Imagine universe rewound 100 years.

[Dinosaur]

Thought experiment: Imagine the universe rewound to 100 years ago & that a modern history book was magically sent to the time of the rewind. The book could be expected to be correct for at least a few months, maybe a few years.

How long would it take for it to be almost completely incorrect?​

 

[Fraggle Rocker]

Science was well-established in 1915. That was the year when Albert Einstein published the theory of relativity, and it was the fifteenth year for the Nobel Prize in Physics.

Please explain in more detail how this book can be sent back in time, in such a way that the world's scientists would be convinced that it was, indeed, a gift from the future. You can fill it with news reports, but you can't prove that they're true.

The best you can do, perhaps, is to simply fill it with a hundred years of scientific discoveries. It would take the scientists of the era quite a long time to verify them, especially since many of the tests would require building instruments that were beyond the era's technology.

Perhaps in twenty years they would agree that the book had to have been written in the future because they were (barely) able to reproduce a few of the scientific discoveries. However, their work itself will have changed the world immensely! Not only will the book now be largely incorrect, but it may not even have been written. And if it was not written, no one will have read it and changed the future.

The Time Traveler's Paradox.

 

[origin]

Thought experiment: Imagine the universe rewound to 100 years ago & that a modern history book was magically sent to the time of the rewind. The book could be expected to be correct for at least a few months, maybe a few years.

How long would it take for it to be almost completely incorrect?​

Why would it be incorrect at all? Is your point that the existence of the book would change the past or simply that a 'do over' would lead to a different timeline?

 

[sideshowbob]

Thought experiment: Imagine the universe rewound to 100 years ago & that a modern history book was magically sent to the time of the rewind. The book could be expected to be correct for at least a few months, maybe a few years.

How long would it take for it to be almost completely incorrect?​

So 1915. The Great Powers have a book telling them how the war will turn out if they continue their current course of action. Assuming that they believe what they read, what do they do? Do the Germans put Corporal Hitler in the fast lane for promotion or do they kill him?

 

[Dinosaur]

Folks here seem to ignore the fact that the classical world of our senses is built on a quantum level of reality governed by probabilistic laws.

If rewound to 100 years ago, history would not repeat.

The question I had in mind is

How long would it take for a modern history book to be totally incorrect?

History would surely match the book closely for at least a few hours, maybe for weeks or months.

I was not factoring in any consideration of the effect of the book if it were transported back & read by a lot of people.

I doubt if it would be close to correct for as much as one year.

What is your guess?

 

[danshawen]

Even under the best of circumstances, such a find (a time-traveling history book) would probably be viewed with skepticism, which would tend to protect the timeline the way it was.

If accessed and used by only one individual, for the purposes of, say, gambling, like the character Biff in BTTF, only those events touched by Biff's newfound wealth and prosperity would be affected in a manner to change the unfolding of those events. I think it was a brilliant movie in terms of addressing the consequences of the grandfather paradox. A derailed timeline would likely not evidence itself by something like Marty McFly not being able to strum his electric guitar or disappearing in the middle of a performance, however. He would never have even made it to the stage, much less have a second shot at changing his destiny. But it worked pretty well for dramatic effect, and that was the point.

 

[Sarkus]

Folks here seem to ignore the fact that the classical world of our senses is built on a quantum level of reality governed by probabilistic laws.

If rewound to 100 years ago, history would not repeat.

The question I had in mind isHistory would surely match the book closely for at least a few hours, maybe for weeks or months.

I was not factoring in any consideration of the effect of the book if it were transported back & read by a lot of people.

I doubt if it would be close to correct for as much as one year.

What is your guess?

I get what you're asking... nothing to do with how people use the book, but the probabilistic nature of things...
It all depends on whether the macro-world is chaotic or whether the relationships in existence at a given time dampen down the possibilities, so that while there may be some fuzziness around the edges the larger scale actions still occur.

I'm not sure anyone has an answer to that, or whether there is even a way of establishing it.
But I would guess the smaller the detail you are looking at, the less likely it is to match exactly.
How long does it take quantum differences to ripple into observable macro differences?

 

[Yazata]

The question of what effect a history of the 20th century would have in 1915, and how quickly the new time-line would deviate from this one, depends on the book's influence. Would it even be read? If it appeared on an obscure bookshelf somewhere, would anyone recognize it as something new, pull it off the shelf and look at it? Who would have an opportunity to read it?

Even if it was transported to a world leader's desktop, what influence would it have?

A history of the 20th century would probably be read as science fiction in 1915, a darker and grimmer version of H.G. Wells' scientistic fantasies.

If it described World War I battles, political events and seemingly chance natural disasters in detail that could subsequently be verified, opinion might start to change among the small circle familiar with it. That might be too late to end the war before 1918. The Russian revolution might still have happened.

If people in positions of influence believed the book, it's unlikely that Hitler would have been elected Chancellor in 1933. The Japanese wouldn't attack Pearl Harbor.

If World War II never happened, Europe's dramatic decline in world leadership might have been a lot more gradual. European cultural, economic and scientific leadership might have continued to the present.

Of course, the more the people in the new timeline deviate from what the book describes, the less predictive power the book would have. The book's uncanny predictive power would only exist initially. The more events in their 20th century differ from events in ours, the easier it would be for them to point to events that didn't happen as the book describes.

 

[Yazata]

Folks here seem to ignore the fact that the classical world of our senses is built on a quantum level of reality governed by probabilistic laws.

I'm not a physicist, but I'm inclined to agree with you.

If rewound to 100 years ago, history would not repeat.

There's this idea that if the same rules of system evolution are retained (the laws of physics in the physical universe's case) and if precisely the same initial conditions are fed in over and over, the system will evolve through the same states in each iteration. That's temporal determinism.

But as you say, what if the rules of system evolution aren't deterministic and are probabilistic instead?

The question I had in mind isHistory would surely match the book closely for at least a few hours, maybe for weeks or months.

I'm inclined to agree that if time were rerun, with precisely the same laws of physics and precisely the same initial conditions, events wouldn't necessarily unfold the same way each time.

I was not factoring in any consideration of the effect of the book if it were transported back & read by a lot of people.

I doubt if it would be close to correct for as much as one year.

Most of the events that have relevance to human life and to history seem to unfold in a classical (hence arguably deterministic) manner. Probabilistic physics seems more applicable on the micro (quantum) scale. So the question becomes one of understanding what effect quantum probabilism has on the macro-scale.

There's also the question of understanding what kind of causality is applicable to history and to historical events. Understanding historical events is vastly more complicated than understanding the behavior of simple physical systems in isolated experimental conditions.

So bottom line: I don't think that we currently know enough to answer your question. It's fun to speculate about it though.

 

[C C]

Thought experiment: Imagine the universe rewound to 100 years ago & that a modern history book was magically sent to the time of the rewind. The book could be expected to be correct for at least a few months, maybe a few years.How long would it take for it to be almost completely incorrect?

If the effects of the book eradicated the original future, then there's no longer a standard for basing an "incorrect" judgement on: That a revision across 100 years did indeed transpire. To clarify, as well explore the apparent remedy:

The book would at least have a very mild significance in terms of of disturbing atoms and particles in the local environment it appeared in, even if authorities did not believe it. However, let's say it did have a major butterfly effect or have a direct impact upon civilization, so that there would be no question about the book altering the future as we know it.

Despite the "magical" transportation, I take it the history book was made and sent from this world in the current era, rather than some supernatural realm being the provenance. Since our present and its version of the past is the source of the cause which brings about the changes, it cannot be eliminated by those changes. So the consequence, in order to preserve this version of the present and its history as the cause, and also allow "a past" to be altered, is something at least in the neighborhood of the multiverse version of time-travel which David Deutsch and Michael Lockwood elaborated on in SCIENTIFIC AMERICAN, March 1994 issue, titled "The Quantum Physics of Time-Travel".

Your history book resulted in a parallel world or timeline splintering off 100 years ago (or to be more exact, that circumstance was already an existent relationship), in which that book became a causal factor contributing to what unfolds there, not "here". Doesn't matter whether a multiverse version of spacetime or a block-universe is actually the case or not, since a fictional event or thought-experiment of a history book being sent into the past necessitates that fictional reality having a make-up which allows the origin of the book to be preserved. That is, IF one desires that fictional reality be coherent rather than be open to hanging as incongruously together as a dream.

If our present is eliminated (or that "our present" of the thought-experiment is eliminated), the book then becomes an orphan in terms of having its very own cause. It becomes a miracle, a ready-made complex object indeed magically manifesting in the past like a Boltzmann Brain. Someone might conceive a story or hypothesis that it came from the future, but once its account of the future is never realized (due again, to our condition that authorities are significantly affected by it), the hypothesis goes unvalidated. One is babbling metaphysical speculation that can't be tested: "Why, there was once this present era, different from our present era, which sent this book back into the past and accordingly eradicated itself from a static spacetime. Which then would not be so so static after all if it allowed the whole extent of itself from those coordinates onwards to be transformed (at least as regarding events on Earth)."