The Time Travel Paradoxes of Back To the Future 454
brumgrunt sent in a fun little piece to get your brain going on a cloudy monday morning. Despite countless viewings of BTTF I still never thought of a few of these. "Throughout Back To The Future Part III, there has to be two Deloreans in 1885. Also, why don't George and Lorraine recognize their son? Why doesn't the time machine disappear in the alternative 1985? These and more Back To The Future paradoxes explored..."
Re:The one they always overlook (Score:5, Insightful)
Even if you're precise on the exact time of day and year you'll still be in space. the solar system moves too!
Re:The one they always overlook (Score:4, Insightful)
We (my "main" circle of friends) discussed this very topic once after watching BttF 2. We concluded that anyone smart enough to create a working time machine (especially one that didn't turn its occupant into goop) was smart enough to do the mathematical calculations. ::shrug::
Re:The one they always overlook (Score:4, Insightful)
Yet not smart enough to *require* enough plutonium in the chamber for a return trip.
Words of Wisdom from UHF Television of the era (Score:3, Insightful)
Repeat to yourself: It's just a show, I should really just relax.
Frame of Reference Problem (Score:5, Insightful)
I picture a lone Delorean, forever floating through empty space at 88 miles per hour.
I don't understand why you post first about a frame of reference problem and then joke about 88 miles per hour ... in reference to what? In the movies the DeLorean is traveling at 88 miles per hour as would be seen by an observer standing on Earth's surface. But to someone standing perfectly still in reference to the absolute center of the solar system -- as you seem to imply time machines are initially calibrated to -- then the velocity of the DeLorean would change with the velocity of the Earth around the Sun. Why are you only referencing the solar system and not galaxy or nebula or universe? So ... yeah, 88 miles per hour for those of us still on Earth many miles away. But your own post suffers the same problem that the movie suffers which is a frame of reference to the velocity and position.
... Or maybe claim that you machine is anchored to Earth's gravity well to simplify things a bit more?
...
Basically for new writers who write a science fiction time travel story you gotta make sure you mention briefly that you solved the orbit/rotation/surface problem and have calibrated your time machine to account for the ever changing topography of the Earth as well as its orbit and rotation
They were fun movies and nothing more. It might be fun to dissect them but if this is news, stand back in awe for my dissection of about a hundred other movies
Re:The one they always overlook (Score:4, Insightful)
::shrug:: people are stupid in weird ways...a mother may be capable of raising a child to adulthood without getting it killed, yet will inevitably forget the kid in the car at least once.
Re:The one they always overlook (Score:4, Insightful)
No you see, when you travel through time you still remain trapped inside the same gravitational "depression" in space. You remain at the same coordinates in the universe, and therefore still materialize on earth, because you're moving with the gravitational well.
Otherwise if you could escape the gravitational well simply by advancing in time, you could jump have the NASA shuttle jump forward one day, and be in space, without needing to use boosters. That would violate conservation of energy and momentum.
(tongue firmly planted in cheek)
Re:The one they always overlook (Score:3, Insightful)
According to relativity, you never know if your absolute position is changing or not, or even if there is such a thing as absolute position.
So if you time travel, whose reference frame do you use to advance yourself in time while remaining static in position?
Re:Frame of Reference Problem (Score:5, Insightful)
Re:Gambling wouldn't pay (Score:3, Insightful)
From what I remember from BTTF II Biff had made most of his fortune making big bets on upsets for just the first few years, then started rolling his fortune into his casino. That's why he had the Sports Almanac shrink wrapped in a safe in 1985, even though it contained sports scores through 2001.
The one nobody thinks of... (Score:3, Insightful)
Of course, I've thought about time travel more than is healthy [homeunix.net].
Re:Being discrete (Score:3, Insightful)
They were dragging it around with horses and no one noticed. There's a LOT of open country with no one around back then. Worse case scenario, hook the horses up again, throw some brown burlap over the car, and ride on top of it like a buck-board. I seriously doubt anyone would notice a thing from a little distance, and once they get where they're going they can simply hide it as they did previously.
Remembering 'Calvin Klein' (Score:5, Insightful)
The article states: "Even appreciating that they didn't know 'Calvin Klein' for long, his impact upon them was such that they'd still have an idea what he looks like, many years later."
I think the author overestimates how much visual memory is likely to fade after 30 years. I just saw some high school classmates after 25 years and looked over some old HS photos. I could barely recall the linking between HS photos and names of the people I saw daily for over three years - including some I lusted after with all the strength of a stereotypical adolescent. Without photographic backup (did Marty get in any photos at the dance?) I doubt they could remember his look very well after only knowing him for a week or so. Combining this with later knowing Marty's face since birth and gradual growth, I do not find it at all implausible that they wouldn't recognize his as a teenager as looking like "Calvin".
Re:The one they always overlook (Score:5, Insightful)
Well, according to Einstein's description of gravity this may not be such an issue as you think. The Earth's movements are, after all, governed by gravity. Now gravity doesn't so much "curve" an object's course, as it bends spacetime around the object's path (which is a straight line).
And you're here on the Earth's surface, so you're moving along the same line. You hop in your car, start deviating from the straight-line path by 88mph, and then... what, exactly?
Your post (and many people's intuition) assumes that you suddenly change velocity in all dimensions, so that you move in time but stay at a fixed position in space. The problem is, the concept of a "fixed point in space" is a figment of human imagination; there's no such thing. A fixed point in space implies a prefered frame of reference, and there simply is no such thing.
So what spacial trajectory does the time machine follow? Well, why would it not continue moving at 88mph deviation from the straight-line path through curved spacetime that it's already following - that being the same line being followed by the Earth?
Gravity would cause the time machine to "follow" the Earth as it moved through time. Not the Earth's gravity, as many other posters have suggested, but rather the Sun's gravity and the other various forces that move the Earth.
There are many, many, many problems with time-travel fiction, but the idea that you would be lost in space just isn't one of them.
Re:Frame of Reference Problem (Score:2, Insightful)
Re:Frame of Reference Problem (Score:3, Insightful)
Got to make sure? Why? It's fiction, it's a story, entertainment. If you have to make plausible claims and explaination for every little details it'll be a book that bore you to death.
Agreed - take a trick from Doctor Who or Firefly - explain just enough, and only when it's necessary for the plot. How do you get the time machine to keep you in the same relative position? You turn it on and drive really fast.
Gasoline (Score:3, Insightful)
As far as the gasoline aspect goes, you would need the right *kind* of gasoline. I can't find the compression ratios, but the De Lorean would probably need high octane gasoline and since it was in the US it would need a catalytic converter and unleaded gas. There would be more complications if it had a turbo. You would have to reinvent all the chemical processes to create such a fuel. It might be simpler to create a a fuel using local materials such as coal, nitroglycerin, gunpowder etc. like The Doc did. He could have used them to create a sort of HME, rocket fuel, which burns very hot. But that creates the question of why didn't he just make a couple of RATO packs? The Diesel engine was out since it wasn't invented until 1897 and may have required precision machine work.
Just a few thoughts.
Re:The one they always overlook (Score:2, Insightful)
It isn't, cat is the opposite of split.
Re:The one they always overlook (Score:3, Insightful)
Re:The one nobody thinks of... (Score:1, Insightful)
Gasoline (Score:3, Insightful)
As a kid, I wondered why they didn't just get gasoline from the stored-in-a-cave DeLorean. I don't wonder any more though. Any DeLorean owner will tell you, don't leave the car sitting with the same gasoline more than six months, especially without a fuel stabilizer. I doubt the Hill Valley General Store stocked Sta-bil in 1885, so I'm guessing Doc Brown drained it.