In one game which I shall not name, the evil guys have a plan to detonate a nuclear weapon above a city to initiate a compton effect, which, IIRC, were supposed to act like an EMP device, basically destroying all of the electronics within the city.
Would this really work without completely wiping the city from the map, or coating it in layers of radioactive fallout?
There’s an interesting article about EMP weapons here
EMP effects tend to have a longer range than the light/heat/blast effects. If you detonate the weapon at a high enough altitude (the altitude I have been taught in NBC training is 30km), EMP will knock out all the electronics but leave the city standing. Fallout is not such a huge problem. Most fallout is produced when the dust/debris from the classic “mushroom cloud” (which is produced when the fireball touches the ground) falls back to earth. If the burst is exoatmospheric, the fireball won’t be touching the ground so all you have to worry about is the weapon casing and the fission products themselves.
Whoever made that game did not make up the weapon for the game. The idea has been around for a very long time. The military even used to have nukes specifically designed for this purpose. There was a lot of talk back in the 1970’s about using these weapons on the battlefield. There has been a lot of debate about exactly how effective these weapons would be, and the military folks haven’t been talking about them much since the early 80’s, at least not so much that I’ve heard. In the 90’s, the crackpots seemed to have seized upon EMP weapons, for the inexplicable reasons that crackpots latch onto whatever it is they lach onto, so a lot of what you read on the web is oversensationalized or just plain wrong.
If you surround something with solid metal, or a metal screen (which to radio waves looks pretty much the same as a solid piece of metal, as long as the holes are smaller than the wavelength of the radio wave), then radio waves outside the box tend to stay outside the box, and radio waves inside the box tend to stay inside the box. Such a box is called a “faraday cage” (you can google that term for more details). As people with cell phones have discovered (much to their annoyance), steel frame buildings tend to act as natural faraday cages. Cell phones don’t work inside of them, and EMP blasts are relatively well shielded by them as well, for exactly the same reason. Even something like a metal tool box will act like a faraday cage. You would therefore likely find that a lot of devices inside the city would survive the EMP blast.
Personally, I seriously doubt that EMP weapons live up to their hype. The city wouldn’t be wiped from the map, the fallout wouldn’t be that bad, and the weapon wouldn’t be anywhere near as effective as the game might lead you to think.
Still, better not try this at home, kids.
It wasn’t the EMP I was talking about that would wipe out the city, but rather the thermo-nuclear blast the EMP wave originated from.
The EMP weapons that the military had were all fairly small devices that were specifically designed not to destroy everything underneath them.
When I said “The city wouldn’t be wiped from the map, the fallout wouldn’t be that bad,” I was referring to the blast itself. Unforunately, I tucked that into the same sentence where I was making the point tha the EMP blast wouldn’t destroy all of the electronics in the city also. Sorry for the confusion.
FWIW, there is a nice exhibit at the USAF Armament Museum right outside Eglin Air Force Base, FL that talks about some volunteers (photos of them included) who stood underneath nuclear devices that were exploded high in the air. They suffered no (short term) ill effects.
I do not remember if this was a fission or fusion weapon, though. I THINK just a fission device, but am by no means sure.
It wasn’t covered, but I could not help wondering about the LONG TERM effects upon them…from the radiation, of course, not from any blast effects.
I showed a film once for an Environmental Science class once - I can’t remember which one, maybe “Trinity and Beyond” [ http://www.vce.com/trinity.html ]… anyway, in one of the declassified experients shown, was a small-yield EMP test in the upper atmosphere.
The scenario included a bunch of observers having a barbecue on the beach, listening to the radio, etc… and the missle was sent some 30-40 mi up. It was pretty cool, after it exploded, you could see the cooling air rushing back to the relative vacuum at the center… anyway.
The point is, the AM radio they were listening to went to static that lasted 5-10 seconds or so… pretty cool.
IIRC, that scene was actually a construct of the film (Trinity and Beyond). The director basically put the various elements together to make it appear that they were having a BBQ on the beach while a nuke was going off, but in reality, was simply film edited together to give that appearance, with sound effects added to make the radio sound like it was going to static. (At least I think that’s what he says in the commentary.)
The military was working on non-nuclear versions of EMP weapons, and as a WAG, I’d say that they probably have them, since they’re really worried that modern terrorists will build their own.
Non-nuclear EMP weapons were available in WWII. The military had the idea that if you fired an EMP at a bomber its engines would all quit, and you could knock it out of the sky much more easily than you could with bullets. In practice, the system didn’t work very well. I don’t know if it was ever tested in actual combat.
engineer_comp_geek, if it is true that vacuum tubes are immune to EMPs, then the funny thing about the WWII EMP devices is that they would not have been able to directly kill the one thing they would be sure to kill on a modern craft: The radio.
(But if they did manage to knock out the engines it seems the radio would surely die with them.)
Awe, man!.. I’m going to have to review that cr@p… I almost forgot I could turn the commentary thing on, thanks.
There’s a couple of other “construct” scenes in that film, IIRC. One of them is a nuke blast which was made by taking a series of still images and morphing them. The voice over narration in the beginning is completely modern, as well, and not from any newsreel footage (even though it appears to be).