnimpotent omniscient entity capable of perceiving paradox before it occurs and preventing it from happening. Vazor replies:
However it makes little sense to me to call out one theory as suddenly ascribing the way things work as due to something other than just "the way things work", when you likely would not claim the same for the average mathematical theory.I see his point, but I do not believe these are at all the same thing. For example, he cites gravity:
Gravity, as you have probably been taught, is a law. It's just what happens. There's no intelligence making sure that whenever any apple is loosed from a tree that it falls towards the largest body of mass near it rather than away.Yet I can overcome this law. It is what happens, given specific circumstances.
I remember pointing out to a friend of mine not so long ago that when he would be transporting helium-filled balloons in his van, if he stepped on the brakes they would all move to the rear and if he accelerated they would move to the front. The reason for this is simple: the acceleration of the vehicle has an effect similar to gravity on the air in the vehicle, causing the heaviest air to "fall" in the direction opposite that acceleration, whether the acceleration was positive (accelerating) or negative (braking). The balloons, however, were lighter than the air, and thus as the air "fell" the balloons were forced in the opposite direction. In the same way, objects which are lighter than the air around them are bouyed up by the air falling around them. Similarly I can use principles of aerodynamics or sheer force to push against gravity, and so cause objects to rise.
Yet the fixed time theorists maintain that I cannot alter history no matter what steps I take. It is not merely that the law is unbreakable (arguably I have not broken the law of gravity but merely countered it by the application of itself or other laws), but that it cannot be countered by any means. As the computer in The Time Machine says, you cannot change the past because you cannot travel to the past. If you could, then you could--or else, why couldn't you? The answers in that movie are lame at best: Hartdegen has changed the past, but not as he wished. He can change the past. Why, though, can he not change it in accordance with what he desires? The poor answer he gets is that were he to do so it would create a paradox. Yet how can the universe distinguish which changes will create a paradox and which will not? Emma is killed by a mugger; then he saves her from the mugger only to have her killed by a steamer with a failed brake. Did he change history? The mugger will hang if he is caught in the first history, but did nothing in the second; the owner of the steamer is likely to be more careful about his brakes in the second history, but not so much in the first. History has changed. The life and death of Emma is not the only detail that matters to the universe. Why should the universe care that Emma die but not that the mugger be caught and executed? It apparently is said to be connected to the fact that Hartdegen would try to change whether or not Emma dies but not whether or not the mugger dies. This is the logic of the position, and it is a poor logic to my mind. History cannot prevent paradox.
Of course, the truth of the Fixed Time Theory really is not that nature prevents paradox, but that history cannot change. If you travel to the past, it is because you traveled to the past. This, though, means that time is neither linear nor sequential, that all events occur at once. It also means that the future is just as fixed as the past, because the future is already the past for that which is further future yet. Nothing we will do is anything other than what we have done. This paper, this discussion, is meaningless, because I cannot sway you and you cannot sway me, and neither of us can be unswayed, for or by anything other than whether we will or not. It is about as nihilistic a theory of reality as I can imagine. I can stop writing now, because I have written what I had already written, and I could not have written other than what I wrote. Never mind that I started writing this with different words, lost what I wrote in a blackout, started again and moved to a different format for the page and the composition, and reformatted it--it is what it always was going to be. Your answer, whatever it will be, is already fixed, and there is no point in either of us thinking about what you are going to write, because it has nothing to do with what you think or what you choose, but only with what you are going to write. And yes, the kettle will boil, whether or not I turn on the heat.
Again I thank you for your contribution to my thoughts, and for your patience with my response.