Taking a cue from Time Traveler's Immunity, let's pretend that Crono goes back in time to 600 A.D. from 1000 A.D., and changes time to that the world becomes a desert. As time reflows to reflect the change, a new Crono is born before 1000 A.D. who is indigenous to this new timeline and desert world. The original, time traveling Crono then goes to 1002 A.D. The question is, are there now two Cronos? That is, will Crono the time traveler be able to meet the new Crono native to the new timeline of the desert world? If so, would this not violate the conservation of energy in the universe? Indeed, if a new Crono existed, he'd be a duplicate of the original and the conservation of energy would be violated. "Something," the new Crono, would be created from "nothing," the new timeline. The game also confirms this; when Crono returns from time traveling, there is no duplicate of himself. What happens? What mechanism in time prevents duplicates by acting as an extension of Time Traveler's Immunity? Presuming that the new Crono also travels through time doesn't solve the problem, because it doesn't eliminate the copy, and introduces some trouble with cause and effect.
A Problem of Duplicates
Time Bastard attempts to repair this. It stemmed from two observable events in Chrono Trigger and Chrono Cross (not to mention the absence of player character duplicates when they return home). Specifically, during the new Ocean Palace Incident, Melchior and Janus are safe in Last Village. Recall that originally, Melchior and Janus were dispatched to 1000 A.D. and 600 A.D. respectively by temporal distortions. However, in this new timeline, the two are safe in Last Village, oblivious to what happened in the Lavos timeline originally. While Crono and his team are still in the Ocean palace, these new versions somehow phase out into black Gates and disappear entirely. Note that even though Melchior and Janus were far away from the Ocean Palace, they still disappeared presumably at the same time their original counterparts disappeared in the Ocean Palace Incident that occurred originally before Crono intervened. Secondly, in Chrono Cross, after the dimensions are unified, Serge returns to Opassa Beach. Assuming the dimensions did unify and the ideal timeline was created, what happened to the Serge who grew up in this new version of El Nido? He is nowhere to be found when Serge the hero returns from the Darkness Beyond Time, completely replacing him on the beach.
This is where the theory of Time Bastard comes in. In its simplest forms, Time Bastard states that counterparts of time traveling persons or matter cannot exist past the exact time of the original article's departure. Serge originally crossed the dimensions with Leena's discussion on the beach; with Time Bastard, the new version of Serge created by the Ideal Timeline would be shunted to the Darkness Beyond Time at the exact moment of Serge's original departure.
Using the analogy above concerning Crono and a new version of him indigenous to a more arid climate, let us say that Crono originally went back on time on 10:00 AM, June 1, 1000 A.D. He returned two days later, at 10:00 AM, June 3, 1000 A.D. Now, the world's history has been changed, and a new version of Crono is born who has never known anything outside the desert climate he observes. When 10:00 AM, June 1, 1000 A.D. rolls around, this new counterpart will be eliminated. This is the time that the original Crono, protected by Time Traveler's Immunity, departed. This ensures that a duplicate of Crono cannot exist; as a result, no matter or energy is added or subtracted from the sum of the universe.
Now, let's complicate things. Say that Crono, in 1002 A.D., wants to go back to 1000 A.D. and check out what he was doing in the past. He arrives in 1000 A.D., meets up with his past self, and discusses a few things. But wait -- does this not mean a duplicate of Crono exists? No, it does not; Crono is the same person, but merely in a different frame of time. The Crono indigenous to 1000 A.D. has existed for, say, 16 years, while the version from 1002 A.D. has lived for 18 years. They are the same person, but are merely in a different frame of time; in the words of Doctor Emmett L. Brown, you must "think fourth-dimensionally." Now, consider the case of the Red Vest and the Red Plate in Chrono Trigger. You can retrieve the plate, the evolved version of the red vest, from the future, and then go back in time and receive its counterpart. Should the plate vanish? No, because you traveled back in time with it, granting Time Traveler's Immunity. But aren't they duplicates then, and shouldn't the vest be subject to Time Bastard? No again -- because the Red Plate is merely the Red Vest after four hundred years passage of time. After the Red Vest ages 400 years, it would disappear, as that would mark the time of its being taken back by Crono and the time of the original Red Plate's receiving Time Traveler's Immunity. The same can explain why Robo can visit himself plowing the fields in 600 A.D. after the Fiona's Forest sidequest. Magus can also warp back to Zeal and encounter his past self, Janus, but there is no duplication.
A Review of Time Bastard
The premise behind Time Bastard is that time travel cannot be used to create duplicates of entities. It is possible for past and future versions of entities to exist in the same point in space-time, but duplicate entities from the same time period cannot coexist. The doubles in Chrono Cross do not violate this because Home and Another are separate dimensions.
Consider this scenario:
At the Millennial Fair Crono warps 400 years into the past. His presence in 600 AD creates a new timeline, and the original is sent to the Darkness Beyond Time. In the new timeline, a new version of Crono will exist, but the original version of Crono in 600 AD is not affected because he has time traveller immunity.
In 1000 AD, the new version of Crono may enter the warp to 600 AD, but where does he go? He cannot arrive in 600 AD, because the original version of Crono, who is protected by time traveller immunity already exists there. Based on evidence in Chrono Trigger, time periods do not fill up with duplicate time travellers. Thus, the new version of Crono is eliminated from the timeline and sent to the DBT.
Basically, if changes to the timeline result in the version of a time traveller entering a time-warp not being identical to the same traveller exiting the warp, the traveller entering the time-warp is sent to the DBT.
And if Crono continued time traveling:
The original version of Crono warps from 600 AD to 12,000 BC, creating another timeline. Yet another version of Crono would enters the warp in 1000 AD, and is sent to the DBT. The original version of Crono, protected by time traveller immunity, arrives in 600 AD. However, due to the new timeline, when this version Crono warps to 12,000 BC, he is not identical to the original Crono, and is sent to the DBT.
Perhaps if the changes to the timeline are severe, the new version of Crono would not enter the warp in 1000 AD (or the version of Crono in 600 AD). Would the original version of Crono return to the present to find a duplicate of himself? Since there are no duplicates, the new version of Crono must have been sent to the DBT at the same time the original Crono left.
A proof demonstration:
Suppose an entity X exists on timeline Y.
If X time travels from time A to time B, such that B < A; for time > B, Y is sent into the DBT, and Y' is created, containing X'.
For time > A, two identical entities X and X' will exist in Y'.
Conservation of Energy requires that only one entity X or X' exist.
Therefore, X' will be expunged from Y' at time A, and sent into the DBT.
The Theory in a Nutshell
Duplicates of entities cannot be created through time travel because this would violate the conservation of energy in the universe. If a time travel scenario would cause a duplicate entity to exist, the entity with the least seniority of time traveller immunity would be sent to the DBT.
Time Bastard may seem ruthless and cruel, as it shunts people to the Darkness Beyond Time impartially. The concept does seem cruel, but it is no worse that the millions of people sent into the DBT every time Crono time travels, which is canon! In fact, the condemnation of these people is the basis for some of Lucca's fears about time traveling repercussions in Chrono Cross. Lucca worried that the people sent to the Darkness Beyond With with the ruined future they averted may one day try to exact revenge (though this is impossible with established principles). Plus, people who are erased and sent to the DBT don't exist anymore at all, so they don't really suffer or even become conscious of their erasing. On the contrary, people who were killed becaused of Lavos (for example) did suffer physically and were conscious of their death afterwards since, apparently, ghosts exist in the Chrono world.
Case Study: Schala's Pendant
If Schala gave Kid her pendant before sending her to 1004 A.D., it means she kept her pendant with her after the Ocean Palace incident. How then would the pendant exist on the outside world and come into possession of the Guardia royal family, eventually ending up with Marle, who used it in Chrono Trigger? How was it originally passed down anyway before Crono started time traveling? Would its absence potentially undo Chrono Trigger, preempting Marle from reacting with the Telepod to enter 600 A.D. or charge it up at the Mammon Machine to get around Zeal?
Time Traveler's Immunity and Time Bastard dictate that regardless of what Marle or Crono were doing at the Millennial Fair in 1000 A.D., they would appear in 600 A.D. and their versions in 1000 A.D. would disappear at the original time of departure. Additionally, all matter going with them, such as Crono's wood sword or Marle's pendant, would be subject to these laws and would appear in 600 A.D. and be removed from the present. Under these theories, the pendant would materialize with Marle in 600 A.D. when she first time traveled and was thought to be Queen Leene, circumventing the need for the pendant to be physically passed down among the royal family for 13,000 years. For the issue of Time Bastard applying to the pendant itself, please see below.
Time Bastard's Application to the Pendant
Some debate that the answer is flawed because the pendant on Kid would be subject to Time Bastard. That is, since the pendant would go to 1004 A.D. with Kid from the Darkness Beyond Time, it would "pass" Marle's instances of time traveling, which take precedence. However, it is important to consider that Time Bastard operates on personal time. Let's examine the pendant's personal history.
Pendant is created in 12000 B.C.; used thirteen thousand years later.
Pendant is created in 12000 B.C.; used almost instantly afterwards.
Thirteen thousand years would have to pass until the pendant disappeared due to Marle's original time traveling with it. It would disappear roughly in 14004 A.D. to appear in 600 A.D. with Marle. The same case can be applied to the Vests and Mails in Chrono Trigger. Crono can use both the vest and mail because he has traveled through time with the mail before retrieving the vest. After four hundred years, the vest would presumably be subject to Time Bastard and disappear. Crono is not violating the conservation of energy or time in this manner; he is merely using the same item in two different stages of its personal history.
Thought, Eske, chrono eric
Time Bastard also applies to dimensional travel, which can be thought of as "horizontal" time travel along timelines rather than "vertical" travel back and forth on a timeline (compare to traveling to areas of Time Error, like the End of Time). Thea absence of Time Bastard for dimensions (which some might call "Dimensional Time Bastard"), a paradox could arise. chrono eric provides an example:
- Two dimensions exist which are parallel to each other in time. In Dimension 1 a man called Dimensional Traveler exists in the timeline. In Dimension 2 he was never born. A person called Time Traveler was born in Dimension 2 and may or may not exist in Dimension 1 (doesn't matter).
- Dimension 1: Time X: Dimensional Traveler goes to dimension 2 via some dimensional gate.
- Dimension 2: Time X: Dimensional Traveler appears in dimension 2. Time Traveler meets Dimensional Traveler, decides he is an asshole, and travels first to Dimension 1 with the intent of going back in time to kill his grandfather so he never exists.
- Dimension 1: Time X+1: Time Traveler arrives in dimension 1, goes back in time to X-100.
- Dimension 1: Time X-100: Time Traveler kills Dimensional Travelers grandfather, changing history in Dimension 1 so that Dimensional Traveler never crosses the dimensions to Dimension 2, then travels back to the present in Dimension 1 and goes back to his home dimension of Dimension 2 at Time X+2.
- Dimension 2: Time X+2: Time Traveler returns to his home dimension anticipating that Dimensional Traveler wouldn't be there. Does he meet Dimensional Traveler, or not?
Quite a thinker, eh?
In this situation, the act of Time Traveler killing Dimensional Travelers grandfather in Dimension 1 is preserved via TTI. The act of Time Traveler reappearing in the future of Dimension 1 is likewise preserved via TTI. But is the act of crossing the dimensions preserved by DTI/DB? This situation actually doesn't prove whether or not Dimensional Traveler will be there when Time Traveller returns, but lets analyze what would happen if Time Traveler did not disappear at the original instance of his dimensional crossing (ie: if Dimensional Bastard does not exist):
At Time X Time Traveler would not vanish. At Time X+2 this Time Traveler would meet his future self arriving from his journey to kill Dimensional Bastards' grandfather. There would be a problem of duplicates. Therefore Dimensional Bastard must necessarily exist to eliminate duplicates from the timeline.