9 Laws of Physics That Don't Apply in Hollywood

Posted by Alex in Mentalfloss, Movies & SciFi on March 6, 2007 at 1:12 am

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 world really works.

1. Those Exploding Cars

No car explosions, please – found at LookyLuc [Flickr]

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.

From mental_floss’ book Condensed Knowledge: A deliciously Irreverent Guide to Feeling Smart Again, published in Neatorama with permission. [Update 3/6/07: Originally written by UC Berkeley physics professor Richard Muller]

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COMMENT

137 comments to "9 Laws of Physics That Don't Apply in Hollywood"

JJTony
March 6th, 2007 at 2:37 am
The main problem here is what the audiences wish to see and hear (what they expect) and what is possible in the real world. It isn't necessarily right that the filmakers get it wrong, but that when they get it right, the audience runs from the theater.

Case in point, there have been many experiments in big budget films to try and record things as they actually occured while filming. Usually something like 80%, including dialog, is recorded after the fact, in the studio. One film (I think it was Barry Lyndon) used real on-set recordings to film battle scenes, having the sound arrive seconds after seeing the smoke from the guns and cannons. The test audiences simply couldn't get their heads around the discrepancy, and so it was changed to showing the shots and sounds simultaneously.

The same audience disconnect would be applied to #6 above as well (if you slowed down the voice, the audience would go, "Huh?"
salsa
March 6th, 2007 at 3:06 am
Filmmakers are storytellers, and space and time are not linear in stories. Everything is carefully placed and lit for the composition of the image, but we don't see the world as a rectangular image-- it's a roaming, sweeping gaze, and the filmmaker's job is to lead our gaze around the frame and put a story together. We buy into the continuity because the filmmaker crafted the images that way, but the reality is that set pieces are wild and everything is carefully composed from footage shot at different times in different places, sometimes at different scales. The problems above are just storytelling techniques, devices as artificial as the screen you're watching them on. I'd like to add: (10) outrunning explosions (shock waves), (11) cars flipping when they wreck, (12) people flying up when they slip and fall, (13) bright night time lighting.
Dan
March 6th, 2007 at 7:12 am
There's also petrol/gasoline being ignited by a lit cigarette.

http://www.guardian.co.uk/science/story/0,,2022042,00.html
Acedia
March 6th, 2007 at 7:37 am
I'm not so sure about the radioactivity not being contagious. I had radiation (RAI) to burn my thyroid into submission and was not supposed to get within four feet of my child for several days...and could not brush my teeth or, um, use the facilities in the same bathroom as anyone else in the family for a week.

And what about that spy who was poisoned with radiation? Wasn't there a ton of concern about people he had interacted with?

Maybe what the writers intended to say was that simple background radiation isn't particularly catchy. (My neighbor, a nuclear plant employee and his wife, an oncology nurse, both wore badges to track their radiation levels. They said it's how they found each other in the dark!)
kamy
March 6th, 2007 at 9:33 am
So correct on number 2... It always pisses me off to see that in movies.
brad
March 6th, 2007 at 9:36 am
Great, now movies are ruined for me.
king20878
March 6th, 2007 at 11:31 am
Actually, intensely radioactive sources can glow. One of the reasons the Goiania accident was so bad, was that children were fascinated with the glow and wanted to play with the material:

http://www.answers.com/topic/goi-nia-accident
"The two attempted to further open the casing, but were unable to. However, they did manage to break the iridium window, which allowed them to see the cesium chloride emitting a deep blue light. The light was caused by some process involving the radioactivity of the source. The exact mechanism by which the light is generated was not known at the time when the IAEA report was written, it is now thought that the blue light is caused by the immense energy being released by the cesium exciting electrons on surrounding air molecules, and as they drop back down to their regular orbitals they emit light. This blue light has been observed at Oak Ridge during the disencapsulation of a 137Cs source in 1988. The light is thought to be either fluorescence or Cherenkov radiation associated with the absorption of moisture by the source. It is stated in the IAEA report that further research work is being undertaken at Oak Ridge to establish the nature of this glow."
Jan Nielsen
March 6th, 2007 at 11:54 am
Don't forget this classic that defies the laws of psysics: Whenever a character looks in the mirror, the reflection is going towards the camera, not towards the actor.
Chocolate Cowgirl
March 6th, 2007 at 11:55 am
"Exploding Artillery Shells that Blow Straight Up" Yes and explosions always have a way of just blowing the hero out of harms way, although typically through a plate glass in a very dramatic way.

The net effects are a few black smudges to the face and tatted clothes.
Geoffrey Spear
March 6th, 2007 at 11:57 am
You might want to think a bit about #4 there; it's obvious you think you understand physics more than you do. The person doing the kicking is only going to fly backwards due to conservation of momentum if he/she had no forward momentum before the time of impact.

If you can explain how someone can impact with someone who's not moving without moving toward them (and thus, having momentum), I'd love to hear about it.
williambraski
March 6th, 2007 at 12:00 pm
I get what you're saying but the thing with The Matrix, while yeah technically correct, you forget the setting of the movie. It's inside a computer which the characters are intentionally manipulating. So as part of the story (and I grant you to look cool) a slo-mo chest kick that only launches the target backwards could be seen not as a mistake on the part of the filmmakers, but more a representation of how the characters are manipulating the system.

Of course that's just my opinion.
Bo
March 6th, 2007 at 12:06 pm
It turns out you learn your physics from Mythbusters. In number 4, your explanation of physics is horrid.

Its correct that shotguns won't blow someone backwards but it doesn't require the shooter to fly backwards. This is because the shotgun is much heavier than the shell. The combination of human arm (mass and resistance) and the weight of the shotgun counter the momentum of the much smaller shotgun shell.
Mijin
March 6th, 2007 at 12:42 pm
#5 could be phrased a bit better, it's not Wile. E. Coyote vs real physics.

The mistake that people make is in believing that objects thrown off the edge of a cliff, say, will follow a curved path, continually getting further from the cliff face.

But when you consider that objects accelerate downwards, and that air resistance will dampen the forward momentum, you see that objects basically go straight down after very little time.
Mijin
March 6th, 2007 at 12:45 pm
velocity
Rob J
March 6th, 2007 at 12:48 pm
Problems with #4 and #8. Kicking someone with a good solid side kick or flying roundhouse will not make them fly across the room but it will indeed knock them back a few feet. The person doing the kicking will not be knocked back an equal distance but rather be in the same spot he/she was when they made contact. Movies do exagerate this quite a bit but objects do move. Ooh and the same applies for shooting a large mass with a 12 gauge shotgun at near point blank w/ 3.5" 00 Buckshot.

Now onto the sparking bullets. I have no idea where this individual is from but lead bullets haven't been made in quite some time. Most bullets whether for consumer or military use are copper jacketed with or without a ballistic tip, this applies only to rifle ammunition. Most pistol ammuntion is either full metal jacket or semi-jacketed. Either way the bullet itself is not entirely lead or very little lead if any. This does lend itself to spark when glancing another metal object. Although bullets will not spark as often in real life they do.
Rusty
March 6th, 2007 at 2:21 pm
Rob J said:
>Now onto the sparking bullets. I have no idea
>where this individual is from but lead bullets
>havenâ€™t been made in quite some time.

Not sure where YER from but most bullets are made from lead and still are. Manufacturers of SHOT for shotguns have gone away from lead for a number of years but lead shot is still quite available. Some states have outlawed lead shot for environmental reasons (being eaten by water fowl, etc) Shot is not considered a bullet.

Many military bullets have steel cores now, I believe,
for deeper penetration and they fly at a higher velocity. Unjacketed lead bullets can have surface melting from friction with the barrel at high velocities and this will affect their flight characteristics -- thus the reason for the copper jacketing, semi- or otherwise.

>Most bullets whether for consumer or military use
>are copper jacketed with or without a ballistic
>tip, this applies only to rifle ammunition.

Uh... I've got a whole mess of 9mm and .45ACP that's fully jacketed with copper. Those are pistol rounds.

Ummm... what material is that copper jacketing or covering? Lead mostly, especially for consumer ammo.
I have a hundred pounds or so of ammo and it's mostly lead, usually jacketed or semi-jacketed with copper.
Sometimes the copper is simply a "wash" over the bullet and it's very thin. I have a number of bricks of name-brand .22LR ammo that have no copper jackets at all.

>Most pistol ammuntion is either full metal jacket
>or semi-jacketed. Either way the bullet itself is
>not entirely lead or very little lead if any.

Full metal jacket is simply a covering. By mass or weight, the bullet will be mostly lead, lead with steel core, or steel. There are other materials used for bullet cores, including nylon(!).

True, the entire bullet is not made of lead, in many cases but if the core is steel or other hard metal, upon contact with a hard surface, that surrounding lead will deform and the core explosed. Now you have steel against steel and that can cause sparks. It will all depend on what type of ammo is being used. In the "macho" gun-toting movies (ones with sparking ricochets), you can believe that military style ammo is used (or at least it's plausible that the movie is "suggesting" that it is used).

A reasonable explanation of bullets can be found at
http://en.wikipedia.org/wiki/Bullet
jokono
March 6th, 2007 at 2:26 pm
#1 Problem: Didn't Ford Pintos of the 1970s explode after being rear-ended? Also, if the gasoline tank in a car is 7% full, then the other 93% is... air. Boom!

#6 Problem: Ok, not a problem, but an inaccuracy. Middle C is 440 Hz, not 256 as you stated. Also, I think most people realize that sound oscillations will change with the speed of the video. But, time compression and expansion is added for artistic effect. The most prominent example that comes to mind is Forrest Gump -- "RRRRrrrruuuuunnnnnnnn FFFFfffffooooorrrreeeeeessssssst!" The little girls's voice wouldn't have the same emotional impact if she sounded like Andre the Giant.
tek
March 6th, 2007 at 2:26 pm
middle c is 262Hz, not 256. maybe you were thinking of an 8bit number?
tek
March 6th, 2007 at 2:27 pm
jokono: concert a, the a above middle c, is 440Hz.
Christopher
March 6th, 2007 at 2:28 pm
As an addendum to #6... If characters in a film are made larger or smaller (a la Honey I Shrunk the Kids) their voices would change appropriately. Smaller vocal cords would produce higher frequencies at a lower amplitude. A full-size person wouldn't be able to hear somebody that was a 1/2 inch tall even if they were *in* their ear. Also, I doubt that even characters of the same size would be able to hear each other. Would your inner ear change frequency range? Would your brain even be able to interpret the sound if it did?
Erich the Mad Bassist
March 6th, 2007 at 2:30 pm
Number six (The Sounds of Science) had me laughing, because I remember a movie that got it so right. Anyone remember Return of the Pink Panther? There's a scene where Inspector Clouseau is fighting with Kato, and they slow everything down--especially the sound.

Seeing Peter Sellers flying through the air, howling at low frequency, and driving an iron bar through his TV set is comedy at its finest! Okay, perhaps the firework effect used when breaking the picture tube is way out there, but the slow motion parts were awesomely funny!
Andrew
March 6th, 2007 at 2:32 pm
To join in the physics beat down, sound is not the vibration of air. You can hear underwater, and sound will travel through solids as well.
Paul Nagelkerke
March 6th, 2007 at 2:33 pm
My pet peeve: smart bullets - they stop after 100 feet!

Think of any A-Team episode: lots of flying bullets, no broken windows, or injured bystanders.

Mind you we have shoot-outs quite regularly now where 15-30 bullets go flying and nobody gets hit.

Really Bad Movie: The Gauntlet (Clint Eastwood) - Police in Phoenix fire on a bus (from both sides!) and only hit the bus, not each other.

Realistic Movie: Heat, Ronin: Lots of bullet hits, flying flowers, hit bystanders, broken (car) windows. Not enough building windows hit in either though...
JimmyJimmyJim
March 6th, 2007 at 2:57 pm
"Master and Commander" is a notable exception to #2, and was used brilliantly. It made the scene with the cannon fire dramatically more fear evoking.
Uberfiend
March 6th, 2007 at 3:27 pm
The shotgun blasts (or other gunshots for that matter) are sometimes irritating. Some modern war movies get gunshot wounds right, but Hollywood action flicks almost never do. People who get shot typically either remain as they were when shot, or collapse.

In some ways, it's probably better for Hollywood action movies not to be too realistic. Realistic violence is very disturbing to ordinary folks (as it should be). Our society is bad enough as it is, without being any more desensitized to real violence than we already are.

Now... will someone, for the love of all that is decent, please deconstruct the Borat vs. Manager fight scene?
ron
March 6th, 2007 at 3:37 pm
Even worse regarding #2 is they do this in "nature" programs all the time. just pay attention the next time a storm rumbles across the serengeti or the amazon jungle on PBS.
sepelester
March 6th, 2007 at 4:00 pm
What about the slow flying laser beams in Star Wars and War of the Worlds?
Norman
March 6th, 2007 at 4:07 pm
#4. Radioactivity is not contagious. Are you kidding me? Those traces of radioactivity were planted. If you get close to a source of say Gamma radiation you won't emit gamma rays. LOL!!! But you WILL suffer injury from the exposure. Death by radiation exposure is not a pretty death. And the people who die of this aren't usually radioactive.
Greg
March 6th, 2007 at 4:10 pm
#4 is only partially correct. First, bullets can and will spark if it is the right round and hitting a hard surface. As far as the kicks go, someone else was correct in that the person being kick will move while the person kicking will not, unless they just suck and don't know what they are doing. Part of martial arts are the stances which are there for a reason. When done right, the stances are very stable. If he thinks #4 is that big of an issue, how does he explain the famous 2 inch punch that Bruce Lee is famous for performing in front of a large crowd? For those of you who don't know, he placed his middle finger tip on someone's chest, and in an instant, pushed forward forming his hand into a fist and hitting the persons sternum. The person was reported to go back more then just a couple of feet, while Bruce stayed in the same exact spot he was in.
I'm no scientist, but I am very much into weapons (guns in particular) and martial arts.
Someone else who posted is also corrected that most modern day ammo is either steel or lead that is covered with a layer of copper. Thus the term full metal JACKET.
We all have habits of jumping to conclusions about things or hearing something and sometimes thinking we are an expert on it. But come on, if your going to make a public post about this and sound as if your an authority on the matter, why don't you do your research first. Kinda reminds me of Tom Cruise making a fool of himself on Opera's couch...
Kyle
March 6th, 2007 at 4:13 pm
I've got to sorta/kinda disagree with #8. Jacketed bullets do cause sparks at the barrel and at the impact point, assuming you're shooting something hard enough. Jacketed bullets can be found for pretty much all classes of firearm, and in my experience are far more common than non-jacketed.

So, if you're watching a relatively modern war movie, or gangster flick, or (these days) romantic comedy, it's feasible that a bullet impacting a concrete wall or car will throw off a few sparks.

However, if you're watching an old western or civil war movie and you see sparks from bullet impacts, you should be justifiably pissed.
Ghil
March 6th, 2007 at 4:17 pm
The delay between seeing an event and hearing it provides a sense of distance. Seeing and hearing a lightning strike or an erupting volcano simultaneously can make the viewer feel dangerously close to the action.
RadioBill
March 6th, 2007 at 4:17 pm
Very nice. But middle C is not 256 Hz. In A 440 tuning it's a bit over 261.625 Hz. In concert pitch its around 251.5 Hz. Newer definitions for the benefit of folks with 32768 Hz crystals and flip-flops to divide by powers of 2 are bogus.
eduo
March 6th, 2007 at 4:18 pm
For an example that a movie that gets shots right the recent Pan's Labyrinth clearly shows what Uberfiend mentions. The shots (or the bottle scene) are all more disturbing precisely for the lack of actual physical effect other than the death of its victims.
lou
March 6th, 2007 at 5:45 pm
>As an addendum to #6â€¦ If characters in a film are made larger or
>smaller (a la Honey I Shrunk the Kids) their voices would change
>appropriately. Smaller vocal cords would produce higher frequencies
>at a lower amplitude.

That's the least of their problems. If their atoms were shrunk (or enlarged) to accomplish this feat (are there any other explanations?), even assuming it were possible, then their physiology would no longer be able to process *normal* sized atoms, such as from the O2 in the air or the H2O they drink or food they eat. Unable to process the O2, they would quickly die. Fantastic Voyage got around this problem by shrinking the entire system, including their air supply, but not HISTK.
Dave
March 6th, 2007 at 5:49 pm
When gravity fails...

Think about movies like Star Trek, or TV shows like Firefly or Battlestar Galactica: characters are in a gravity field as long as they stay in their ship, but become weightless as soon as a gate is opened to the void. This stems from the fact that space movies usually rely on a ship/space to ship/sea metaphor (best example being Treasure Planet), so opening a hatch to the void would be like opening a gate inside a submarine. As soon as the room gets flooded with water, you float. In space that would be weightlessness.

Once you have accepted their rules of the game, watching a space movie is easy. If you think for a minute about gravity and why people do not fly in all directions, you are sucked into endless thoughts about artificial gravity systems and the like.
Jared
March 6th, 2007 at 5:57 pm
I was waiting for the one where space vehicles do not fly like airplanes. There is no pulling up, there is no air to pull up against thus any change in direction of movement or direction that the ship is pointing must be done by some sort of thruster. Which is a real shame, the fighting scenes in Star Wars look so cool.
Mike
March 6th, 2007 at 6:08 pm
"Iâ€™m not so sure about the radioactivity not being contagious....And what about that spy who was poisoned with radiation? Wasnâ€™t there a ton of concern about people he had interacted with?"

One must keep two things separate. 1) The source of the radiation and 2) the radiation. Radiation is not "contagious". Someone who is merely been exposed to radiation, as a general rule, will not be radioactive. Someone who is contaminated with radioactive material, i.e. has radioactive atoms on his person, is as radioactive as those radioactive atoms he carries.
Obviously (at least I hope it is obvious), the radioactive atoms don't care if they are on a person or not: it will not change the rate which they undergo radioactive decay.
Phil
March 6th, 2007 at 6:35 pm
#1 is a very real threat to life and health. Last year, my wife and I witnessed a terrible crash on I-5 in central California. By the time my wife (a nurse) crossed the median to assist, others had already dragged the victims from their cars. No doubt a lifetime of exposure to Hollywood and television made them fear imminent gasoline explosions (which didn't happen). They probably thought they were doing the right thing, and they simply didn't know that you should *never* move an accident victim unless it is absolutely necessary because of the severe risk of further damage to the spinal cord.
Phil
March 6th, 2007 at 6:52 pm
#4, you probably drank or were injected with radioactive iodine-131 (I-131). Iodine concentrates in the thyroid, and since I-131 is radioactive, it irradiated and killed the diseased thyroid tissue while minimizing the dose to the rest of your body.

The I-131 didn't actually make *you* radioactive. But because it was physically present in your thyroid, anyone near you would also have been exposed to some of its radiation. Thats why you had to avoid your children for several days. I-131 has a half life of 8 days and is also slowly washed out of the body in saliva, urine and feces. That's why you could not share a bathroom with your family for a while.
Brian
March 6th, 2007 at 6:53 pm
> Would your inner ear change frequency range? Would
> your brain even be able to interpret the sound if it
> did?

As stated, vocal cords would shrink, allowing them to vibrate at a higher frequency. However, the cochlea is filled with tiny hairs of decreasing length, each with a different frequency it resonates at. In a shrunken person, each of those hairs would shrink, and like the vocal cords, have a different higher frequency response.

Given that both the vocal cords and the hairs in the cochlea are both of the same relative shape (i.e. strings), I suspect that the shift in frequency response would be the same, meaning a shrunken person's voice would still vibrate the same shrunken hairs.

What's more, since the nerves connected to those hairs are unchanged, the brain would perceive the incoming shrunken voice no different than if the speaker and listener hadn't been shrunken at all.

What would change is that the voices of normal people would now be at a frequency that was too low to vibrate any of the hairs in the shrunken person's ear making them inaudible.
Lionell
March 6th, 2007 at 6:56 pm
Item 4. The Martial Arts one.

Martial arts is all about reaction forces. If I want to kick somebody and knock them back, I need a damn good reaction force. The most popular one is the combination of friction and gravity that you would use to stop me from pushing you backwards. Martial Artists spend years learning to make the most of available reaction forces.

I have personally knocked people backwards, sometimes off their feet, with kicks. Never once did I suffer the fate you've suggested; my stance and balance were right, and I was able to find enough reaction force to knock my target back without being knocked back myself.

Momentum is another one. If I build up some solid body momentum (by jumping), or even just momentum with the arm or leg I'm striking with (by extending it rapidly), then the equal-and-opposite-force to the one that knocks my target backwards serves to STOP my existing momentum, not knock me back equally.

Try writing about something you understand, instead of just collecting common gripes and parroting them back (to an admittedly under-educated public).
Eglis
March 6th, 2007 at 6:57 pm
Doh, you broke all creativity in real life by exposing physics laws that i should have learnt in school but i volontarely ignored them!

Aaaah no, my poor eyes, i cannot see hollywood the sameway anymore!
ScienceGuy
March 6th, 2007 at 7:00 pm
If this type of thing interests you, you should check out: http://www.badastronomy.com/

Among lots of other amusing stuff, it has great reviews of gaps in reality in many popular movies.

Enjoy!
Tim
March 6th, 2007 at 7:02 pm
As someone who actually edits sound effects for movies, I'd like to point out that everyone in my field is entirely aware of the true physics of sound, but what's more important to any of us than scientific accuracy is storytelling and doing what's best for the film that's being presented. This more than anything usually means making sure that there is nothing to distract you from the attemtped reality of the story. If this means taking certain creative liberties with the laws of physics, so be it. Now you can argue that obvious violations of the laws of physics do take you out of a movie, but unfortunately, that only applies to a very small group of people, and if you're among them, I'm sorry, you're the minority, and we're not going to cater to you.

To be honest, there is nothing that makes me happier than when a director uses accurate physics to enhance the storytelling of his film (ie Master & Commander, Kubrick's 2001), but lets face it, that just doesn't happen all that often. Usually something like that has to be developed from the script phase, and filmed/edited with that intention, other wise, by the time it gets to us, it's too late for us to do anything about it.

On day one of my first sound class in film school, we watched the opening starship battle of Star Wars with completely scientific accuracy (silence). Try it sometime. I promise, you'll be glad we take the liberties we do.

Also, I'd like to point out that while there are a number of movies that have 80% or more of the on set dialogue replaced, for the most part, we try to save as much of the production dialogue as possible. It is always better than anything we can record later and if we can salvage it, we do. Granted, large action films like Black Hawk Down or Van Helsing require a good deal of dialogue replacement, most films don't come anywhere near those kind of figures.
Fuzzy
March 6th, 2007 at 7:11 pm
Number 5 is incorrect. Although objects do fall with the same acceleration regardless of horizontal velocity, the point is to make it fast enough to reach the other side without falling too far. It's certainly possible that in the time you take crossing the gap you fall only a little bit, which your tires absorb, regardless of whether your car can actually drive that fast, depending on the size of the gap. There may also be a slight upward lift while in the air.
David Henderson
March 6th, 2007 at 7:35 pm
Re: #6, There are actually many movies where the sound is also slowed down (i.e. lowered) during slow motion scenes. It's most often used when someone sees something bad about to happen, and they're too far away to stop it in time: The thing happens in slow motion, and we hear a low "Nooooooooooooo...".

davidh
Dan V
March 6th, 2007 at 7:36 pm
I would add one. In space everything has gravity. In fact everything has the same gravity as earth. I've gotten tired of seeing science fiction movies where all space ships have gravity. Even small ships like the Millenium Falcon has so much gravity you can walk around and play games just like its on earth. I think 2001, a Space Odyssey, did a great job in creating a rotating space station so that it would have gravity (OK, its centripetal acceleration). Also, what about the fact that Mars has 1/3rd to gravity of earth. That would totally change movies like Total Recall. So I would like to see, for once, a sci-fi movie where gravity is an issue!
George Ou
March 6th, 2007 at 7:45 pm
Ok you missed a couple of good ones.

Newton's first law of physics. In Star Trek, even the loss of so-called "impulse" power in a shuttle will cause it to slow down to a stop.

The other big problem in all sci-fi flicks is the jet fighter effect in space. They assume that space fights are just like jet fighters fighting in an atmosphere and that they need wings. The assume you can bank and turn like you're in air.

Another big problem is that laser guns in movies have to be slower than you can throw a baseball so the good guys can always somehow dodge the laser beams. They're slow enough that you can see the beginning and end of the beam flying through the air. If laser guns really acted like they do in the movies (or even video games), it's time to toss them aside and stick to regular firearms because they're at least so fast you can't see the projectiles.
Jim
March 6th, 2007 at 7:56 pm
On the TV series Firefly, when the characters were watching something happen out in space, there would be no sound, which was wonderfully eerie as well as more realistic. However, in the movie Serenity that followed, the Hollywood types apparently insisted on outer space being the air-like conductor of instantaneous sound like it is in nearly every other space-faring film.
Loudmouth #1
March 6th, 2007 at 8:07 pm
In a setting where spacecraft can go faster than light you're worried about the same ships having gravity? Just assume that the same hyperspace physics that allow FTL travel allow artificial manipulation of mass an inertia. And then you can add secondary consequences to the system that require, for example, ships using artificial gravity or inertial compensation to bank and such. Boom, all Star Wars physics tied up with a single bow.

Except the sound, granted. However, the sound makes perfect sense as an in-cockpit generated effect; sensor data on the position and velocity of other spacecraft translated by the onboard computers into sounds humans are trained by life planetside to interpret correctly. So the sound you're hearing is actually heard by the people in the spacecraft even though sound doesn't travel in space.
Joseph Brenner
March 6th, 2007 at 8:18 pm
The bit about the woman who tried to jump the gap
in the bay bridge after the earthquake is an Urban
Legend, as I understand it.
MovieManMan Man
March 6th, 2007 at 8:19 pm
Movies are art. I don't hear too many people complain about Picaso's lack of reality.
If you want reality, watch a documentary.
JJ
March 6th, 2007 at 8:26 pm
Referring to the previous comment about Serenity, actually, they didn't add any sounds in the space scenes - except when you were inside the craft, where the was air, and you could hear. Additionally, the music and editing actually tricks you into THINKING that you heard the explosion, but you actually didn't. It was really cool, actually.

Also, the movie Red Dawn followed rule number 2 in an early scene where an explosion in the background takes a few seconds to be heard. Of course, when I watched it, my friend actually thought it was a goof, until I explained that it was actually more accurate. It kinda gets to the heart of the matter on some of those mistakes... we're so used to them and reality sometimes feels so unnatural itself that it's almost jarring to see something realistic on these matters.
HPA
March 6th, 2007 at 8:43 pm
The myth of radiation coming with a green glow probably comes from the use of radium salts in clock faces in the 19th and early 20th centuries. These salts would fluoresce with a green tint, and since they were energized by their own radiation, rather than from stored light, they would never dim.

That, plus of course the desire to show to the audience that something is dangerous. Highly radioactive substances will indeed glow in air or in water, but the glow appears blue to human eyes, not green. It also means radiation doses which are likely to be deadly unless observed through shielded glass or via a camera.
M
March 6th, 2007 at 8:57 pm
Sound of science - your explanation is wrong. If you're going to try and look smart in your blog you might want to get your explanations correct. Sound isn't limited to air, or is it limited to your ear drum. Good try though.
happyjuggler0
March 6th, 2007 at 9:03 pm
It is indeed possible to jump a gap in the road. But you do need an upslope in the road prior to the gap, or a lower surface on the landing side for that to happen of course. Haven't you ever heard of, or seen, cars or motorcycles jump over rows of other cars? They use ramps....

Thanks for including number 1 by the way. I can't tell you how many people I've tried to explain that to who simply don't believe it, and like poster number 38 pointed out, such a belief is hazardous to life, or at least to not being paralyzed. Now if there is a fire that you can't put out, feel free to be a hero and drag somebody out of the car. Nobody will explode if you don't, but they will be burnt to a crisp.

Another physics one I've read about, but am too lazy to google for, is bullets shot into the water. My understanding is that if you are at least a foot under water you can't be shot. The water effectively acts as a wall and radically slows the bullet down to at least below penetrating force. If I'm right then the opening scene of Saving Private ryan is in part BS, which would be sad if true since it is an amazing several minutes overall til they finish their initial combat. I hope this is true and not yet another misuderstanding though, so don't try this at home kids....
Alex
March 6th, 2007 at 9:10 pm
Wow - thank you for the comments, guys. (And for first-time visitors, please take a look at the rest of Neatorama)

Here's another movie pet peeve: how characters can find parking right in front of a popular restaurant/store.
Xune
March 6th, 2007 at 9:10 pm
'In space, nobody can hear you scream.'

There is no comma in that, dorkface. Look at the poster again. You americans are so weak willed.
Alex
March 6th, 2007 at 9:20 pm
Regarding #4 - I think the article is (mostly) correct. Momentum is conserved. However, since momentum = mass x velocity, you *can* kick a smaller object of less mass across the room without moving yourself backward by much.

As someone correctly pointed out, in real life, your backward momentum can be negated by friction.

If you have forward momentum and you impart a momentum on a standing person (say, with a kick), then both of you will move forward.

Also, let's not confuse kicking someone and causing them to lose balance and fall with what you see in the movies.
ghonzo
March 6th, 2007 at 9:20 pm
Nice summary! Here's another good source of bad movie physics:
http://intuitor.com/moviephysics/
twinotter
March 6th, 2007 at 9:31 pm
#3 radiation not visible: wiki Cherenkov radiation

Most radioactive decay actually is visible, but you might need a lot of radioactive material to be able to detect it with your eyes (or normal camera). We were using photomultiplier tubes that can detect single photons to detect it under the ice at the south pole.
Alex
March 6th, 2007 at 9:41 pm
Regarding the car that tried to jump the gap across the bay bridge, that was real. What we can't know was the intent of the driver (whether she did it because she panicked, thought she could jump the gap, or because she didn't see it in the first place).
Chris Taylor
March 6th, 2007 at 10:05 pm
"I was waiting for the one where space vehicles do not fly like airplanes. There is no pulling up, there is no air to pull up against thus any change in direction of movement or direction that the ship is pointing must be done by some sort of thruster. Which is a real shame, the fighting scenes in Star Wars look so cool."

Actually this is not quite right. at OUR space velocities you just thrust but NOT at there velocities. These ships of sci-fi do not have the same limitations as "we" do for fuel and speed and acceleration. They also have artificial gravity this does many things.

First by "banking and maneuvering like an aircraft does you optimize your PRIMARY thrust unit your main engines. your "thrusters" can you shove you sideways at 2g's but if you spin and then use the main engine you can.

also buy maneuvering like this you make the AG field's job easier since it would probably be harder for it to "pull" you sideways or upwards to counter such maneuvers. the most realistic "space fighter" scenes I have seen are in BSG - they do it like it probably would really happen ie spin and aim with thrusters and push with the main engines.

Also so far most "sci fi" AG fields have limited range so when you go "outside" the ship OR they "turn off" the AG Field where your at then YES you go weightless.

as for sound in space. This must be given to them. They have to. Go watch BSG or Star Trek or Star Wars but first mute your sound every time you see space.

Pretty boring ehh ?

Sound is NOT the vibration of air sound is the vibrations of MATTER ie sound goes faster or slower the more or less dense the matter it goes through. so sound is faster in water or steel than it is in air.

Also another thing people whine about. Aerodynamics WILL be important in space. space is NOT a vacuum its just really close to one. about what 1 part per million for atoms ? at our speeds thats vacuum but at say .9c suddenly thats a shit load of matter your running into

"If you have forward momentum and you impart a momentum on a standing person (say, with a kick), then both of you will move forward."

This statement is not false but its also not true since it depends on your mass and inertia and there mass inertia.

IE go punch a brick wall and see if your fist keeps moving forward so how far they move will depend on how fast your moving and how much mass you are and they are. I have had kids run into me and I get shoved back slightly and they go flying back the way they came in rebound I significantly out massed them

the only way they would move backwards and you would move forward is if yo imparted enough energy to move them and then STILL had some energy left over and that would allow you to continue to move forward.
Martin
March 6th, 2007 at 10:15 pm
My friend's father worked for the Australian Road Research Institute(?) and in one of the coolest experiments they ever did, they got the money to drive
50 cars off a cliff. Apparently 3 of the 50 burst into flames when they hit bottom. So it does happen, just it's not very likely to happen. Just last year a car on a road in Melbourne had an accident where it hit another car and rolled and then burst into flame, I drove past it while it was still there on the other side of the road.
Deceites
March 6th, 2007 at 10:17 pm
Number 10:
Airplane and spacecraft interiors are always pressurized to 1000 psi, resulting in strong winds "sucking" papers, heavy objects, and even humans out of the craft when a small hole is created in the hull. As an example, in one of the Alien sequels an alien is sucked out of a spaceship at the end thru a tiny bullet hole. Back in reality there is only a pressure difference of 1 atm between the interior and exterior of a ship in space, and even less for an aircraft. Creating a small hole would be the equivalent of turning on a good vacuum cleaner in a room and for a larger hole it would be like turning on several vacuum cleaners at the same time. Nobody is going to go flying.

Number 6 seems trivial; by the same logic the light frequency would be altered just as sound would, resulting in a complete alteration of colors during slow motion shots.
JAL
March 7th, 2007 at 12:00 am
Bullets can travel more than a foot underwater. While they do decelerate quickly, you need to be about 3 meters underwater to be safe from all conventional bullets. Some special-purpose bullets can travel substantially further than 3 meters.
Xeno
March 7th, 2007 at 12:57 am
...Oh, yes, and while I'm at it...

The Army used to paint things with radium to make them visible at night.

This is because radium - a RADIOACTIVE SUBSTANCE - emits visible light.

You fail again.
Nirenjan
March 7th, 2007 at 1:10 am
I'm surprised that nobody picked up this one...

Simple experiment: Take a standard laser pointer and shine it anywhere. Do you see the beam? No, only the beginning and end (though you might wind up in the hospital if you look into the beam).

Laser beams are composed of parallel waves (or photons, depending on how you look at it), and you cannot see a laser beam in the Earth's atmosphere (on a normal day). The only time you can see the beam (or rather part of it) is when you shine it through a medium that scatters light, say for example, through a very dusty room.
Keifamus
March 7th, 2007 at 1:29 am
"Iâ€™m not so sure about the radioactivity not being contagious. I had radiation (RAI) to burn my thyroid into submission and was not supposed to get within four feet of my child for several daysâ€¦and could not brush my teeth or, um, use the facilities in the same bathroom as anyone else in the family for a week.

- That's because you messed with your thyroid

And what about that spy who was poisoned with radiation? Wasnâ€™t there a ton of concern about people he had interacted with?"

- Yeah, who he interacted with. As in who did it to him....
Will
March 7th, 2007 at 2:00 am
You seem to have forgotten the "constant thrust equals constant velocity in space".
eric
March 7th, 2007 at 2:23 am
actually if something is radioactive, it will transmit radiation to any thing nearby. thus if a nuclear bomb goes off, n u hide behind a magical tree. it will eventually kill u. so this article is bs :p
JKFan
March 7th, 2007 at 2:24 am
Just becuase hte video is in slow motion doesn't mean that the director wants the AUDIO to be too.

Newsflash for you...the audio of a movie is NOT supposed to be what you would hear if you were wherever the camera happens to be. Otherwise you could complain about pretty much EVERY scene,since when a camera zooms in or out, the audio level doesn't change.

Same concept with clow motion. The video is slowed down. That doesn't mean the audio has to be.
critic
March 7th, 2007 at 2:24 am
"The movie Aliens corrected this misimpression with its tagline: â€œIn space, nobody can hear you scream.â€"

The image of the movie poster with said tagline is showing you misquoted! Embarrassed?
Calvin
March 7th, 2007 at 2:42 am
And what about all those Van Damme films? The fight often goes for several minutes, and main character always receives large number of clear hits to the head, and he stands on his feet with no problem at all, than he decides to cut the crap and knocks out bad guy. Have you guys ever seen MMA fights?
mrben
March 7th, 2007 at 2:48 am
Good to see Firefly get a couple of mentions here, as they worked very hard to not have sound in space, and it's very eery in places. They do also try and work with the fact that, even if you are in a spaceship in space, if something knocks against you, you will hear it.

There is still a questionmark over the space battle in Serenity - some argue that you can only hear sounds from within the ship, others argue that the battle takes place within the high atmosphere of the planet. Either way, there are still some nice "silent in space" moments in the film.

The gravity thing is an issue (ref comment 35 and others), although I suspect it's a practical consideration for the studios. Certainly in the pilot for Firefly the actors are weightless even when entering the ships airlock, and only regain weight when the pressure has been equalised and (presumably) the gravity "switched on". Later in the series, in the episode "Out of Gas", when they blow out a good chunk of the air in the ship to remove a fire, the gravity remains as normal even with the ship running out of air, which is good to see.
Van
March 7th, 2007 at 2:52 am
Regarding the previous comments about Firefly an Serenity:
I was always really happy about how Firefly obeyed rule #9, but was kind of pissed when Serenity appeared not to. However, when you think about it, the only scene where they had sound in "space" was after the reavers burst through a big "space cloud" thingy toward a planet - so one could argue that since there was a cloud there was a medium for sound. One could also note that they were not in the cloud, but as they were beneath the cloud and due to basic physics the cloud had to be floating on SOMETHING, they were probably still in a gaseous medium. Good god, I doubt the makers of the movie gave it this much thought.

Now that I'm done with my uber-nerdy nitpicky sci-fi commentary, you may resume your discussion
Van
March 7th, 2007 at 2:54 am
Dude no way! mrben beat me to it!

Firefly fans of the world unite!
Andre
March 7th, 2007 at 3:07 am
Point 4. with the kung fu kicks. It is not really true what you are saying. It is possible to kick or punch someone so that he flies across the room without you moving an inch. This is due to "rooting" of the body to the ground. That is, the force will be routed to the feet, which, if done right, will even strenghten the position the kicker is in.
Van
March 7th, 2007 at 3:26 am
Well, for that kung fu kick to work, the friction of the one grounded foot would have to exceed the force exerted upon the kicker by the target (which of course would be equal to the force exerted on the target by the kicker) so that the normal exerted upon the kicker by the ground would allow the kicker to remain stationary. Given even ground, the normal couldn't exceed the force of gravity upon the kicker, and given that the vector of the force exerted upon the target would be near perpendicular to the normal, and the force exerted upon the target would have to be SIGNIFICANTLY higher than the pull of gravity upon the target (due to the fact that the force in the upward vector alone has to exceed the pull of gravity in order for the target to become airborne at all and the majority of the force would be on the horizontal vector), the mass of the kicker would have to GREATLY exceed the mass of the target for the kicker to remain effectively stationary.

That is, of course, if the kicker is on the ground. If the kicker is airborne (as he/she always seems to be) then no amount of physics could reasonably why he/she remains stationary.

Given these basic principles of physics, the only "footing" where this would be possible is with the grounded foot butted against a nearly vertical surface (such as a wall as suggested by Rule #4).

I may have missed something, but I should be pretty close.

Sorry, just the way the universe is my friend.
jocs
March 7th, 2007 at 3:33 am
Hey, but the films are really amusing .. and what if you hear a volcano explode at the same time you see it exploding? But the bus driver case is more serious. Maybe he saw "speed".
Andy Canfield
March 7th, 2007 at 3:40 am
The real reason why almost all movie space ships have gravity is because it would cost a fortune to film a two hour movie in the Vomit Comit (weightless airplane). The only one that got it correct was Imax's "Space Station" documentary.
Andre
March 7th, 2007 at 3:52 am
You are indeed correct about the kicker that is airborne, but I have to disagree with you on the other point. Through the right positioning of the foot it is possible to create a stance similar to "leaning forwards" so that the force is not moving through the kickers body but is routed into the ground. I have seen myself a small old man pushing ("pushing hands") a huge bloke across a room without him moving an inch.
A Competitive Shooter
March 7th, 2007 at 4:12 am
Another important one that I am always amazed about is where somebody is shot between the eyes with a pistol from 50-100 yards away. As a shooter, I can say that in general, pistols simply aren't that accurate. For one, the barrels are short thus giving less guidance to the bullet. Second, a pistol shooters arm simply isn't that stable a platform. Finally, the sights on a pistol at arms length are not that fine to begin with. Sure, there are a few people in the world (world class competitive shooters -- some of whom I've known) that can pull of a shot like that but they have dedicated their lives to it and shoot literally 1,000's of rounds day in practice. Pistols are great in close quarters combat where there is no need for precision shooting but it doesn't take much distance to make pistols very inaccurate.
Van
March 7th, 2007 at 4:17 am
"pushing hands" is different than kicking someone across the room. It is possible using certain stances to redirect the force exerted upon the pusher (for lack of a better term) be the person being pushed down the legs of the pusher, thus causing the force of the normal to increase significantly.

This, however, has a very low rate of energy release and can't really compare to a punch or kick, where the force is rapidly exerted - at least not where forces strong enough to impart enough energy in an instant to hurl someone across a room are concerned. Bare in mind that pushing someone across a room involves the constant impartation of energy to the person being pushed. A punch or kick would require all of that energy (plus the energy to get the target off the ground) to be imparted all at once, since the point of contact is very brief.

I'm not arguing that this stuff doesn't look great on screen, btw...it's just not possible as it's portrayed.
A Competitive Shooter
March 7th, 2007 at 4:18 am
Another issue that should be brought up is how many people have died because of these "artistic" oversights? For example, the bus driver trying to accelerate across the bridges gap mentioned above. By teaching improper laws of physics, the movie industry is giving some people the only (improper) physics lesson(s) they will ever receive and ones that someday, they may stake their lives upon.
Van
March 7th, 2007 at 4:36 am
Good point, Competitive Shooter, but I serously doubt that many Hollywood types will ever be interested in educating anyone about anything other than their own opinions.

Maybe they should hire "Physics Consultants" the same way that they hire "Wardrobe Consultants"? Not likely, but we can all dream.
Joe
March 7th, 2007 at 5:16 am
I agree with all of these except number 6. Yes, if you slow down the video the sound will drop in pitch, but you could also say that in real life time doesn't slow down when you are about to crash. It is done for effect so it doesn't need to be accurate.

I am surprised that you haven't mentioned laser beams, which cannot normally be seen in real life.
shmuel
March 7th, 2007 at 6:34 am
I would add another one. People who become non-physical and can walk through walls are somehow supported by floors and can pick up objects. They can even ride in elevators. This can be excused in comic cartoons like Casper, but why did it happen is Star Trek NG?
kruemi
March 7th, 2007 at 6:42 am
What are you telling about laser beams not visible.
Sury, you can't see the beam of you 0.5mW Laserpointer. But take a laser with some more power (15mW upwards in the dark, some more power needed in lighted areas) and you'll see the beam in the air. We're not livin in vacuum here, and even clean air does absorb and scatter some light ("dirty" air like it is around us even more).
For some cool examples visit http://www.wickedlasers.com/ (I'm not associated with them).
Gopal Aggarwal
March 7th, 2007 at 7:36 am
Movies with special effects should come with a warning: â€œLaws of physics are violated in this movie. Donâ€™t try these stunts at home.â€

Wonderful!
John Smith
March 7th, 2007 at 7:59 am
In space, everyone can hear you scream because you have a radio...

On kung fu kicks, etc. The striker relaxes their limb an instance after strike contacts, so they are not inelastic and their muscles can subsequently do work to counter the recoil. As someone has already mentioned, stance are set as such so that forces perpendicular to the ground are redirected into the ground. Not that films are even remotely realistic even taking this into account.
Bashar
March 7th, 2007 at 8:42 am
It's a damn 100% correct yet incomplete article, if you want to list all the law physics that don't apply. I would suggest you take a look also at Indian movies. Man are you gonna be grateful to Hollywood or what!
Emmanuel
March 7th, 2007 at 8:45 am
(Re: jokono's #17 comment)
If there is 7% gasoline left in a tank, the remaining 93% is not air. It is almost pure gasoline vapor.
phill
March 7th, 2007 at 8:52 am
If people didn't fly "up" when they fell over it wouldn't be as funny.
benqish
March 7th, 2007 at 9:01 am
Walk into a lift (= elevator in USA) and try and find the button that stops it mid floor! In the films someone wants to do something in a lift (have a quiet talk, escape through the hatch at the time (do they exist)) so they press the magic button and the lift stops. I have never found this button in real life.
h
March 7th, 2007 at 9:26 am
The two kung-fu films mentioned, The Matrix and Charlie's Angels, both include scenes where someone jumps up in bullet-time and kicks a bad guy across the room - I think the writer was referring to this phenomenon. Obviously The Matrix is a fantasy film and Charlie's Angles moreso so anything goes really.

My major space gripe is that in sci-fi films there seems to be no up or down, everything exists on one plane. At the end of Return of the Jedi, when the rebel forces are caught between the Death Star and the empirial ships, they say "OMG WE'RE TRAPPED!". But they could have just gone UP or DOWN, and saved a whole load of bother.
Devotion
March 7th, 2007 at 9:29 am
Interesting discussion.

Biologicals vs. radiation: important point here is to remember that the measurement unit Gy is a unit of radiation absorbed by tissues (i.e. how much you should care , which is affected more by tissues in question and the type of radiation in question. If you are 'irradiated', your tissues have absorbed radiation in the form of cell damage. Would be nice if you could radiate that away, but no such luck; this is why medical personnel can go in to treat a patient of radiation therapy as soon as the treatment is over without fear of being exposed themselves. For example in the case of the spy the concern was for people exposed at the same time as the spy; if the source of radiation was something he carried with him unknowingly, people he met during that time might have been exposed (though of course total irradiation much less due to the smaller time involved).

One popular tv show which featured Newtonian physics in space battles was Babylon 5, which managed to even make it look cool, with all kinds of clearly space-only maneuvers, as well as ships losing power drifting far out battles if without power. This has also been tried in a number computer games (I-War for example), and while requiring some getting used to, turned out to be both doable and logical after a little while.

The initial #4 and the following commentaries both have a point in them. Yes, it is possible to kick people backwards without flying back yourself, by e.g. assuming a proper martial arts stance. In think the point in #4 is that in order to punch or kick anyone across a room would result in at least multiple fractures, if not in catastrophic implosion of hand or leg bones. Compare energy needed to kick someone 10 meters away with dropping from a height of 10 meters, and add the upward power needed to keep the target aloft for the distance. Not to mention breaking, say, causing the target to break a concrete wall at that distance. Boom.

A pure hypothetical: one could also imagine that a laser cannon with sufficient power to destroy spaceships from ranges of several kilometers would have sufficient power to cause interplanetary/stellar dust to emit radiation, which could result in visible laser shots. I'm sure someone will correct me in this ...

So; movies are fun, but trying to learn physics from them can be awkward and dangerous .
Ryan
March 7th, 2007 at 9:40 am
I hate it when movies show two people in front of a stage at a rock concert (or in a night club) and not yelling at each other to talk, but talking in normal conversation tone. How'd the concert volume lower so they could hear each other?
Ron
March 7th, 2007 at 9:49 am
Number 4 is not correct
Just because you kick someone across the room doesn't mean you will go flying back yourself

You're forgetting you're standing on a floor here, if you kick someone across the room they'll be flying in the air hence the force negating them is the air resistance which is minimal in force, the friction of the floor will take out a lot of this equal momentum, momentum can also be exerted within your joints inside your body but its mainly friction

just think about it like this, if i pushed someone on concrete i would be unlikely to fall back myself
but if i pushed them on ice, yes i might go back the same distance or roughly as which i pushed them

different surfaces, different friction, different forces exerted on your bodily joints and mass in relation to gravity
Ron
March 7th, 2007 at 9:53 am
#5 is technically dependent on the object you're talking about

falls usually depend on projectile motion which is determined by the weight of an object and the velocity that it is travelling at the point of fall. if a car was travellin at an extremely high speed, it would still be able to clear a gap
miendo
March 7th, 2007 at 10:05 am
Although it's not really a law of physics, why do ALL computers in movies emit this slight beep/whistle when printing some content on the screen?
Wille Beamin
March 7th, 2007 at 10:32 am
What about fire and explosions in space? If there is no air or O2 to fuel fire and explosion then how do they exist.
Brian Emenaker
March 7th, 2007 at 11:29 am
Uhm, you can kick someone across a room without flying across a room yourself. I study Kung Fu and I have been sent flying across a room from a kick more than once, without the kicker flying back.

Other than that one piece of bad info, good article.
Merlin Alphabeta
March 7th, 2007 at 11:56 am
Just a quick note on inertia (and what can get rid of it) in outer space.

First, as noted, space isn't completely empty. And just like the accelerated viewpoint of a blackhole provides a tenuous, but detectable, atmosphere, similarly accelerating through space will have the affect of causing those sparse molecules to look more and more like something that might exert some viscosity.

Second, once you start experiencing time dilation, there's a consequence of relativity most people are unaware of. Because the speed of light must be measured the same in all frames of reference, different frames of reference see photons as being more or less energetic. Specifically, photons coming from your point of origin will be less energetic, while photons from your direction of travel will be more energetic (the ratio is the exact same as your current time dilation) - net effect being that you have more energy pushing on you from in front than in back, resulting in deceleration.

This effect acts at relativistic velocities as a sort of space-friction... sapping inertia in a way very similarly to air viscosity would in an atmosphere.
Ken
March 7th, 2007 at 12:02 pm
About half the items in your list have nothing to do with physics but rather center on chemical properties.

Anyway, you left off the most prominent physics error seen in movies: If two people are falling, one person first followed by another person moments later, the second person cannot catch up to the first person in midair to save him or her. It doesn't matter if the second person is heavier than the first person. Objects (or people) all fall at the same rate, it has nothing to do with how much they weigh.

We saw this mistake in Batman Forever, when Robin is ejected from a chute and seconds later Batman is dropped. Batman speeds up in midair (without any tools from his utility belt, just gravity at work) and saves Robin.

We also saw this in Spiderman when Mary Jane falls from the city hall building balcony and Spiderman jumps out and he too manages to speed up in midair and catch up to Mary Jane just before they hit the ground.
rhit09
March 7th, 2007 at 12:18 pm
Ken, it is possible to catch up with someone if you're falling after them. The trick is to lower your drag. If Mary Jane is falling normally, flailing her arms around and panicking, and Spiderman lines himself up vertically, he'll have a smaller cross sectional area. He'll therefore have less wind resistance, and will thus fall faster.

And in regards to everyone mentioning laser guns in various sci-fi movies; the guns are pretty clearly NOT shooting lasers. A quick laser blast wouldn't do the kind of damage these weapons do, and they would move much faster. It's pretty clear that they are only called lasers for convenience sake, while in the fictional setting they are actually some other sort of energy, whether it be plasma or some as of yet undiscovered substance.
Fazia
March 7th, 2007 at 12:23 pm
You can actually talk in space, but the helmets of each astronaut have to be touching.
Richard Muller
March 7th, 2007 at 12:33 pm
I am the original author of that piece, "The Nine Laws of Physics that don't apply in Hollywood." It appears in the Condensed Knowledge book under my name. It is interesting to see how original work can get so much attention with the name of the author not even mentioned.

I found this site because one of my students said it covered some of the things I had said in class. Does this web site really have permission to reproduce that part of the book? Does the permission form that they presumably have on file mention anything about giving correct attribution to the author?
Eric
March 7th, 2007 at 1:23 pm
I beg to differ about #8 Sparking Bullets. I own an arsenal of weapons and I have seen bullets spark over and over. It's true they do spark. Try doing some night shooting. You will see sparks. Who wrote this crap?
Bruce
March 7th, 2007 at 2:26 pm
Re: sound in space. In a recent comic book, JUSTICE, Captain Marvel and Superman were flying to the sun and talking. Captain Marvel asked Superman if he wondered why they could talk in space, and the answer was: Magic. Captain Marvel is a magic-based guy, Superman is a science-based guy from another planet.
Foodog
March 7th, 2007 at 2:27 pm
The "Ford Pinto exploding" in the 70's was setup. There were 2 million Pintos built and only 27 people died due to fire. The car was no more or less dangerous than the other junk cars built in that era.

The news story was staged, the gas cap was removed and very little gas was in the tank. This allowed lots of air to be mixed with the gas in the tank. Upon impact the car exploded, big surprise.
James
March 7th, 2007 at 2:42 pm
No Sh*t Sherlock. Its called Drama.
chorpler
March 7th, 2007 at 2:58 pm
Some lasers can be seen in the air. If a laser is at the right frequency or is powerful enough, the atoms of oxygen, nitrogen, CO2, etc. that the beam interacts with have an electron kicked up to a higher orbital by the impact of a photon; when it drops back down to its proper orbital an instant later, it emits a photon of the same energy as the photon that hit it in the first place (therefore the same color as the laser) in a random direction. The result is that you can see the beam through the air, but of course the beam is less bright when it hits whatever it's being aimed at.

(Hopefully that was clear.)
Geoffrey A. Landis
March 7th, 2007 at 3:03 pm
Fazia wrote:
>You can actually talk in space, but the helmets of each astronaut have to be touching.

Nope.

Some of the Apollo astonauts tried this. Didn't work. There isn't enough contact area to conduct enough sound to be audible.

Another SF plot device shot to bits by real life.

...say, if Richard Muller wrote this, he ought to get credit! (however, he might get more credit for things if he didn't put typos into his own website address! The correct URL is muller.lbl.gov/ )
Rich
March 7th, 2007 at 3:33 pm
"The â€œFord Pinto explodingâ€ in the 70â€™s was setup. There were 2 million Pintos built and only 27 people died due to fire. The car was no more or less dangerous than the other junk cars built in that era."

Sorry, dude, but you're wrong. I saw one explode in that Leslie Nielsen movie, and the car behind it barely tapped the Pinto.
ab
March 7th, 2007 at 4:22 pm
The bus driver obviously didn't see Speed. Speed the movie was released in 1994. If the earthquake was in 1989, then either you have a time-traveling bus driver, or a poor on-staff fact-checker.
Anti
March 7th, 2007 at 4:50 pm
Martial arts kicks, hit from an angle, so the force on the kicker goes into the ground... Just a simple point.
Leon
March 7th, 2007 at 5:52 pm
About #8...actually, most bullets, while made of lead, are coated with steel, called a jacket. Hence the term "Full Metal Jacket" (FMJ). FMJ ammo is the most commonly available type for private use. Jacketed ammunition is also required by the Geneva Convention, I think it is, because unjacketed rounds break up as they travel through a target, inflicting much worse damage than a round that stays intact. The use of unjacketed bullets was part of what made wounds so horrendous in the Civil War.
Uriah
March 7th, 2007 at 7:35 pm
Although a lot of people have a problem with number 4, it is correct. If I kick you back a meter, I must exert a force equal to that on my self.

You can push someone back a meter or so, since they often stagger whilst falling back and since when you kick you actually accelerate your entire body and use relativity to ensure that your foot has a lot more force then just your extending leg can exert. However in the movies they greatly exagerate this. Which is perfectly inline with your statement, and explaination of the physics. The shutgun is a more accurate display of this, since the person is generally not moving, a shotgun will not push you back, except for your feet staggering backwards from being hit with it. I've seen someone actually shot with a shotgun before, he fell backwards and bled.

However Number 7 shell shock has a few problems, a shell which hits at an angle with force, can create a non-symetrical explosion. Additionally a lot of shells just explode in a non-symetrical pattern, due to design flaws. Also if you're talking about grenades / rpg's the effective kill radius is about 6 feet, this is why you walk in a staggered and dispersed pattern out in the field, so a grenade should only be able to kill one person.

Also Ken wrote earlier:
If two people are falling, one person first followed by another person moments later, the second person cannot catch up to the first person in midair to save him or her.

A second person can catch up to the first person if the first person is less aero dynamic (Such as when skydiving the first person is in the boxman position and the second person is in a standing up position, he will be moving much faster). This is due to the drag being decreased in the second skydiver.

Either way, not a bad article.
Alex
March 7th, 2007 at 9:21 pm
Prof. Muller is right - he is the original author of the piece, as confirmed to me by mental_floss.

My copy of the book does not have authors' names attached on the individual articles, but his name was in the physics section of the book (which I kind of skipped going into the articles). So a mea culpa is in order: I am sorry to have omitted Prof. Muller's name as the original author - it was unintentional, and had I been more diligent, this wouldn't have happened. The post has been corrected to reflect his authorship.

Actually, I will have to go back and update the original author info for all the book-derived mental_floss articles on Neatorama.

As further credit to Prof. Muller, here's his short contributor bio:

Richard A. Muller is a professor of physics at the University of California at Berkeley. His research includes astrophysics, geophysics, elementary physics, and climate. He has received a MacArthur Prize and the NSF Alan T. Waterman Award. He currently teaches a course called "Physics for Future Presidents."

And lastly, yes, Neatorama does have permission to reprint the articles.

On a personal note, I actually took a physics course with Prof. Muller when I was in college at UCB. Go Bears!
MÃ½r Fantasy
March 7th, 2007 at 9:32 pm
As long as the movie maker makes profit, they will continue doing it.
plagiar
March 8th, 2007 at 6:01 am
Just to let you know that a plagiarized version of this article is today on the homepage of the biggest italian newspaper:

http://www.corriere.it/Primo_Piano/Spettacoli/2007/03_Marzo/07/hollywo od.shtml

Congratulation! You have been paraphrasated!
BranchfromIndy
March 8th, 2007 at 8:28 am
Not to mention all of theose Flaming dynamite/Nitro expolsions. Nitro is an almost perfectly concusive detonation, 0 heat component, no flames at all.
cruise
March 8th, 2007 at 9:55 am
Nice to see /someone/ mentioned Babylon 5.

Newtonian flight physics for spaceships (and even a mention of g-force effects on pilots), and rotating sections on all human spaceships for the gravity (the alien races have figured out artifical gravity, however).

Beam weapons are instant hit, no slow moving lasers there.

Admittedly they do have explosion sound effects, but hey, 3 out of 4 ain't bad, right?

Oh, and why aren't more people mentioning http://www.intuitor.com/moviephysics/ ? Not only does this cover all the above and then some, it includes actual conducted experiments to back themselves up. Not to mention damn funny.
Varn Nine
March 8th, 2007 at 6:33 pm
When I was about twelve, my father walked in on me watching a VHS tape with an adult feature. I was even caught red-handed. He said: Son, it's not like I can stop you from doing that, but keep the dosage low and bear in mind at all times that things are not at all the way they're shown here.

Funnily, he didn't say that about other movies, although he probably should have. Good thing I had a very decent physics teacher.

And regarding kicks: that the person flies is possible, yes, but wasteful. A real kung-fu fighter would kick a hole into you, not make you fly. The point of a deadly kick is to execute it so fast that the majority of the victim's body stays where it is (due to inertia), while great trauma and deformation is caused around the point where the foot connected with the body.
karmy
March 14th, 2007 at 3:10 am
i wondering if i could translate this in croatian and publish on my blog?
john
March 21st, 2007 at 3:15 pm
karmy are you a woman. I think Croatian girls are hot!
CHiron613
June 11th, 2007 at 4:25 pm
With regard to martial arts kicks, you *can* send someone flying. The "secret" is that you thrust somewhat upwards, from a lower position. This way your reaction is directed downward into the ground, which allows you to stay put while the opponent goes flying.

The notion of a martial artist sailing through the air, kicking someone, and sending that person flying while the kicker doesn't, is of course inaccurate. Also, most martial arts discourages flying kicks (or even high kicks) as having little practical use, and being dangerous. If you miss, you keep sailing to wherever you were headed. If you connect, your trajectory is affected, you have no power (just your own momentum), and you'll bounce back. Bad form.

The preferred way is to retain firm contact with the ground, and (as I said) strike upwards. That gives you all your strength, which can be considerably more than your momentum when airborne. It uproots your opponent, causing him to get off balance or take flight completely. And it allows you to recover quickly if things don't go exactly as planned.
tuvie
September 17th, 2007 at 7:46 am
exploding cars happen so often, I kinda feel like always hoping it to happen every time I see action movies.
Stella
March 29th, 2008 at 2:15 am
Hey Joe, Who says laser beams can't be seen. I have a laser from Dragonlasers who sell really powerful green lasers and the beam is clearly visible in the light.
Ken
June 9th, 2008 at 8:01 pm
rhit09,

It actually IS possible for one PERSON to fall at a faster rate than another PERSON: this one time, at band camp, a saw a girl fall off of the drum major stand and the second on the stand hit the ground before her; it was mainly because the first girl bounced off some stuff like drum cases and whatnot, but is IS possible--I SAW IT, plus I read on the internet that you can take those "Fast Pills" like Wyle E. Coyote did...
green laser pointers
June 14th, 2008 at 4:37 am
Very interesting post,thanks for sharing.
Daniel Kim
November 1st, 2008 at 8:47 am
Re: Comment that radium-dial watch faces glow, therefore radioactivity makes things glow. The radium watch dials are a mixture of a rather small amount of radium and a mineral phosphor that absorbs the emission from the radium (dunno what type) and re-emits visible light.

The blue glow that comes from a nuclear reactor core is the real McCoy, but requires a really large amount of radioactivity to be visible. It is due to the effect of the ionizing radiation on the surrounding cooling water or surrounding air.

On another subject: Speed of sound.
The movie "Quigley Down Under" has Tom Sellick as an American sharpshooter in Australia. There is a scene in which he kills two (three?) men from a long distance away with his high-powered rifle. The single bullet went through the men, who were lined up together. There was only a very soft sound, and then the two men collapsed. Shortly afterward, the gun's report was heard. Very nice effect to indicate the distances involved.

The movie "2001: A Space Odyssey" used the soundlessness of space to good effect, dramatically contrasting the relatively noisy interior of the spacecraft with the stark silence of the outside.
John Grindle
November 2nd, 2008 at 6:55 am
In regards to #9, technically sound can travel in space, as it is not a perfect vacuum. Space is made up of matter, though significantly less dense than within the atmosphere of planets. And technically a perfect vacuum isn't possible anyway. Meaning sound CAN travel through space, though it would be much more distorted and slower than here on earth.
Nikki
December 1st, 2008 at 9:13 am
You're right about the sound in space thing - that's on eof my most hated mistakes! Also, sounds of equiopment being 'beefed up' and overdubbed with something that sounds more scary or impressive. e.g. jet packs, like the one in Thunderball. There's a good explanation here:
https://www.bigbangblogs.org/library/movie-physics-sound,464,AR.html
laser pointers
July 12th, 2009 at 9:50 pm
there is no perfect film, hollywood should hire an physic expert to avoid any scene that is very impossible in reality.
danielpower
October 22nd, 2009 at 8:50 am
Very meaningful post!
green laser pointer

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