(This is a slightly modified version of an article which appeared in Volume 12 of The Heinlein Journal. Permission for publication here is granted by the publisher and the author)

A Look at Time Travel in Science Fiction
Time Enough for Everything
By David Wright Sr.
Part Two: Multiplex Time Travel

"Studied any mathematical philosophy, Don? Familiar with infinite universe sheafs and open-ended postulate systems?"
"Uh, I’m afraid not, sir."

"Simple idea and very tempting. The notion that every­thing is possible--and I mean everything--and everything has happened. Everything. One universe in which you accepted that wine and got drunk as a skunk. Another in which the fifth planet never broke up. Another in which atomic pow­er and nuclear weapons are as impossible as our ancestors thought they were. That last one might have its points, for sissies at least. Like me."[23]

This casual paragraph appeared in Between Planets in 1951. This was the first Heinlein novel, I believe, that I ever read and this paragraph was casually given and then only a single brief reference made again to it. It was my introduction to the thought that there might be other worlds lying in some other dimension than that of our familiar world and the thought intrigued me.

Recently, as I thought more and more on the subject of linear time travel, I realized that that concept is one that arises fairly naturally in most people. The phrase, "If I had only done so and so", which I am sure most of us has uttered more than once in our lives, is often followed by the phrase, "If I could just go back and change things". Conversely, we might also think, "If I could only see what the future holds". On the other hand, the thought that there might be other worlds in which our counterparts actually did do things differently does not seem quite as natural as the other.

Stories about travel backwards, or forwards in linear time, were the subject of Part One of this essay. Considering the naturalness of thinking about time travel of this sort, it is not surprising that such stories are common in science fiction. In this part I discuss stories which deal with the concept that there exist worlds which are in other dimensions than our own.

Elsewhen was not Heinlein’s first mention of the concept. "Elsewhen", or "Elsewhere", as it was called on first publication in 1941, used the concept as its framework. In this story, travel to alternate worlds was done using hypnosis to free the traveler from his/her original world, allowing access to a variety of others. Professor Frost, the main protagonist explains:

"Now I have reason to believe  --to know-- that time is analogous to a surface rather than a line, and a rolling hilly surface at that. Think of this track we follow over the surface of time as a winding road cut through hills. Every little way the road branches and the branches follow side canyons. At these branches the crucial decisions of your life take place. You can turn right or left into entirely different futures. Occasionally there is a switchback where one can scramble up or down a bank and skip over a few thousand or million years--if you don’t have your eyes so fixed on the road that you miss the short cut.
"Once in a while another road crosses yours. Neither its past nor its future has any connection whatsoever with the world we know. If you happened to take that turn you might find yourself on another planet in another space-time with nothing left of you or your world but the continuity of your ego.
"Or, if you have the necessary intellectual strength and courage, you may leave the roads, or paths of high probability, and strike out over the hills of possible time, cutting through the roads as you come to them, following them for a little way, even following them backwards, with the past ahead of you, and the future behind you. Or you might roam around the hilltops doing nothing but the extremely improbable. I can not imagine what that would be like-perhaps a bit like Alice-through-the-Looking-Glass."[69-70]

The kinds of worlds that one could achieve depended in large part on the basic personality of the traveler, and as mentioned above, in their "intellectual strength and courage".

"To one who believes in Bishop Berkeley’s philosophy the infinite possibilities of two-dimen­sional time offer proof that the mind creates its own world, but a Spencerian determinist, such as good friend Howard Jenkins, would never leave the road of maximum probability. To him the world would be mechanistic and real. An orthodox free-will Christian, such as Miss Ross, would have her choice of several of the side roads, but would probably remain in a physical environment similar to Howard’s."[71]

Moving forward 38 years in our own time line, we come to Heinlein’s The Number of the Beast. The basic underlying concept for the framework of the story is similar to "Elsewhen", but there are both similarities and differences. A major difference is that the method of travel has been changed from mental to physical. Beast utilizes a "continua device" which can be used to "move" the vehicle to which it is attached not only in the normal three dimensions of space, and travel up and down the current time line, but also allows switching of the time dimension to either of two others. Because of the switch in method, the rather picturesque description of time as quoted above from Professor Frost changes to a more formal mathematical model:

"I can’t follow Jake’s math; I have to accept his transfor­mations without proof. But it is based on the notion of six space-time coordinates, three of space, the usual three that we see--marked x, y, and z--and three time coordinates: one marked ‘t’ like this--" (t ) "--and one marked ‘tau,’ Greek alphabet--" (T) "--and the third from the Cyrillic alphabet, ‘teh’--" (m)
"Looks like an ‘m’ with a macron over it."
"So it does, but it’s what the Russians use for ‘t."’
"No, the Russians use ‘chai’ for tea. In thick glasses with strawberry jam."
"Stow it, Sharpie. So we have x, y, and z; t, tau, and teh, six dimensions. It is basic to the theory that all are at right angles to each other, and that any one may be swapped for any of the others by rotation--or that a new coordinate may be found (not a seventh but replacing any of the six) by translation--say ‘tau’ to ‘tau prime’ by displacement along x."[51]

Another difference is that there is no hint of the kind of travel that Professor Frost had himself experienced:

"While in prison I had time to regret my mistakes. I real­ized that I had never been cut out for a business career, and I earnestly wished that I had stayed in school many years before. Prison has a peculiar effect on a man’s mind. I drifted further and further away from reality, and lived more and more in an introspective world of my own. One night, in a way not then clear to me, my ego left my cell, went back along the time track, and I awoke in my room at my college fraternity house.
"This time I was wiser-- Instead of leaving school, I found part-time work, graduated, continued as a graduate fellow, and eventually arrived where you now see me." [70]

This is essentially the same method of time travel that Piper used in his story "Time and Time Again".[22] although the transfer in that story took place as the result of the protagonist being killed, (which certainly breaks one away from his original world). Both usages come straight from Dunne as I discuss below. Piper explicitly mentions Dunne in his story[23] as Heinlein did in this one[69].

As I mentioned, the method of travel changed from mental to physical, but one aspect of the mental concepts in "Elsewhen" remains here in that the worlds accessible to the travelers depends on the type of personality that they have:

"Jacob," said my wife, "suppose  we were people who don’t like fanciful stories. What sort of worlds would we find?"
"I don’t know, Hilda. Probably only humdrum slice-of-life universes indistinguishable from the real world. Correction: Sub­stitute ‘Universe-zero’ for ‘real world’--because, as your theory requires, all worlds are equally real. Or unreal."[355]

Although, Heinlein describes his "Elsewhen" time universe as a two-dimensional, it seems to me to be a three-dimensional one just as it is in Beast as shown by the additional description of "hilly" and further described in this passage where he speaks of the "hilltops".

"Or you might roam around the hilltops doing nothing but the extremely improbable. I can not imagine what that would be like-perhaps a bit like Alice-through-the-Looking-Glass."[70]

The most important difference is that with this work, Heinlein explicitly introduces his concept of the "World-As-Myth" rather than just slightly alluding to it in the earlier work. The above quoted paragraph relates to some of the results of that concept. Continuing with the quote from above:

"Jacob, why do you call our universe ‘universe-zero?"’
"Eh. for convenience. Our point of origin."
"Didn’t you tell me that no frame is preferred over any other? Each one to the Number of the Beast is equally zero in six axes?"
"Well. . . theory requires it."
"Then we are fiction in other universes. Have I reasoned correctly?"
I was slow in answering. "That seems to be a necessary cor­ollary. It’s a disturbing idea: that we ourselves are figments of imagination."[356]

Essentially, the concept is that all worlds exist as the figments of someone’s imagination. This, especially in the context of Beast, means that some of the worlds they visit are worlds created by other authors. An examination of these worlds shows that they are not exactly the worlds as written in the authors’ works, but are worlds which are similar to the written ones. The ones that the travelers find depend on their own "personal and combined" experience with the written works. Speaking of worlds they see, but don’t recognize Hilda says:

"Maybe they are places about which stories will be written or maybe stories have already been told but aren’t favorites of us four, so we don’t emerge close to their scenes. But those are guesses. So far as my theory is concerned, such universes are ‘null’--they don’t count one way or the other. We find our uni­verses."[344]

The hooker in Beast is that if all worlds are figments of someone’s imagination, then that someone is himself a figment of someone else’s imagination, This is what Heinlein means when his characters speak of  "Multiple-Ego/Multiperson Solipsism"

Continuing with the quote from above, Zeb says:

"Sharpie, you have just invented pantheistic multiperson so­lipsism. I didn’t think it was mathematically possible."
"Zeb, anything is mathematically possible."
"Thanks, Jacob. Zebbie, ‘solipsism’ is a buzz word. I’m saying that we’ve stumbled onto ‘The Door in the Wall,’ the one that leads to the >Heart’s Desire. I don’t know how and have no use for fancy rationalizations. I see a pattern; I’m not trying to explain it. It just is."[345]

The laws of the various universes can be different from one another as mentioned when visiting the land of Lilliput from Swift’s Gulliver’s Travels, and of course in their visit to Baum’s world of The Wizard of Oz. This hearkens back to my original quotation from Dr. Jefferson in Between Planets:

"One universe ….Another in which atomic power and nuclear weapons are as impossible as our ancestors thought they were."[23]

Underlying all of this is Heinlein’s massive joke. He himself is the Beast as demonstrated by all of the anagrams of his or Virginia’s names which are found in the work, and thus, he can "erase" the pasts of his characters with a "blue pencil" or "eraser", easily explaining how their time lines were changed as mentioned in Part One.

Given that "The World-As-Myth" encompasses all worlds, including especially the worlds of all writers of science-fiction, and that the laws of each universe can vary from others, then it is easy to see that the two versions of ordinary linear time travel discussed in Part One become special cases of the general multiplex one. Both time-alterable and time-unchangeable versions exist because authors have written them that way and depending on the laws of each type, they will adhere to the structure defined for them, i.e., the laws of one precludes any change whatsoever whereas the laws of the other type allows changes.

More than just living in worlds created by the imaginations of others, the characters in this story recognize that they themselves are creating universes as they go. But more importantly, they can control their own universe. Zeb says:

"I am a firm believer in Murphy’s Law: Given any possible chance, it will go wrong. Anything.

Libby had been wholeheartedly converted both to Jake’s six-axis plenum of universes to the awful Number of the Beast but also to Sharpie’s multiple solipsism, and asserted that they were two sides of the same coin; one was a corollary of the other and vice versa. Combined, they (it) constituted the ultimate total phi­losophy: science, religion, mathematics, art, in one grand con­sistent package. She spoke of a "ficton" being a quantum of imagination/reality ("imaginary" being identical with "real" what­ever that is) as casually as a physicist speaks of photons. "Could a mistake be made? Yes. And would create a new universe. Jacob, you spoke of the empty universes your family had visited. One by one they fill as fictons are created." She added, "But a mistake was not made; we snatched Maureen safely. We ourselves create the fictions-fictons-ficta that will make it real."[438]

A pre-cursor to this can be found in Heinlein’s Waldo:

"Very well. Accept it. Act on it. The world varied according to the way one looked at it. In that case, thought Waldo, he knew how he wanted to look at it. He cast his vote for order and predictability!
He would set the style. He would impress his own concept of the Other World on the cosmos!
It had been a good start to assure Gleason that the Schneider ­treated deKalbs were foolproof. Good. So let it be. They were foolproof. They would never get out of order.
He proceeded to formulate and clarify his own concept of the Other World in his mind. He would think of it as orderly and basically similar to this space."[309]

The basis for some of Heinlein’s ideas about time are found in the works of J.W. Dunne and P.D. Ouspensky. He explicitly mentions both of these writers in "Elsewhen".[69]

Dunne in An Experiment in Time[190-199] thought of time as a never-ending series of spatial dimensions, all at right angles to each other. An expression of this is found in Citizen of the Galaxy[164-165]. In Dunne’s theory, the notion of time derives out of the relationship between all of the dimensions at a given level and the next higher one.

Dunne, in his explanation of pre-cognition speaks not only of an infinite number of dimensions, but also of "the ultimate observer" which is the "self" existing at all levels in the infinite dimensions[190-199]. The "focus of presentation" at the first level, i.e. that which we perceive as our normal space-time, could be displaced and moved to another focus. This occurs primarily through dreams, but he theorized that the same would happen through death[197] as described in the Piper story mentioned earlier.

Ouspensky in A New Model of the Universe, like Dunne, thinks of all of the dimensions as spatial. However, he restricts his theory to one of a six-dimensional space-time rather than an infinity of dimensions. He says that six dimensions are all that there can be[372] and he says this about them:

"The three dimensions of time can be regarded as the continuation of the dimensions of space, i.e. as the ‘fourth,’ the ‘fifth’ and the ‘sixth’ dimensions of space. A ‘six-dimensional’ space is undoubtedly a ‘Euclidean continuum,’ but of properties and forms totally incomprehensible to us. The six-dimensional form of a body is inconceivable for us, and if we were able to apprehend it with our senses we should undoubtedly see and feel it as three-dimensional. Three-dimensionality is a function of our senses. Time is the boundary of our senses Six-dimensional space is reality, the world as it is. This reality we perceive only through the slit of our senses, touch and vision, and define as three-dimensional apace, ascribing to it Euclidean properties. Every six-dimensional body becomes for us a three-dimensional body existing in time, and the properties of the fifth and the sixth dimensions remain for us imperceptible."[373]

It would appear that Heinlein used this as the basis for his time concepts in Beast. With regard to these three time dimensions, however, Jake also says:

"I don’t want to get lost. My equations appear to be a descrip­tion of six-dimensional space of positive curvature; they’ve worked--so far. But Euclidean geometry and Newtonian me­chanics worked as long as our race didn’t monkey with velocities approaching the speed of light. Then the approximations weren’t close enough. I don’t know that the plenum can be described with only six space-time coordinates. It might be more than six--pos­sibly far more. Mathematics can be used for prediction only after test against the real world."[367]

However, one of the concepts presented in Beast cannot be attributed to Dunne or Ouspensky. By the time of the publication of Beast, another concept of time had appeared and it may be that Heinlein was thinking of this when he spoke of "creating worlds". This concept arises out of attempting to interpret some of the phenomena of quantum physics. In 1957, a young Ph.D. candidate named Hugh Everett at Princeton in his doctoral dissertation, conceived of an interpretation to explain the effects of an experiment using light shown through two parallel separated slits. Examining the pattern formed by this experiment showed clearly the wave nature of light by showing interference patterns. The same results could be shown by focusing a wave of electrons through the same slits. However, when looking at the results of examining single electrons, it always happened that an electron would appear in a single position on the resulting target behind one or the other of the two slits, thus demonstrating its particle nature. The classic interpretation of this, called the Copenhagen interpretation, was that the wave-front produced by the electrons as well as light collapsed into a single result whenever it was examined. In essence Everett proposed that, instead of the wave-front collapsing into one of two possible positions, that both positions actually resulted, each one being in its own world. This is the so-called "Many-Worlds" interpretation of quantum physics. Heinlein’s references to "Schrödinger’s cat" in The Cat Who Walked Through Walls would seem to be a nod to this notion since the term "Schrödinger’s cat" derives from a gedanken-experiment from the early days of quantum studies. Heinlein, in describing Pixel the cat and namesake for the book appears to me to be making a joking comment about Schrödinger’s (hypothetical) treatment of cats. Whereas his cat was to be closed up in a box to wait upon possible death, Heinlein lets his cat escape through the walls!

Although Heinlein’s characters explicitly talk about "creating new time lines" in both Beast and Cat, they also seem to act as if some of what they do is simply changing the past of the time line that they are on, e.g. when a food package is placed under the body of General Walker Evans by a time agent, thus preventing his colleagues, including Richard from the necessity of having to eat him. Richard then begins to "forget" the memory of that event and he is told that eventually, it will be totally forgotten.  In To Sail Beyond the Sunset, Heinlein again appears to fall back to the changeable time line scenario when rescuing Ira Johnson from the Battle of Coventry. In researching the events coming out of the Battle of Coventry, they realize that the history they knew didn’t match, so the rescue of Ira becomes secondary to "Operation Coventry Cusp", an operation to help give Britain the victory during the battle rather than the defeat as written in the histories. I think that the answer to these apparent inconsistencies lies in the quote above from Libby, "We ourselves create the fictions-fictons-ficta that will make it real". In other words, the characters themselves have the same potential as the "author", and can create whatever results they feel necessary. Regardless of the answer to that question, Heinlein presents us in these three books with a very complex, possibly inconsistent, but very entertaining and thought provoking view of this aspect of time travel. To me, one of the most interesting scenes in Cat is when Marshall Sam Beaux, having wounded Richard, is killed by the others in the Circle and then "disappears" exactly as if he is being "erased", and Richard’s wound disappears, all this being done in an apparent direct interaction with the characters in the story by the "author".

Glory Road is a fantasy rather than straight science fiction, but I don’t want to overlook anything. It has 20 universes that can be accessed by what is essentially magic.

Before we leave the works of Heinlein, let us not forget Job. In this story, the protagonist Alexander Hergesheimer is apparently shifted from world to world, seemingly at random. In the end, however, it turns out that the worlds in which he and his companion find themselves are not complete, but are only being changed locally around them[358-359].

Other Writers:

Heinlein was not the first, nor the last to write stories about other dimensions. Murray Leinster wrote his classic "Sidewise in Time"in 1934. This is the earliest story with which I am familiar. The setting for this story is similar to "Elsewhen" in that it deals with a professor and a selected class of students. In this story, however, the people do not do the shifting, but instead, some natural cosmological event which the professor is able to foresee causes large portions of the earth to shift from one dimension to another along some form of "temporal fault lines". Crossing these lines after the shift puts the characters face-to-face with the inhabitants of these areas. Thus we have worlds populated with modern day Roman Legions encountering people in a mid-western town, patches of Jurassic times complete with dinosaurs appearing in a farmer’s backyard and a salesman for The American Flag Company being arrested by police from the Confederate States of America for displaying the American flag on his car. Professor Minott, the main character, is determined to take advantage of these shifts to find a world in which he can rule using his superior knowledge. He wants to take all of the students with him, but they rebel against him and in the end he is forced to go alone with one exception. He had been smitten with one of the students and wanted to make her "his queen", but this is foiled by the other students. In the end, one of the other female students decides she likes the idea and goes off with him. At the end of the story, most, but not all, of the shifted time areas return to their normal state.

Other writers have written considerably about travel to other dimensions. One of these is H. Beam Piper, another writer from the "golden age" of science-fiction of J.W. Campbell’s Astounding Science Fiction

Piper wrote the paratime stories in which a main character Verkan Vall plays a significant part in most of the stories. Piper also explicitly based his time stories on the theories of J.W. Dunne, although for some reason, he always spoke of "10 to the 100th" or "near infinity" of universes rather than the infinity from Dunne’s work. He also explicitly uses Dunne’s theory[Paratime, 51] when describing the phenomena of pre-cognition. As Heinlein does, he uses a common background not only in all of these stories, but also in his own version of "future history" stories.

Piper also wrote a short story, apparently unrelated to the paratime series, called "Crossroads of Destiny" in which a group of men discussing a possible television series about alternate worlds are overheard by a quiet man who as it turns out is a visitor from just such a world. We find at the end that the world in which the story takes place had Benedict Arnold as being the "father of his country".

L. Sprague DeCamp wrote "The Wheels of If" in which a lawyer named Alister Park is shifted through a series of worlds by a procedure performed on an analog of his by a person in one of the other dimensions. An experimenter, who was attempting to get rid of a powerful political opponent, causes Park to shift through a series of worlds until he reaches the one of the experimenter. Although the experiment works to the extent that it moves people through the various worlds, it ultimately fails in that Park turns out to be an even more formidable political opponent than the original and he decides to stay in the new world. Park finds by experience that which Heinlein often quoted from Shaw about the customs of the tribe. He goes nude swimming on a beach where this appears to him to be the custom and is arrested for not having a band to cover up his belly button! In the unusual technique area, DeCamp did a fairly credible job of creating a language in the new world which matched its history by lacking much of the French-Latin influence in our own English. Park’s arrest for what for us would be "charged with indecent exposure" becomes "marked with shameful outputting"[35].

DeCamp in collaboration with Fletcher Pratt also wrote a series of humorous stories about yet another professor named Chalmers and a graduate student of his named Harold Shea. Chalmers, similarly to Professor Frost’s method in "Elsewhen", uses a form of self-hypnosis to shift to other dimensions. They create "descriptions" of the sought worlds using symbolic logic. The worlds that they access possess their own laws, such as those of magic. As in the "World-As-Myth" of Heinlein, Shea, Chalmers, and a comic character named Vaclav "Votsy" Polacek travel through the worlds of Norse mythology, Spenser’s Faerie Queene, Coleridge’s Xanadu and Ariostos’ Orlando Furioso.

In a very similar vein, Keith Laumer wrote a series of humorous stories about travel to other dimensions with a character named Lafayette O’Leary.

Laumer also wrote more seriously in his Imperium novels about Brion Bayard. Bayard is originally kidnapped by agents of the Imperium, the ruling government, in a parallel world to take the place of his analog in yet another world where he is a dictator and appears to be a threat to the Imperium. Things don’t turn out as expected, but Bayard completes his ultimate mission and becomes an agent of the Imperium. In later works, he continues with trips to other dimensions and even encounters non-human inhabitants in some of these who were descended more directly from apes and chimpanzees. A unique aspect of these works is that most of the worlds surrounding the few remaining inhabited dimensions were either destroyed or horribly mutilated by the forces unleashed in those worlds when the dimensional shifting device was improperly used by the inventors.

The first novel that I ever recall reading on this theme was Sam Merwin Jr.’s The House of Many Worlds. In this story, history is divided at each crucial cusp in time and the subsequent worlds can be reached by being at various locations called "tangential points" at the proper time.[25]  Each such point provides a means of traveling to one or more different worlds created by earlier crucial historical events having taken place there. The protagonists, Ellie Mariner and Mack Fraser are recruited into an organization whose purpose is to try to keep catastrophes from happening in the various worlds. There is a surprising twist, reminiscent of Heinlein, in that one of the characters is a real-life version of the fictional John Henry. It is worth mentioning, I think, that Merwin was ahead of his time in that he showed an interracial relationship between Ellie and John. This story is one variation on the "fork in time" theme. Like Moore’s novel, mentioned in Part One, the protagonists do not originate in our own time line, but one in which America won its independence for a while, but lost it during the War of 1812.

Another version of the "fork in time" provides the underlying structure of Richard Meredith’s timeliner trilogy.  In these stories, there are organizations somewhat like Anderson’s Time Patrol, whose job it is to force the creation of worlds in which the ultimate history of the creators of the organization would be preserved. Unlike Anderson’s Danellans, Meridith’s Tromas are not benevolent at all. Their goal is to create the maximum probability that their world will be the one left after the dimensions all collapse back to a single one at some point in the future. This collapsing is caused by the fact that the universe is limited in the number of worlds that it can support.

Frederik Pohl, basing his framework strictly on the "many-worlds" interpretation of quantum theories, wrote The Coming of the Quantum Cats. Basically, machines are used to open up gates to the alternate dimensions. The plot really gets mixed up as it turns out that a number of different worlds are all accessing each other at the same time. We follow the story using the points-of-view of a number of characters in several of their analogs. One such character is Nicky DeSota. In one world, he is a small time mortgage broker, in another a Senator and so on. Another character named Larry Douglas is an FBI informant in one dimension. He is the inventor of the gate in another and is the ambassador from Russia, named Lavri Djugashvilli, in a third. They all had the same name for their grandfathers, Joseph Djugashvilli, who was a small time crook who had immigrated to America in Larry’s world and was the communist dictator Joseph Stalin in some others. Ronald Reagan appears in a couple of worlds, one, as an avowed socialist, with his first wife Jane Wyman, and another as "First Gentleman" with Nancy, who is President of the United States.

In the end, it turns out that all of this crossing back and forth is causing the continuum to become unstable and a more advanced world puts an end to it and collects many of the people involved into a world no longer inhabited by people.

The novel Alternities by Michael P. Kube-McDowell is yet another treatment of the alternate worlds theme. This story involves unsavory characters and politicians who attempt to take advantage of gates to other worlds to escape the events in their own world.

Gregory Benford has perhaps written the most thorough and accurate story built on the concept of the "many-worlds" interpretation of quantum physics in his Timescape. This is not surprising since he is himself a theoretical physicist in this field. One thing which has always bothered me about the "creating of new worlds" aspect was how did all of these experiments at the microscopic world of light waves and electron waves relate to the macroscopic world of everyday reality. In other words, what would cause universes to be created by the events of ordinary life? Benford seems to give a rationale for this in that new worlds are created only when attempts are made to create paradoxes in the past. His characters use tachyons to send messages to the past to effect these changes.

Fredric Brown wrote a classic novel about travel to a parallel world, What Mad Universe, in which an editor of a science fiction fan magazine is displaced into an alternate world by the release of tremendous electrical energy given off when an experimental moon rocket crashes on top of him. He finds himself in a world where space travel is common. There are two interesting links to the works of Heinlein, although they were probably not intentional. The first is that the device used for space travel in the new world is a simple device made from winding a coil in a certain way. The first discovery of this device was done by a scientist using his wife’s sewing machine. This reminded me of the continua device of The Number of the beast made by using gyroscopes. The second, and more direct, link was that the choice of worlds was determined by the thoughts of the traveler. In this case, the magazine editor found in the new world a very prominent character named Dopelle who was simply unbelievable and the protagonist considered that any editor who had read a story with such a character would have rejected it because he was so unbelievable. It turns out that the reason that this character is in this world because he, the editor, was thinking about a young adolescent fan in his own world named Joe Doppelberg at the time of the transition, and this world was selected because the editor was imagining what kind of a world Doppelberg would have imagined. A close analogy to Heinlein’s World-As-Myth. In the end, the protagonist helps to save the world from invaders by doing a kamikaze run against their ship with a warhead which was an enhanced version of the device that had brought him there, thus propelling himself again back across the dimensions. This time he chooses to select a world to improve his original situation and finds himself in a world where he is now the owner of the magazine chain for which he was originally merely an editor.

We can see from William Tenn's foreword to the book below that Brown's concept appears to be identical to Heinlein's 'multiple-ego solipsism'and incidentally shows the influence of Lewis Carroll which might also have influenced Heinlein.

What Mad Universe, was for Fred Brown the ultimate cosmic question, the investigation of the belief he voiced in "It Didn’t Happen," that "the entire universe is the product of one’s imagination--in my case, my imagination." He carried it about as far as his master, Lewis Carroll had done, when Alice said of the Red Knight

"He was part of my dream, of course--but then I was part of his dream too!"[foreword]

Alternate Histories

Some works are considered simply as ‘alternate histories’ with little or no thought of travel or connection to others. Some of them are considered here.

A Transatlantic Tunnel, Hurrah! is a light, somewhat melodramatic novel set in a world where Spain and Portugal never developed. This eventually led to the present world, dominated by the British Empire, where Augustus Washington, an American colonial and descendant of the hanged traitor George Washington, is in charge of developing an underground tunnel which is to connect America and Europe for high-speed travel. The basic setting of the novel is a world which is somewhat technologically backward to our own and the society is still basically Victorian. In America, the native peoples were never conquered as in our own and live on a par with everyone else. Interestingly, a glimpse into our own world is given through a psychic medium during séances. A counterpart of our real-life Arthur C. Clarke appears in a cameo as well as does a counterpart of the fictional Dick Tracy.

He makes extensive use of this knowledge in his Agent of Byzantium, a connected set of light adventure stories set in a 14th century altered universe where Mohammed converted to Christianity and became a Christian Saint. Thus there was no Islam and no fall of Constantinople in 1453. Many of the events that happened during our own history with respect to The Orthodox Church have not happened in this history. Instead the protagonist, Basil Argyrios, an agent of the Imperium, is instrumental or at least prominent in the development of some of the same events at much later dates. Notable among these is the Iconoclast controversy during which the church is thrown into turmoil by those who claim icons to be heretical. As for foreign threats, instead of Islam, Constantinople is beset on the west by a strong Franco-Saxon Roman Catholic realm and the Persian Empire on the east. No matter how different things are, the split between Rome and Constantinople, the so-called Great Schism, still took place. A prominent theological point of this division between the Roman Catholicism of the Franco-Saxons and the Orthodoxy of Byzantium is brought out when Basil, spying out a western monastery, is recognized as being Orthodox when he fails to use the filoque ["procession from the Son"], in his recitation of the Nicene creed.

Although, on the surface, Phillip K. Dick’s The Man in the High Castle is simply another alternate history novel, there are deeper levels to this work as was the case in most of Dick’s works. The surface story is that this is a world in which Germany and Japan won World War II. America is divided into basically three zones, the eastern part ruled by Germany, the west by Japan and a middle zone where neither hold complete sway. The point of divergence for this world appears to have a successful attempt to assassinate Franklin D. Roosevelt, and the failure of his successors to come to the aid of England and Europe. On one level, it is, I think, a strong polemic against racism, shown by the extremes to which Nazism could lead and less obviously in the notion of ‘place’ in the Japanese dominated sphere. On another level, the work continues Dick’s ideas of subjective reality as shown in his other works.[Brunner] This is shown most directly by the dependency on the use of I Ching or The Book of Changes. The Chinese philosophy embedded in this book has permeated all of the Japanese dominated society to the extent that almost all of the main characters use it constantly to determine what is the reality underlying their actions or choices. A related element which challenges their sense of reality is the popularity of a book, written and published in the middle zone and banned in the German realm. This novel is itself an alternate history story about a world in which Germany and Japan lost, but which is most definitely not our own world. In the end, it turns out that this novel was itself written with the aid of I Ching, thus presenting the concept that the fictional world represents the true reality, not their own. It is interesting to note that Dick claims that he wrote TMITHC itself using I Ching.[Dick, 1965] This work won the Hugo for best novel of 1962. As strange as these concepts might seem, they are not really that different from Heinlein’s World-As-Myth in that reality may ultimately reside in the mind (or minds). A major difference between the two authors being the hopeful, confident, fight-any-odds outlook of Heinlein’s characters versus the passive, accept-your-fate, even border-on-insanity outlook of Dick’s characters.

British author Keith Roberts wrote Pavane, a novel, which appears to be a history of the world that develops after the assassination of Queen Elizabeth I in 1588. As a consequence, the Spanish Armada succeeds, restoring England to Roman Catholicism. This in turn provides the basis for The Roman Catholic Church to rule most of Europe with all secular rulers completely under its control. The story runs from 1968 through four generations, a period of 50 or so years.

The title of the book is taken from a very slow medieval dance and the chapters of the book, (published originally as separate stories), are called measures indicating the musical structure of the novel. However, not being musically inclined, the analogy I drew was visual rather than musical. Roberts was so extremely capable at describing the settings of the stories that they reminded me of a large mural done by some great painter, or better yet, a finely woven tapestry showing a series of episodes related by common threads moving throughout the work. The stories are elegant and incredibly rich in detail.

I said above that this ‘appears’ to be a simple alternate history story such as those of Turtledove. However, the last section of the book called ‘Coda’ implies that rather than lying in a parallel timeline, the theory is one of ‘cyclical’ time, where the world stops and restarts again, repeating closely what happened before. In this particular cycle, it is implied that history develops differently because of knowledge about the earlier cycle held by the church as well as knowledge held by a group of beings, which we and they call Fairies, or The Old People. In describing a graffiti mark which appears at the front of each measure and is referenced throughout, Roberts has one of his Fairy characters write:

"Two arrows point outward ran the letter. Two point in, toward each other. This is the end of all Progress; this we knew when we first carved the mark many centuries ago. After fission, fusion; this was the Progress the Popes fought so bitterly to halt.

The ways of the Church were mysterious, her policies never plain. The Popes knew, as we knew, that given electricity men would be drawn to the atom. That given fission, they would come to fusion. Because once, beyond our Time, beyond all the memories of men, there was a great civilisation. There was a Coming, a Death, and Resurrection; a Conquest, a Reformation, an Armada. And a burning, an Armageddon. There too in that old world we were known; as the Old Ones, the Fairies, the People of the Hills. But our knowledge was not lost.

The Church knew there was no halting Progress; but slowing it, slowing it even by half a century, giving man time to reach a little higher toward true Reason; that was the gift she gave this world. And it was priceless. Did she oppress? Did she hang and burn? A little, yes. But there was no Belsen, No Buchenwald. No Pass­chendaele.

Ask yourself, John, from where came the scientists? And the doctors, thinkers, philosophers? How could men have climbed from feudalism to democracy in a generation, if Rome had not flooded the world with her proscribed wealth of knowledge? When she saw her empire crumbling, when she knew dominion had ended, she gave back what all thought she had stolen; the knowledge she was keeping in trust. Against the time when men could once more use it well. That was her great secret. It was hers, and it was ours; now it is yours. Use it well."[275]

Conclusion:

Science fiction writers, and especially Robert Heinlein, have given us many glimpses into the worlds of "what-if". Many such stories talk about trips to other worlds in space and time.  In Part One of this essay, I discussed Heinlein’s and other writers’ stories dealing with the main concepts of linear time travel. Here in Part Two, I have attempted to present another side of the "what-if" of time in science fiction. What if there are worlds in dimensions not our own, i.e. a multiplex of time lines, but which we might be able to reach in some way, or at the very least, think about? What would we find there? What would life be like in those worlds? In what ways would history have changed from what we know? Many are the questions that can be asked and Robert Heinlein and others have given us clues to what some of the answers might be while providing us with many hours of fascinating entertainment. Such world presentations often give us the insight by which we can examine our own world.

Works Cited

Benford, Gregory Timescape. Bantam Paperback, 1992.

Brown, Fredric What Mad Universe, E.P. Dutton, New Bantam Edition, August 1978.

Brunner, John "The Work of Phillip K. Dick", New Worlds, No. 166, September 1966. [pp. 142-149]

DeCamp, L. Sprague "The Wheels of If." collected in The Wheels of If, Paperback, 1970.

Dick, Phillip K. The Man in the High Castle, Vintage Books,New York, 1994.

Dick, Phillip K. "Schizophrenia and the Book of Changes", publisher unknown, 1965.

Dunne, J. W. An Experiment with Time. Faber & Faber, 1934.

Dunne, J. W. Serial Universe. Faber & Faber, 1934.

Harrison, Harry A Transatlantic Tunnel. Hurrah!Tor Books, October 1991.

Heinlein, Robert A. Between Planets. Charles Scribner’s Sons, 1951.

Heinlein, Robert A. Citizen of the Galaxy. Charles Scribner’s Son, 1957.

Heinlein, Robert A. "Elsewhen." collected in Assignment in Eternity, Signet, 1953.

Heinlein, Robert A. Glory Road Avon Paperback, 1964.

Heinlein, Robert A. Job. Ballantine Del Rey, 1984.

Heinlein, Robert A. The Cat Who Walked Through Walls. Putnam’s, 1985.

Heinlein, Robert A. The Number of the Beast. Fawcett Paperback, 1980.

Heinlein, Robert A. To Sail Beyond the Sunset. Ace Paperback, 1987,

Heinlein, Robert A. Waldo. collected in Three By Heinlein. Doubleday, 1951.

Kube-McDowell, Michael P. Alternities. Ace Paperback, 1968,

Laumer, Keith The World Shuffler. Ace Paperback, 1970,

Laumer, Keith The Time Bender. Ace Paperback, 1971,

Laumer, Keith The Shape Changer. Ace Paperback, 1972,

Laumer, Keith The Galaxy Builder. Ace Paperback, 1984.

Laumer, Keith Worlds of the Imperium. Berkeley Paperback, 1961.

Laumer, Keith The Other Side of Time. New American Library, 1965.

Laumer, Keith Assignment in Nowhere. New American Library, 1968.

Laumer, Keith Zone Yellow. Baen, 1990.

Murray "Sidewise in Time." collected in The Best of Murray LeinsterDel Rey Paperback, 1978.

Meredith, Richard At The Narrow Passage. Playboy Press, 1979,

Meredith, Richard Vestiges of Time. Playboy Press, 1979,

Meredith, Richard No Brother, No Friend. Playboy Press 1979,

Merwin Jr, Sam The House of Many Worlds. Avon, 1955.

Moore, Ward Bring the Jubilee. Avon, 1955.

Ouspensky, P.D. A New Model of the Universe. Knopf, 1969,

Ouspensky, P. D. Tertium Organum. Alfred A. Knopf; distributed by Random House, 1981.

Piper, H. Beam "Crossroads of Destiny." collected in The Worlds of H. Beam Piper. Ace Paperback, 1983,

Piper, H. Beam Paratime. Ace Paperback, 1981,

Piper, H. Beam Lord Kalvan of Otherwhen. Ace Paperback, 1965,

Piper, H. Beam "Time and Time Again." collected in The Worlds of H. Beam Piper, Ace Paperback 1983,

Pohl, Frederik The Coming of the Quantum Cats. Bantam Paperback, 1986,

Roberts, Keith PavaneDoubleday & Co, Garden City, New York, 1968.

Turtledove, Harry Agent of Byzantium.

Acknowledgements

I acknowledge a great debt to the following:

Bill Patterson, who asked me to write this article, did some excellent editing to smooth out the narrative in Part One and gave me pointers to Ouspensky and Dunne and to works by P. Schuyler Miller, David Gerrold, Phillip K. Dick and an additional work by Keith Laumer.

I wish to thank Father Deacon Anthony Bridges for giving invaluable advice on style and grammar on an early draft of Part One.  Any stylistic, grammatical or typographical mistakes that remain are strictly my responsibility.

The following articles gave me insights into Heinlein and helped me form the basis for my thinking on the subject.

LeGere, John "Wells, Dunne, Heinlein", The Heinlein Journal, Issue 6, January 2000

Patterson, Bill "A Study of Elsewhen", the Heinlein Journal, Issue 4, January 1999

Patterson, Bill "A Study of Life-Line", The Heinlein Journal, Issue 2, January 1998

I found the following very useful in trying to understand the "many-worlds" theories.

"Everett's Relative-State Formulation of Quantum Mechanics"
http://plato.stanford.edu/entries/qm-everett/

"The Everett FAQ", http://www.hedweb.com/manworld.htm

"Many-Worlds Quantum Theory", http://www.innerx.net/personal/tsmith/ManyWorlds.html

"Sagan on Time Travel", http://www.pbs.org/wgbh/nova/time/sagan.html

"David Deutsch’s Home Page" http://www.qubit.org/people/david/David.html

"An Excerpt from Timescape by Gregory Benford," http://www.phys.uregina.ca/sparro/huber/timescape.html

"Time Travel and Modern Physics" from Stanford Encyclopedia of Philosophy
http://plato.stanford.edu/entries/time-travel-phys/#1

The following was helpful with my limited understanding of the philosophy of I Ching.
"I Ching Wisdom - Advanced Ideas and Insights"
http://www.ichingwisdom.com/IChingWisdom/index.html

By no means do the works mentioned in this essay represent the total of works which deal with this subject. I have used those works with which I am most familiar and offer my apologies to any author or reader who might feel that his favorite work should have been included.

Appendix

Robert A. Heinlein's short story, "All You Zombies" is considered one of the ultimate of all time travel stories.
The major twist to the story is the fact that *all* of the main characters turn out to be one and the same person at various stages of life, starting as a baby and ending up as a veteran agent of the "Time Corps". The unusual aspect of this is that this person is his own mother and father. Many people reading this story become entangled by the thought that the hero/heroine is caught in a permanent "time loop" from which he never escapes. Even more than that, they are bothered by the problem of "where does it all start".

Below is a diagram which I have drawn to try to make the events in the story clear. The key to avoiding confusion is to start at the right point, in this case, with the birth of the baby at point A. Assume, for the purposes of discussion, that the POV of the character begins at that point in time. Don't worry about 'where did it all start'. Keep your focus at all times, (no pun intended), on the point-of-view of the individual as she/he goes through time and the various loops. It should be noted that he does finally exit the loop at the end.

(Note: this might make it appear that there is a 2-dimensional time continuum, but that is not the case. The various lines are simply separated for demonstration purposes. Furthermore, the diagram can be thought of as being the viewpoint that a fifth-dimensional observer would have. All of the first four dimensions, 3 space and one of time are contained in the lines going back and forth across the page and we are looking at them from the next higher dimensional viewpoint.)

The timeline for "By His Bootstraps" is shown below. It is not quite as complicated as that for "Zombies" as it is not a closed loop, but it does feature four loops to the same time.

Usually, one encounters people who criticize time travel stories such as "Bootstraps" and "Zombies" using one of two types of logic problems.

The first of these is the predestination versus free will question. I don't really see this as a logic problem except that logically one viewpoint would seem to exclude the other. The only answer I see to this is what is demonstrated by the choices that Bob Wilson makes in "Bootstraps". From the outside of the system looking in, these choices would appear to be predestined, but from the inside, from Bob's viewpoint at every point in the loops, he is free to make any choice he wants. But because of all of the conditions, his own mindset, the actions of the other Bobs and everything else he chooses the same course which he had seen himself make on previous loops.

The second of these is cause and effect. In other words, how can something be an effect from a cause that hasn't happened yet. This is simply a failure to understand that while an agent of cause may be from the future, the cause actually occurs in the past after that agent has arrived in that past so that it becomes the cause. A specific criticism lodged against "Bootstraps" would appear to derive from this particular "cause and effect" notion. During an online internet discussion, the following quote was made.

"[The story] depends on having a man from 1952 bring himself into the future year of 30,000, he [Heinlein] needs an initializer. Some agent that would fetch the man to start the ball rolling."

Apparently, the writer of this quote feels that without Diktor himself having gone into the past and having fetched Bob into his present that the logic falls apart. I say this because he later accepts the logic of "Zombies" because the main character actually does all of the "fetching". His flaw here in "Bootstraps" is that he is being blinded by the notion that some master cause is required at the earliest point in time to start off the whole sequence. He can't accept that a sequence can start at any point in time even though the narrative in this case does start at the earliest point.