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?'"

Comments

Doesn't need to be a spaceship

[Yvan256]

Since it was in space for 0.0000E+999 seconds, i.e. never.

It did travel in time and moved from one point to another in the universe (to stay in the same spot on earth) but it didn't "travel in space", hence no need to be a spaceship.

Re:Doesn't need to be a spaceship

[shaitand]

'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.'

I think you misunderstood his point. Yes being at the same location on earth requires a spacial movement. But in back to the future that movement is instantaneous just as your movement through time is. You never actually occupy the space in between and are never in outer space. There is no reason the delorian must be pressurized or carry oxygen tanks, exercise equipment, etc like a 'space ship'.

Re:Doesn't need to be a spaceship

[EllisDees]

I think the problem is that there is no universal frame of reference that you are moving through. Sure, the Earth is spinning, the galaxy is rotating, etc. - but without some force acting on whatever is moving through time, it would follow the exact same trajectory as the surface of the planet.

Re:Doesn't need to be a spaceship

[Ephemeriis]

Since it was in space for 0.0000E+999 seconds, i.e. never.

It did travel in time and moved from one point to another in the universe (to stay in the same spot on earth) but it didn't "travel in space", hence no need to be a spaceship.

Seems to me that you're misunderstanding the terminology.

Nobody is claiming that the DeLorean needs to be able to survive the vacuum of space. Nobody is claiming that it is capable of leaving the Earth's atmosphere.

The article is referring to the two seperate aspects of spacetime - space, and time. Space as in the distance between two locations. The inches between my keyboard and monitor...the feet between my desk and the door...the miles between my office and my house. That kind of space. Not the interstellar void.

The Earth is constantly spinning as well as orbiting the sun. The sun itself, as well as our entire galaxy, is moving. The only reason we don't notice all that is because we're stuck to the ground and moving along at the same speed as everything else.

If you were to simply remove yourself from the flow of time for a moment, the rest of the universe would keep chugging along. It would leave you behind. The Earth would spin away from you, as well as orbit away from you. When you re-entered the flow of time you'd be in a different place than where you started from.

Given the (literally) astronomical distance that everyone moves over the span of a few years... Any machine that was capable of traveling through time would also have to be able to travel great distances in space. Otherwise you wouldn't pop back in to the same geographic location you left from.

Granted, this is all fiction. There was no real DeLorean that traveled through time or space. It's all made up. But that's kind of the point of this article... To explore what it would actually take to accomplish that kind of feat, using real world mathematics. To illustrate just what a fantastic proposition it is.

Re:Doesn't need to be a spaceship

[Cederic]

So when travelling back in time, the car moves forward to where the Earth would be as far into the future as the car went in the past - while the earth in the past hasn't reached where it was in the present yet.

To go back in time inertia is insufficient.

Re:Doesn't need to be a spaceship

[Bozzio]

Here, let me help.

``It did travel in time and moved from one point to another in the universe (to stay in the same spot on earth ) but it didn't "travel in space", hence no need to be a space ship.''

He's being pedantic, folks.

Re:Doesn't need to be a spaceship

[Talderas]

Whenever life gets you down, Mrs. Brown,
And things seem hard or tough,
And people are stupid, obnoxious or daft,
And you feel that you've had quite eno-o-o-o-o-ough...

Just remember that you're standing on a planet that's evolving
And revolving at nine hundred miles an hour,
That's orbiting at nineteen miles a second, so it's reckoned,
A sun that is the source of all our power.
The sun and you and me and all the stars that we can see
Are moving at a million miles a day
In an outer spiral arm, at forty thousand miles an hour,
Of the galaxy we call the "Milky Way".

Our galaxy itself contains a hundred billion stars.
It's a hundred thousand light years side to side.
It bulges in the middle, sixteen thousand light years thick,
But out by us, it's just three thousand light years wide.
We're thirty thousand light years from galactic central point.
We go 'round every two hundred million years,
And our galaxy is only one of millions of billions
In this amazing and expanding universe.

The universe itself keeps on expanding and expanding
In all of the directions it can whizz
As fast as it can go, at the speed of light, you know,
Twelve million miles a minute, and that's the fastest speed there is.
So remember, when you're feeling very small and insecure,
How amazingly unlikely is your birth,
And pray that there's intelligent life somewhere up in space,
'Cause there's bugger all down here on Earth.

Re:Doesn't need to be a spaceship

[Bruiser80]

I think what gets everybody messed up is the 88mph requirement. This gets you into the mindset that the car is driving through a portal to move from one time and space-point to another.

If you consider it more like an near-instantaneous trip of "The Time Machine." The Delorean never leaves the earth - it just travels in the time axis, allowing the vehicle to move in a normal frame of reference from time A to time B.

I can't believe this hasn't been on Slashdot before - this is the ultimate geek-out :-)

Re:Doesn't need to be a spaceship

[billcopc]

Do we need special "time ships" to travel through space ? No.

Then you don't need "space ships" to travel through time.

Re:Doesn't need to be a spaceship

[Scrameustache]

Do we need special "time ships" to travel through space ?

You do if you expect to be at the same point in time when you get to your space destination.

you don't need "space ships" to travel through time.

As long as you don't expect to be at the same point in space when you reach your time destination.

"Law of Cosines" ...

[Sebastopol]

as serious math?

Did a communications major write this?

Reference frames are relative

[omnilynx]

But how far has this reference frame itself traveled during that one minute?'

Relative to what? Relative to itself, it hasn't traveled at all. And since we don't know the mechanism for time travel, there's no reason to use any other reference frame. Really, until we understand how they are supposed to travel through time we can't discuss the interactions of reference frames across time skips.

Re:inertia

[thedonger]

Distilling down time travel for the masses requires some dumbification of the minutia. Did you see "Primer"? Excellent, but required a flow chart. That's why the BTTF series was more popular.

Re:wear your space suit

[gardyloo]

Because a second/minute/year/millenia ago that spot was occupied by empty space. The earth is moving very fast through space.

You're assuming some immutable aether to give an absolute reference. Why assume that the place the object might appear later in time is some position stationary with respect to Sol, but not to the galaxy? Or the parent supercluster? Or some other object? We've abolished the Machian idea of an absolute reference frame by now.

Problem with his approach

[damburger]

There is no absolute frame of reference in space or in time. By taking into account the motion of the Earth around the Sun and around its axis, he is arbitrarily picking implying the heliocentric-ecliptic coordinate system is the absolute frame of reference.

To be honest though, I can't suggest a better way of doing this. The DeLorean can simply pop out of existence in one spot in spacetime and pop into existence at another. If this ability is a given, I'm not sure its necessary to treat travelling through space separately.

I call AC

[frovingslosh]

I call AC. ACs don't get to call BS.

Re:It's really quite simple

[MobileTatsu-NJG]

Nah, it was at the beginning of the first movie when he was showing off how the input panel worked.

This is a messy discussion. They don't address the problem and they don't not address the problem. I mean, if you wanted to argue against my point, you could mention that the ability to precisely place the vehicle in the same relative point on Earth would also mean he had the ability to any point in the universe instantaneously. Seems like he'd be even more excited about that than time travel.

Makes the ol' head hurt. ;)

Re:Does it explain

[HTH NE1]

Notice in Revision 2 (the Locomotive), there were no contrail.

Also notice that in Revision 2 (the Locomotive), the movie ends just as the Locomotive disappears directly into the camera, with no image existing showing the aftermath of its departure from a time frame, so you can't say whether it left flaming trails for certain.

Animated series are never considered canon except by special recognition by series creator.