Time travel

[Butters]

Assuming you could travel back in time - it would mean you were ALREADY a part of what happened on the date you travelled back to. In the case of say, "I'm going to kill Hitler before he comes to power.."; it's NOT that the 'timeline knows and somehow prevents you'; it's that you were already there originally and couldn't get it done, becauase if you had done it successfully; history wouldn't have unfolded the way it in fact did. I hink IF time travel is possible, the reason things can't be changed is they unfolded the way they did with the respective time travcellers already involved with what occured.

That's right. You explained it more succinctly than I could. The point is that, if your time traveling to the past is already part of history, then the concept of "changing" the timeline is meaningless. Anything you did in the past has already happened, and is already a part of history, even before the actual act of going back in time takes place, so you wouldn't actually be changing anything by going back in time.

Yes - according to the Novikov SCP, a time traveller couldn't change the past because the past already "contains" his temporal intervention.

The problem is, a well informed time traveller can be stopped from "modifying" his temporal intervention only if probability, causality and the laws of physics are broken for this purpose.

If a future version of you travels to the past, your future actions have already taken place at some point in history. You are/will be part of historical events, however uneventful of newsworthy those events were.

Because the past has already happened, with your involvement, you are now fated to be involved and there is nothing you can do about it. However well informed the time traveler, his/her actions are based on events and decisions yet to be taken. Its at this point that the question of fate, free-will and destiny get thrown in, but its not neccessary, its just a sequence of events viewed from a different perspective.

I think the confusion around this stems from the need to somehow reconcile freewill and/or avoid paradoxes. The simple truth is that a paradox cannot exist, therefore an action that would lead to one is simply not possible, and multiple universes are just a device to negate the impossible.

Time travel is not about changing anything, that would be impossible, its about being involved in events outside of the normal chronological sequence. If you have never been visited by a future a version of yourself, you can rest assured that you will never travel through time to meet an earlier version of yourself either.

 

[TeknoNurd]

Going back in time and killing Hitler would create something of a paradox anyhow. The reason one would decide to kill Hitler is the horrors he caused... were you successful at killing him, said horrors would not of occurred, at least not by his orders, and you would therefore have had no reason to go back in time to kill Hitler.

This is probably the crux of why the time line would be somewhat resilient, once you changed an event, you would not have a reason to time travel to change the event. Inadvertant changes would be a horse of a different color.

 

[ProtoAvatar]

That's right. You explained it more succinctly than I could. The point is that, if your time traveling to the past is already part of history, then the concept of "changing" the timeline is meaningless. Anything you did in the past has already happened, and is already a part of history, even before the actual act of going back in time takes place, so you wouldn't actually be changing anything by going back in time.

Yes - according to the Novikov SCP, a time traveller couldn't change the past because the past already "contains" his temporal intervention.

The problem is, a well informed time traveller can be stopped from "modifying" his temporal intervention only if probability, causality and the laws of physics are broken for this purpose.

If a future version of you travels to the past, your future actions have already taken place at some point in history. You are/will be part of historical events, however uneventful of newsworthy those events were.

Because the past has already happened, with your involvement, you are now fated to be involved and there is nothing you can do about it. However well informed the time traveler, his/her actions are based on events and decisions yet to be taken. Its at this point that the question of fate, free-will and destiny get thrown in, but its not neccessary, its just a sequence of events viewed from a different perspective.

I think the confusion around this stems from the need to somehow reconcile freewill and/or avoid paradoxes. The simple truth is that a paradox cannot exist, therefore an action that would lead to one is simply not possible, and multiple universes are just a device to negate the impossible.

Time travel is not about changing anything, that would be impossible, its about being involved in events outside of the normal chronological sequence. If you have never been visited by a future a version of yourself, you can rest assured that you will never travel through time to meet an earlier version of yourself either.

As I said:
"The problem is, a well informed time traveller can be stopped from "modifying" his temporal intervention only if probability, causality and the laws of physics are broken for this purpose."

This time traveller will know in detail the actions he took/will take in the past - those actions took place in the past. Let's say he wants to change something in his behaviour, to make some detail different. How can he be stopped - and the Novikov SCP preserved - without breaking probability, causality and the laws of physics?

 

[Butters]

Hitler died under those peculiar circumstances because thats how history played out. The inevitable result of one event following another following another. We know the outcome of Hitler's reign. Any atempt to change that outcome will fail 100% because we already know the outcome. It happened, its unchangable.

Time travel, possible or not, does not rewind the tape of history, it just moves your focus along it. If you consider the implications of a changable history it has the some pretty profound revelations. Firsty, the whole idea is extremely self-centric, in that the entire universe is reset to an earlier state of your choice in order to allow your freedom of expression within events that have already happened differently. Secondly, it renders everyone else invalid. The life experiences of everyone else are somehow transient but the time traveller's are permanent. The time traveller is, by this logic, the only conscious observer in the universe that has any significance. AKA God.

Any train of thought in time travel logic that leads to a paradox is an indication that your logic is flawed and needs to be re-thought.

Perhaps it is easier to think of future events in a historical context. Tomorrow has already happened, we just haven't seen it yet. Tomorrow has so many variables that it is meaningless to say you have any influence. You can plan your day, but an unknown medical condition or another 9/11 can change your plans in an instant. Even if you think you have knowledge of the future, changing the events as prophesised only proves that the knowledge of the future was wrong. How can it be future knowledge if the event didn't happen? What ever will be will be.

If you can't change the events of tomorrow, why is it so hard to accept that you can't alter the events of yesterday. Its all set in stone dude, we're just along for the ride.

 

[ProtoAvatar]

If there is only ONE TIMELINE, the ability to change the past has, indeed, very serious implications. In fact, I already mentioned them in my first post from this thread - if history can be changed, than:
"we are nothing but flies who live for a day - until a time traveller changes the past and we cease to exists or we "exist" in a completly different form - one second we're rich, the next one we're beggers, the third one we don't exist. And we would never know any of this - we think we lived full lives and have the memories and status in the world to prove it - all of which is ephermal and easily changed by temporal intervention."

But HOW can the past be preserved when a well informed time traveller (a time traveller who knows exactly what happened in the past) tries to change it?
There is only one solution - I said it repeatedly in this thread: break probability, causality and the laws of physics. If you found out another solution to stop this time traveller - let's hear it.

BTW, the difference between the events of yesterday and the events of tomorrow is INFORMATION. You know what happened yesterday. You don't know what will happen tomorrow.

But what if there are MULTIPLE TIMELINES that exist independently? In this case, you wouldn't need to break the laws of the universe in order to prevent paradoxes.
The problem is, one needs an enormous amount of mass-energy in order to create a new timeline/universe.

In my interpretation, even the mass-energy problem is resolved:
"information, at least, can be sent into the past. What happens then?
Let's say a new timeline appears and the old one disappears.
But, in this case, where did the information that changed the past come from? From nowhere? In this case, the information disappears and the old timeline reappears.
But, if the old timeline exists again, then that information also exists. And if the information exists, then the new timeline appears again and the old timeline vanishes.
And so forth.
Essentially, I'm saying that both timelines exist, but consecutively not simultaneously."

 

[Anticitizen]

If time travel is possible, there's no good reason why you couldn't, say, go back in time and shoot Hitler. The thing is, we know that nobody is going to do that - because Hitler was never shot. If someone was going to shoot him he'd have been shot already.

 

[Butters]

There is only one solution - I said it repeatedly in this thread: break probability, causality and the laws of physics. If you found out another solution to stop this time traveller - let's hear it.
"

And thats the problem isn't it. As if it wasn't hard enough to find the means to travel through time, you then have to break the laws of physics, causality and probability, probably a few by-laws too, to achieve the desired result of a changed history, which then creates a theoretical alternate universe which, thanks to chaos and the law of unintended consequences (unless you break that law too) could be anything, but if the new alternate universe exists independently from your origin universe, which must still exist for you to travel from with the original motive, then that history of the origin universe remains unchanged anyway. Which leaves us talking about multiple universes and a parallel dimensions, which isn't really science.

Information isn't the only difference between today and yesterday, tomorrow isn't the lack of information, its more about experience. If you had absolute knowledge of tomorrow, you would have to experience it, at which point we'd have to rename it 'yesterday'.

In your examples, if you were to fuck up an attempt to change history so had another go at shooting Hitler, would the later version of you to travel back supercede the earlier you? Or would the later version apear next to the earlier you and take the shot successfully? If the latter, would you have any memory of future you appearing to take the successful shot when you were earlier you?

In a time travel model where one unchangeable time-line exists, there are no contradictions, no paradox and no placeholder technologies or theories like multiple universes. We just have 1 continuous line, one which you can leap about and enjoy taking part in history or the future, but from the perspective of both an external and exernal observer, the time line is logical and consistent.

But this doesn't allow for Back to the Future type stories or wishing you'd done things differently. To move away from the 'one-line' model, you have to bend every rule, law and universal constant you can imagine to think up something, anything, however plausible or preposterous, to support the desired outcome, which is a history that can be changed or a moment relived.

It may well be that time travel is in fact impossible, and because of that, no history can be changed, but purely as a thought experiment, every logical path points at a solid unchangable past.

 

[Meredith]

Everyone Kills Hitler on their first trip: http://www.abyssandapex.com/200710-wikihistory.html

 

[ProtoAvatar]

And thats the problem isn't it. As if it wasn't hard enough to find the means to travel through time, you then have to break the laws of physics, causality and probability, probably a few by-laws too, to achieve the desired result of a changed history, which then creates a theoretical alternate universe which, thanks to chaos and the law of unintended consequences (unless you break that law too) could be anything, but if the new alternate universe exists independently from your origin universe, which must still exist for you to travel from with the original motive, then that history of the origin universe remains unchanged anyway. Which leaves us talking about multiple universes and a parallel dimensions, which isn't really science.

Information isn't the only difference between today and yesterday, tomorrow isn't the lack of information, its more about experience. If you had absolute knowledge of tomorrow, you would have to experience it, at which point we'd have to rename it 'yesterday'.

In your examples, if you were to fuck up an attempt to change history so had another go at shooting Hitler, would the later version of you to travel back supercede the earlier you? Or would the later version apear next to the earlier you and take the shot successfully? If the latter, would you have any memory of future you appearing to take the successful shot when you were earlier you?

In a time travel model where one unchangeable time-line exists, there are no contradictions, no paradox and no placeholder technologies or theories like multiple universes. We just have 1 continuous line, one which you can leap about and enjoy taking part in history or the future, but from the perspective of both an external and exernal observer, the time line is logical and consistent.

But this doesn't allow for Back to the Future type stories or wishing you'd done things differently. To move away from the 'one-line' model, you have to bend every rule, law and universal constant you can imagine to think up something, anything, however plausible or preposterous, to support the desired outcome, which is a history that can be changed or a moment relived.

It may well be that time travel is in fact impossible, and because of that, no history can be changed, but purely as a thought experiment, every logical path points at a solid unchangable past.

For a time traveller, yesterday can be tomorrow, if he so wants. He can know everything about yesterday and he could change it after he travels in the past and this yesterday becomes tomorrow.

And you appear to have misunderstood: the universe has to break his own laws in order to stop the well informed time traveller from changing history.

In the "go back and kill Hitler example" - there is only one you. You are in the future, so you have access at information about how your 1938 attempt failed - an attempt you haven't comitted yet, because you will travel to 1938 only tomorrow. And once you travelled into the past, you can change your actions accordingly, creating a new timeline and a paradox - where did you get your information?
Do you have any ideea to what extent the universe has to break its own laws to prevent you from doing that? It may try to mess with probability, preventing you from getting an accurate history book. But you do have a time machine - you can send spy devices into the past to record everything - the universe can't allow that, so, let's say, the time machine won't work - bye bye, laws of physics. And the mess just gets bigger and bigger, until the universe has to transform you into some kind of remote controlled robot (disregarding the laws of biochemistry and quantum mechanics) in order to preserve the timeline.

In a time travel model where one unchangeable time line exists, the universe will have to break its own laws of probability, causality and physics in order to stop the well informed time traveller from creating paradoxes.

And a time travel model where more than one timeline exists is real science. It's called "the many-worls interpretation" in quantum mechanics. And I find it easier to accept than a model where the universe constatntly breaks its own rules.

Time travel is not possible? You may be right. Many scientists claim that - it's called the Chronology Protection Conjecture - but it's far from proven.
Nobody really knows if time travel is possible or not - and no human will know for a long time, in my opinion.

 

[Butters]

In the "go back and kill Hitler example" - there is only one you. You are in the future, so you have access at information about how your 1938 attempt failed - an attempt you haven't comitted yet, because you will travel to 1938 only tomorrow. And once you travelled into the past, you can change your actions accordingly, creating a new timeline and a paradox - where did you get your information?
Do you have any ideea to what extent the universe has to break its own laws to prevent you from doing that? It may try to mess with probability, preventing you from getting an accurate history book. But you do have a time machine - you can send spy devices into the past to record everything - the universe can't allow that, so, let's say, the time machine won't work - bye bye, laws of physics. And the mess just gets bigger and bigger, until the universe has to transform you into some kind of remote controlled robot (disregarding the laws of biochemistry and quantum mechanics) in order to preserve the timeline.

In a time travel model where one unchangeable time line exists, the universe will have to break its own laws of probability, causality and physics in order to stop the well informed time traveller from creating paradoxes.

This is the focus of our disagreement.

Where you see prevention of changes to the timeline as a violation of the laws of nature, I see the opposite. Changing a known event is impossible purely because the outcome is known. Its like watching a game twice and hoping that the final score is different.

I believe that the multiple universe theories are a cop out.

Picture the scene. I find my Grandpa's rusty old time machine in the attic, and it works. So I quickly chek last nights lottery numbers, noting that one lucky winner bagged £80m. Wanting a piece of that, I hop back a day and confidently buy the winning combination. I leap back to today and report my winnings to the lottery board, expecting to share my fortune with the other winner, but imagine my delight when I learn that the only winning ticket purchased before the draw was mine. I was that one lucky winner.

Now, having filled my pad with wine, whores and trinkets, I decide to reverse some historic injustice as my good deed for the day. I know, I'll kill Hitler. Nope can't do that. To kill Hitler, I would have to either enter a war zone, becoming a soldier, and take him out, or visit him earlier in his life and kill him in cold blood. I'm neither a soldier or murderer, so, what if I simply prevent his conception? Visit his father on the night of his conception and connect the whole booty nad thing, rape his mother so she's really not in the mood? What could I do? Well, I do a bit of research and all the History books tell me that Hitler rose to power and devasted a continent. Thats not the outcome I desire, I ask myself, will my efforts fail? I haven't decided what I'm going to do yet, but I already know its failed, so sod it, I'll go back to 1920 and knife the bastard.

The machine works, I travel back and stab him in the back. I return to the now and read the books. Nothing's changed. I dig a bit deeper and find that some bloke, with an uncanny resemblence to Hitler, was randomly knifed in the back, the killer was later found and hung. Bugger, I think to myself, as I find a grainy picture of me swaying in the breeze.

Somewhat freaked by the knowledge of my own death, I resolve to make this never happen, but I still want Hitler dead too. I can't prevent myself committing the crime because I distinctly remember doing it. I could swap the innocent dude for Hitler, so that when earlier me sinks the blade, he gets the right target. But history records a random knife attack, and my hanging. I start to panic, I've fucked up. Best to just destroy the machine now, thus preventing its future use and any possibility of my cumuppance in 1920.

I pick up the machine and raise it above my hand, but as I stand ready to smash it to the ground I notice something new, a toggle switch. On closer inspection I can just make out the inscription. The device has two settings, "Linear Chronology" and "Multiverse Induction". Am I reading this correctly? I need only flick the switch and never again be twunted by the cold indifferent hand of fate and causality? I can reset the day, any day? Throw the dice again. I can kill Hitler, the innocent guy I knifed will live, and I can enjoy a 2009 without a single WW2 movie to be seen. "Hitler who?" They will say, and I will smile, smug in my knowledge that I saved everyone.

So off I go, to do God's work and kill Hitler. Its 1919, again, and Hitler is walking his dog along the ravine. Have flicked the switch to multiverse, I sneak up behind the young Hitler and push him over. The screams of the innocent youth are snuffed out, along with his life and future, by the head splitting rock that waited at the bottom. I am a multiple murderer, but at least my latest deed will scrub clean my first murder, and save a generation from the horrors that would follow.

Feeling very pleased with myself, I return to future Europe. I was never born, my baby boomer parents were never born in the aftermath of a war that never happened. My wife, my friends, everyone, never born. I am alone in an alien culture. There were no Beatles, no Concorde, no Star Trek, No European Union, no Marshal Plan, no NHS. I could spend a lifetime trying to reshape history the way I like it, but instead, I think back to my whores in my mansion back in that parallel 2009. I had a everything and I wanted it back. Hitler would have to live.

I return to 1919, where Hitler walks his dog, just in time to see myself on tippy toes, creeping toward Hitler and his fate. I jump in, not a moment to soon and despatch my earlier self down the cliff. Confusion follows, Hitler's poodle attacks me and he reaches for his gun (I never knew he carried a gun when walking the dog but now I do) and I fall to the floor. I fumble with my machine, I want these changes to stick so flip the toggle back to 'Linear Chronology'. Time is short as Hitler's gun bares down on me, I need to get out so nudge the dial and leap forward through time.

Still on the floor but in another time and place, I am jostled and trampled by a crowd. My machine is knocked from my hands and is crushed beneath the wheels of a passing horse and trap. I hear screaming nearby as I am helped to my feet by a familiar face. It is Hitler and he recognises me as the murderer of a stranger one year before. But it gets worse, I murdered a man in cold blood, it was a few days ago to me, but to the 1920 contemporaries, his blood his still warm and he has yet to draw his last breath. There are witnesses and I find myself deep in custardy.

There is a trial, I plead my innocense but its not long before I find myself in familar surrounds. A town square I'd seen somewhere before, in a photo perhaps, of a hanging.

So as I stood there, awaiting the telling of history as I knew it would be told I fanally realised the truth about time travel. Its bollocks.

The End.

Wow, not sure if that made any sense but I certainly enjoyed typing it with my saturday morning Turquino Latte.

 

[Gepard]

In sum: it doesn't matter how perfect you think your research is; whatever you're planning to do has already been done, in the past, by you. People are fallible and whatever mix of accurate, inaccurate and/or just plain goofy research you do before setting out then played its part in creating the situation you're trying to change.

 

[Anticitizen]

Everyone Kills Hitler on their first trip: http://www.abyssandapex.com/200710-wikihistory.html

That is hilarious!

 

[Johnny Rico]

Well, let's see...time travel forward...sure. That's the whole theory of relativity thing with regards to speed as it approaches the speed of light.

Time travel backwards? Sort of. Viewing celestial events now that happened millenia ago, due to once again the speed of light.

 

[Argus Skyhawk]

Butters, I'm impressed. I would have enjoyed a happier ending, but I still enjoyed that story a lot.

Meredith, I also loved that "Everyone Kills Hitler" link.

 

[ProtoAvatar]

This is the focus of our disagreement.

Where you see prevention of changes to the timeline as a violation of the laws of nature, I see the opposite. Changing a known event is impossible purely because the outcome is known. Its like watching a game twice and hoping that the final score is different.

I believe that the multiple universe theories are a cop out.

Picture the scene. I find my Grandpa's rusty old time machine in the attic, and it works. So I quickly chek last nights lottery numbers, noting that one lucky winner bagged £80m. Wanting a piece of that, I hop back a day and confidently buy the winning combination. I leap back to today and report my winnings to the lottery board, expecting to share my fortune with the other winner, but imagine my delight when I learn that the only winning ticket purchased before the draw was mine. I was that one lucky winner.

Now, having filled my pad with wine, whores and trinkets, I decide to reverse some historic injustice as my good deed for the day. I know, I'll kill Hitler. Nope can't do that. To kill Hitler, I would have to either enter a war zone, becoming a soldier, and take him out, or visit him earlier in his life and kill him in cold blood. I'm neither a soldier or murderer, so, what if I simply prevent his conception? Visit his father on the night of his conception and connect the whole booty nad thing, rape his mother so she's really not in the mood? What could I do? Well, I do a bit of research and all the History books tell me that Hitler rose to power and devasted a continent. Thats not the outcome I desire, I ask myself, will my efforts fail? I haven't decided what I'm going to do yet, but I already know its failed, so sod it, I'll go back to 1920 and knife the bastard.

The machine works, I travel back and stab him in the back. I return to the now and read the books. Nothing's changed. I dig a bit deeper and find that some bloke, with an uncanny resemblence to Hitler, was randomly knifed in the back, the killer was later found and hung. Bugger, I think to myself, as I find a grainy picture of me swaying in the breeze.

Somewhat freaked by the knowledge of my own death, I resolve to make this never happen, but I still want Hitler dead too. I can't prevent myself committing the crime because I distinctly remember doing it. I could swap the innocent dude for Hitler, so that when earlier me sinks the blade, he gets the right target. But history records a random knife attack, and my hanging. I start to panic, I've fucked up. Best to just destroy the machine now, thus preventing its future use and any possibility of my cumuppance in 1920.

I pick up the machine and raise it above my hand, but as I stand ready to smash it to the ground I notice something new, a toggle switch. On closer inspection I can just make out the inscription. The device has two settings, "Linear Chronology" and "Multiverse Induction". Am I reading this correctly? I need only flick the switch and never again be twunted by the cold indifferent hand of fate and causality? I can reset the day, any day? Throw the dice again. I can kill Hitler, the innocent guy I knifed will live, and I can enjoy a 2009 without a single WW2 movie to be seen. "Hitler who?" They will say, and I will smile, smug in my knowledge that I saved everyone.

So off I go, to do God's work and kill Hitler. Its 1919, again, and Hitler is walking his dog along the ravine. Have flicked the switch to multiverse, I sneak up behind the young Hitler and push him over. The screams of the innocent youth are snuffed out, along with his life and future, by the head splitting rock that waited at the bottom. I am a multiple murderer, but at least my latest deed will scrub clean my first murder, and save a generation from the horrors that would follow.

Feeling very pleased with myself, I return to future Europe. I was never born, my baby boomer parents were never born in the aftermath of a war that never happened. My wife, my friends, everyone, never born. I am alone in an alien culture. There were no Beatles, no Concorde, no Star Trek, No European Union, no Marshal Plan, no NHS. I could spend a lifetime trying to reshape history the way I like it, but instead, I think back to my whores in my mansion back in that parallel 2009. I had a everything and I wanted it back. Hitler would have to live.

I return to 1919, where Hitler walks his dog, just in time to see myself on tippy toes, creeping toward Hitler and his fate. I jump in, not a moment to soon and despatch my earlier self down the cliff. Confusion follows, Hitler's poodle attacks me and he reaches for his gun (I never knew he carried a gun when walking the dog but now I do) and I fall to the floor. I fumble with my machine, I want these changes to stick so flip the toggle back to 'Linear Chronology'. Time is short as Hitler's gun bares down on me, I need to get out so nudge the dial and leap forward through time.

Still on the floor but in another time and place, I am jostled and trampled by a crowd. My machine is knocked from my hands and is crushed beneath the wheels of a passing horse and trap. I hear screaming nearby as I am helped to my feet by a familiar face. It is Hitler and he recognises me as the murderer of a stranger one year before. But it gets worse, I murdered a man in cold blood, it was a few days ago to me, but to the 1920 contemporaries, his blood his still warm and he has yet to draw his last breath. There are witnesses and I find myself deep in custardy.

There is a trial, I plead my innocense but its not long before I find myself in familar surrounds. A town square I'd seen somewhere before, in a photo perhaps, of a hanging.

So as I stood there, awaiting the telling of history as I knew it would be told I fanally realised the truth about time travel. Its bollocks.

The End.

Wow, not sure if that made any sense but I certainly enjoyed typing it with my saturday morning Turquino Latte.

I enjoyed your stories, but they only make sense if you are a not so well informed time traveller.
A WELL INFORMED time traveller wouldn't check only the lottery numbers and the sum; he'll send spy devices into the past (where and when he will go shortly) and watch himself buy the lottery ticket. Only afterwards will he go into the past - and if he wished, he could change any number of details - unless the universe stops him by breaking its laws of physics.
A WELL INFORMED time traveller would't need to read history books full of potentially inacurate facts. He would know exactly how his trip in the past will end before he even makes the journey. He could very well decide to NOT go into the past - and kill the wrong person, then die.
I ask you - what's stopping him from deciding this? What can compell him to commit suicide by travelling to 1919?

Maybe I should define what I mean by "laws of physics". It's pretty simple, actually. I'm referring to the laws of relativity, quantum mechanics, chemistry, etc. So, for example, breaking the law of gravity happens when a rock does't move at all when it is released in a gravity field - saying that this is not a violation of the laws of nature, under any circumstances, makes no sense.

 

[Butters]

I enjoyed your stories, but they only make sense if you are a not so well informed time traveller.
A WELL INFORMED time traveller wouldn't check only the lottery numbers and the sum; he'll send spy devices into the past (where and when he will go shortly) and watch himself buy the lottery ticket. Only afterwards will he go into the past - and if he wished, he could change any number of details - unless the universe stops him by breaking its laws of physics.
A WELL INFORMED time traveller would't need to read history books full of potentially inacurate facts. He would know exactly how his trip in the past will end before he even makes the journey. He could very well decide to NOT go into the past - and kill the wrong person, then die.
I ask you - what's stopping him from deciding this? What can compell him to commit suicide by travelling to 1919?

Maybe I should define what I mean by "laws of physics". It's pretty simple, actually. I'm referring to the laws of relativity, quantum mechanics, chemistry, etc. So, for example, breaking the law of gravity happens when a rock does't move at all when it is released in a gravity field - saying that this is not a violation of the laws of nature, under any circumstances, makes no sense.

Thanks for the story compliments.

Ok, the well informed time traveller, he has absolute knowledge of yesterday, and knows exactly what he needs to do to change the past. In your opinion, the past would have no evidence of the traveller, only the unaltered events that await the arrival of the traveller to change.

The issue with this is that the knowledge cannot be accurate and wrong at the same time. Either you were part of the events you want to change or you weren't. The well informed traveller must know this from his recordings. If you make the change, what happens to your original records? Do they change to reflect the new history?

What yu're suggesting is more of a reset. You don't travel back to yesterday, you bring yesterday to you. Resetting the universe to point of your your determination, so that events can play out again with a different outcome, a new and seperate tomorrow that is more of your liking. This approach is entirely without paradox because nothing is actually changing.

Its a bit like the Japanese film Ring and its sequel. Spiral was shit, some may disagree but I'm happy with the general opinion, so a new sequel was shot that completely ignored the original.

If you travel through time to an earlier point on the time line, you become part of that timeline, whereas taking advantage of the cosmological restore point lets you keep one timeline, and play events differently. This though is not wthout its own problems. You reset back to yesterday, the laws of probability reset too. From the point the cosmos is restarted, events are playing afresh. Different cards can be dealt, the die rolls anotherway. The well informed time traveller ends up with an outine of the day that might play out entirely differently.

The biggest problem though, whether you want to call it a reset or a multiverse is that it relies on you being at the centre of creation. All of time and space revolves around you, your obseravations and actions. I'm not really convinced it works that way, though sometimes it feels that way. There is no way to prove that anyother observer is conscious and that everything happens is entirely for my appreciation but I doubt it.

I'm not sure if I'll be able to convince you that there is only one solid and unchangable timeline, but there really is nothing in science to suggest the existence of multiverses. Probability might create a separate reality based on a different outcome, but we'll never know about them, so its irelevant anyway, but to try another approach:

If you we're to receive a warning from the future, something dire but within your means to prevent. If you act on the warning and make the change, and the terrible event never happens, your future information becomes wrong. If you received the warning by email, but didn't get it until it was too late, but a friend cc'd received it and took action instead, how would you view the warning? 'phew, lucky that was averted?' or 'what rubbish is this? Chicken Little?' How can an event that never happens be reported to the past?'

How would you prove to a third party that you could change the past? The third party would be a product of any event that you claimed to have changed. Their records would show that the event had always happened with your intervention. History would record no change. Any evidence you present in your defense would not be varifiable as there is no control available. Any attempt to repeat the experiment would wipe the original, making the whole exercise unavalable to peer review or independent repeat. Its not science. Your evidence would prove you were there, not what you had changed.

 

[Butters]

Forgot to add:

Maybe I should define what I mean by "laws of physics". It's pretty simple, actually. I'm referring to the laws of relativity, quantum mechanics, chemistry, etc. So, for example, breaking the law of gravity happens when a rock does't move at all when it is released in a gravity field - saying that this is not a violation of the laws of nature, under any circumstances, makes no sense.

Which is the biggest violation of the laws of nature et al:

Buying your eight year old self a shiny new bike on your birthday when you know that you got nothing?

or

Your time machine exploding in your face because you wired it wrong?

The second one is unfortunate but its an oversight and could happen to any other device, why is it a violation of nature that your time machine wouldn't work the way you expect but your air con is well with in natural law to go the blink.

What if you can't change history because you don't have a time machine? Is that a violation of nature? The events of the past are unchangable, an attempt to change them will fail because the events have happened, you can be there while they happen, but they only happen once.

You could perform a entire shakespearen play, with you playing every part, but every part you played would involve a trip through time. You could fill every seat in the theatre with you, but you would have to travel through time a lot times to ocupy each seat once. This scenario would violate no laws, but after the first performance, there would be no surprises. From the very start of this exercise, every version of future you would be present. You wouldn't start in an empty theatre, with you building up the performance with each trip. That would make no sense at all.


Apologies for the crudeness of the following but I can't find a better example of a biased agreement (from a straight perspective):

Suppose you could use your time machine, travel 1 day into the future and do yourself up the bottom. This would lock you in to a temporal contract that you can never break. All you can do is await the time of the intrusion. You can't change your mind because you would then be remembering something that never happened. There is nothing in any law of any principle of science and our understanding of the nature of reality to allow for that. And besides, the person YOU did is YOU, YOU agreed to be done up the bum by a future YOU shortly after doing YOU up the bum. Call it a closed time loop if you want, but eitherway, its a closed system. If you were to change your mind and back out of the agreement, it would have to be before the deed happened anyway and there'd be nothing to change, but if original future you had no cause to disagree, why would current you when you reached that time? And remember, the future you taking the goods has already done the giving bit in his past. Any reason you may have to refuse would have been present for the other you, the fact that future you agreed, means you will too.

As far as we can tell, time travel is against the laws of nature, using it to your advantage is an abhoration. However you slice it, you and your actions are integral components of the universe; to have the knowledge the WELL INFORMED traveller would need, and the power to give one event two outcomes, you'd need a lot more than a time machine. You would have to be an outside observer. God perhaps?

 

[ProtoAvatar]

Butters

Any person with a time machine (which he controls) can be a well informed time traveller, if he so choses.

For example, this person could send into the back in time spy devices (undetectable at the time to which they were sent) to record everything. The well informed time traveller will then study the data his devices gathered.

Afterwards, the well informed time traveller can travel back in time and "reset the universe" or create a paralel timeline.

And the only way this time traveller can be stopped from gathering accurate information or changing the past is to break not only probability, but the laws of physics themselves.


You asked which is worse - breaking the laws of physics (causality) or changing the past (and causality).
This is like asking how would you like to be killed - stabbed or shot? The end result is the same - so it doesn't really matter.

You will be able to convince me that there is "only one solid and unchangable timeline" when you can show me how the well informed time traveller can be stopped without breaking the laws of physics.
Any theory that requires the universe to break its own laws of physics is very unconvincing. That's why I support the multiverse theory - it contains a few outrageous concepts, but at least it preserves causality.


As you said, once the well informed time traveller reached the past and the universe resetted itself, due to probability, some events will play out differently - especially in the quantum realm. However, the time traveller acts in the macroscopic world. I'll say his chances of reaching his desired outcome are quite high.

And yes, in this instance, the entire universe will be changed because of the time traveller. Is he "god"? Depends of the definition you give to the concept.
If one analyses these existentialist questions, one gets nowhere. For example, did you know that, if intelligent aliens exist, we - and, indeed, this entire universe - are, almost certainly, nothing more than a simulation?


As to how will anyone be able to prove that a new timeline has appeared?

In the newly created timeline:
If only information was transmitted into the past, this is, indeed, impossible. But if this information contains instructions about how to build a time machine and the procedure to follow in order to change the past, than it can be proven - theoretically - that the history can be changed.
If a time traveller went into the past, his existence is the proof. Where did he come from?
The time traveller might carry technology from the future. Also, his genetics might prove that he could only be born in an alternate future - because he killed his grandfather or so - I realize that this genetic tech is way beyond what we have today.

In the original timeline:
Again, it can be proven that history can be changed - both the time machine and the required information are available.
If the traveler went into the past, his absence may prove that a new timeline has appeared.

 

[Butters]

Butters

Any person with a time machine (which he controls) can be a well informed time traveller, if he so chooses.

For example, this person could send into the back in time spy devices (undetectable at the time to which they were sent) to record everything. The well informed time traveller will then study the data his devices gathered.

Afterwards, the well informed time traveller can travel back in time and "reset the universe" or create a paralel timeline.

And the only way this time traveller can be stopped from gathering accurate information or changing the past is to break not only probability, but the laws of physics themselves.

We're going in circles with this and I'm not sure I'll be able to convince you.

If you send back your undetectable spy devices back to view the event you wish to change, why would they not detect your involvement?

The only plaisible explanation is that something beyond your control prevented the trip. Your cameras are there, but theres no sign of you.

The alternative is that because you haven't yet departed, your actions can't be recorded, but thats not very 4th dimensional. The past happened the way your cameras recorded it.

Your machine allows you to travel in either direction along the time line, but just because your departure point hasn't arrived from your perspective, your arrival point must still exist in the past. You arrive before you set off from everyone else perspective.

The way you describe it, a time traveller needs to depart from the future before he can arrive in the past, but under those terms no future traveller could ever appear in our time because the future has yet to happen.

Yesterday is in my past, but to my dead ancestors its the far future. To my descendants, yesterday is the distant past, but their today is my distant future. Its a matter of perspective and there are points of view other than those of the traveller. To say the events of yesterday exist as they do because I haven't changed them yet elevates the travellers personal experience of the universe above everyone elses; the implication of which is that the traveller is the centre of a universe that exists only for them and only at the point of their consciousness. The future being blank until the one observer is there to experience it. It doesn't matter that the future doesn't exist yet, because it will exist eventually, and only then can a traveller visit. I can't get my head round that point of view.

What happens when the traveller goes forward? Is it just a potential future? Based on what? Does history record the travellers permanent disappearence
until they actually return to the past from their point of view, and thus create a different future? Thats a bit like the universe holding its breath for the time traveller and being a slave to his every whim.

Another problem with all of this is that I might not exist if one time traveller buys a newspaper in the 1890 or some other seemingly insignificant interaction. But I do exist, and most likely because a traveller did buy that paper. If time travel is possible, then we already live in that future that exists because of their travelling, not one that is unchanged, because the visited 'altered' events are in the past.

Altered timelines and parallel universes are irrelevant. There may well be universes out there where I'm a different shoe size, and others where the universe never developed laws of physics that could support matter as we understand it. Its irrelevant because they don't interact.

Just pondering the other implications of a changable timeline.

In a solid unalterable model, the time machine borrows the matter from the future, moving it to an earlier point in time, for a while, those atoms etc will exist twice, but the status quo will be returned to normal the traveler returns to the future, or when the earlier version reaches the point in time when they travel back. Matter/Energy Net gain to universe = 0

In alterering the past, the traveller moves a group of matter energy to the past where they exist twice, but they either return to a future from which they never departed, the altertered time line, or the alternate counter part matter never reaches the point where they loop back, because its a different time line. Matter/Energy gain = big.

How much matter in a human, and what energy cost to have it pop in to existence?

The future is there waiting to be experienced, its not a blank sheet waiting to be written, thats just the subjective human interpretation.

 

[ProtoAvatar]

You have misunderstood me. The recording of the past may show the time without the intervention of the time traveller or with it.

If there is one unchangeable timeline:
The time traveller will not see himself in the past if his "destiny" is not to travel to that time. The universe will prevent him from travelling to that time - by any means necesarry.
The time traveller will see himself in the past if he will go the past. He will be forced to repeat the actions he observed - the universe will bend its laws to make sure of that.

If there is only one changeable timeline:
The traveller can may see history unfolding without his intnervention or he may see himself being in the past. Either way, he can travel to the past and change it, creating a new future.
Numerous paradoxes are unavoidable. I know that. You know that. We both already know that! There is no need to keep repeating that in your posts.
In my opinion, these paradoxes invalidate this hypothesis as a credible model of time travel.

If there are many parallel timelines:
The time traveller can may history without his intervention (if he is from the "original" timeline). He may also see a past in which he is already present (in this case, he is from a timeline created by his temporal intervention).
He can go back and create another timeline, but the future from which he came remains unaltered.
As for the mass-energy problem - at first sight, the time traveller can create an entire universe worth of mass-energy (very difficult to accept). However, in my interpretation, multiple timelines can exist without creating mass-energy.
If a time traveller goes back in time and makes changes:

"Let's say a new timeline appears and the old one disappears.
But, in this case, where did the information that changed the past come from? From nowhere? In this case, the information disappears and the old timeline reappears.
But, if the old timeline exists again, then that information also exists. And if the information exists, then the new timeline appears again and the old timeline vanishes.
And so forth.
Essentially, I'm saying that both timelines exist, but consecutively not simultaneously."

And about mass-energy: two waves of opposite amplitude will cancel each other - this means, their energies will delete each other. What happened to that energy?