Die hard physics

One of my favorite blogs, Scott’s Blog of Doom, posted this one with a whole list of un-natural physics that would make the Die Hard series rather boring and plain. I enjoyed reading them. But at least the writer also takes the un-realistic and says that its still pretty cool.

The Lounge List: Die Hard

The Lounge List: 8 Laws of Science and Nature Broken By The Die Hard Franchise

Now, I love John McClane as much as the next guy. The original Die Hard trilogy formed an indelible part of my movie-going experience in my teen years, like Back to the Future or the Star Trek movies. And heck, I even really enjoyed Live Free or Die Hard, which I picked up for $10 from Future Shop and felt I had underpaid after seeing it, because it’s a tremendously entertaining movie (at least the unrated version is) that strives to go over the top in the quest to make stuff blow up bigger and better in each scene. I can respect that. However, as a human being with a functioning brain, there are some trends in movies (and specifically in the Die Hard movies) that bug the hell out of me and they all seemed to come together in that one two-hour package, inducing groans instead of wows. So although I don’t long for a hyper-realistic experience in the cinema, here’s eight examples of stuff that happened to John McLane (and other action heroes) that could not possibly occur in real life and that offend me as a former math major.

8. John McClane outraces a fireball. Twice.

Here’s the thing about fire: It moves FAST. And yeah, it’s hardly fair to pick on Die Hard for this because every action has a scene where the hero leaps into the air to escape an explosion, but god I’m getting sick of seeing it when really the hero would be fried to a crisp long before he had time to calmly whip out his shades and walk away with only some soot on his shoulder. John gets away with this twice — once in the first movie when he dives away from an elevator shaft full of explosives, and then in the fourth movie when he slides down a concrete embankment to escape certain fiery death. The problem, of course, is that the human body can’t move fast enough to escape the shock wave caused by an explosion of the magnitudes seen in the movies. Sure, you might THINK that getting away from the visible fire will save you, but in fact the concussive force of the blast would probably liquefy your skull long before you had a chance to pull out your sunglasses and pose. The science?


7. John McClane shoots himself in the shoulder and kills a bad guy standing behind him.

I’d have to count this one under a more general category of “Unrealistic depictions of gunshot wounds in movies” because again, it’s not unique to the franchise here. That being said, this particular scene is so ludicrous that I couldn’t even suspend disbelief long enough to count it as a good death scene. First of all, it defies the internal logic of Hollywood in the first place. How many action movies have we seen where the hero uses someone as a human shield, absorbing bullets so he won’t get hit? But let’s take it on faith that the bullet can now pass through and hit someone standing behind you. Assuming McClane was firing a good-sized weapon at close range to his shoulder, it wouldn’t have produced a neat little hole in the front and passed a bullet to the back, it would have blown his whole damn arm off at the shoulder and probably set his shirt on fire, too. Never mind that the momentum of the bullet would have been absorbed by the impact of shattering his shoulderblade into powder and wouldn’t have allowed it to pass straight through like it did. No, my biggest problem is that no one who gets shot in the movies ever reacts to it realistically. Hell, the obnoxious Mac kid gets KNEECAPPED, the most painful gunshot wound you can get, and he just stands right back up again. Guess what? You get shot in the leg, you’re not walking again for a good long time.

6. John McClane jumps out of a moving car, rolls with it, and lives to tell about it.

Oh man, I hate this one so much. Everyone always forgets about the laws of physics when they’re crafting an exciting escape, and a big law is that if you’re sitting in a car moving at 50 MPH, then you also are moving at 50 MPH relative to the road. And if you then leap out of that car, you don’t magically grow a parachute out of your ass and slow down, you’re still moving at 50 MPH. You’d be lucky to survive without breaking every bone in your body, and if you’re REALLY lucky you won’t hit your head on the concrete 500 times and shatter your skull. Movie stuntmen can do it because the car is driving much slower, and they leap out wearing protective gear and land in a sandpit.

5. John McClane (before jumping out of that moving car) aims it at a concrete barrier and causes it to jump into the air and ram into a helicopter, destroying both vehicles.

OK, this one was pretty cool.

4. John McClane lights a trail of gasoline coming out of a plane, thus blowing it up in mid-air.

So much wrong with this one. It seems like a reasonable thing if you (like most of us) don’t know anything about airplane fuel and have never tried it. However, again physics steps in and tells us that a plane is taking off much, MUCH faster than gasoline burns, so even if the plane was somehow magically leaving an unbroken trail of liquid hundreds of feet in the air, it would be able to outrace the burning gasoline with ease. However, it’s entirely a moot point, because lighting that stream of fuel with a standard lighter is impossible. Jet fuel has to be ignited in aerosol form in order to actually produce a burn. Perhaps if John was packing a jet engine to light his cigarettes, he’d have a shot. Although even then, he was lighting it on snow, which would leave it too cold to be ignited anyway.

Still, an awesome bit of Hollywood science theory.

3. John McClane shoots a fire extinguisher to blow it up, propelling a terrorist out of the window due to the force of the explosion.

Again, Isaac Newton to the rescue. This one offends me on two levels. First up, the idea that shooting any sort of pressurized container will cause it to rupture with explosive results, something shown both in Live Free or Die Hard and in the last Bond movie as well. Yeah, it might shoot off some shrapnel and you’ll go “Ow, that really hurts!” or lose an eye, but a FIRE EXTINGUISHER having enough force packed in it to propel a human being out the window? If that was the case, just using the thing would cause it to explode and kill everyone in the room. Not exactly the kind of dangerous weapon you’d want hanging on your wall in an emergency. And really, the Mythbusters have shot the shit out of enough pressurized airtanks to show that even something far more lethal than a fire extinguisher isn’t going explosively rupture when fired on. But let’s pretend for a second that it WOULD explode upon impact of a single bullet. The laws of physics again step in and note that in order to hurl a 200 pound bad guy out of a window, the object exploding has to also experience enough force to get hurled backwards from the blast. Clearly that didn’t happen, so again the worst that would happen is fatal injury from shrapnel. Certainly dangerous, but not as dramatic a payoff.

2. John McClane jumps 100 feet off a bridge and lands on a moving boat, gets up unharmed.

You know why people jump off bridges to commit suicide? It’s not because they drown, it’s because from that kind of height as soon as your body hits any kind of impact you’re instantly knocked out. Not to mention that the velocity achieved would shatter all the bones in your legs. In fact, falling from over 100 feet onto a hard surface is generally considered one of the most foolproof ways to kill yourself, although there’s always people stupid enough to survive even that. So unless he had a bungee cord and landed in a big pile of mattresses or a crash pad, John’s not walking away from that death-defying leap in real life.

1. John McClane jumps off the top of a building, tethered to a firehose, and survives a drop several stories down.

This one kind of ties into the last one, with the problems of terminal velocity and such, but adding the complication of running away from a fireball. Plus using a firehose as a bungee cord. If you want the REALLY dry science behind it, check this out:


The short version is that no, using a firehose as a bungee cord will not save your life, and in fact will probably result in you being sliced in half because it’s not elastic enough to give way when stretched. So if he didn’t get fried by the fireball, and he didn’t get killed by the concussive blast, and he didn’t break his neck from the freefall and sudden stop…well, he’d get cut in half by the hose anyway.

Die hard, indeed.

I love the Die Hard series, I don’t care how fake it is, they could make eight more movies and I’d still go see them.


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