Star Trek IV was also the first film in which the crew of the Enterprise would travel in time; it has therefore also traveled to our discussion of temporal anomalies.

Continuing from Star Trek III, the skeleton crew of the Enterprise is returning home in a stolen Klingon Bird of Prey, having blown up the original Enterprise NCC-1701 to get it.  They are departing from Vulcan to stand trial for their unlawful and irresponsible actions in the rescue of Spock's body in direct violation of Star Fleet orders.  However, Star Fleet has its hands full at the moment:  some huge alien device has attacked the earth, vaporizing the oceans, and threatening to destroy all life on the surface in the process.  Becoming aware of the problem, Mr. Spock determines that the device is trying to get a response from the long-extinct humpback whale.  Kirk determines that the best hope for the world is for his tiny crew to take their ship back to the twentieth century, steal a couple of whales, and bring them back to the present to reply to the device, which they decide to refer to as a probe.

  There is an absurdity in the premise which for some reason is never asked.  Given that the probe has traveled from light-years away (beyond anywhere to which the Federation's fleet of faster-than-light exploratory starships has been) because it no longer hears whale song, and given that whale song is an audio frequency signal, traveling roughly a thousand feet per second (much slower than the 186,000 miles per second of light) and incapable of traveling through a vacuum, how did the aliens who sent the probe receive the sounds of whale song in the first place?  But the movie does not attempt to offer an explanation, so we have no way of evaluating it.

  There is another problem at this point.  The team is going to use the technique of sling-shotting around the sun to go back in time.  Forgive my confusion.  Although this technique is used in the Star Trek television series, and elsewhere, it makes no sense.  It is a fallacious extension of the notion in relativity that as velocity approaches light speed time for that object slows, and that time for that object ceases at light speed.  Thus we are given to imagine that if we exceeded light speed, we would go backward in time.  (The TV comedy It's About Time began with that premise.)  But relativity also makes it clear that anything which traveled at that speed would have infinite mass and absolute density, and would be reduced to a singularity.  The complications of accelerating an object of infinite mass, absolute density, zero dimension, and static time are--in short, well beyond the capabilities of anything so insignificant as a small yellow star in the outer arm of the galaxy.  But somehow they want us to believe that moving somewhere in excess of warp nine (which I am told is not nine times the speed of light, but exponentially faster) will cause you to move backward in time.  They also want us to imagine that this small increase in gravity will propel the ship at such a velocity even though their warp engines, which permit them to travel between stars in a matter of hours, will not--and that at these speeds we won't fly right past the sun so fast that it will be light years behind us before we achieve the necessary velocity!  But just so we all understand the absurdity of the notion, they suggest at the end of the film that the process can be reversed by using the same method, but flying around the sun in the opposite direction!  I'm sorry to burst the Star Trek bubble, but if you can fly faster than light to reach other stars, you can't also use it to go back in time, and you certainly can't use it to come forward in time again:  it is the velocity which causes the temporal reversal, not the direction.  (I should also mention that the concept of relative time does not mean that the object moves through our time at a different rate, but that it experiences time itself at a different rate.  The astronauts who travel to another star at 90% of the speed of light return to us in the same number of years we would expect--about 11 years to go 10 light years--but they would only have aged slightly.  Following this logic, to exceed the speed of light would result in the craft continuing to be perceived in our own time, but the persons aboard getting younger.)

  But it is not the purpose of these pages to quibble with how time travel is accomplished; theories abound, none of them very good.  Our purpose is to examine the consequences of time travel, to determine what might or might not happen.  To this end, let us examine the time line.

The purpose of the journey is to return to the past to find two humpback whales and bring them to the future, to repopulate the species.  This is an excellent purpose.  Note that Kirk has no intention of attempting to prevent their extinction--to do that would be to create an infinity loop, since if the whales are not extinct, the probe will not come, and Kirk will not come to the past to save them.  All he wants to do is take a couple of whales from the past to the future.  It is a relatively safe mission, from that perspective.  However, he is changing history, and in several ways.  Each of the details should be examined for their effects; any one of these has the potential to seriously alter the future, and create a major problem.  What we need to understand is whether any of them will necessarily create a problem, and what kind of problems might occur.

Let us list the major changes which occur.  Of course, perhaps thousands of people will see the travelers, but few will take any note of them.  Other than the garbage collectors who saw the trash can smashed by the invisible space ship, and the whalers who were interrupted in their hunt, it is unlikely that anyone in the past will have any life-changing memories related to aliens or time travelers.  Three whales (Gracie is pregnant) are removed from the past, which may change the gene pool of the humpbacks somewhat; however, the evidence suggests that they might have been killed a few minutes later anyway, so this is a minor change.  It is possible that one of the adult whales would have escaped; it is also possible that the whalers will continue to hunt for another whale which would not have been killed, but just as plausible that they would abandon whaling temporarily or permanently following their close encounter (as they wonder whether they have met aliens from outer space, or if Greenpeace has a new weapon).  Mr. Scott has given the formula for transparent aluminum to Dr. Nichols.  Dr. McCoy has extended the life of an elderly dialysis patient.  Mr. Chekov has left a non-functional phaser and a communicator in the hands of the United States Navy.  Doctors have seen McCoy perform an instant diagnosis of head trauma with a pocket scanner, Kirk melt a lock with a ray gun, and a comatose patient revived miraculously with the push of a few buttons.  Military police lost a group of suspects who boarded an elevator and vanished.  And one marine biologist disappeared from the face of the earth for several hundred years.  How serious are these events?  What impact will they have on the future?

There is the matter of the eyeglasses.  Kirk is selling his antique eyeglasses, a gift from McCoy, for a hundred dollars.  Now, these glasses are actually about four hundred years old, but were made only a hundred years before.  For their age, they are in remarkable condition; yet we must wonder whether they are in very good condition for the time elapsed since their creation.  But they fetch a hundred dollars.  What is more significant is that Spock asks Kirk if they weren't a gift from Dr. McCoy; "and will be again, that's the beauty of it" is the Admiral's response.  But that suggests that he expects to receive that pair--unlikely in the extreme.  These glasses are a temporal duplicate; they already exist somewhere else in this time.  Dr. McCoy will buy the other pair, and give it to Kirk, who will bring it back to this time and sell it.  Returning to the future, he will no longer own them.  This duplicate set might survive to that time, but he will not know where they are.

So let's see what else they've done.

A number of these changes could have serious consequences related to the essential future.  The removal of the whales from the twentieth century reduces the number of an already endangered species.  This loss could result in the shortening of the time until the extinction of the species, especially if robbed of their prize of one whale the whalers manage to hunt and kill another.  On the other hand, if these whalers are spooked, some or all of them may give up whaling permanently, reducing the number of whales which are killed even if by one or two, and extending the survival of the creatures.  Even removing a cetacean biologist could affect the time remaining on the earth for these creatures.  After all, Gillian has a doctorate and is working at the only facility in the world to have a pair of humpback whales to study.  It would not be unreasonable to suggest that she is one of the world's leading experts on these creatures, and that her research or her position on the whales could extend their presence on earth, such that her absence from the earth will shorten it.

  You might not think it matters how long the whales survive.  After all, by the time the probe reaches earth, the creatures are declared to have been extinct for centuries.  However, what we are asking is not whether the probe will arrive, but when.  A few weeks before, Kirk and Mcoy were on earth, at Star Fleet headquarters, trying to get permission to recover Spock's body; a few days later, they will arrive at earth to face trial.  Even if the probe should arrive a few days earlier or later, our heroes will not be in the same place, and could become trapped by the probe themselves.  But the premature disappearance of three whales, or the change in whaling habits, or the loss of a scientist contributing to their survival could make as much difference as an entire generation--possibly two--never being born, or as many additional years of survival on the planet before extinction.  This changes the date on which the whale song ends, and thus the date on which the probe departs for earth; and now Kirk is not in the right place at the right time, because the right time has been moved possibly into the next generation.  And if relationship between the time schedule of the enterprise and that of the probe is altered by so much as few hours in one direction, or a few days in the other, they will not be in the right place to be able to make their trip in response to the probe.

  However, it is not necessarily so.  The net effect on whaling could be zero; the whales could still become extinct on the same schedule.  Even if the whales die out a generation earlier, it is possible that the probe would be sent at the same time.  Our aliens monitoring whale song must have to do something to receive it, and they might be checking for the whales every day or every decade; there could be considerable leeway in the time between when the whales become extinct and when the aliens discover this; even if the survival is extended a generation, it could as easily be that the extinction is discovered at the same time.  Furthermore, galactic objects are in constant motion.  The right time for launching a probe toward a distant star might require a narrow window which will only present itself at certain points in time--moments during which their planet and ours are both moving in the right direction at the right time.  The decision to send the probe earlier or later than that time could change the window significantly, altering the travel time by years, and we might therefore assume that the aliens will send their device at a time at which the best possible flight could be assured.  In short, although the change in the whale population could be critical to the decision and timing of the time trek to recover the whales, it is not necessarily so.  This is one point on which the travelers took a risk--a big risk--and got away with it.

  There is a smaller matter of the change in the gene pool of the whale population itself.  We would be fairly safe in suggesting that due to Kirk's interference in the whale population, the entire genetic identity of succeeding generations will be altered--that is, before the last generation of whales dies out, they will be entirely different whales.  Were it a change in the gene pool of the human population, this would almost certainly eliminate the births of Kirk, McCoy, Sulu, Checkov, Uhura--even the half-human Spock--as their ancestors would have chosen other mates from those available in the altered race.  That is what it has done to the whales.  However, the effect on the whales will not prevent the human travelers from making this trip, and therefore will create only an N-jump in any view of the matter, a simple revision of details of history which are not essential to the facts supporting their own change.

The potential changes to the human population are far more serious.  One person's life has been extended; another's has for practical purposes within the twentieth century been ended.  Either of these changes could change the human population significantly, and given several hundred years, critically.  One of the two, a dialysis patient who grows a new kidney in response to Dr. McCoy's regenerative medications, is unlikely to have children given her apparent advanced age; the other, a young healthy attractive professional woman, claims to have no family or ties to keep her in her time.  But neither of these facts is sufficient to assure that they will not have an impact on the children of the future.  Even their presence or absence in the world will affect those around them in innumerable ways which could have lasting effects (how many of us have quoted parents, grandparents, uncles, aunts, friends of the family, or other persons from whom we derived wisdom, whose earlier death would have robbed us of some small principle which forms part the basis of our thought and decision-making processes?).  But there are other ways in which they can impact upon the race itself without bearing children.  Will the children or other younger relatives of the elderly patient be too involved in caring for their infirm relative to become involved in another relationship?  Or will not being at the hospital, or at the funeral, prevent them from meeting someone they would have met?  Will someone secretly in love with the younger woman (or even with one of the preoccupied children of the older woman) miss the opportunity to find happiness with someone else?  Relationships are very much dependent upon timing:  meeting someone one year instead of the next, or whether in crisis or in calm, can make all of the difference to the nature of the relationship--so much as the difference between someone with whom you would spend time, fall in love, have children, and someone you would never see again.  Those rather unbelievable events that start with a cup of coffee in a strange place and end with a lasting friendship are much more common than we might imagine.  The lives of two people not themselves part of the genetic mix might still as part of the social mix impact upon the genetic mix.  And Gillian is not so old that her present social circumstances matter.  She has in effect just lost a job; but she is one of the world's leading authorities on humpback whales, and will have undoubtedly gotten another, perhaps teaching at a university in Massachusetts or Delaware or Florida, a world away, surrounded by new people.  Although her age is not given in the story, she would be insulted if we were to suggest her already old enough that her window of opportunity for motherhood were as short as a decade.  In the eighties perhaps she has no one; but will she have been a mother in the nineties?  That's a long time for life to change, and they should not have removed her from it.

But the changes were made, and they were not fatal to the situation.  We therefore are safe to assume that although once again they took a terrible risk, they got away with it, and the time line resolved again to a safe and simple N-jump, no significant changes in the population of the future having occurred.

There is the matter of the phaser and communicator left in the hands of the United States Navy.  Now, it is obvious that our lieutenant conducting the interrogation is skeptical regarding what he has; but he does have these devices nonetheless.  On top of this, the military police at the hospital will have filed extensive reports, and questioned everyone involved.  Chekov claimed to be from Star Fleet, and was clearly human.  Our naval officers at first believed him to be crazy.  However, there are several points in the events which follow which will have made an impression.  A ray gun is used to melt a lock.  A pocket scanning device correctly identifies the hidden physical abnormalities within the skull.  A group of fugitives vanishes from an elevator with a patient who is either still comatose (unable to move himself) or miraculously recovered.  It is possible that the doctors from their vantage point in the secure side room were aware that he had been revived.  All of this lends credence to the suggestion that Pavel Chekov is not crazy.  Perhaps he is not Russian, but an alien who looks human and speaks English with a similar accent.  Perhaps the Russians have developed a level of technology beyond anything known to the United States.  Perhaps he has traveled from the future.  Whatever has happened, the government is going to require a thorough examination of the devices which were brought back from the future; and our travelers make no effort to recover these (an important point--they could do so while they are still here, to prevent any damage to the timeline, but could not return from the future later to undo what was done).  There is a serious risk that study of these devices will alter the science and technology of the day, accelerating discoveries in one area (possibly at the expense of knowledge in another), and undermine the entire technology of the future.  An earth with an accelerated technology would be a greater force against Klingons and Romulans, and the universe of the future could have a very different shape.

But we should consider this possibility carefully.  I think that on reflection it will appear not to be so serious as one might suppose.  To put this in perspective, let's suggest an alternate scenario.  Let us take a popular video game system--the type with the compact laser disk games--and deliver it to Thomas Alva Edison, at the end of the nineteenth century.  Edison is the inventive genius of his day, and electronics is his field.  He invented the vacuum tube, basis of all electronics, and maintains a well-stocked and well-staffed laboratory for the purpose of creating new inventions.  If anyone in the nineteenth century can understand our video game, it will be him.

I imagine that he will be able to supply power to it, and determine the basic functions of the switches and the proper placement of the disk.  He invented records and, although his were originally cylinders and his competition changed the format to disks, he will recognize an information storage medium that similar, regardless of its alien materials and design.  He will probably also identify the audio output, and may be able to connect it to a speaker system of some type to hear very faintly whatever sound comes from it; I am not well enough versed in his history to guess whether amplification of the audio signal would have been within his grasp.  But the video output would elude him entirely.  The cathode ray tube is the child of his vacuum tube, and television is still a generation away, even as an experiment.  Even merely having the tube would not be sufficient, as the matrix of video signals involves creating two sets of fine lines across the screen, identifying which dots are lit and which are dark.  The interpretation of that stream of data as a picture is in the receiver, not the transmitter.  Without the receiver, the image is a data stream--not much different from the noise your modem makes when it connects to your server, except that you can't hear it at the frequency used for television.  The laser also would be a conceptual mystery to him.  It will appear as a light--a very tiny version of the light bulb he invented, with an unusual focusing method.  But the concept of the laser is dependent upon the theory of relativity, to be propounded by Albert Einstein early in the next century.  In Edison's understanding of the universe, light does not act that way, so he will not know what it is doing; and the disk it reads looks blank to you, who know something of what should be there.  To him, it is not only blank, but made of a material not yet created, the nature of which he can present as little more than an educated guess.  Finally we have the internal components.  Edison is familiar with resistors, capacitors, inductors, lights, and several other primitive components.  In half a century, diodes and transistors will be discovered, replacing the vacuum tubes for which a few uses have been developed in his time.  I dare say that if Edison received a transistor or a diode, it would be little effort on his part to divine something of what they are and how they work.  But within our game system there are few if any such components.  They too have been replaced by integrated circuits.  An integrated circuit uses silicone and other materials to create transistors, resistors, capacitors, and diodes, all as microscopic etchings on a piece of matter smaller than a pencil eraser, attached to the pins on the casing by wires thinner than human hair.  Even to see the etchings would probably require a scanning electron microscope--I am not convinced that any meaningful information could be gained from an optical instrument--and this would reveal only the surface of this multi-layered device.  But if we are to assume that somehow he is able to identify the materials and the patterns in the chip, these do not look like the transistors whose function they replace, and he wouldn't recognize them if they did.  No, given a mere hundred years, the best and brightest of technologists would be stymied by one of our devices.

Of course, our ability to examine devices is far beyond his.  Our top technologists would have no problem identifying the parts of the game system; they could probably tell you who built it.  But technology is expanding at an accelerating rate, and the time between the present and the origin of these Star Trek devices is more than twice as great as that between Edison and us.  Star Trek has also suggested several areas in which major scientific theories will be developed--antimatter systems, subspace, gravity generation, and warp fields all leap to mind--so there will almost certainly be components which, like the laser, are incomprehensible to us.  No, Chekov's lost equipment will eventually end up in a government warehouse, an unexplained device whose function and origin are unknown.  There is little danger of a change to the future from this mistake.

I believe that leaves us only the matter of Dr. Nichols and the transparent aluminum.  This actually is a fine example of why the explanation of time lines expounded in the Multiverser game system (of all places) is superior to other concepts of temporal paradox and anomalies.  What we have is an invention being brought from the future to a point before its discovery, so that it will be invented before it is invented.  In traditional time theory this creates a loop, a paradox in which the past is dependent upon the future, and the future upon the past.  However, viewed from the Multiverser system, it results in a simple N-jump (in this case, an N-jump termination to a sawtooth snap), barring any other circumstances stemming from it.

Let me first make it clear that whether Dr. Nichols was the original inventor or not has little impact on the anomaly.  In the film, Mr. Scott allays Dr. McCoy's concern about altering the future with the flippant remark, "How do we know that he didn't invent the thing?."  I'm told that the book version (which I am not critiquing) expands this to assure us that Mr. Scott knew full well that Dr. Nichols was the inventor.  But let us assume that in the original timeline, Dr. Nichols or anyone else was working on materials properties, and realized that it was possible in theory to arrange the molecules in aluminum such that visible spectrum light would pass through it.  After years of research, the material is developed in, say, 2010, and Dr. Nichols, or someone else, becomes fairly wealthy from this.  Now let us imagine that Mr. Scott gives Dr. Nichols the foundation for the research.  Dr. Nichols' research is now focused differently.  He knows it is possible sooner than he might have, and he has more information on which to base his work.  Now he will invent it sooner, perhaps in 2000.  He will be the one to become rich, and more so, since he has a ten year head-start on his alternate history.  He will have done different work.  And neither he nor anyone else will have completed the foundation work on which the discovery of transparent aluminum is based.  It matters little to the nature of the problem who it is who will not do that basic research which makes the material possible; what matters is that it will not be done.  Therefore, in traditional temporal reconstruction, the invention of transparent aluminum is without an essential foundation, and impossible.

However, we would propose an entirely different reconstruction of time.  According to our approach, the original timeline, which we call the A-B segment, exists.  In this timeline, someone does extensive research in materials properties and invents transparent aluminum around 2010.  Whales become extinct, and Mr. Scott returns to the past with his crewmates to whale-nap a couple, creating the divergent time line which we call the C-D segment.  In the process, he needs plastic, so he trades the secret for transparent aluminum for the material needed.  Perhaps he knows who discovered that secret, and perhaps it was Dr. Nichols; perhaps he knows the date of the discovery.  But he rescues the whales and travels to the future.  Meanwhile, Dr. Nichols invents transparent aluminum in 2000, whales once again become extinct, the probe is sent, and Scotty and the crew return to the twentieth century to grab the whales.  Now, although the initial work was not done, it is clear that transparent aluminum has been invented, the matrix has been explored, and Mr. Scott can still give the secret to Dr. Nichols.  Only this time we are in the E-F segment if Scotty has any knowledge.  This time if he knows who invented it, his knowledge will be that Dr. Nichols invented it in 2000--even if in the A-B line Dow Corning invented it in 2010, for this Mr. Scott, the history is that of the C-D segment in which he gave the secret to Nichols, who invented it in 2000.  And at the end of this segment, that is the same information, so time is resolved and continues into the future, an N-jump termination.  There will have been changes to the distribution of wealth, possibly having effects on the world otherwise, but none of these effects are necessarily fatal to the future--they will not in any event change the survival of the whales nor the arrival of the probe, and if they do not cause significant changes in the human population (if Dr. Nichols does not marry or choose not to marry based on his earlier enrichment or focus on his project, for example), then there is no necessary reason why the crew of the Enterprise will not repeat their same rescue effort.

  Thus, in their first theatrical contribution to time travel, the creators of Star Trek have avoided the pitfalls admirably, giving us a film which is not merely fun and exciting, but plausible from the perspective of the timelines which are created and destroyed in the process.