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
3. Everything is Illuminated: The Myth of Radioactivity
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
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
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