The coolest time machine of all time has got to be Back to the Future's DeLorean.
But according to doc brown it needs to go an exact speed for everything to work.
"When this baby hits 88 miles per hour, you're gonna see some serious ..."
Shift your mind and consider though:
What if doc was wrong? Does the DeLorean really go 88 miles per hour
in the movie? Let's find out. The DeLorean travels through time in
four different scenes in Back to the Future. But in the fourth time-travel (at
the very end of the movie) the car is flying not driving so we're going to
ignore this scene and just focus on the other three. The first clip we'll look at
is when Marty tries to escape from the Libyans, gets up to the magical speed,
then disappears through time to the year 1955. It's a good place to start
because the camera doesn't move in the clip we'll look at which makes our
method easier to explain. To calculate miles per hour we need to know two
things: the distance the car travels and how much time it takes to travel that
distance. The time part is simple. This movie plays at 24 frames per second. So
by counting the number of frames we can figure out exactly how much time passes.
In our case the car travels from our starting point to just before it starts
to disappear here in 12 frames. Divided 12 frames by 24 frames per second to
figure out the car is driving for exactly half a second. That's one of the
numbers we need. But how far has it driven? To measure distance will use the
dimensions of the car as a reference point. The wheelbase of the DeLorean is
exactly 95 inches, meaning the distance from the center of the front wheel to
the center of the back wheel is 95 inches. We can use this number to mark
distance as the DeLorean drives along. First at frame 0 we'll mark the starting
point of the front wheel. Next we roll forward, measure the wheelbase, and place
a mark 95 inches from the starting point. We roll forward more, re-measure the
wheelbase, and repeat this process again and again as the car gets further away.
Finally we've measured to frame 12 (or half a second later) just before the car
disappears. In this position the front wheel
doesn't line up exactly with our marks. But if this mark is 285 inches and this
one is 380 inches, that means the front wheel is about 357 inches away from the
starting point. That's our total distance traveled in just half a second. Let's
convert these numbers to miles per hour to see if the Delorean is really driving 88.
We start with 357 inches traveled per half a second. With the help
of some boring math and unit fractions this works out to be just 41 miles per hour.
Nowhere near the advertised speed! "Great Scott!"
One scene down, two more to go. Let's look at the very first time travel
in the movie. Einstein is loaded in the Delorean, gets up to 88 miles per hour,
and disappears one minute into the future. Again we'll mark the starting
point of the front wheel at frame 0. Roll forward,
measure the wheelbase, and put a mark at the 95-inch point. Roll forward,
re-measure the wheelbase, put a mark at 190 inches, and keep going all the way to
the last frame where we can clearly see the car before it disappears. We're at
frame 16 here, and 16 frames divided by 24 frames per second means this has
taken exactly 2/3 of a second. That's our time measurement. The front wheel is
between two marks again. Based on where these neighboring marks are this line is
about 1,105 inches from the starting point.
That's our distance traveled. Is the car going 88 miles per hour?
Let's convert these numbers and find out. 1,105 inches traveled per 2/3 of a second
gives us: the Delorean is traveling an average speed of 94 miles per hour here.
Instead of being too slow now we're definitely too fast. Maybe the third
scene got it right. In the third time travel scene Marty gets the Delorean up
to 88 just as lightning strikes and Doc connects the cables to send Marty back
to 1985. This shot is more head-on so we'll put our marks on the road.
Also because the car is driving straight down this road we can measure our span
of 95 inches just once, then slide this down and up the road and
it scales properly at any spot. Our starting line is here at frame 0 and
distance 0. From here we mark out distances using our span of 95 inches.
Then, roll forward, say hi to the mystery man riding shotgun, and the Delorean
drives 19 frames before it starts to disappear. The front tire is here and
based on the neighboring marks the car has driven about 644 inches to this point.
Last time with the math. 644 inches traveled per 19 frames (which is 0.79 seconds)
means the car is driving 46 miles per hour. Again the time machine is
going much too slow! Three different time travels in back to the future and not
one of them at 88 miles per hour! Two time travels are way too slow, and one is a
little too fast. So maybe doc was wrong!
"Eighty-eight miles per hour!!"
Or maybe Back to the Future is still a magical movie, even if 88 isn't really a
magical speed. The Delorean looks fast when it matters and that's enough to
fool the audience. It turns out we're just really bad at looking at a car and
telling how fast it's going. What did you think of our review? What do you think of
Back to the Future? If you had a time machine what year would you travel to?
Finally, what movie should we fact check next? Tell us in the comment section below.
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Thanks for watching and remember:
"I'm your density... I mean, your destiny."