Nightsider
Chrono Cadet
Hi, below is the time travel section from my RPG. It is a free download on the website. That's not important. I would love to see some of the intelligent posters on this board give views on this game version of time travel.
QUOTE:
The Romance of Science: Time Travel
But for him it was his last afternoon as himself,
An afternoon of nurses and rumours;
The provinces of his body revolted,
The squares of his mind were empty,
Silence invaded the suburbs,
The current of his feeling failed; he became his admirers.
Now he is scattered among a hundred cities
And wholly given over to unfamiliar affections,
To find his happiness in another kind of wood
And be punished under a foreign code of conscience.
The words of a dead man
Are modified in the guts of the living.
IN MEMORY OF W.B. YEATS, W.H. Auden
Once, there was a man who could travel in time and space. He fought evil, did not doubt, even for a second, the rightness of his own moral position and commitment and always won. Always.
Unfortunately for the Universe, although this man successfully defended the world from alien invasion he was less adept at filtering the evil within. Eventually human-origin, garden variety, suburban, evil triumphed. His enemies had little chance to rejoice however. The same force that consumed their nemesis consumed them as well. Now there are a handful of human replicas of
his equipment, his alien enemies, and his appearance left to remind us of our greatest cosmic champion. A traveller in time, he now belongs firmly to the past.
One of the ultimate expressions of technology is time travel. The ability to physically travel “through time†into “the past†or “the future†or even into parallel worlds formed by divergent history is a staple of more recent pulps. If a GM mixes in gangsters and super-villains, their campaign is set for a series of colossal adventures.
Also, given that the GOLDEN sourcebook includes a detailed and fairly exhaustive 100-year timeline, time travel and the concept that the game world’s “true†history will be significantly different from that of our own Earth leads some players to consider the consequences of changing events. Does World War 2 have to happen? If it doesn’t happen, or doesn’t happen in the same way as on our Earth, what effects will this have down the track? Were there positive effects of the great conflicts of the Twentieth Century? Or would it be worth the effort to stop the future from unfolding in that way? Comicbooks and even the original literary pulps are full of such intended divergences from our own “real†timeline of history.
In the STEEL part of the present book, in the Feats section, there are various Feats listed as only being available for characters with the Time Lost background. Scrutiny of these Feats shows that amongst them are all the tools needed to create a Time Travel campaign. Chief amongst these Feats is of course Time Travel itself, an incredibly powerful ability, and one that any GM would be wise to most closely monitor once it is in play.
TIME TRAVEL FOR FUN AND PROFIT
FUTURE, n.
That period of time in which our affairs prosper, our friends are true and
our happiness is assured.
THE DEVIL’S DICTIONARY, Ambrose Bierce
The GM can run Time Travel in a number of ways.
Firstly, he or she can simply allow swashbuckling time travel adventures in which the players meet historical figures, duke it out with period bad guys and get home again with a minimum of effort and historical accuracy.
The second way is to have the campaign structured around a group of characters whose adventures occur in time and space, with the Time Lost character as the chief motivator of the adventures. Perhaps whatever mechanism the Time Lost character uses for time travel has malfunctioned, and the characters are trying to get home again. Or perhaps there is a convoluted plot across time that requires the characters to return again and again to the same physical location but in different eras of the past present and future.
A third way is to have Time Travel used as a “save game†mechanism for the players. The Time Travel character then uses his or her time travelling powers to return the group to an earlier point before some disaster occurred. This requires the time traveller to not be amongst the dead or injured. If this method is employed then the GM should specify the number of times that the time traveller can “save†the game. Each of these “saves†is considered a “Heisenberg Junctionâ€, a point from which timelines diverge. It is suggested that the GM only allow a number of Heisenberg Junctions for the time traveller equal to their character level. Once chosen, the Laws of Time forbid a time traveller from ever changing their chosen Heisenberg Events.
For example, a 3rd Level Time Lost character with Time Travel nominates the start of her adventures as a Heisenberg Junction. Then she goes off on an adventure where a team mate screws up badly and dies. She then nominates to time travel back to her recorded Heisenberg Event, tell herself not to allow the adventure to continue, and thus prevent the team mate from dying. If the time traveller makes her power check for Time Travel, this occurs successfully. Otherwise temporal paradoxes, the disbelief of her earlier self, the Laws of Time or whatever have prevented the restoration of the “saved gameâ€.
All well and good. However, from the point of view of a Multiverse or Omniverse, ie of not just a single line through history but a multitude of infinity of parallel worlds, there is still the original world where the team-mate died. There are also the worlds where the team-mate didn’t die, and worlds where the time traveller didn’t invoke their Heisenberg Junction. And right there one has the basis for a series of interesting crossovers between versions of the heroes from worlds events have fallen out very differently…
Time Travel in a Pulp game can be incredibly subversive. Events such as the Kennedy or Lincoln assassinations can be linked via some insane cross-time plot, or a super team can have members from a dozen different time zones, or even from different parallel worlds. It also encourages players to think about what they are doing. Which in itself is a good thing.
“I KNEW THOMAS JEFFERSON…â€
A Time Traveller’s unique perspective confirms again and again how fragile causality can be. So often, he hints at or inadvertently lets slip some future event or personage unknown to his companions. On other occasions he displays equally eerie knowledge of the distant past.
People of other times, especially “historical personagesâ€, are an essential part of the fun of roleplaying time travel. It is much more important to get personal details of famous people correct than it is to make sure you have worked out what level character they are. In fact it isn’t really necessary to even have statistics for famous people the time travellers meet, unless they encounter a historical figure who is a pirate or an air ace or something similar.
The recommended way to prepare for running a time travel adventure or campaign is for the GM to have some grasp of the historical time it is likely that the group will want to go to. Other than that, the GM will need to become a magpie concerning biographical trivia of famous faces, details of period costume and manners and so on. Care needs to be taken that it is always emphasized, especially to the nerd or “anarak†type player, that the time travelled to is the game’s version of that time, not our world’s equivalent era. If the GM is less knowledgeable about the period than one of the players, too bad. The GM could allow that player some input into how the period is run, but still it is the GM’s game, not the player’s. And if player knowledge that a character couldn’t have starts entering play itself, the GM needs to stamp on that quickly to avoid anachronisms destroying play.
Some key points to remember:
1. Different time periods will have different proportions of classes or some classes completely absent. In ancient Rome for example there will be no scientists to speak of at all, but many of the philosophers who taught the children of the rich would have a surprisingly flexible mind, able to accept advanced concepts with little trouble.
2. The mental processes of characters don’t really vary with time period, but their social conditioning and beliefs will vary radically. These beliefs will dictate how they see, or perceive, what they encounter. Thus a time machine might be seen as a living monster or a devilish engine depending where and when one is.
3. In most cases time travellers will not stand out so much that they will not still be thought of as living people. This means that locals might want to capture, enslave, sleep with or recruit the time travellers.
4. Sometimes time travellers might be seen as gods or angels… or devils.
5. If the heroes can time travel, so can other characters.
THE LAWS OF TIME
There was a young man who said: "God,
I find it exceedingly odd
That a tree, as a tree,
Simply ceases to be
When there’s no one around in the quad."
"Young man, your astonishment’s odd;
I am always about in the quad.
So the tree, as a tree,
Continues to be
Since observed by yours faithfully God."’
PAIRED LIMERICKS, traditional.
The so-called Laws of Time are a set of rules that have to be obeyed, not because to disobey brings the sanctions of some sort of “time policeâ€, but rather because to try and disobey them frustrates any sane purpose of time travel in the first place. The Laws of Time summarise the fantasy physics of time travel for GOLDEN and beyond.
The Laws of Time are widely known of by time travelling characters and species, since they form the cornerstone of any sane approach to time travel. Even the most despicable and dangerous of time-travelling villains and monsters do not dare toy with the Laws of Time. To do so would risk intercosmic annihilation on a multiversal scale.
Each multiverse is comprised of a near-infinity of parallel universes. The effect which prevents an actual infinity of universes existing is simply entropy – a certain fraction of the whole falls into heat death or some other form of universal destruction and undergoes superstring collapse.
Consider each multiverse to be akin to a coral reef. The beautiful and dangerous ocean in which the multiverses expand and contract is the Omniverse: the sum of all that was, is, will be – and can never be. The multiverses are what is; the Omniverse includes was, and is and will be – and maybe, and never.
So here they are: The Laws of Time.
Law 1: THE PRESERVATION OF THE ENERGY OF INFORMATION
The Law of the Preservation of the Energy of Information states that the difficulty of changing an event in a specific time period varies with the square of the amount of knowledge relating to that event.
Every measurable moment of time is a product of an infinite number of previous and future moments. Thus completely isolating an “event†in time (the signing of a treaty, the beginning of a war, a love affair, a death) is an impossibility. Two pieces of information about a man’s political career (or any other “eventâ€) makes it four times harder to change the course of his life. In ignorance lies the power to change details. As soon as someone becomes anonymous for any period of time, any number of “lost years†or “missing adventures†can be added to the sum total of their life.
Law 2: THE PRINCIPLE OF ORTHOGONAL HISTORICITY
The tendency of any timeline is to follow its most likely thermodynamic and chronodynamic track, and its applicable laws of physics and sociology will dictate the degree of change possible by someone entering the reference frame from another time period.
Leading on from Law 1, because any event is a part of a tapestry of surrounding events, it is difficult to stop the inertia of history from fulfilling its existing tendencies. For example attempting to prevent the outbreak of World War 2 by faking orders or some such would only delay the outbreak, not prevent it, because of all the other factors leading to that point in history. And since few people have detailed knowledge of the causes of wars it would make no real difference to most people if there were “new†details in the history of the war, unless those details were so huge (eg identity of the Fuhrer) that all history books might include them. It is therefore much easier to modify an event (new or different battles in a war, slightly different chain of events in a love affair, etc.) than to prevent an event or create a new replacement event. For example killing Hitler does not undo all the pre-existing factors leading to the Nazification of Germany in the 1920s and 1930s. And there are a surprising number of alternative candidates for any existing “big figure†in history. The identity of the Fuhrer might be altered (might) but the existence of a Fuhrer in Germany had become a virtual certainty by 1933 and quite likely by much earlier even than that date.
Law 3: THE LIMITATION PRINCIPLE
The number of basic changes to any event is limited by the relative certainty of the event. The chance of successfully changing an event varies with the inverse square of the number of time travelling attempts to alter it.
Isolating an event to alter is the relatively easy part. Once any such event is examined however, the mere act of examining it creates the potential for the event to eventually become better known and documented, thus bringing into operation Laws 1 and 2. Thus Law 3’s effect acts as an absolute break on time travellers affecting “key eventsâ€. The moment that people begin to investigate an event and interfere, that act of interference increases the knowledge of the event, thus making the event harder to change.
The first time an event is interfered with, the basic chance of successful minor change is whatever is set by the GM – anywhere from 100% to 1%. The moment that the first attempt fails and a second attempt is undertaken, the base chance is divided by four (number of attempts = 2, 2 squared = 4). On the third attempt the chance is divided by 9. By the tenth attempt, the original success chance has been reduced to 1% of what it was.
Law 4: THE DIRECTIONLESS MOMENT
Time’s smallest measurable passage has no objective direction. For any moment, there is at least one supporting moment, but this relationship does not imply a direction of flow of time.
Perhaps the strangest concept in time mechanics, the Principle of The Directionless Moment identifies the dimension we call time as being less like a river and more like an avalanche of wreckage composed entirely of pigeonhole shelving. Any particular “timeline†created by mortal perception of the passage of time is in reality a random sampling of moments strung together by the subconscious into a coherent whole. The degree to which history as taught and remembered is founded, not on personal experience but on acceptance of other people’s stories is truly remarkable.
A more profound implication is that, whilst most people understand how the “past†can affect the “futureâ€, the “future†can similarly affect the “pastâ€. The first and second Laws simply say that, due to relative knowledge, the choice of perceiving a set of events as the “past†makes the “future†easier to change. In fact, one could define the future as the period of time that we have deliberately blinded ourselves to, the better to retain free will.
The central concept to keep in mind is that by definition true paradoxes are impossible. Thus all those nerdy half-smart ideas like “killing your own grandfather and ceasing to exist†can’t happen. If you could travel back and meet “your own grandfatherâ€, one of two things is true. Either he is your grandfather, and you don’t kill him, or you kill him and he is the grandfather of someone who would have been virtually identical to you, but who never existed in the universe you find yourself in.
The post-war science fiction author H. Beam Piper believed himself to be from a parallel world, and as a consequence of this belief had a very strong grasp of the “diagonal†nature of time travel. The past or future travelled to is not “directly in line†with your present time, since your present’s past presumptively did not include you travelling back into it. Or if it did you were not aware of it. Either way, a state of imperfect knowledge allows the continuum to unfold in a normal linear way, resembling a timeline even when the elements of the “conveyor belt of history†are taken from a smorgasbord of elements rather than a predictable linear series of very similar settings. History is nothing more than an imperfectly remembered dream within which alien invasions, conspiracies, pulp heroes and unexplained phenomena form part of the architecture. Within this melange the more recognisable detritus of politics and culture materialise and dematerialise. History is hallucination by consensus.
/QUOTE
QUOTE:
The Romance of Science: Time Travel
But for him it was his last afternoon as himself,
An afternoon of nurses and rumours;
The provinces of his body revolted,
The squares of his mind were empty,
Silence invaded the suburbs,
The current of his feeling failed; he became his admirers.
Now he is scattered among a hundred cities
And wholly given over to unfamiliar affections,
To find his happiness in another kind of wood
And be punished under a foreign code of conscience.
The words of a dead man
Are modified in the guts of the living.
IN MEMORY OF W.B. YEATS, W.H. Auden
Once, there was a man who could travel in time and space. He fought evil, did not doubt, even for a second, the rightness of his own moral position and commitment and always won. Always.
Unfortunately for the Universe, although this man successfully defended the world from alien invasion he was less adept at filtering the evil within. Eventually human-origin, garden variety, suburban, evil triumphed. His enemies had little chance to rejoice however. The same force that consumed their nemesis consumed them as well. Now there are a handful of human replicas of
his equipment, his alien enemies, and his appearance left to remind us of our greatest cosmic champion. A traveller in time, he now belongs firmly to the past.
One of the ultimate expressions of technology is time travel. The ability to physically travel “through time†into “the past†or “the future†or even into parallel worlds formed by divergent history is a staple of more recent pulps. If a GM mixes in gangsters and super-villains, their campaign is set for a series of colossal adventures.
Also, given that the GOLDEN sourcebook includes a detailed and fairly exhaustive 100-year timeline, time travel and the concept that the game world’s “true†history will be significantly different from that of our own Earth leads some players to consider the consequences of changing events. Does World War 2 have to happen? If it doesn’t happen, or doesn’t happen in the same way as on our Earth, what effects will this have down the track? Were there positive effects of the great conflicts of the Twentieth Century? Or would it be worth the effort to stop the future from unfolding in that way? Comicbooks and even the original literary pulps are full of such intended divergences from our own “real†timeline of history.
In the STEEL part of the present book, in the Feats section, there are various Feats listed as only being available for characters with the Time Lost background. Scrutiny of these Feats shows that amongst them are all the tools needed to create a Time Travel campaign. Chief amongst these Feats is of course Time Travel itself, an incredibly powerful ability, and one that any GM would be wise to most closely monitor once it is in play.
TIME TRAVEL FOR FUN AND PROFIT
FUTURE, n.
That period of time in which our affairs prosper, our friends are true and
our happiness is assured.
THE DEVIL’S DICTIONARY, Ambrose Bierce
The GM can run Time Travel in a number of ways.
Firstly, he or she can simply allow swashbuckling time travel adventures in which the players meet historical figures, duke it out with period bad guys and get home again with a minimum of effort and historical accuracy.
The second way is to have the campaign structured around a group of characters whose adventures occur in time and space, with the Time Lost character as the chief motivator of the adventures. Perhaps whatever mechanism the Time Lost character uses for time travel has malfunctioned, and the characters are trying to get home again. Or perhaps there is a convoluted plot across time that requires the characters to return again and again to the same physical location but in different eras of the past present and future.
A third way is to have Time Travel used as a “save game†mechanism for the players. The Time Travel character then uses his or her time travelling powers to return the group to an earlier point before some disaster occurred. This requires the time traveller to not be amongst the dead or injured. If this method is employed then the GM should specify the number of times that the time traveller can “save†the game. Each of these “saves†is considered a “Heisenberg Junctionâ€, a point from which timelines diverge. It is suggested that the GM only allow a number of Heisenberg Junctions for the time traveller equal to their character level. Once chosen, the Laws of Time forbid a time traveller from ever changing their chosen Heisenberg Events.
For example, a 3rd Level Time Lost character with Time Travel nominates the start of her adventures as a Heisenberg Junction. Then she goes off on an adventure where a team mate screws up badly and dies. She then nominates to time travel back to her recorded Heisenberg Event, tell herself not to allow the adventure to continue, and thus prevent the team mate from dying. If the time traveller makes her power check for Time Travel, this occurs successfully. Otherwise temporal paradoxes, the disbelief of her earlier self, the Laws of Time or whatever have prevented the restoration of the “saved gameâ€.
All well and good. However, from the point of view of a Multiverse or Omniverse, ie of not just a single line through history but a multitude of infinity of parallel worlds, there is still the original world where the team-mate died. There are also the worlds where the team-mate didn’t die, and worlds where the time traveller didn’t invoke their Heisenberg Junction. And right there one has the basis for a series of interesting crossovers between versions of the heroes from worlds events have fallen out very differently…
Time Travel in a Pulp game can be incredibly subversive. Events such as the Kennedy or Lincoln assassinations can be linked via some insane cross-time plot, or a super team can have members from a dozen different time zones, or even from different parallel worlds. It also encourages players to think about what they are doing. Which in itself is a good thing.
“I KNEW THOMAS JEFFERSON…â€
A Time Traveller’s unique perspective confirms again and again how fragile causality can be. So often, he hints at or inadvertently lets slip some future event or personage unknown to his companions. On other occasions he displays equally eerie knowledge of the distant past.
People of other times, especially “historical personagesâ€, are an essential part of the fun of roleplaying time travel. It is much more important to get personal details of famous people correct than it is to make sure you have worked out what level character they are. In fact it isn’t really necessary to even have statistics for famous people the time travellers meet, unless they encounter a historical figure who is a pirate or an air ace or something similar.
The recommended way to prepare for running a time travel adventure or campaign is for the GM to have some grasp of the historical time it is likely that the group will want to go to. Other than that, the GM will need to become a magpie concerning biographical trivia of famous faces, details of period costume and manners and so on. Care needs to be taken that it is always emphasized, especially to the nerd or “anarak†type player, that the time travelled to is the game’s version of that time, not our world’s equivalent era. If the GM is less knowledgeable about the period than one of the players, too bad. The GM could allow that player some input into how the period is run, but still it is the GM’s game, not the player’s. And if player knowledge that a character couldn’t have starts entering play itself, the GM needs to stamp on that quickly to avoid anachronisms destroying play.
Some key points to remember:
1. Different time periods will have different proportions of classes or some classes completely absent. In ancient Rome for example there will be no scientists to speak of at all, but many of the philosophers who taught the children of the rich would have a surprisingly flexible mind, able to accept advanced concepts with little trouble.
2. The mental processes of characters don’t really vary with time period, but their social conditioning and beliefs will vary radically. These beliefs will dictate how they see, or perceive, what they encounter. Thus a time machine might be seen as a living monster or a devilish engine depending where and when one is.
3. In most cases time travellers will not stand out so much that they will not still be thought of as living people. This means that locals might want to capture, enslave, sleep with or recruit the time travellers.
4. Sometimes time travellers might be seen as gods or angels… or devils.
5. If the heroes can time travel, so can other characters.
THE LAWS OF TIME
There was a young man who said: "God,
I find it exceedingly odd
That a tree, as a tree,
Simply ceases to be
When there’s no one around in the quad."
"Young man, your astonishment’s odd;
I am always about in the quad.
So the tree, as a tree,
Continues to be
Since observed by yours faithfully God."’
PAIRED LIMERICKS, traditional.
The so-called Laws of Time are a set of rules that have to be obeyed, not because to disobey brings the sanctions of some sort of “time policeâ€, but rather because to try and disobey them frustrates any sane purpose of time travel in the first place. The Laws of Time summarise the fantasy physics of time travel for GOLDEN and beyond.
The Laws of Time are widely known of by time travelling characters and species, since they form the cornerstone of any sane approach to time travel. Even the most despicable and dangerous of time-travelling villains and monsters do not dare toy with the Laws of Time. To do so would risk intercosmic annihilation on a multiversal scale.
Each multiverse is comprised of a near-infinity of parallel universes. The effect which prevents an actual infinity of universes existing is simply entropy – a certain fraction of the whole falls into heat death or some other form of universal destruction and undergoes superstring collapse.
Consider each multiverse to be akin to a coral reef. The beautiful and dangerous ocean in which the multiverses expand and contract is the Omniverse: the sum of all that was, is, will be – and can never be. The multiverses are what is; the Omniverse includes was, and is and will be – and maybe, and never.
So here they are: The Laws of Time.
Law 1: THE PRESERVATION OF THE ENERGY OF INFORMATION
The Law of the Preservation of the Energy of Information states that the difficulty of changing an event in a specific time period varies with the square of the amount of knowledge relating to that event.
Every measurable moment of time is a product of an infinite number of previous and future moments. Thus completely isolating an “event†in time (the signing of a treaty, the beginning of a war, a love affair, a death) is an impossibility. Two pieces of information about a man’s political career (or any other “eventâ€) makes it four times harder to change the course of his life. In ignorance lies the power to change details. As soon as someone becomes anonymous for any period of time, any number of “lost years†or “missing adventures†can be added to the sum total of their life.
Law 2: THE PRINCIPLE OF ORTHOGONAL HISTORICITY
The tendency of any timeline is to follow its most likely thermodynamic and chronodynamic track, and its applicable laws of physics and sociology will dictate the degree of change possible by someone entering the reference frame from another time period.
Leading on from Law 1, because any event is a part of a tapestry of surrounding events, it is difficult to stop the inertia of history from fulfilling its existing tendencies. For example attempting to prevent the outbreak of World War 2 by faking orders or some such would only delay the outbreak, not prevent it, because of all the other factors leading to that point in history. And since few people have detailed knowledge of the causes of wars it would make no real difference to most people if there were “new†details in the history of the war, unless those details were so huge (eg identity of the Fuhrer) that all history books might include them. It is therefore much easier to modify an event (new or different battles in a war, slightly different chain of events in a love affair, etc.) than to prevent an event or create a new replacement event. For example killing Hitler does not undo all the pre-existing factors leading to the Nazification of Germany in the 1920s and 1930s. And there are a surprising number of alternative candidates for any existing “big figure†in history. The identity of the Fuhrer might be altered (might) but the existence of a Fuhrer in Germany had become a virtual certainty by 1933 and quite likely by much earlier even than that date.
Law 3: THE LIMITATION PRINCIPLE
The number of basic changes to any event is limited by the relative certainty of the event. The chance of successfully changing an event varies with the inverse square of the number of time travelling attempts to alter it.
Isolating an event to alter is the relatively easy part. Once any such event is examined however, the mere act of examining it creates the potential for the event to eventually become better known and documented, thus bringing into operation Laws 1 and 2. Thus Law 3’s effect acts as an absolute break on time travellers affecting “key eventsâ€. The moment that people begin to investigate an event and interfere, that act of interference increases the knowledge of the event, thus making the event harder to change.
The first time an event is interfered with, the basic chance of successful minor change is whatever is set by the GM – anywhere from 100% to 1%. The moment that the first attempt fails and a second attempt is undertaken, the base chance is divided by four (number of attempts = 2, 2 squared = 4). On the third attempt the chance is divided by 9. By the tenth attempt, the original success chance has been reduced to 1% of what it was.
Law 4: THE DIRECTIONLESS MOMENT
Time’s smallest measurable passage has no objective direction. For any moment, there is at least one supporting moment, but this relationship does not imply a direction of flow of time.
Perhaps the strangest concept in time mechanics, the Principle of The Directionless Moment identifies the dimension we call time as being less like a river and more like an avalanche of wreckage composed entirely of pigeonhole shelving. Any particular “timeline†created by mortal perception of the passage of time is in reality a random sampling of moments strung together by the subconscious into a coherent whole. The degree to which history as taught and remembered is founded, not on personal experience but on acceptance of other people’s stories is truly remarkable.
A more profound implication is that, whilst most people understand how the “past†can affect the “futureâ€, the “future†can similarly affect the “pastâ€. The first and second Laws simply say that, due to relative knowledge, the choice of perceiving a set of events as the “past†makes the “future†easier to change. In fact, one could define the future as the period of time that we have deliberately blinded ourselves to, the better to retain free will.
The central concept to keep in mind is that by definition true paradoxes are impossible. Thus all those nerdy half-smart ideas like “killing your own grandfather and ceasing to exist†can’t happen. If you could travel back and meet “your own grandfatherâ€, one of two things is true. Either he is your grandfather, and you don’t kill him, or you kill him and he is the grandfather of someone who would have been virtually identical to you, but who never existed in the universe you find yourself in.
The post-war science fiction author H. Beam Piper believed himself to be from a parallel world, and as a consequence of this belief had a very strong grasp of the “diagonal†nature of time travel. The past or future travelled to is not “directly in line†with your present time, since your present’s past presumptively did not include you travelling back into it. Or if it did you were not aware of it. Either way, a state of imperfect knowledge allows the continuum to unfold in a normal linear way, resembling a timeline even when the elements of the “conveyor belt of history†are taken from a smorgasbord of elements rather than a predictable linear series of very similar settings. History is nothing more than an imperfectly remembered dream within which alien invasions, conspiracies, pulp heroes and unexplained phenomena form part of the architecture. Within this melange the more recognisable detritus of politics and culture materialise and dematerialise. History is hallucination by consensus.
/QUOTE
