Time Travelling Bruce

[tsofian]

Bruce is either a Time Traveler or he is not.

Time is either a single stream or it is not.

The Time stream may either be changed by time travelers or it may not.


Time Is Immutable Time Can be Changed
Single Time Stream Closed Loop- How are paradoxes resolved?
No Paradoxes,
no free will

Multiple Streams All time streams Each change is resolved by a
exist as individual branching of time
closed loops All paradoxes could be
resolved by a “dead end” branch
that is terminated and doesn’t go
forward. All other possibilities exist




If Bruce is moving forwards and back through Time and brings back advanced technology that means in the future civilization has been rebuilt and has achieved science, technology and industry that exceeds our current state, let alone the state of 1960. If there is but a single timeline it means that the Morrow project must have been successful in its overall mission, because otherwise why would Bruce be supporting it? Maybe he went forward in time and discovered that something called The Morrow Project was the key to recovery and went back in time and built it?

Here is an interesting article on closed loop time travel
http://discovermagazine.com/2010/mar/02-the-real-rules-for-time-travelers

"Do closed timelike curves necessarily lead to paradoxes?

If they do, then they cannot exist, simple as that. Logical contradictions cannot occur. More specifically, there is only one correct answer to the question “What happened at the vicinity of this particular event in space-time?” Something happens: You walk through a door, you are all by yourself, you meet someone else, you somehow never showed up, whatever it may be. And that something is whatever it is, and was whatever it was, and will be whatever it will be, once and forever. If, at a certain event, your grandfather and grandmother were getting it on, that’s what happened at that event. There is nothing you can do to change it, because it happened. You can no more change events in your past in a space-time with closed timelike curves than you can change events that already happened in ordinary space-time, with no closed timelike curves."

The implications for this in terms of Bruce's free will are concrete. If it is a closed time loop Bruce has no free will. He goes through time and performs the actions at specific points in time/space that he performs. His actions are immutable. If Time is a loop there is no past or present there are only events and these events that occur and exist at specific fixed points along the loop.

For those of us living within the loop it means that all of our actions are fixed. It doesn't matter what we (or in this case a character) chooses to do. It

For multiple time streams all actions can happen, all events have implications for other changes.

[tsofian]

If Bruce travels through time how does he not know the Project won't wake up on time, if there is only a single timeline? If he does know why doesn't project planning address this issue?

[mmartin798]

If Bruce travels through time how does he not know the Project won't wake up on time, if there is only a single timeline? If he does know why doesn't project planning address this issue?

My fall back position on this has always been Krell. We know he is also from the 20th century. He is a chaos vector that is reacting to the changing timeline and distorting the probabilities back to the dystopia that Bruce wants to change. This would also explain Bruce's desire to know who Krell is.

[tsofian]

That means the timeline is constantly in flux

[mmartin798]

If we assume temporal mechanics has similar attributes as quantum mechanics, this is defensible. Assume the future is not fixed until observed. Hence at any given moment, there are infinitely many possible futures. Thus, the path taken is the one that the current probability function determines. If events take place to change the probability function, the future Bruce saw will change.

[tsofian]

I absolutely agree with this. I am a proponent of the "many worlds" interpretation of time and space. Every decision point is a separate branch.

I've espoused this before. In some iterations, everything goes perfectly and there is no war. In others, the Project wakes up in 5 years and the mission goes as planned. Conversely, there are universes where all life on Earth was wiped out.

The published game setting is just one of the more interesting in which to role play.

Terry

[cosmicfish]

The implications for this in terms of Bruce's free will are concrete. If it is a closed time loop Bruce has no free will. He goes through time and performs the actions at specific points in time/space that he performs. His actions are immutable. If Time is a loop there is no past or present there are only events and these events that occur and exist at specific fixed points along the loop.
The existence of a loop does not preclude free will, it simply implies that the individual is for one reason or another unable to change their mind.

For those of us living within the loop it means that all of our actions are fixed. It doesn't matter what we (or in this case a character) chooses to do.
Again, no it doesn't, it just means we don't get do overs.

For multiple time streams all actions can happen, all events have implications for other changes.
Certain actions become easier with multiple time streams, that doesn't mean that other things cannot happen in a single time stream.

Two of the biggest issues in time travel (besides it being impossible so far as we know) are the basic issues of Foundation and Energy.

Foundation is the idea that information does not randomly occur, nor does it occur when it is already known to exist. That is to say, if something is to be created, someone must create it from scratch at some point without said creator being able to point at an existing example. This idea of Foundation is used in a number of paradoxes, including Bootstrap and Grandfather. Note that Foundation is based on the idea of Linear Time, which in turn is required for adjacent time steps to be on a "reasonable" energy scale - if time is not locally linear then there arise massive questions in how large time steps account for the energy difference between temporal states.

Energy is the idea that the conservation of matter and energy does not cease to apply in the case of time travel, that transferring between two identical energy states cannot physically be lossless, and that this energy difference must somehow be accounted for. If you are in the world of Jan 1 2020 and see a nuclear hellscape and want to change that, doing so must require an amount of energy equivalent to putting all those molecules and quarks and rays and waves into new places for the corresponding times, and that is a TON of energy. Alternately, you can create a whole new future/universe (which requires even MORE energy while failing to erase the old one), or step into an existing similar universe that is more agreeable (requiring perhaps very little energy but again leaving the original universe to burn).

So let's consider 4 options: Infinite universes, finite universes, single universe, and no time travel.

1) Infinite universes. Everything happens somewhere. Time travel as we consider it may not be even be possible in this scenario, nor recognizable when it happens. Foundation and Energy are not problems because there are always universes where the ideas are created from scratch and the universe you want already exists for free - you just need to step into it, knowing that there is already another one that is exactly identical save for the fact that you never entered that one.

Unfortunately, this also renders everything morally meaningless. If the universes are infinite, then so are your potential choices. You've lived your life as a saint? Well, out there are universes where you just this second became the worst human being ever imagined. You've lived a lifetime of evil? There are universes where you are about to have a radical change of heart.

With infinite universes, the moral decisions are not about saving anything. Nothing can be saved. Everything is always saved in some universes and destroyed in others, and those universes will always be there. All individuals can do is make choices knowing that their decisions are morally inconsequential, and that would likely be ruinous.

2) Finite universes. This gets tricky because it depends on how many universes there are and how similar to ours they would be. Energy becomes a big deal here in just understanding the mechanism - were there always a large number of universes, each developing separately, or are existing universes split at different points? If the former, are there even humans in any universe but our own? If the latter, how does the split work - does the universe get copied or cut down the middle?

Even stepping past how the universes came to be, time travel becomes a huge Energy problem. There are likely no conveniently similar universes to step into, so you either need to recreate the universe (or some part of it) or shift the existing version... which puts you back into the Foundation problem.

Finite universes provide no moral quandaries, and Foundation is not necessarily an issue... but getting over that Energy problem can be huge.

3) Single universe. In this case, Foundation and Energy both rule and morality remains constant - one universe, so no escaping consequence. Time travel may be possible, provided that Foundation is preserved and Energy managed, and indeed, the Energy problem may not even be one.

One of the common problems in applying mathematics to physics and chemistry is that there are some times when the mathematics suggest multiple solutions where the physics or chemistry permit only one. You see this frequently in circles and triangles, where one solution is imaginary, or where what initially appear to be two solutions are revealed to be identical. So it may that you don't really have free will in a sense meaningful to time travel. Or it may be that the stable solution is the one where you always were going to go back in time and either fail or simply choose to avoid directly replacing any instant of your experience.

You go back in time to kill Hitler... and fail. Or you go back in time and kill Hitler... but it wasn't Hitler, the "real" Hitler simply assumed the identity. Or you do go back in time and kill Hitler and save all the Jews, but you pull a Millennium and maintain the illusion of the Holocaust until you return to the present to avoid paying the unimaginable energy cost of rewriting history when you can simply add a footnote for much less.

4) No time travel!

Okay, this isn't like the other scenarios at ALL, but it is worthwhile discussing. Time travel is not actually required for the Project. What is required? The actuality of the war, the technology to survive the it hidden, and the ability to recruit people. Time travel explains the latter two, but it is not the only explanation and is only really necessary for specific cases.

If fusion power and cryogenic storage of living beings can be produced with (for example) 80's technology then they just need people to invent them, by brilliance or luck. No other technology is really vital (and even they aren't, technically), so you only need time travel for the story if there is no other way to conceive of and create a vital technology.

As to people, I think we could all imagine a sufficiently charismatic leader convincing tens of thousands of people during the Cold War to go underground against a "certain" nuclear holocaust. Again, it becomes more about the details - convincing "top-shelf" candidates would require the kind of certain proof that perhaps only clearly defined time travel could provide, but if you lower your standards enough you can staff the Project with only the illusion of time travel or simply with strong rhetoric.

And do you need the war to be certain, from the perspective of the early Project? The war needs to happen, or at least something that looks like the war*, but the organizers could have been guessing or even running some long con with the expectation that the war would never happen.

Depending on the reality of the universes (i.e., options 1-3 above), this may be the actual solution even if Bruce really does travel in time. Maybe the war he sees is in another universe and he knows nothing about what will happen in this one. Maybe he brings back fusion power from another universe but it is already being invented by someone here. Maybe the reality of BEM's time travel is like crossing a time zone, a formality with no real physical significance.

Anyway, just a few thoughts that (obviously) snowballed on a sleepy Christmas evening.

*: E.g. the "war" is really aliens attacking, or some large meteorite bombardment, or was accidentally or intentionally initiated by the Project itself!.

[tsofian]

1) Infinite universes. Everything happens somewhere. Time travel as we consider it may not be even be possible in this scenario, nor recognizable when it happens. Foundation and Energy are not problems because there are always universes where the ideas are created from scratch and the universe you want already exists for free - you just need to step into it, knowing that there is already another one that is exactly identical save for the fact that you never entered that one.

Unfortunately, this also renders everything morally meaningless. If the universes are infinite, then so are your potential choices. You've lived your life as a saint? Well, out there are universes where you just this second became the worst human being ever imagined. You've lived a lifetime of evil? There are universes where you are about to have a radical change of heart.

With infinite universes, the moral decisions are not about saving anything. Nothing can be saved. Everything is always saved in some universes and destroyed in others, and those universes will always be there. All individuals can do is make choices knowing that their decisions are morally inconsequential, and that would likely be ruinous.



I do not agree with your stance whatsoever. Just because there are an infinite number of mes and yous it doesn't mean the pain and joy of those individuals doesn't exist. It doesn't mean that the decisions of those people doesn't have consequences in their realities. For the vast number of people (the 99.999999% plus) that can't zip between realities there is only a single universe, and a single life. I fully believe that there are an infinite number of realities. I do hope that in at least some the "me" in them has made better decisions and know that in others that "me" has done things far worse that I have. In an infinite number there is no "me" at all. However even with that I carry my moral framework with me, and would if I jumped into another universe. I don't understand why you would say the decisions I make in the only existence I know are meaningless. They have meaning in this existence and meaning to me. Since I am the only "me" I have direct knowledge of I care about where this "me" is and to "me" the things around "me" are not meaningless.

In this Universe I am one of billions of people here. How are my decisions morally meaningful on that scale? Who decides right and wrong? Morality is a cultural construct. "Rights" are a cultural construct. I'm not sure how having infinite universes affects any of this, unless the "me" in that universe decides it does.

[cosmicfish]

It's similar to the Trolley Problem, but let me give you a variant.

Imagine that you are in a room, with an innocent person strapped to an electric chair, and that you have the switch and the sole decision to kill them or free them. Individually, the decision to throw the switch or not is your personal moral decision, with real consequence for that person and the world. With me so far?

Now imagine that there is another room, with another innocent person in another electric chair and someone else holding that switch. Whatever decision you make, they will make the opposite - if you spare your innocent, the other innocent dies, but if you kill yours then the other goes free. Your personal morality may compel you to choose one way or the other, but the net result will always be the same - one dead innocent person, one innocent person freed.

This is what infinite universes means - you can make your personal moral decisions but in the grand scheme they are meaningless. Your choices merely decide which reality you personally experience without actually changing the sum total of reality. If you know that this is the case, then does your morality have any meaning? All of your options are simultaneously realized, so you really don't have options per se - the combined infinity remains the same.

The joy of the person you saved exists simultaneously with the pain of the person you killed in another universe. The probability curve, sampled infinitely, does not vary.

If you are aware of this, like if for example you were a member of an organization predicated on the existence of time travel and the ensuing revelation of infinite parallel universes, then your decisions are ones of comfort rather than meaning. You choose to experience the joy and, perhaps, try to ignore the reality that there is equal pain that you are simply choosing not to see.

[mmartin798]

In the case where all the alternates continue to exist, then your example is a valid one. However there exists also the following possibility.

Canon indicates that there is one past. For example, in 4e the 1989 war was prevented. That event is locked in. This would seem to indicate that for each moment in time, we have a single past worldline and infinite possible forks going forward. So while the decision process may be your modified Trolley Problem, the way I see the worldlines progressing is more like Schrödinger's Cat. Until you make decision as to pulling the switch, your innocent person in the chair is already both alive and dead in the future infinite worldlines. But once the decision is made, the event is now known and locked in. From this point on, all the worldlines that existed contrary to the decision you made are gone and we now have an infinite number of worldlines where only the possibility left by your choice remains.

This view seems consistent with canon, as Bruce finds his wife and children dead in the future after he stops the war. His actions to stop the war destroyed the worldlines where his family existed. This also can help explain why the Project is still ill prepared for what comes. Bruce stopping the 1989 war was to give the Project more time to prepare. But as there are other actors working against Bruce's ideal, that resulted in the Project successful worldlines being rendered non-existent. Know this make Bruce seek out the actors doing this, and one of their names seems to be Krell.

[tsofian]

It's similar to the Trolley Problem, but let me give you a variant.

Imagine that you are in a room, with an innocent person strapped to an electric chair, and that you have the switch and the sole decision to kill them or free them. Individually, the decision to throw the switch or not is your personal moral decision, with real consequence for that person and the world. With me so far?

Now imagine that there is another room, with another innocent person in another electric chair and someone else holding that switch. Whatever decision you make, they will make the opposite - if you spare your innocent, the other innocent dies, but if you kill yours then the other goes free. Your personal morality may compel you to choose one way or the other, but the net result will always be the same - one dead innocent person, one innocent person freed.

This is what infinite universes means - you can make your personal moral decisions but in the grand scheme they are meaningless. Your choices merely decide which reality you personally experience without actually changing the sum total of reality. If you know that this is the case, then does your morality have any meaning? All of your options are simultaneously realized, so you really don't have options per se - the combined infinity remains the same.

The joy of the person you saved exists simultaneously with the pain of the person you killed in another universe. The probability curve, sampled infinitely, does not vary.


No it isn't. Here are some differences
A) The decisions I make in this universe are in no way directly linked to the decisions other mes make in other universes.

B) Who cares that there is no net change in goodness in the Universes? Who can measure such a thing? Who has a point of view that would let them even notice that such a balance exists? Who says that isn't the way things work where all things are balanced out across the entire multiverse?

C) The Trolley Problem and this variant have no basis in alternative universes or in fact in any reality at all but are thought experiments in ethics. There is absolutely no evidence that it has any relevance to the question of multiple universes.

D) Given your basic premise, I would just sit on my butt and do nothing, satisfied knowing that in a different universe a me has decided to work and have a job, earn a living and have a nice place to live. That is great but the me that does that is still going be pretty unhappy living in a cardboard box wearing old newspapers for shoes. I only experience the universe I exist in, based on my decisions within it. And guess what,the me writing this wants to experience pleasant things, or at least do the right thing.

[cosmicfish]

A) The decisions I make in this universe are in no way directly linked to the decisions other mes make in other universes.
Every coin flip and die roll is independent and individual events are unpredictable, and yet for a large number of either the aggregate is thoroughly predictable in their diversity. If there are an infinite number of universes then there are an infinite number of yous and I see no reason not to expect a correspondingly infinite number of actions you would take at any given time. And just as rolling a 1 or a 6 on a die may be thoroughly independent, for a large number of rolls I can find a 1 for just about every 6.

B) Who cares that there is no net change in goodness in the Universes? Who can measure such a thing? Who has a point of view that would let them even notice that such a balance exists? Who says that isn't the way things work where all things are balanced out across the entire multiverse?
If you care about the net change of goodness in your own universe, why would you not care about other universes if you knew about them? Especially when the people experiencing that change of goodness are more like you than anyone in your own universe ever could be? And if things balance out... then that proves my point.

C) The Trolley Problem and this variant have no basis in alternative universes or in fact in any reality at all but are thought experiments in ethics. There is absolutely no evidence that it has any relevance to the question of multiple universes.
Yes, it is a thought experiment. Presented as a thought experiment for the reason all thought experiments are presented - to help illustrate a concept that has a bearing on the situation. In this case, the morality of action and inaction with the existence of infinite multiple universes. If you don't like thought experiments, we cannot even have this discussion until someone proves that infinite multiple universes exist.

D) Given your basic premise, I would just sit on my butt and do nothing, satisfied knowing that in a different universe a me has decided to work and have a job, earn a living and have a nice place to live. That is great but the me that does that is still going be pretty unhappy living in a cardboard box wearing old newspapers for shoes. I only experience the universe I exist in, based on my decisions within it. And guess what,the me writing this wants to experience pleasant things, or at least do the right thing.
Some versions of you may do just that. I suspect most people would take a path of personal comfort, rather than either moral excellence or total apathy, but if you think you would personally lean towards apathy... okay.

[cosmicfish]

In the case where all the alternates continue to exist, then your example is a valid one. However there exists also the following possibility.

Canon indicates that there is one past. For example, in 4e the 1989 war was prevented. That event is locked in. This would seem to indicate that for each moment in time, we have a single past worldline and infinite possible forks going forward. So while the decision process may be your modified Trolley Problem, the way I see the worldlines progressing is more like Schrödinger's Cat. Until you make decision as to pulling the switch, your innocent person in the chair is already both alive and dead in the future infinite worldlines. But once the decision is made, the event is now known and locked in. From this point on, all the worldlines that existed contrary to the decision you made are gone and we now have an infinite number of worldlines where only the possibility left by your choice remains.

This view seems consistent with canon, as Bruce finds his wife and children dead in the future after he stops the war. His actions to stop the war destroyed the worldlines where his family existed. This also can help explain why the Project is still ill prepared for what comes. Bruce stopping the 1989 war was to give the Project more time to prepare. But as there are other actors working against Bruce's ideal, that resulted in the Project successful worldlines being rendered non-existent. Know this make Bruce seek out the actors doing this, and one of their names seems to be Krell.
Canon indicates multiple pasts, at least from BEM's perspective. While I like the idea of a probability field collapsing to a single event, the question remains what causes the collapse? If the past is fixed, and BEM travels into the future, then the intervening period becomes part of his past and is then presumably fixed? And if not, why not? Is the past only fixed by majority?

I am not at all trying to say your idea is not potentially valid, just trying to understand how it would work.

[tsofian]

Every coin flip and die roll is independent and individual events are unpredictable, and yet for a large number of either the aggregate is thoroughly predictable in their diversity. If there are an infinite number of universes then there are an infinite number of yous and I see no reason not to expect a correspondingly infinite number of actions you would take at any given time. And just as rolling a 1 or a 6 on a die may be thoroughly independent, for a large number of rolls I can find a 1 for just about every 6.

Human actions are not random. Your analogy falls apart. If human actions are random and will


If you care about the net change of goodness in your own universe, why would you not care about other universes if you knew about them? Especially when the people experiencing that change of goodness are more like you than anyone in your own universe ever could be? And if things balance out... then that proves my point.

Your original point was that if there are infinite universes than no one would care what happens in their own and what a person does in their own universe doesn't matter. Maybe it does maybe it doesn't. The bottom line is that unless you are a being capable of seeing the big picture who cares? You do your best as a person and move as you choose.






Yes, it is a thought experiment. Presented as a thought experiment for the reason all thought experiments are presented -



to help illustrate a concept that has a bearing on the situation. In this case, the morality of action and inaction with the existence of infinite multiple universes. If you don't like thought experiments, we cannot even have this discussion until someone proves that infinite multiple universes exist.

This thought experiment was not developed to have anything to do with multiple universes and it doesn't. I don't mind thought experiments if they are used within their limits. Your example has nothing to do with the topic at hand.

"A thought experiment is a device with which one performs an intentional, structured process of intellectual deliberation in order to speculate, within a specifiable problem domain, about potential consequents (or antecedents) for a designated antecedent (or consequent)" (Yeates, 2004, p. 150).

I do not agree that your particular thought experiment has anything to do with the "problem domain".



Some versions of you may do just that. I suspect most people would take a path of personal comfort, rather than either moral excellence or total apathy, but if you think you would personally lean towards apathy... okay.

Sign, you know that is not my point. You want to make fun of me and that is fine. Don't use a ploy like reductio ad absurdum if you don't want to be called out on it.

[mmartin798]

Canon indicates multiple pasts, at least from BEM's perspective. While I like the idea of a probability field collapsing to a single event, the question remains what causes the collapse? If the past is fixed, and BEM travels into the future, then the intervening period becomes part of his past and is then presumably fixed? And if not, why not? Is the past only fixed by majority?

I am not at all trying to say your idea is not potentially valid, just trying to understand how it would work.

You are correct in the BEM does perceive multiple pasts, but not infinite. Only the pasts that are created when he travels back to a previous point in a established worldline. The 1989 war is a case in point.

The first time around, it happened and all the subsequent events. Then in say 2016 TET (Third Edition Timeline) he sees the failure of the Project by Krell and decides to try and give the Project more time to prepare. He goes back and stops the computer malfunction and that act, in concert with all the other decisions in the universe, spawns 1989 FET (Fourth Edition Timeline). It is when he goes to 2023 FET, or whatever year it is, and finds his family had died that he become despondent, grieves, finds out what happens, decides not to mettle in the course of events again and wants to find Krell, possibly because of his connection to his families demise.

So BEM only has one past to enter, though he knows there have been different ones. When he goes into the future, he can only chose between ones that are most likely to happen, not go into ones that are highly unlikely, like the universe where all the world leaders simultaneously disintegrate from a statistical improbability of thermodynamics. It is this limitation that makes it impossible for him to go to a future where his family still exists. If he goes back and tries to stop the 1989 in a different way, he is still not assured that it would bring his family back, or that the Project would have more time to prepare or succeed.

This is the way I have structured time travel for my game and, just to mess with BEM, Krell has a slightly different way to messing with the future for his own ends.

[cosmicfish]

Human actions are not random. Your analogy falls apart. If human actions are random and will
The analogy is not dependent on random events, they are dependent on the existence of a nonuniform distribution of results. The idea of a random element was used to illustrate a range of results including the opposites to the "good" results.

Your original point was that if there are infinite universes than no one would care what happens in their own and what a person does in their own universe doesn't matter. Maybe it does maybe it doesn't. The bottom line is that unless you are a being capable of seeing the big picture who cares? You do your best as a person and move as you choose.
Not that people would not care about what happened in their own, but yes, that one's actions in their own universe do not matter. Because it doesn't. There are infinite more worlds with every possible permutation of results. That child you may or may not saved will be saved in an infinite number of worlds and die horribly in an infinite number of worlds. Your contribution has no uniqueness, there is nothing you are creating or preserving that does not exist simultaneously elsewhere.

As to who cares? Well, in a world with a real Project, where time travel is an inherent part of how you get a bunch of dedicate scientists and soldiers to sacrifice everything... well, I think a lot of people would care. And would be able to see the big picture, since the nature of time travel and the number of universes is key to the whole question of whether or not things can be saved and how. This is some of the most fundamentally important information in the universe of the game, so unless your scientists are the unquestioning kind with no concept of philosophy, it's going to be an issue.

This thought experiment was not developed to have anything to do with multiple universes and it doesn't. I don't mind thought experiments if they are used within their limits. Your example has nothing to do with the topic at hand.

"A thought experiment is a device with which one performs an intentional, structured process of intellectual deliberation in order to speculate, within a specifiable problem domain, about potential consequents (or antecedents) for a designated antecedent (or consequent)" (Yeates, 2004, p. 150).

I do not agree that your particular thought experiment has anything to do with the "problem domain".
Considering that I posed said thought experiment with this specifically in mind, I hope you understand if I disagree.

For every universe where you try your best and succeed, there is another where you try your best and still fail, and another where you watch apathetically from the sidelines, and yet another where you are the villain rather than the hero. Besides which, the sheer number of "you"s in infinite universes means your contribution is mathematically infinitely close to zero. Just like evil villain you.

Sign, you know that is not my point. You want to make fun of me and that is fine. Don't use a ploy like reductio ad absurdum if you don't want to be called out on it.
I have not been making fun of you anywhere here. And reductio ad absurdum is implicit in the situation of infinite universes - the argument is already starting at a literal extreme, pointing out the results of your starting point is not in any way logically invalid. For that matter, reductio ad absurdum isn't logically invalid in general, although specific applications may be.

[cosmicfish]

You are correct in the BEM does perceive multiple pasts, but not infinite. Only the pasts that are created when he travels back to a previous point in a established worldline. The 1989 war is a case in point.
That was my point - not that he experiences infinite pasts, but rather that he experiences multiple pasts when your proposed multiversal theory claims only one past.

So BEM only has one past to enter, though he knows there have been different ones.
But what is the mechanism of this? If there is only one "past" at a time, then when he goes backwards in time he creates a new past, so there are multiple, realized "pasts" even if only one appears accessible at a time.

Let's consider time travel between the years 1960, 1980, and 2000. If our intrepid traveler starts in 1980, the years 1960-1980 are that single, fixed past. If they then travel to 2000, all of 1960-2000 are now that single, fixed past. But when they travel back to 1960, any change means replacing all of that 1960-2000 past with some new past. The old past is not probability or theory, it actually existed and must now be replaced by something else that is, again, neither probability nor theory. This goes back to the Energy issue I raised earlier - collapsing probability is potentially a zero-energy issue, but replacing one concrete past with another isn't.

When he goes into the future, he can only chose between ones that are most likely to happen, not go into ones that are highly unlikely, like the universe where all the world leaders simultaneously disintegrate from a statistical improbability of thermodynamics. It is this limitation that makes it impossible for him to go to a future where his family still exists. If he goes back and tries to stop the 1989 in a different way, he is still not assured that it would bring his family back, or that the Project would have more time to prepare or succeed.

This is the way I have structured time travel for my game and, just to mess with BEM, Krell has a slightly different way to messing with the future for his own ends.
I like the idea of probability influencing what he can do - just as it would take less energy to knock something balanced precariously on a perch than it would to do the same to something entrenched firmly in the ground, it makes sense that whatever energy Bruce gets to use would have the most effect spent in conjunction with "temporal potential" (to coin a term) than opposing it. But I am still not sure how that squares with the fact that the probability curves were already collapsed as soon as he traveled into the future in the first place.

[mmartin798]

But what is the mechanism of this? If there is only one "past" at a time, then when he goes backwards in time he creates a new past, so there are multiple, realized "pasts" even if only one appears accessible at a time.

The way to think of this is from BEM's perspective. Let's first make some definitions. Let's let A(0) represent a point on a worldliness where time travel begins and A(t) represent a point on a worldline at time t from A(0).

Let's consider time travel between the years 1960, 1980, and 2000. If our intrepid traveler starts in 1980, the years 1960-1980 are that single, fixed past. If they then travel to 2000, all of 1960-2000 are now that single, fixed past.

So if we let A(0) = the year 1980, then A(t<0) is indeed a single, deterministic path. But when our time traveler decides to go to time t, there is no single path. So they choose one from the available worldlines and choose a point, A'(t). The choice is limited by the light cone that extends from any given point A(t). Any worldlines outside the light cone are not accessible. So our traveler is not creating the worldline that contains A'(t), but simply goes to A'(t) which is already on an accessible worldline. Once the traveller arrives at A'(t), it becomes A(0) and again there is just a single deterministic worldline for all A(t<0). So we agree here.

But when they travel back to 1960, any change means replacing all of that 1960-2000 past with some new past. The old past is not probability or theory, it actually existed and must now be replaced by something else that is, again, neither probability nor theory.

So now our traveller is going to A(-40). As this is a simple deterministic route, no problem. But now when we reset this to be A(0), the additional information that the time traveller beings back, will change the probability of the worldline and normal time may follow a different path. So we have three worldlines that all exist. The first would be the one that started in 1980 and would have progressed along a worldline, on which "future" events would be on, that we will call A1980(t). The second is the worldline that contains choice the traveler made and all "future" events from that point we can call A'1980(t). The third worldline is the one that will be followed after bringing back the information, A'1960(t).

So we have three worldlines that co-exist, but the people in the worldlines only know about the one they have always been on. Therefore, only BEM knows there have been differences. So quite literally, BEM perception is reality. But because his available choices of worldlines is limited, there is only so much change he can effect. Also, this is what caused him to lose his family. The change in worldline that was introduced when he stopped the 1989 war moved him to a point where his family only exists outside of his lightcone. He has no way to get back to them, unless he goes and stops himself from preventing the 1989 war, but that will put him on yet another worldline and still may not be able to reach them. Who knows, maybe he has tried it many times and just can't get back to them. It's kind of sad. But if we look at this from his family's perspective, he disappeared one day and just never came back.

Most of this heavily draws on work by David Deutsch and presumes a multiverse. Though Deutsch's work has been criticized because even though his models do eliminate things like the Grandfather paradox, it suffers from a knowledge paradox that Deutsch's model cannot solve. But since this is just a game, close counts.

If you are interested, here are some published papers:
http://thelifeofpsi.com/wp-content/uploads/2014/09/Deutsch-1991.pdf
http://www.academia.edu/6059479/The_Quantum_Physics_of_Time_Travel
https://conjecturesandrefutations.com/2015/09/02/a-problem-with-david-deutschs-model-of-time-travel/

[mmartin798]

For those not going to read the articles, one the the implications of this form of time travel is that within most of the closed timelike curves (CTCs) created by BEM, there will be more than one BEM. I assume most will be working in concert with each other, but this does leave open the possibility that Krell is BEM from a "different" worldline. Just food for thought.

[tsofian]

Maybe the problem is word infinite. If so let's just remove it and go multiple. In an infinite series of universes all possible outcomes are found an infinite number of times. If there are just a large number of universes then the distribution of outcomes will be distributed by likelihood.