How realistic is an EMP attack on the US (Red Dawn movie...)

[AndroAsc]

Wasn't sure where to post this, it can be under the science fiction or science section... but anyway

Was watching the remake of Red Dawn (2012), and the plot is basically an invasion of the US by N.Korea + Russia, and they knocked out the US defences using an EMP pulse in the opening salvo.

Let's just have a suspension of belief and assume that N.Korea + China + Russia would want to invade the US. Yes, I know a ground invasion is not very realistic, but let's assume that they have the logistical capability of shipping their forces for a land invasion.

So my question is how effective would an EMP pulse (like detonating a nuke mid-air) be against the defences on the West Coast? Is the plot line in Red Dawn remotely plausible? I'm hazarding a guess that some of our military tech is "EMP resistant"?

[Ahriman238]

We usually just say HEMP (High-altitude EMP.)

Can an EMP blanket an area the size of the US? Kind of. A lot depends on the yield and altitude. Worst case scenario graphic.



Mind, if that looks bad consider that EMP has been a known problem since '45. Electronics can be hardened against EMP for some cost. IIRC, sticking them in a Faraday Cage will work in extremis, but don't quote me on that.

HEMP would be a moderate inconvenience to the US military, not a death knell. They have the most shielded equipment, and available spare parts. Civilian infrastructure would be hit pretty hard, but in and of itself it's not a game-winner.

[Tethis]

Detonating a multi-megaton nuclear bomb at a couple hundred kilometers altitude would probably have a huge effect on the civilian power grid. Civilian power and eletronics equipemnt tends to be build with cost as a primary objective. Protecting against EMP is usually not a consideration (I've been told that surge surpressors for lightning supposedly simply aren't good enough to protect against nuclear EMP although in many ways the effect is much the same, except worse). I wouldn't be surprised to see lots of people without power. I'm sure they could eventually get everything back up, but it might be awhile.

Military equipment (if they haven't been trying to cut costs too much) is designed to withstand EMP. It's one of the reasons military equipment is so expensive. While I"m sure some things would be down, I doubt it would be devestating.

Acutally, it's likely that not all military equipment is really designed against nuclear EMP, but I guerantee the things they'd most want to disable is. I.e. ICBMs. Probably most stuff would be ok. Submarines which are submerged don't even need special consideration, the ocean protects them just fine.

Messing up civilians and not the military is probably not a winning proposition from their point of view.

By the way, that same EMP would very likely damage a LOT of the civilian satellites and not just US satellites. They'd probably piss off a lot of neutral contries.. Either kill them outright or lower their lifetime by a lot. A big chunk of Canada would end up being hit just as hard. Maybe Mexico or other neighbor countries depending on where it detonated. So they'd piss of some neutrals too.

In reality, Russia and North Korea wouldn't do that unless we dismantle a lot of our military or they have a death wish. That's how you get a full blown, no holes barred nuclear war. After the dust settled China would be able to walk in and take over Russia just for the asking if they wanted.

If you think something like this is going to happen, you might want to unplug your computer. Won't be able to run it for awhile, but at least you'll be able to run it when the power comes back up.

So in the end, if they did that they'd piss us off no end, but the part of the US which could destroy them will still be up and running.

[Tethis]

Thought of something else but I can't add it to my previous post.

In reality, I doubt someone would do an EMP attack on the US and leave it at that with the rest conventional. It makes no sense. A more likely scenario is it would be the first shot of a general nuclear exchange. The old fashioned World War III/End of the world scenario.

Unless we dismantled a big chunk of our military so they thought they could do that WITHOUT getting the same (or worse) done to them. But as it is now, that's not the case.

The US -- don't hit them. You'll just make them mad.

[Stark]

Entire human race held hostage to American pride = go joe!

Anyway, who thinks anything about Red Dawn is realistic? Its time people realised that America is just not in peril. Shall we take a stroll down Homefront memory lane? Could a backstory even get more dumb?

[Ahriman238]

Entire human race held hostage to American pride = go joe!

Anyway, who thinks anything about Red Dawn is realistic? Its time people realised that America is just not in peril. Shall we take a stroll down Homefront memory lane? Could a backstory even get more dumb?

I'm sure we could do worse backstories if we really worked at it. Besides, without constant vigilance against vaguely defined threats, how could we maintain our FREEDOMS?

But yeah, HEMP is something the US military, and I believe other NATO powers, are pretty well equipped to survive. If it comes up in discussions of military strategy, it's other nations complaining the US will HEMP them.

I seem to dimly recall recall the news featuring a story about Russia and/or China developing a super-EMP weapon that would fry even hardened electronics, maybe six or seven years ago. I haven't heard anything new about it since, so it probably didn't pan out.

[Simon_Jester]

Entire human race held hostage to American pride = go joe!

Anyway, who thinks anything about Red Dawn is realistic? Its time people realised that America is just not in peril. Shall we take a stroll down Homefront memory lane? Could a backstory even get more dumb?

Red Dawn was, so far as I know, intentional camp with a bit more sense of irony than much of its own fanbase- notice that it ends with the typical fate of a guerilla band, some modest successes against the occupiers who then get clever and slaughter the band with helicopter gunships.

The original was less dumb in that at the time the US was locked in a big staring match against an enemy that worked very, very hard to maintain a powerful military. The Soviets couldn't realistically have invaded the US barring alien space bats, but they at least had enough men under arms, enough organization and international scope, that the idea wasn't totally batshit a la Homefront.

Since then... the idea has, alas, just turned into an excuse to imagine dangers since the Cold War.

[Sea Skimmer]

Its wont do shit to all the US nuclear weapon systems which proceed to obliterate the enemy invasion force, and inflict similar wide area disruption to communications and power networks of whoever launched the HEMP nuke in the first place. This is why the danger of nuclear HEMP was never taken very seriously for anything but nuclear deterrence force weapons and early warning system.

For everything else, vulnerability depends on the details. The damage effects are kind of light a lighting strike from HEMP, except much more dependent on the antenna that conducts the waves into the vunerable object. Longer conductors are bad, coiled conductors, like a reel of cable, are really bad, buried cable is much better protected then wiring hung in the air. Surge protectors work to a point (power quality filters are also needed, in depth, for optimal protection), but the cable between the surge protector and the device can still absorb more energy unless specifically shielded. A device like a computer can also directly absorb some voltage. As that posted graph shows, the maximum absorbable voltage per area is variable with distance. It will also vary depending on the time of day and precise altitude of the burst, besides of course its yield.

End result though for a high yield attack is the high tension power lines are very vulnerable, and while the wiring is easy to fix, the transformers are not. Power could be out for years in low priority areas, though realistically people would be able to restore some level of distributed local power generation much earlier.

Few conventional weapons systems are specifically shielded against HEMP, except duel role manned bombers, on the other hand most of them are not exceptionally vulnerable either. All the more as at any given moment the vast majority are turned off (same story with lighting, it helps a lot) and not plugged in the power grid. So an M1 tank parked in a depot might have its radios damaged, while the engine still guns and the gun fires.

[Sea Skimmer]

Mind, if that looks bad consider that EMP has been a known problem since '45. Electronics can be hardened against EMP for some cost. IIRC, sticking them in a Faraday Cage will work in extremis, but don't quote me on that.

A faraday cage is ideal and required for a high level of protection, many nuclear facilities create one by welding together all the rebar in the concrete work and then grounding that. But most of the area affected by HEMP will be weak enough that the EM waves going directly into the device are not a serious problem, only those collected over power and communications firing and antennas are. This was the cause of almost all the damage in the historical tests which caused HEMP to be discovered in the US and USSR. So for considerable basic protection just turning the device off (increasing voltage needed for damage), and/or disconnecting it from long power and communications leads will do well. This requires warning. However HEMP voltage does not appear instantly, and some military electronics have shutoffs that automatically detect the rising voltage spike and shut down to avoid it.

Now if you want to be heavily protected while operating with little or no warning, then it gets expensive. First of all this you need preforations in the faraday cage to get that those power and communications lines in. Those holes have to be protected through metal baffles against penetrationand stuff radiating off the cable. basically the EM waves bounce back and forth down the baffle until they are absorbed.

Then you need surge protectors and power filters to absorb anything coming up the damn cables directly. The trick is, a high power pulse will actually reradiate harmful emissions back out of those protection systems! Thats also an issue concerning damage can be hard to predict. So anyway you have to go make another inner faraday cage around those protection systems, like having a double gate on a castle or whatever analogy, then place more filters behind that. This is nothing complicated to think about once you understand the basic principles, but it requires a lot of expensive detail work to implement, requires maintenance and because of volume requirements it can be near impossible to backfit to existing systems. End result is we just don't bother for conventional warfare systems because at least for now, the only way to make a high power wide area HEMP is using a nuclear weapon. So all that matters is making sure nuclear deterrence systems still work after such an attack.

If you have a large facility like a bunker, you also need to seal up all the gaps pesky humans need to use. So metal doors will have wire mesh edges that seal against a metal frame, air intakes will have copper mesh screens ect..

Also keep in mind, the protection of a faraday cage is actually not limited if it comes to high intensity nuclear attack, though this is more relevant for a bunker or hardened building like an early warning radar site that can survive very close to a nuclear bomb burst and such emissions fall under SREMP, as opposed to HEMP attack. But that depends on the HEMP of course. Yeild, locations ect, do the NOrth Korean hoards have a 25 or even 100 megaton bomb? At that point you may need multiple layers faraday cages and even more protection devices, particularly if your using the welded rebar method rather then a fine copper mesh. The later gets very expensive, very quickly. If money were no issue I think you'd just build the walls out of silver sheeting. Some nuclear facilities did use welded solid metal plates to make HEMP proof citadels.

Also if you go bury yourself underground, certain kinds of rock are vastly more effective then others at stopping certain electromagentic waves.

[Metahive]

Great, do we need any more wanking to the american self-victimisation fetish? I find it really grating the way the US are butchering people all over the globe while simultaneously going "O woe is us, o woe is us!".

How about we instead go down the path tread by Bush Jr. and Obama and look at a future America that's trying to violently gobble up Mexico and Canada? Mountie Dawn, now that's a new one!

[Metahive]

Mountie Dawn

It is the year 2022, the United Freedemocratic Republican States of America, unified under the ideology of Randian Plutocratic Christofascism are on the move. The ruling council of corporate fat cats that control Gault's White House and president Strings Pinocchio (who's a genetic experiment combining white, black, chinese, native american and martian DNA) of the Eternal Coalition Republicratic Party of the Independent People have decided they don't like the way the peasants up north put "eh" at the end of their sentences are all half-french half limey anyway. So they send F-9999 Superfreedomstarfighters north who obliterate the canadian military in microseconds. A long string of UFRSA M-001 Oliver North tanks (armed with depleted annihilation ammo made of dried infant tears) rolls northwards, followed by a billion of the UFRSA Rough'n'toughmanhandler Marines (motto "Semper Fuck Da Furrina") to secure Canada. The UFRSA Council of Scientific Truthiness declares all Canadians to be non-white, non-heteronormative, atheist, heretic abominations and only 2/5ths worth of a person who may be enslaved to dig precious oil out of the shales on the coast - with their bare hands. Reeducation Drones cruise hourly over all the country and desintegrate all nay-sayers with punishment death rays. In schools canadian pupils are bullied daily and dunked in toilets by the Glorious 50's Squad. The situation is dire, but a small and dedicated group of canadian mounties who were stationed somewhere in some remote corner have survived the wicked invasion and stage a counter-revolution.
They arm themselves with heroic weapons and heroic attitude, heroically and single-handedly fight their way through the occupied provinces to Washington DC, were they defeat president Pinocchio in his Megadeath Mecha and further on to Neo New Rapture York and the Wallstreet Palace of Forever Fortune and Wealth where they butcher the corporate fat cats with brass-knuckles made out of the bones of victims of UFRSA oppression. The day is saved and the UFRSA are defeated forever and then there's no more evil and misery on the world. The End

Yeah, that's more like it. Where's my Oscar nomination?

[Replicant]

Mountie Dawn

It is the year 2022, the United Freedemocratic Republican States of America, unified under the ideology of Randian Plutocratic Christofascism are on the move. The ruling council of corporate fat cats that control Gault's White House and president Strings Pinocchio (who's a genetic experiment combining white, black, chinese, native american and martian DNA) of the Eternal Coalition Republicratic Party of the Independent People have decided they don't like the way the peasants up north put "eh" at the end of their sentences are all half-french half limey anyway. So they send F-9999 Superfreedomstarfighters north who obliterate the canadian military in microseconds. A long string of UFRSA M-001 Oliver North tanks (armed with depleted annihilation ammo made of dried infant tears) rolls northwards, followed by a billion of the UFRSA Rough'n'toughmanhandler Marines (motto "Semper Fuck Da Furrina") to secure Canada. The UFRSA Council of Scientific Truthiness declares all Canadians to be non-white, non-heteronormative, atheist, heretic abominations and only 2/5ths worth of a person who may be enslaved to dig precious oil out of the shales on the coast - with their bare hands. Reeducation Drones cruise hourly over all the country and desintegrate all nay-sayers with punishment death rays. In schools canadian pupils are bullied daily and dunked in toilets by the Glorious 50's Squad. The situation is dire, but a small and dedicated group of canadian mounties who were stationed somewhere in some remote corner have survived the wicked invasion and stage a counter-revolution.
They arm themselves with heroic weapons and heroic attitude, heroically and single-handedly fight their way through the occupied provinces to Washington DC, were they defeat president Pinocchio in his Megadeath Mecha and further on to Neo New Rapture York and the Wallstreet Palace of Forever Fortune and Wealth where they butcher the corporate fat cats with brass-knuckles made out of the bones of victims of UFRSA oppression. The day is saved and the UFRSA are defeated forever and then there's no more evil and misery on the world. The End

Yeah, that's more like it. Where's my Oscar nomination?

Angry much today? Whats wrong? Did you get interrupted during your morning jerk-off session?

[Metahive]

No, just describing what kind of impression those american self-victimization fetish movies leave on me and turning them around for demonstrative purposes.

Not that you would understand, trailer trash.

[bilateralrope]

Detonating a multi-megaton nuclear bomb at a couple hundred kilometers altitude would probably have a huge effect on the civilian power grid.

What sizes of nuclear weapons are likely to be used in any nuclear war ?

Would it be more effective to use those nukes to generate HEMP, or to use them to blow stuff up with the EMP just being a side effect ?

[Simon_Jester]

Depends on who's shooting; a multi-megaton bomb more or less has to be the single payload of an entire heavy ICBM. Small nations like North Korea and Iran are going to have trouble making fusion bombs, or big enough rockets.

With modern guidance, it is usually more effective to deliver a 200 kiloton or so warhead right on the target than a 20-megaton bomb somewhere in its general vicinity; this is why the yields of the heaviest active US missiles and nuclear bombs have dropped by about an order of magnitude from their 1960s peak. This does not mean someone couldn't build and field ten or twenty megaton warheads feasibly, say to crack open heavily fortified places like Cheyenne Mountain, or to cause extremely broad devastation with high-altitude airbursts. But it's not likely to come from the nations most likely to launch on the US in the next few decades.

[Tethis]

Detonating a multi-megaton nuclear bomb at a couple hundred kilometers altitude would probably have a huge effect on the civilian power grid.

What sizes of nuclear weapons are likely to be used in any nuclear war ?

Would it be more effective to use those nukes to generate HEMP, or to use them to blow stuff up with the EMP just being a side effect ?

Use a few big ones for the EMP. Use the rest to blow stuff up. If you're really going to launch an attack like this, your smart move would be to use the rest to kill as many of the US nuclear weapons as you can, because it's a sure bet the ones you don't get will be used on you. EMP won't get you any of those nuclear weapons. And you really really want to get them. That's why suvivability has always been a big deal in US war planning.

There are a few other things which are possible, but probably not worth diverting weapons from killing US weapons, which you have to do if you hope to live through it (if you're the attacker that is).

That EMP can only take you so far. And that's not very far.

Nuclear weapons come in all sizes from a few kilotons to a few dozen megatons. I think one of the old Soviet missiles had about a 20 MT warhead which would have probably been the biggest that would have been used on either side. Much bigger have been made (USSR detonated a 57 MT one in 1961, the biggest ever) but I doubt you'd see many. Some of the biggest would go towards that EMP though. I think the yield of the warheads in the US Minuteman III were in the hundred kiloton range. I suspect the Peacekeeper would have had bigger warhead(s) but I don't know what. Typical yields of Soviet ICBMs were a megaton or so. Tactical nukes would typically be a few kilotons. I don't know if Russia still has that ABM system around Moscow but that probably has/had a nuclear warhead -- I doubt they'd be able to do straight hit to kill (no warhead, just ram the thing at several miles per second) like the US can do. If they were intended to intercept incoming missiles in the atmosphere (endoatmospheric) the yield would have been small -- maybe 5-10 kilotons. If intended to intercept outside the atmosphere (exoatmospheric) it would have been in the megaton range.

Ironically, one way you can tell if a country is seriously considering a first strike, is by what they defend. If they defend missile silos it's because they expect they would have to absorb someone else's first strike. If they defend cities, they know that by the time missiles are headed towards them their own missile silos will be empty since the missiles would have been used in that first strike.

And if you're going to defend you WILL have to absorb that first strike. Launch on warning is for reckless fools. (although some presidents liked to leave that in doubt none actually said they'd do that for sure. Thankfully.).

Of course, there's another possability. Depending on the trajectory, and if they identified it for what it was before it detonated (as opposed to say, thinking it was a satellite launch) the US might be able to shoot the thing down before it detonated. That might actually be the best outcome for everyone. If no damage has been done up to that point, and if the president doesn't go nuts and order an immediate strike, it might give the attacker a moment to rethink and ask themselves if they really want to go through with it after seeing their opening shot get killed. Might give a chance to avert the whole mess. Maybe. At that point you're dealing with the mindsets of basically two people. The US president and whoever is running the other side. But at least there would be a chance to call it off.

[amigocabal]

Detonating a multi-megaton nuclear bomb at a couple hundred kilometers altitude would probably have a huge effect on the civilian power grid.

What sizes of nuclear weapons are likely to be used in any nuclear war ?

Would it be more effective to use those nukes to generate HEMP, or to use them to blow stuff up with the EMP just being a side effect ?

The latter.

That is why until recently, there has not been much concern with figuring out how to shield civilian infrastructure from EMP, when dealing with blasted cities and fallout would make EMP a minor inconvenience.

(Of courser, I do wonder if there are cosmic sources of EMP which would require us to deal with the issue directly.)

[Sea Skimmer]

Solar flares have effects similar to some aspects of EMP, but we already have satellites that can provide early warning and allow key systems to be turned off. Its been talked about on and if more effort should go into hardening, the main concern being destruction of power transformers but the costs involved are very high. The transformer issue is a big deal because even disconnecting the transformers may not be sufficient protection, and enclosing them would be more expensive then just buying a stockpile of replacements. Were talking the really big transformers, ones that weigh 500 tons.

The source region EMP generated by an atmospheric nuclear explosion is only a concern for systems which can withstand several psi of blast pressure without serious damage; oh and everything being set on fire by the thermal pulse. Back in the day, the entire backbone of US telephone system was protected against SREMP and a serious amount of blast, like 30psi, but the shift to fiberoptics and satellites saw the AT&T long lines systems scrapped.

[Tethis]

Actually, there are three regimes of nuclear explosions (well, more then three but three for the purposes of this discussion).

Only high altitude explosions at altitutdes of, say ~200 km do the continent wide HEMP we were talking about. It MUST be at high altitude or it won't generate the effect.

For a burst at relatively low altitude, but still above the ground, relatively little EMP is generated even if it's with the exact same warhead as the continent wide HEMP burst, just lower altitude. It might still be enough to mess up completely unprotected electronics but I"m not even sure about that. Incidentally, there are other ways to design electronics against EMP then putting them in Faraday cages which isn't always possible (such as anything which needs to be connected to an antenna).

Ground bursts generate a lot of EMP but only in a localized area.

Most likely the 200 km high burst would only happen if deliberately set off to generate EMP. As already discussed, a few very high yield warheads might be set off like that in the opening stage of a major war.

A burst in the atmosphere (an airburst) is the way a city would be attacked. Also other soft targets. The way the altitude is determined by the attacker has nothing to do with EMP. It has to do with maximising the effect of the shock (i.e. blast) on the city as shock causes most of the damage. This produces much less EMP. While the thermal pulse (the thing which sets fires etc.) will certainly cause a lot of damage, it's thought that the shock wave which follows will do must of the damage.

A ground burst is typical of something used to kill a hardened site such as a missile silo. This will also generate a lot of EMP but only in a very localized area. Not even close to the continent spanning scope of the high altitude EMP, although in the area close to the blast it would be pretty intense. Although that only matters to whatever's inside the silo since everything outside is going to get blown away. Incidentally, ground bursts are by far the worst culprits for generating fallout due to neutron activation of the rock, soil, etc. (Air, specifically oxygen and nitrogen, doesn't activate well).

The key dividing line between a ground burst and an air burst is if the fireball touches the ground. The fireball is an area of extremely hot air generated by the detonation. The shock is started at the edge of the fireball and spreads out from there. The fireball eventually rises (hot air rises) and forms the crown of the characteristic mushroom cloud (the stem is typically debris which is swept up -- not all airbursts have a visible stem). (incidentally, you don't need a nuclear explosion to form a mushroom cloud -- watch the blasts in your typical action movie with stuff blowing up -- miniture mushroom clouds. Nuclear explosions just make bigger mushroom clouds).

The reason an airburst generates little EMP while a ground burst generates a lot is because EMP in that case is generated when you have plasma expanding which isn't spherically symmetric. In an airburst it's very close to a perfect sphere when it's doing it's expansion so there's little EMP. The ground stops a fireball's expansion in that direction so there's a lot of asymmetry hence lots of EMP.

[Sea Skimmer]

Actually, there are three regimes of nuclear explosions (well, more then three but three for the purposes of this discussion).

Umm, no. If it explodes over about 40km altitude you get a wide area HEMP, which is generated in the 20-40km altitude band. If it bursts much below this altitude you will only get a source region EMP, the exact range of which will depend on the exact altitude and weather conditions, but it won’t be any further then the destructive blast wave goes and does not involve magnification via the earths magnetic field. No distinct third regime exists.

Incidentally, there are other ways to design electronics against EMP then putting them in Faraday cages which isn't always possible (such as anything which needs to be connected to an antenna).

Interestingly I already addressed that.

[Tethis]

A few of the altitude regimes I was thinking of.

0 Ground burst, which I discussed. Relevant when discussing side effects of just using nuclear weapons to blow stuff up. Localized EMP. The intent of such a burst is to kill something by very strong blast wave which has nothing to do with EMP.

>0, <~25 km (depending on yield) usual low altitude burst. Same kind of relevance. Lower end of this regime relevent for blowing soft targets up. Again, EMP is not the intent of such a burst.

>~25 km, < 90 km MUCH greater thermal pulse. more EMP etc. due to greater assymetries. If at night likely to cause permanent retina damage to people who happen to be looking at the burst over hundreds of miles. (all above ground nuclear explosions -- especially low yield ones ironically can cause eye damage, but this altitude regime is much worse then others). Detonate enough stuff in this regime and you can cause fires on the ground over many hundreds of miles. All of these also cause things like disruption of the ionosphere etc.

>~ 90 km. <~ 120 km more of the above. ever increasing effects like disruption of the ionosphere, not just EMP.

>120 really classic HEMP.

The US has detonated several bombs in all these altitude regimes up through the early 60s. Starfish Prime in particular is the most relevant (400 km). Google Starfish Nuclear Test, Starfish Prime or somesuch. I agree that all of them generate EMP and other kinds of interference, but you get to those altitudes it appears to get much worse.

Wikipedia has a summary of the Fishbowl tests (of which Starfish was one). It's pretty obvious from the description that Starfish generated a much larger EMP then any of the other lower altitude tests. Not only that but it also killed or greatly reduced the lifetime of several satellites then in orbit including Telstar, the first active communications satellite.

While the details are classified, notice in the description, that the incidental EMP damage was getting worse at higher altitudes. More incidents with Kingfish and the most with Starfish.

I agree that all of them generated high altitude EMP. So I guess it's a matter of definition. But if you're out to generate the biggest EMP you can over as wide an area as you can, you go for something more like Starfish as opposed to something lower.

There's a lot of declassified information on this stuff on the Internet nowadays which anyone can find if they use Google for a few minutes. Anyone reading this board can certainly do likewise. I mentioned actual data from real tests. There are also calculations. It looks like Ahriman238 posted one (hopefully unclassified). From the description of electrons spiralling along the magnetic field, this must be for a high altitude detonation (hundreds of km altitude) since if it were lower altitude (say 50 km) collisions with air molecules would have kept many from spiraling like that. Once a detonation gets high enough interactions with the Earth's magnetic field cause all sorts of effects not seen at lower altitudes.

One last thing, to directly answer the OPs question, I think the plotline is not very plausable in my mind if that EMP burst was the only one. You don't start World War III and then launch a single nuke. The fact that military hardware wouldn't be that effected doesn't help plausibility. I didn't see the movie so I don't know the altitude it was supposedly detonated at, but if it was <100km that would reduce the realism even more since if you're going to go for the EMP, that's not the way to go about it.

About the terminology. There are many types of EMP. I've long since forgotten all of them (years ago I worried about such things but that's in the past). HEMP is only one of many. I've just been calling everything EMP, but what ground bursts emit is not called HEMP. Can't recall the name. The key point is they all generate a fast initial pulse which can mess up unprotected electronics.

I don't want to get into a flame war, so I think I"m going to leave it at this. I don't plan to come back to this thread. If you want to say that something at 20 km creates as much EMP as something at 200 km be my guest. It would be wrong, but be my guest. I've done what I could to set the record straight but I"m not going to keep beating a dead horse.

[Sea Skimmer]

Wikipedia has a summary of the Fishbowl tests (of which Starfish was one). It's pretty obvious from the description that Starfish generated a much larger EMP then any of the other lower altitude tests. Not only that but it also killed or greatly reduced the lifetime of several satellites then in orbit including Telstar, the first active communications satellite.

Gee, maybe it generated much larger effects because it was a much higher yield warhead. Did you think about this at all? Your talk of intent means not a damn thing as far as weapons effects go. Not unless you go out of the way to redesign the weapon to be HEMP focused anyway, which none of the historical tests were and I doubt you are aware is even possible. Given your inability to read basic data present on your own link to freaking wikipedia, I'm not holding out much hope for you. Finding information, yeah easy, apparently for you reading and understanding it is a complete fail.

[weemadando]

Entire human race held hostage to American pride = go joe!

Anyway, who thinks anything about Red Dawn is realistic? Its time people realised that America is just not in peril. Shall we take a stroll down Homefront memory lane? Could a backstory even get more dumb?

Yes. http://www.amazon.com/Invasion-Eric-L-H ... 0515128422

CHINA INVADES VIA THE CARIBBEAN.

[The Disintegrator]

First off, a disclaimer; I have not seen the Red Dawn remake, so my entire knowledge of its plot comes from wikipedia.

For the sake of having an invasion scenario to begin with I was willing to just accept the idea of North Korea landing an army on the continental US. This would have been much more plausible if they'd stuck with the original premise of a Chinese invasion, which was then changed to avoid offending the Chinese market. Truth be told, I can't imagine many Chinese went to go see Red Dawn regardless of the changes, but whatever.

The thing that I found most implausible was the MacGuffin of the EMP resistant phone. Maybe its just me, but it seems a little ridiculous that there isn't a single method of communication left in the US that would enable the military to contact its forces overseas. Really, there has to be something that will work. I'm sure if we really had to we could send a carrier pigeon to Mexico with a message for them to pass on to CENTCOM. Almost anything would have been easier than trying to steal a phone from the invading army and hoping that you can get the thing to work. But I suppose having a gang of high school students change the course of a major war between major powers requires a ridiculous solution. What was nice about the original Red Dawn was that the final battle scene wasn't some over the top plan to win the war. It was merely a distraction to allow the rest of the Wolverines to escape to safety.

Maybe the original Red Dawn wasn't 100% plausible, but it was way closer than the remake was.

[Simon_Jester]

Unfortunately, since the 1980s we've started typecasting most action movies as the "summer blockbuster," and on a summer blockbuster you're basically forced into over-dramatic plots- a summer blockbuster has to have a hero for a protagonist, not just a Joe Average caught up in the middle of a larger story.