10 Laws of Physics That Don't Apply in Hollywood

In general, Hollywood filmmakers follow the laws of physics because they have

no other choice. It’s just when they cheat with special effects that we seem to

forget how the physical world really works.

1. Those Exploding Cars

When you’re watching an action flick, all it takes is a crash, or maybe a

stream of leaky gasoline that acts like a fuse, and suddenly, bang! You see a

terrific explosion that’s complete and violent. But gasoline doesn’t explode

unless mixed with about 93% air. Gas-induced car explosions were discovered on

film relatively recently (you don’t see them in the old black-and-white movies),

and now audiences just take them for granted. In general, there’s no need to

rush out of a crashed car, risking injury, because you fear an imminent

explosion – it’s probably not gonna happen.

2. Sound that Moves at the Speed of Light

Hollywood always gets this one wrong. On film, thunder doesn’t follow

lightning (as in real life, because sound is slower); they occur simultaneously.

Similarly, a distant volcano erupts, and the blast is heard immediately rather

than five seconds later for each mile. Explosions on the battlefield go boom

right away, no matter how far away spectators are. Even a small thing, like the

crack of a baseball player’s bat, is simultaneous with ball contact, unlike at a

real game.

3. Everything is Illuminated: The Myth of Radioactivity

Film

would have you believe that radioactivity is contagious and makes you glow in

the dark. Where did this idea come from? The Simpsons? Perhaps, but the truth is

that the most common forms of radioactivity will make you radioactive only if

the radioactive particles stick on you. Radioactivity is not contagious. If a

person is exposed to the radioactive neutrons from a nuclear reactor, then he

can become slightly radioactive, but he certainly won’t glow. And because

radioactive things emit light only when they run into phosphor – like the

coating on the inner surface of a TV tube – you don’t really need to worry.

4. Shotgun Blasts and Kung Fu Kicks Make Targets Fly across the Room

With the string of new kung fu films out (they run the gamut from The Matrix

to Charlie’s Angels), you just can’t escape the small matter of bad physics.

Yeah, the action scenes look great and all, but in reality momentum is

conserved, such that every action has an equal and opposite reaction. So, when

you see a gal kick someone across the room, technically, the kicker (or holder

of a gun) must fly across the room in the opposite direction – unless she has a

back against the wall.

5. Legends of the Fall

We

aren’t surprised when the cartoon character Wile. E. Coyote runs off a cliff and

is suspended there momentarily before he falls. But in the movies, buses and

cars shouldn’t be able to jump across gaps in bridges, even if they go heavy on

the accelerator. The fact is, a vehicle will fall even if it’s moving at a high

speed. During the 1989 San Francisco earthquake, a driver saw a gap in the

bridge too late, and probably inspired by the movies, accelerated to try to make

it across. Unfortunately, the laws of physics were not suspended, and he fell

into the hole and crashed on the other side. Movies with special effects should

come with a warning: “Laws of physics are violated in this movie. Don’t try

these stunts at home.”

6. The Sounds of Science

All across the silver screen, you’ll catch people screaming as their car

flies in slow motion across the gap in the bridge. The problem, though, is that

their voices don’t change. In reality, if you slow down motion by a factor of

two, the frequency of all sounds should drop by an octave. Women will sound like

men, and men will sound like Henry Kissinger. Sound is an oscillation of the

air. Middle C, for example, is 256 vibrations per second. If time is slowed

down, there are fewer cycles per second, and the resulting sound is lower in

pitch.

7. Shell Shock! Exploding Artillery Shells that Blow Straight Up

In movies, shells tend to kill only the person standing directly over them.

It seems like a waste of artillery, since – if you believe the movies – each

shell can’t kill more than a single rifle bullet can. But in real life,

artillery shells blow out in all directions, killing people all over. Movie

directors like to have their actors running through a field of such shells, but

they don’t want their actors killed, so they arrange for underground explosions

in holes that blow straight up, missing anyone who’s more than 5 feet away.

8. The Sparking Bullet

Sparking bullets are relatively recent invention in movie special effects.

The gimmick provides a way of letting the audience know that the bullet just

barely missed its target. In real life, sparks do occur when you scrape steel or

other hard metals on hard surfaces (such as brick) because little pieces of

brittle materials are heated to glow and fly off. The problem here is that

bullets are generally made of lead because it’s dense and soft, and you don’t

want the bullets scarring the steel of the gun barrel. Ever notice that no

sparks fly from the front of the gun? That’s because you’re seeing lead bullets.

9. Sound Travels in Space

This is the granddaddy of all scientific complaints about space movies. For

instance, in space the hero shouldn’t be able to shout out instructions to the

other astronauts from a spot several yards away. The movie Aliens corrected this

misimpression with its tagline: “In space, nobody can hear you scream.” And it’s

true. Sound is the vibration of air, and it’s sensed when the air makes your

eardrums vibrate. But try to forget this rule as soon as possible; it’ll wreck a

good many movies for you.

10. Oscars can go to Films that don’t have good science in them

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6 thoughts on “10 Laws of Physics That Don't Apply in Hollywood

  1. “Those Exploding Cars”
    The Ford Pinto exploded in flames when hit in the rear, but I never saw a movie car chase using Pintos. JG

  2. No. 5 can be a real hard one for some folks to get. I don’t know why but I have on more than one occasion been unable to convince someone who has no background in basic physics that, all things being equal, a projectile fired flat level over flat terrain will strike the ground at the same time as the same projectile dropped from the same height. (Assuming, of course, the projectile has no or negligible aerodynamic lift.) You would think that any kid who ever launched himself on a bicycle would know intuitively that unless you have a ramp and some vertical component to the launch your “flight” it will be pretty short lived.
    I would argue that basic, non-relativistic Newtonian physics education should be a required part of in K-12 education, at some appropriate point, just like mathematics is (or is supposed to be), but evidently this is still not the case.

  3. Pypr,
    The Pintos never make it to the movie lot intact, and thats why we never see them on film.
    They’ve been replaced by a new model….the Ford “Splode”

  4. My $0.02…
    Reality doesn’t always make the best entertainment, so I’ll generally cut the moviemakers some artistic slack.
    On #7, VT shells which were first used in WWII explode while still in the air, using a radar transceiver to detonate at a set height above the ground. Real and lethal, but not as picturesque as dirt going up in the air.
    And on #9, sound can travel in any medium which vibrates, so astronauts who touched helmets would be able to faintly hear each other even if their radios were out.
    Back to my own twisted reality, which has very little resemblance to a Hollywood blockbuster…

  5. David and Bassman,
    You are both right about artillery shells.
    Sound may conduct helmet to helmet, muted, perhaps distoted a bit, but probably discernable.
    Reality in Hollywood is always a manufactured commodity. Just today I was in downtown LA, servicing a client at the City Center Studios and they were shooting the CBS TV show “Numbers” in the parking garage… and I had to walk right past to get to my car. FBI signs posted everywhere, and the show uses the office building of the studio as the “FBI” HQ and is show regularly in the show…the outdoor bridge they use for a lot of shots…is the bridge to the commissary over the street.
    But you wouldn’t know that if you weren’t there. It just goes to show, all reality is relative.

  6. “Reality in Hollywood is always a manufactured commodity.”
    Yet very few studios are actually in Hollywood 🙂

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