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Free will is an illusion...


Marcelo
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Hello group :),

 

Here is a very interesting text about time travel:

 

http://www.arts.unimelb.edu.au/amu/ucr/student/1996/m.joyce/timetrav.htm

 

Copyright © Michael Joyce 1996

 

10 Is time travel to the past logically possible? Is it logically possible

 

for you to travel back and have a conversation with your former self?

 

Could you kill your former self? Could you do anything to anyone, or could

 

they do anything to you, which you had not already done or had done to

 

you? Would you, or anyone else, in such circumstances, be a free agent?

 

Introduction

 

Long a favourite topic of science fiction, the notion of time travel is

 

one that raises an enormous number of philosophical problems and

 

quandaries regarding causation, identity and the nature of time itself.

 

While it is fascinating to study these merely as hypotheticals, research

 

in the context of relativity has suggested some circumstances under which

 

time travel, to the past as well as the future, might be possible.

 

Views of time

 

Linear

 

The traditional view of time has been of something flowing inexorably

 

forwards, and in three distinct stages: past, present and future. The past

 

is fixed and unchangeable, the future is unwritten and does not exist yet,

 

and the present is what we are experiencing now. This picture is still the

 

most intuitive and natural way of viewing time. Since the theory of

 

relativity has become more widely accepted, time is no longer seen as

 

being so unique and separate, but as part of a four-dimensional framework.

 

It is still different to the three space dimensions in many important

 

aspects, but it can still be altered by factors such as speed and gravity.

 

It is relativity that gives a little credibility to the possibility of

 

time travel.1

 

Many-worlds

 

Another view of time that I will mention is the "many-worlds" or parallel

 

universe view, in which a time traveller may not actually be visiting

 

their own past, but is actually travelling to a universe similar to his or

 

her original universe. Although it might be seen as an extreme extension

 

of some principles of quantum mechanics, the many-worlds hypothesis is a

 

useful way of sidestepping many of the logical and philosophical problems

 

of time travel. This is often thought of in terms of an extra dimension of

 

time, with different time-lines branching off because of the different

 

events in each system.2

 

Time travel is not a physical impossibility

 

A good simple description of time travel was given by David Lewis3 as

 

being when the personal time of the time traveller differs from the global

 

and historical time of the rest of the world. Lewis makes the analogy of a

 

personal time as a winding mountain railroad and external time as being

 

the distance as the crow flies to demonstrate that this does need a second

 

time dimension, but can fit in with our more usual picture of space-time

 

as a four-dimensional system. The railroad might take a meandering path,

 

even crossing over itself, but it is still contained within the same three

 

dimensions as a straight line between the railroad's origin and

 

destination. So too, a time traveller's personal time might different to

 

the global, external time of the rest of the world, but is still contained

 

within that global time.

 

Possible types of time travel

 

Future

 

The type of time travel that is easiest to explain is travel into the

 

future, which could be accomplished by a spacecraft travelling at

 

relativistic speeds4. As the ship gets faster, time dilation slows time on

 

board the spacecraft relative to the planet it has left behind. For the

 

viewpoint of those remaining on earth, the astronaut has travelled into

 

the future. Travel in this manner is not usually thought of as time

 

travel, since the astronaut's personal time continues normally, but it

 

would have the same effect as a classic time machine (although it would be

 

disappointing for the astronaut to learn that there is no reverse gear on

 

the time machine). It also differs from the normal description of time

 

travel because, since the time traveller cannot return to his or her

 

natural time, his or her path does not cross over or duplicate itself.

 

The "Twins Paradox" described by travelling at relativistic speeds is not

 

one of time travel, but of time dilation and frames of reference. The

 

notion of time flowing at different paces is unexpected and difficult, but

 

not as counter-intuitive and confusing as the possibilty of travelling

 

backwards in time.

 

Past

 

Like travelling into the future, travelling into the past would also

 

require several gross manipulations and incredible engineering feats in

 

order to exploit some of the more unusual effects of the theory of general

 

relativity. Many physicists are willing to ignore the possibility of time

 

travel to the past because it is so unlikely to occur and the energy

 

required to complete it render it extremely improbable5.

 

A number of schemes have been proposed to travel backwards in time. Some

 

involve a time that loops around itself6, others would use a rotating

 

black hole7, an accelerated wormhole8 or a cylindrical object so massive

 

that time would be bent right around and into the opposite direction9.

 

Although all of them differ to time travel as usually suggested in popular

 

fiction in that they also involve travel through space, the logical

 

complications are much the same.

 

Information

 

Another type of time travel that might be much more possible, although a

 

little less dramatic, would involve tachyons. Tachyons are controversial

 

particles that travel faster than light, and, as a consequence of their

 

superluminal speed, backwards in time10. An ability to control these would

 

lead to the much the same philosophical problems of causation as a person

 

actually travelling backwards. While there would be no problems of

 

physically meeting oneself in a previous time, it might be possible to

 

communicate with oneself with tachyons, or even to use those tachyons to

 

cause (or at least attempt to cause) some events in the past.

 

Meeting a previous self

 

One scenario of backwards time travel that frequently raises concerns is

 

that of a time traveller travelling back and meeting themselves at an

 

earlier stage in life, often with the intention of giving themselves

 

advice in order to improve their lives or avoid a particularly traumatic

 

event. The first issue here is of the problem of duplication: is it

 

possible to have two "copies" of the same person at the same place and the

 

same time, and if so what is the difference, if any between the two

 

people? The second is the problem of the inconsistencies between the

 

traveller's memory of the past and the events that transpire once he or

 

she goes back to the past.

 

In David Lewis' description of time travel, the time traveller's world

 

line might have discontinuities in relation to the rest of the "normal"

 

timeline11, so he has to go to great pains to explain the continuing

 

identity of a time traveller as not only having the same physical

 

characteristics as the time traveller's previous existencein their

 

personal time, but also an element of causal connection. The methods of

 

time travel mentioned above involving travel through space as well do not

 

have these discontinuites, so personal identity is easier to ascertain.

 

Identity

 

If a time traveller did travel back to a time that he or she had already

 

lived through, would we be able to say that the two people are one and the

 

same? There would obviously be some physical differences in age and

 

appearance and mental differences in the older time traveller's extra

 

memories and experiences, but these differences would not normally lead us

 

to make a distinction between a young and old version of an everyday

 

non-time-travelling person as being different people. Although time travel

 

seems more complicated, there is no reason why a time traveller's personal

 

time line could not cross over itself like a mountain railroad crosses

 

over itself on a bridge.

 

Inconsistency with the past

 

The second problem of meeting oneself as one travels back in time is

 

really just a simpler version of the grandfather paradox detailed below.

 

If the time traveller does meet with him or herself in the past, then it

 

follows that the meeting will be a part of his or her own memories and

 

past. Unless the two-dimensional time framework is introduced, the time

 

traveller must have a memory of being visited by an older version of

 

himself in his or her youth. The possibility of a time traveller acting in

 

a way that was inconsistent with the known past raises a few interesting

 

questions.

 

The Grandfather Paradox

 

As the most extreme example of changing the past, a hypothetical is often

 

envisaged whereby the time traveller visits the past with the intention of

 

killing his or her own grandfather or grandmother so that the time

 

traveller will never be born. This is usually known as the Grandfather

 

Paradox12. Numerous variations on the theme exist, but the basic question

 

remains the same: if time travel to the past were possible, would it be

 

possible to change the past, and moreover to change it in such a way as to

 

make the time traveller's existence impossible?

 

The simplest way to avoid this paradox is by invoking the many-universes

 

theory of time. In this case, the time traveller actually kills the person

 

corresponding to his ancestor in a different time, leaving his own

 

ancestor (and thus himself) untouched13.

 

To many, the two-dimensional-time solution is a cop-out, since the time

 

traveller is not visiting his or her own past, just a past that is

 

remarkably similar to it. Even though the time traveller can perform

 

actions that are inconsistent with the past as he or she know it, these

 

actions will still have to be consistent with the timeline of that

 

particular universe.

 

Lewis reminds us not to confuse "logically impossible" with physically

 

incapable14. If we look at the time traveller as just another occupant of

 

that time armed with a gun and all the skill required to kill his target,

 

we would not say that it is impossible for him to complete the task.

 

However, this ignores the important fact of the time traveller's past. We

 

know that the time traveller's grandfather did not die at that stage, so

 

the assassin could not have succeed. We can say the same thing of any past

 

event: John Hinckley could have killed Ronald Reagan when he shot him in

 

1981, but didn't.

 

Doing anything else inconsistent with history

 

The case of killing your own grandmother or grandfather is a particularly

 

interesting one because it involves not only a contradiction with the past

 

as the time traveller knows it happens, but also a paradox that shows why

 

such an inconsistency is illogical. Although the existence of the time

 

traveller's grandfather is of obvious importance to the time traveller, it

 

is not significantly different from any other act that is inconsistent

 

with the time traveller's past, whether he or she knows about it or not.

 

The time traveller's past exists not just for the time traveller, but also

 

for everyone else alive in his or her "natural" time. If the time

 

traveller killed someone else or gave them the blueprints for an

 

invention, the records of the time traveller's natural time would have to

 

show events that correspond with the actions of the time traveller in the

 

past, regardless of whether the time traveller knew if that was how things

 

would pan out or not.

 

Free will

 

The worrying aspect of looking at time travel in this way is that it

 

eliminates free will for the time traveler. Although the time traveller

 

believes that he or she is able to kill a particular person, they are

 

destined to fail since the events of that time have already been fixed,

 

regardless of whether the time traveller knows of them or not.

 

We think of the future as being variable and determined by the actions we

 

take in the present. The presence of a time traveller in our time would

 

shatter this illusion. Our future is the time traveller's past. If he

 

cannot change it, then neither can we. Whatever is written in the history

 

books of the time traveller is what we in the present will do.

 

If the future is fixed as well as the present, we might look at time as

 

like a movie film strip. To everyday people, the film moves past the

 

projector at a steady rate and we see only the present. We know what has

 

already happened in the movie, but can only guess at what will happen

 

next. To a time traveller, the movie is unravelled and spread out on the

 

floor. The whole of the movie is fixed, regardless of which frame the time

 

traveller believes he or she is in. At no stage can anyone alter the

 

course of events once the film has been processed and fixed in its nature.

 

In a two-dimensional description of time, there is no paradox in a time

 

traveller killing what appears to be their own ancestor, so it at first

 

looks as though free will still exists. Although the time traveller might

 

seem to be able to do whatever they want, whatever they do will still have

 

to be consistent with the events that transpire within the timeline that

 

the time traveller now occupies.

 

Imagine two unrelated time travellers both travelling to the same

 

timeline: one is travelling to his or her own past (Traveller-A) and the

 

other to a time-line that is merely similar to his or her own past

 

(Traveller-B). Traveller-A will be in exactly the same situation as if he

 

or she were in a one-dimensional time situation, and will be unable to do

 

anything inconsistent with his or her own past. Similarly, Traveller-B

 

will also be unable to do anything that would be inconsistent with

 

Traveller-A's past. Since the events forward of the time when Traveller-A

 

and Traveller-B meet are fixed for that timeline, the situation is no

 

different to a one-dimensional time situation.

 

Changing the past in fiction

 

Depictions of time travel in science fiction commonly allow the

 

protagonists to intervene with and interfere with the past, although the

 

travellers usually take enormous pains to avoid doing so. Two-dimensional

 

depictions of time apart, the most logical of these depictions is in

 

stories where the memories and records of the past that the time

 

travellers have change to reflect the past: usually instantaneously, but

 

sometimes as a flow-on effect of the change. Such a notion is plausible,

 

so long as the changes they make do not logically rule out the fact that

 

the travellers were able to make these changes. In such a situation, free

 

will is preserved in all aspects but those that will make it impossible

 

for the travellers to exist at that point in time. Of course, the problem

 

with this is in determining what changes would rule out this existence:

 

killing your own grandfather is obvious, but what of merely preventing two

 

of your distant ancestors from meeting, or preventing the time machine

 

from being invented?

 

The more usual story depicted in science fiction is one where the

 

traveller's past does change, but he or she retains her memory of the past

 

as it was. This story is inconsistent from a logical and philosophical

 

point of view, but makes for a more interesting and conventionally

 

comprehensible narrative.

 

Conclusions

 

For a time traveller, the distinctions between past, present and future

 

disappear, so that the future may be fixed and unchangeable. If this is

 

the case, free will is gone too, not only for the time traveller, but also

 

for all the other inhabitants of his or her past. This conclusion is so

 

extreme that we may be better to reject the notion of time travel and keep

 

our precious free will than to accept this consequence of the general

 

theory of relativity.

 

References

 

Davies, Paul (1995) About Time Penguin Books

 

Horwich, P. (1987) Asymmetries in Time: Problems in the Philosophy of

 

Science, MIT Press, US

 

Lewis, D.K. (1976): 'The Paradoxes of Time Travel', American Philosophical

 

Quarterly 13

 

pp 145-152. Reprinted in Source Materials 136-220, 1996

 

Footnotes

 

Davies, Paul (1995) About Time Penguin Books, p 33

 

Lewis, D.K. (1976): 'The Paradoxes of Time Travel', American

 

Philosophical Quarterly 13

 

pp 145-152. Reprinted in Source Materials 136-220, 1996 p 231

 

Ibid p 137

 

Davies p 234

 

Ibid p 244

 

Ibid p 246

 

Ibid p 244

 

Ibid p 246

 

Ibid p 245

 

Ibid p 234

 

Lewis p 136

 

Lewis p 141-146

 

Ibid p 146

 

Ibid p 143

 

Copyright © Michael Joyce 1996.Created by Michael Joyce

 

[email protected]

 

Last Modified October 25, 1996

 

<This message has been edited by Marcelo (edited 24 June 2000).>

 

 

 

 

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Fascinating that this was posted 15 years ago (???) and no one commented... In fact, the title is catchy and the contents are interesting, but I beg to disagree with it. I don't think that free will is an illusion, but at the same time I do agree that most people don't have free will and just march mechanically in the existence.

 

"For a time traveller, the distinctions between past, present and future

 

disappear, so that the future may be fixed and unchangeable. If this is

 

the case, free will is gone too, not only for the time traveller, but also

 

for all the other inhabitants of his or her past. "

 

When past, present and future disappear it's when we achieve a superior knowledge so that's when we in fact have free will.

 

 

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Imagine then that your consciousness (or soul if you will) is creating a worldline depending on the decisions it makes. All outcomes are possible and inevitable in the great spectrum of everything. So I say the the universe you experience is yours and yours alone. And while we may not realise it, everything around us is fluid and malleable, changing specificly because of our input. Whether or not we do this consciously is up to us.

 

"Pay attention to these petals, Steven. The petal’s dance seems improvised, but it is being calculated in real time based on the physical properties of this planet. With hard work, and dedication, you can master the magical properties of your gem and perform your own dance!”

 

~Pearl

 

 

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I have always lived by the firm belief that both are true. We have a predestination... however, how we get there is based on free will. Kind of like the Time Machine. No matter how many times he went back in time to stop her death, all he did was change how she died. We all have certain things in our lives that are preordained. How it happens and how we get to the point for it to happen is up to us, but it happens exactly when it is suppose to happen. Just like death. You are given a date in which you are going to die. When that moment arrives, nothing you do will prevent it or stall it. However, how you died is determined by you.

 

 

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