Seriously thoughtful Is Time Travel possible

[HarryT]

Would the original poster like it to be moved? Happy to do so, if desired.

[pilotbob]

Originally Posted by HarryT

Would the original poster like it to be moved? Happy to do so, if desired.

No, please leave it here. The discussion was meant to be scientific.... also, I was expecting more people to discuss the ramifications of time travel such as, wouldn't history know you were going back in time. Since it already happened there is no way to change anything. (this of course assumes time travel could happen.)

Saying time travel is possible using a fictional device is not really on topic.

BOb

[ahammer]

Originally Posted by pilotbob

No, please leave it here. The discussion was meant to be scientific.... also, I was expecting more people to discuss the ramifications of time travel such as, wouldn't history know you were going back in time. Since it already happened there is no way to change anything. (this of course assumes time travel could happen.)

Saying time travel is possible using a fictional device is not really on topic.

BOb

to this point if you know that whatever effect you could have on history would have already happend. why would you go back in time to try to make a change if you already know what the outcome what be.

time travel will always bring up the ? of free will. for history to be predefined that also meens that the future must predefined (allowing for time travel). that where paradox come in a system that is not predefined then you can change history in a way that will change the future from that point on.

the ways around this have already been put down in this post but have been decided that would not count as time travel becuse it is not your past.

if it is the case we have no real free will and everthing that can happen has happen and time travel is passable the only reason I see people using the thing would be to go back in time is as site seers. im sure people would still try to change things some times.

I think this has been ontopic mostly save a few people I will not name. (points at Icarusbop)

[ahammer]

thoght exparment

speed of light seem to be the speed limit of the U. ( or maybe not as it seems not to be a set number the more we look into it)
given that all your cells and your view of time seems to slow down the faster you go. what happens if we find a way to go faster then the speed of light (I know it not passable given what we know just a what if)

[pilotbob]

Originally Posted by ahammer

if it is the case we have no real free will and everthing that can happen has happen and time travel is passable the only reason I see people using the thing would be to go back in time is as site seers. im sure people would still try to change things some times.

I am not saying you don't have free will... what I am saying (positing) is that if you do travel to the past with plans the "change" something... well, whatever you did already happened which brought things to the current point. Perhaps you did try to go back and kill hitler. Well, it didn't work, because there was a hitler.

I remember show with time travel where the guy went back to kill hitler. And, he did kill Hitler, but the nanny replaced the baby with another so her employer wouldn't fire her... and "that" kid became the hitler we all know about. It was an interesting take on the fact that the past already happened no matter what you do, you already did it.

BOb

[ahammer]

Originally Posted by pilotbob

I am not saying you don't have free will... what I am saying (positing) is that if you do travel to the past with plans the "change" something... well, whatever you did already happened which brought things to the current point. Perhaps you did try to go back and kill hitler. Well, it didn't work, because there was a hitler.

I remember show with time travel where the guy went back to kill hitler. And, he did kill Hitler, but the nanny replaced the baby with another so her employer wouldn't fire her... and "that" kid became the hitler we all know about. It was an interesting take on the fact that the past already happened no matter what you do, you already did it.

BOb

I know that what you where saying and for that to work what time travelr to effect what is happing now he would have had to have gone back in time and set the event into into effect. that meens you would have ever thing up to the point that where the person goes back in time has happen already.

my point is your past is somones present. for you to show up in the past you would have to have in the (from the person past person point of view) future gone back in time and for the same reason. this meens that it has already played out before hand. if this is the case anything you do has been done before you even know you are going to do it. that being said it may be the case and we just dont know it.

of this is all base on a system that would not allow pardoxs. if you have a way of dealing with them all this argment is null.

[Daithi]

Originally Posted by HarryT

There seem to be two schools of philosphical thought about just what "the future" is:

1. That the future is fixed and "pre-ordained" and that the whole of time is "there" - we just cannot perceive it yet.

2. The so-called "multiverse" theory which says that any time any decision is made, the universe "branches" and two entirely new universes go forward, one in which the decision went one way, and one in which it went the other.

If Theory 1 is correct then this means that there is no such thing as "Freewill" because all of your actions are pre-ordained and there is nothing you can do to change them. From the time the dinasaurs exited it was already known that you would exist and what decisions you would make right up until the time you no longer existed.

Furthermore, if Theory 1 is true and I travel 10 minutes back in time and my future self kills my past self then I get into an ugly paradox. But, if Theory 2 is correct then my future self can kill a past self that exists in one of these multiverses and no paradox.

As I was thinking about this it also occurred to me that Theory 2 doesn't preclude the simultaneous existence of Theory 1. E.g. it is pre-ordained that "one" of my future selves must travel back in time and kill one of my past selves.

[Daithi]

If you enjoy the time travel multiverse concept then you might enjoy Neil Stephenson's Anathema.

[HarryT]

Originally Posted by Daithi

If Theory 1 is correct then this means that there is no such thing as "Freewill" because all of your actions are pre-ordained and there is nothing you can do to change them. From the time the dinasaurs exited it was already known that you would exist and what decisions you would make right up until the time you no longer existed.

That's right, but is there any way that we could know the difference between actually having "free will" and merely having the illusion of having free will?

[Daithi]

That's a good question Harry. I'd say probably not. It's a strange thing to think about. I believe I have freewill, but I don't think I can really know for sure.

Another interesting question is "can the world be pre-ordained while simultaneously allowing individuals to still have free-will?"

I believe the argument is -- imagine you live your life and make vast numbers of decisions throughout that life time, and when you die your soul goes back in time to the moment of your birth. Your soul then watches your past self go through life and make the same decisions all over again. From your past self's perspective he is making his own decisions and has free-will but from your soul's perspective everything is pre-ordained.

I believe this is the logic used by the church to explain how god can know what will happen in the future and also allow you to still have free-will. The Muslims flat out say that the world is pre-ordained, and I'm pretty sure this is how they explain freewill as well. Personally, I don't buy it because all my decisions are locked in stone before I've ever made one and before I'm ever born, and to me this is not free-will.

[kovidgoyal]

Originally Posted by HarryT

That's right, but is there any way that we could know the difference between actually having "free will" and merely having the illusion of having free will?

Well yes, by figuring out whether our mental processes are deterministic or not.

[wodin]

Originally Posted by Daithi

That's a good question Harry. I'd say probably not. It's a strange thing to think about. I believe I have freewill, but I don't think I can really know for sure.

Another interesting question is "can the world be pre-ordained while simultaneously allowing individuals to still have free-will?"

I believe the argument is -- imagine you live your life and make vast numbers of decisions throughout that life time, and when you die your soul goes back in time to the moment of your birth. Your soul then watches your past self go through life and make the same decisions all over again. From your past self's perspective he is making his own decisions and has free-will but from your soul's perspective everything is pre-ordained.

I believe this is the logic used by the church to explain how god can know what will happen in the future and also allow you to still have free-will. The Muslims flat out say that the world is pre-ordained, and I'm pretty sure this is how they explain freewill as well. Personally, I don't buy it because all my decisions are locked in stone before I've ever made one and before I'm ever born, and to me this is not free-will.

That argument depends on a couple of assumptions: One, there is such a thing as a soul; and two, if souls exist, they are capable of traveling in time.

If I'm not mistaken, the second assumption is what this whole thread is arguing.

[KarlB]

Sorry if this has already been mentioned in this thread, but a good and enjoyable recent book that covers this subject is "Physics of the Impossible; A Scientific Exploration into the World of Phasers, Force Fields, Teleportation and Time Travel"*by Michio Kaku.

Long story short, Kaku's conclusion is that time travel is "something that does not violate the laws of physics, but that might be possible only thousands to millions of years in the future."

[pilotbob]

Originally Posted by KarlB

Long story short, Kaku's conclusion is that time travel is "something that does not violate the laws of physics, but that might be possible only thousands to millions of years in the future."

Ok, so theoretically if time travel is possible in the future... even 10,000 years from now. Could someone from that time not travel back and bring a time machine with them to make it possible now?

BOb

[Xenophon]

Originally Posted by pilotbob

Ok, so theoretically if time travel is possible in the future... even 10,000 years from now. Could someone from that time not travel back and bring a time machine with them to make it possible now?

BOb

The wormhole approach only lets you travel back to the time when you first moved the ends of the wormhole apart. Or perhaps it establishes a delta-T which you can theoretically traverse in either direction. But both ends continue to move into the future in the ordinary fashion. Whichever version of the explanation you use, that particular approach provides no access to times prior to creation/exploitation of the wormhole.

For other approaches, your mileage may vary.

Xenophon