Autonomy and Time Travel

[Glenn Lyvers]

Speaking from a metaphysical hypothetical.

 

Let's assume that all time exists (generally referred to as the B series of time - temporal time).

 

So the Past, Present and Future all exist right now. In fact, it is not even technically proper to refer to time in tenses, because all time exists simultaneously under this time theory. So we can only refer to time as a measurement (year/date/etc) or as events are relevant to each other. (This happened earlier than that.)

 

OK, so if the B series of time exists, is it true that you still have freewill (Autonomy)? If tomorrow already exists, and what I am going to do is already set, and nothing I can do could possibly change it, then do I really have a legitimate choice?

[Moontanman]

If time travel is indeed possible then were are they? You would think there would be time travel tourists everywhere. Every time something important happens there would be time tourists all over it. I think the idea of multiple universes would show how we can have free will but if there are no other universes then the future and past do not exist, only the ever present "now"

[modest]

Speaking from a metaphysical hypothetical.

 

Let's assume that all time exists (generally referred to as the B series of time - temporal time).

 

So the Past, Present and Future all exist right now. In fact, it is not even technically proper to refer to time in tenses, because all time exists simultaneously under this time theory. So we can only refer to time as a measurement (year/date/etc) or as events are relevant to each other. (This happened earlier than that.)

 

I'm not sure you can say that according to the B-theory of time all events exist "right now" or that they exist "simultaneously". I agree with your characterization of B-theory "events are relevant to each other" and I'll give a little summary of my understanding:

 

A-theorist believe time reduces to a relationship between past, future, and present. Two events (let's say event E1 and event E2) are each related to the fundamental ontological elements of past, future, and present. E1 might exit in the present and E2 might exist 2 days in the past. Events flow from the future to present to past. The future isn't as real as the past.

 

B-theorists would say events in the "past", "present", and "future" are all equally real and that those designations are mental constructs rather than fundamental elements which time reduces to. Time reduces to the ordering of events. E1 is 2 days prior to E2. According to this view, saying an event is 2 days in the past is just a way of saying it exists 2 days prior to the time being discussed as present (the event where the brain says E2 is present rather than an event where the brain says E2 is past).

 

It's described rather well on the Stanford encyclopedia of philosophy:

 

Time (Stanford Encyclopedia of Philosophy)

 

In any case, B theorist would say two events are simultaneous if neither can be said to precede the other. They wouldn't say all events exist simultaneously, but rather that all events (regardless of past, future, and present designation) are equally real. They don't all exist "right now" they just all exist.

 

OK, so if the B series of time exists, is it true that you still have freewill (Autonomy)? If tomorrow already exists, and what I am going to do is already set, and nothing I can do could possibly change it, then do I really have a legitimate choice?

 

Most B-theorists would agree. The difference is between Presentism (which is an A-theory philosophy) and Eternalism (a B-theory philosophy). The former is mostly considered to be non-deterministic (the future is not set) while the latter is considered to be deterministic (the future is set).

 

Many who support a philosophy of Eternalism base their argument on relativity and 4 dimensional spacetime. In special relativity the present instant can be different for one observer than it is for another observer because of the relativity of simultaneity. The argument goes: if one observer's distant present instant event precedes the other observers distant present instant event (it being the same event) then the future of the distant event from the first observer's point of view must be set. It cannot change otherwise the two observers would end up observing the same event two different ways when the light from the event eventually reaches them. The argument is described here.

 

So, yes, I think your deduction that B-theory can be considered deterministic is spot on.

 

~modest

[Glenn Lyvers]

If time travel is indeed possible then were are they? You would think there would be time travel tourists everywhere. Every time something important happens there would be time tourists all over it. I think the idea of multiple universes would show how we can have free will but if there are no other universes then the future and past do not exist, only the ever present "now"

 

On of the general guesses about this phenomena (not seeing tourists around) is that, because this timeline is set, it is unchangeable. For example, you could not go back in time and kill your great great grandfather, because to do so would create an absurdity (paradox). Along that same thought, if you eat a bagel today, you can't go back to yesterday and eat that same bagel, because it already happened later. The events of the timeline are set in place.

 

Therefore, if you do go back in time, and make a change, you alter the timeline and you would create a split in the timeline, thus you would exist in a new (separate) timeline. Thus, the people in this timeline would never encounter the people in the separate timeline. I hope that helps you understand the common answer to your question (hypothetically).

 

It does cause problems, as in the great great grandfather example, and the possibility to create causal loops. Welcome to metaphysics.

[Moontanman]

Thanks for the welcome Glenn, believe it or not I am quite familiar with causal loops, and paradoxes thank you. You forget about the possibility that a time traveler would change time no matter what he did and destroy his future and appear to appear to be out of no where with no past or future, like something that popped out of a quantum singularity. Metaphysics? BB

[Glenn Lyvers]

Of course its all speculation.

 

The idea that a time traveler would destroy his future, and appear to exist from no where (no past or future) as you put it is basically correct - but not exactly.

 

His future would exist in the second time line he created. His "original self" as his past self would remain in the original time line where he came from, and the rest of the world would remain unchanged from his original time. This is because eternally, his jumping to another time line would have always happened. (His present moment would be privileged wherever he appeared on the respective lines)

 

As a traveler, he would manifest himself on the separate time line in the third dimension as a three dimensional slice of his fourth dimensional (temporal) self. He would simply be spreading his slices between separate time lines. You can think of a time line as a world. It is a world where he exists, with all the contingent creation of the old. This split would not affect the world he came from, and his future in the new world would be set, unless he jumps again.

 

You are right, that he would not have a past set in the new world (second time line) but it does not mean he would not have a past at all, or that it would create a paradox or causal loop.

 

Additionally, he could not jump to and stay in a time line which is not new. So once he left this world, he could not return (hypothetically) because his future would not exist in that time.

 

I know Wikipedia is lousy as a reference but you might read this short page. It explains the alternate universe hypothesis and other relevant points. I don't think it s accurate throughout but those points might be easier to understand from that post than my clumsy text on a BB. http://en.wikipedia.org/wiki/Temporal_mechanics

 

So basically, I hope that makes sense and clears up any lingering questions about why we don't see time travelers popping in and out of our time line. Our lack of evidence in this time line does not in any way demonstrate that it is not possible, or otherwise actively happening in other time lines.

 

Glenn