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The Science and Physics of Back To the Future
overthinkingit writes "A scientist has tried to apply serious math and physics, including the Law of Cosines, to analyze how the DeLorean in Back to the Future travels through both Time AND Space: 'in order to pull off the kind of time travel we see in the Back To The Future trilogy — the kind where the traveler is transposed in time, but remains stationary in the same relative position to where he/she left — the DeLorean would have to be an outstanding space ship, in addition to its already laudable work as a time-ship. According to Doc Brown's stopwatch, Einstein the dog travels precisely one minute into the future on this first jump, arriving, relative to their frame of reference, at the same location he left. But how far has this reference frame itself traveled during that one minute?'"
The universe really DOES revolve around the earth in the movie universe, so no special measures are necessary beyond "simply" moving in time.
First off, there are WAY too many pages to this article for me to read but it looks fun so maybe later.
But in regards to this, I would like a physicist to boil large problems down to "We can't do X because of the simple problem of Y." Example with Mr. Fusion: We can't do Mr. Fusion because the amount of energy that goes into creating the conditions for fusion outweigh the amount of energy produced. That's something measurable and approachable to me, a starting point.
If it comes down to the problem requiring a Free Lunch, I'd probably give up early--I'm not one to disobey the laws of thermodynamics.
In middle school I devoted large amounts of time and reams of paper to developing a formula f(n) to produce the nth prime number (at the time I was searching for O(1) oh how naive I was about mathematical induction!) and it was all because a teacher explained how powerful such a formula would be for encryption and many other things.
While I (obviously) never solved it, I sure the hell enjoyed the simplified form of a much more complex problem. And on top of that, it kind of set the tone for computer science in my life. Could hoverboards & time machines turn a movie goer into a physicist? Maybe not often but it happens.
My work here is dung.
anyone that has (in the past) managed to create a time travel device and has tried it, probably thought they made a disintegration machine, because anything they sent back or forward in time was never seen again. (or before, I suppose)
Because a second/minute/year/millenia ago that spot was occupied by empty space. The earth is moving very fast through space.
I've always used that reason to concede that even if we DO make time travel possible, it will be of little practical value.
Then there's the other snag of transposition... if you say, send yourself back in time, what happens to that volume of space where you arrive? Is it destroyed? And what fills in the void where you left? Or one more expected result is it's transposed with your time's space. Thus all time travel is time swapping, something goes forward and something goes back. Now lets say you do make a time travel machine, and test it without considering the earth-travels-through-space issue... that means whatever you send out, you get a big ball of vacuum back. If it's a very brief travel, you may get a chunk of earth, high pressure ocean, or more likely, high pressure magma. Ouch... hope you got insurance. That'll turn your lab into a disaster area real quick.
There are so man "problems" with time travel, that it really doesn't matter if its possible or not. It's not useful.
I work for the Department of Redundancy Department.
Reference frames don't travel with respect to themselves. By definition.
However, you could say that we're that much closer/farther from Vega, or in a different season in our Solar orbit, or in a different timezone, etc. Or the Earth's core has counterspun in relation to its own crust. Or tectonic shifts have occurred.
Just assume the car is locked onto a specific reference frame, such as a given latitude/longitude relative to the Earth's axis of rotation and the nearest large mass: the Earth's crust under the car. And pass the popcorn, it's a movie for chri'sakes.
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But it HAS to travel in space. See, space and time are as intertwined a green and grass. Let's skip the over-the-top explanation and illustrate where this mistake is comprehensible. While, in your frame of reference, you are not moving, in the grand scheme of things you are. The earth is rotating and revolving around the sun. The solar system is likely gyrating around something else. This very galaxy is moving as a whole. So many movements going on that no one even thinks of.
So, think about it... if you moved through time, forward one minute, and somehow skipped any spatial movement, the earth is going to be AT LEAST 1000 miles away from the point, relative to JUST its movement around the sun. That says nothing about how our solar system is moving through the galaxy or the galaxy moving in the universe.
"When life gives you lemons, don't make lemonade. Make life take the lemons back!" -- Cave Johnson
Read my post again.
Of course, even though the wire itself can be the same size, it'll normally look a lot thicker, because 1.21 gigavolts requires pretty serious insulation.
The universe is a figment of its own imagination.
Coincidentally, the first draft for Back to the Future had a fridge for the time machine, but that was changed because the director thought it would end up with kids watching the film, playing around climbing into fridges, and getting trapped.
Bogtha Bogtha Bogtha
Let me take a shot Yvan. The car does travel trough space, but not through the void of space. The car departs from a mall parking lot, then arrives at the same mall parking lot one minute later. Sure, earth has moved 1000km or so in that time, but you are not thinking fouth dimentionally. The car (and the dog) never experianced that minute, so to the dog in the car, nothing abnormal would have appeared to happen. The car never "Travelled" through space. It was in one location and time, then another. There is no transition.
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These kinds of considerations aren't anything new, and injecting them into soft sci-fi like Back to the Future is a waste of time. BttF is enjoyable, though, and does make a great accidental (?) satire of the American dream and hubris. For science, read some Larry Niven or Stanislaw Lem instead.
For example, Vernor Vinge did something like this, involving teleportation. A teleporter could control both the outcome position and velocity, but velocity was "harder" and took effort proportional to the difference in velocity.
Therefore, long distance teleports were only feasible along a longitude, and to the opposite latitude, since you had to match momentum or die by either being crushed or flung off into space. The earth's spin matches at lat X long Y, and lat -X long Y, but nowhere else.
As a result, one of the world's superpowers controlled both semi-polar regions, alternating by season; while the other stuck to the equator.
"They were pure niggers." – Noam Chomsky
i know it was a joke, but i watched the special features on the DVD, and they said that they just thought that it'd be cool if it was hot when it left point A in time and was cold when it got to point B (they put liquid nitrogen in on scene)
Those of us who think they know everything annoy those of us who do.
That depends a bit on how you remove yourself from the flow of time. First, there's how you stay in one place, and that's only half the problem.
If you cause all atoms, down to the smallest level, within the envelope of your craft to be trapped in a void that stops experiencing the timestream and doesn't appear to the outside world, but the void itself is still acted upon by the forces of the outside world, then the void should remain in place until the occupants exit at the designated "arrival" time. The downside to this is that the void should be easily detectable, since you're not jumping through space, you're simply pausing your experience of existence until you want to be un-paused.
Or, as with the latter, the void can be locked to the reference point without actually being interacted with, this would have the same result without being detectable.
Then again, maybe the craft would be detectable, but only if you knew to look for it and happened to look in just the right spot while it was sitting there, just out of visible space, perhaps creating a gravity and energy signature as if it were dark matter.
The third method would be to calculate the exact position of the craft based on the earth moving through space at a perfectly predictable rate and somehow teleport (portal, wormhole, stargate, whatever) from your starting point and time to your end point and time. Obviously, if this were the method employed, interplanetary travel would instantly become trivial as a side effect of time travel. (Pern, anyone?)
I think the middle method is what's implied in the movies, but I'm not sure how you'd get the void to follow the reference frame without being detectable.
The second half is traveling backward through time as well as forward. With the third method, above, this is part of the same operation, the teleportation method's destination coordinates simply include a time component. (Ok, "simply" is a stretch, but...) For the first two methods, creating a forward moving void is, well, "relatively" trivial compared to causing the void to experience the timestream backwards, and still be locked in the backwards-moving reference.
Sometimes I think our understanding of space is even more shaky than our understanding of time. It should be obvious, for example, that distances can only be measured between two objects. So saying that the time ship would need to travel a considerable distance in order to be in the same place is actually rather silly. The distance traveled in space (if that really is distinct from time) is zero if you measure it in any sensible way.
Why would you measure it from some fictitious "stationary" point in space? What does the word stationary really mean in this context? Would it be important in any physical sense?
I think GP means that all movement is relative. Sure, you've got Earth revolving around the sun, sun around the center of the galaxy, center of the galaxy around something bigger, etc. But hey, does the whole universe have a (0,0,0) point which we can effectively measure? What if we're contained in a bigger universe, and our universe is moving exactly so that Earth is always at the (0,0,0)?
I guess I've gotta take some shrooms and check it out by myself.
If conservation of energy still applies in some fashion, then the car wouldn't immediately disappear at one point in time and reappear in the other: it would have to travel along a worldline (that is, it would travel through all intermediate points in time). As it travels, it is reasonably to suppose that it is susceptible to outside forces-- for example, gravity; therefore, the car would stay on Earth for the same reason you stay on Earth. However, if the car can be affected by outside forces, then the car would be likely to run into all sorts of other things as it travels through time-- a collision would be inevitable unless time travel were done in a remote area of the world. One would then have to suppose that part of Doc's invention involves making the car ephemeral (and invisible) as it travels, without negating gravity. One way that might work would be for the car to travel through "hyperspace"; if so, it's possible that the force of gravity extends into hyperspace while the electromagnetic force does not, in which case the car would remain on the surface of the Earth but collisions would not occur.
How's that? :)
That would only make sense if Einstein kept moving with the same speed for the same amount of time with the time we was "time-traveling". This wouldn't be time traveling. just traveling separately. Also, without gravity, Einstein would just fly out to space
That's still every single one of you trying to determine a universal reference point while other things move in it. There's no aether.
Let me put it this way, since a lot of people are getting hung up on the fact that the Earth moves around the Sun. It doesn't, not in the way you think. The math becomes a lot easier and more convenient to work out if you take the center of mass as point (0,0,0). That's all it is, convenience. It's not actually incorrect to choose the Earth as point (0,0,0) of the universe and say that everything turns around it. In terms of physical correctness, any reference point is just as valid as any other. Pick one. The only problem is that if you don't pick the center of mass, calculations are a lot harder.
So, in terms of the Delorian, if you pick your reference frame to be a parking lot in California, and then ask the question, "how much has your reference frame moved in one minute" the answer is "it hasn't, by definition." That's what a reference frame is. You can say it moved a significant amount in relation to the Sun, but then you are picking the Sun as a reference frame. You can say it moved a significant amount in relation to the center of the galaxy, but then you're picking the center of the galaxy as a reference frame. You can say it moved a significant amount in relation to the center of the universe, but then it actually hasn't moved at all because every point in the universe is its center (you're on the spot of the big bang right now. So is the andromeda galaxy. There wasn't a center point from which the universe expended, there was a very small infinitesimal universe, and then space itself expended and got bigger).
Back to the Future wasn't hard sci-fi. They got everything they possibly could get wrong, wrong. Turns out what people are bitching about is actually the one thing they didn't get wrong. It really doesn't matter that the earth moves relative to the sun.
Are you saying Earth is an inertial frame of reference? And that we would end up at the same place in a different time?
Or are you saying, Earth is not an inertial reference frame and that it would move out from underneath you?
One last thing: Sometimes I wonder; "Is that someone's signature? Or do they type that at the end of each post?"