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efreysson
01-10-2019, 11:58 AM
I am hammering out a sci-fi setting, including the details of how combat works. The thought occurred that melee weapons would still have a place, as tools for shutting down powered weapons would be fairly commonplace, so a gunfight might degenerate into a knifefight. Pirates would also have means of paralysing a ship's engine before boarding it.

So, how exactly does an EMP work, why does it shut down electronics, and can I somehow semi-justify one being produced by a futuristic beam weapon or special grenades? And could one theoretically design an electrical system that isn't immune to an EMP, but does recover after a little while rather than being destroyed?

Al X.
01-10-2019, 03:15 PM
What an EMP does is cause a current in conductive metallic objects through induction. There are lots of devices that generate or use inductive current, but an EMP pulse is extremely strong, and foreign, and can overcome many electrical devices' protections against overloads. The more sensitive the electronics, the more affected by an EMP. An electrical distribution grid might be okay. Some of the transformers and switchgear may not. A 1968 VW Beetle might survive. Your 2014 Escalade will be toast beyond salvage.

I read an interesting fictional novel not too long ago that explored just that. It wasn't Sci Fi, just a what if scenario.

lizmonster
01-10-2019, 03:22 PM
I am hammering out a sci-fi setting, including the details of how combat works. The thought occurred that melee weapons would still have a place, as tools for shutting down powered weapons would be fairly commonplace, so a gunfight might degenerate into a knifefight. Pirates would also have means of paralysing a ship's engine before boarding it.

So, how exactly does an EMP work, why does it shut down electronics, and can I somehow semi-justify one being produced by a futuristic beam weapon or special grenades? And could one theoretically design an electrical system that isn't immune to an EMP, but does recover after a little while rather than being destroyed?

It's been some years since I researched this, but EMPs are actually easy to design around, to the point that I'd hesitate to use it this way in an SF book. It's done in the movies a lot for great dramatic effect, but in truth any combat situation where the enemy has the ability to generate them at will, your heroes are going to look drastically unprepared if they swan into battle without any defenses against them at all.

I'm on mobile ATM and can't google, but based on my memory: EMPs can have different sources and varying intensities. Many won't disrupt electronics at all, or will have unoredictable effects, and the hardware won't be damaged. Something stronger, like a nuclear blast, will have a radius of influence, but even there it's not necessarily the EMP causing the destruction, and in some cases the effects will still be temporary.

The TL;DR on EMPs is they're not a magic shutdown-all-electronics weapon, and you want to study your science before using them as such in a story. You can get away with it if you design your tech properly and have reasons people haven't proofed against them, but at this point most SF readers would notice if you get it wrong.

Bing Z
01-10-2019, 05:56 PM
I am myself researching EMP and can't provide much insight.

But since you are thinking about resorting to melee combat after ranged weapons fail, I am assuming you are thinking along the line that all guns are beam (energy) weapons. I have a discussion with a friend the other day, and my conclusion was that ballistic weapons, like handguns that utilize gunpowder to fire bullets, will still be in use in space opera era. (Energy weapons don't need ammos, but ballistic weapons don't need bulky batteries that dry up often.) Anyway, ballistic guns rely on chemical reactions and are immune to EMP (advanced features like auto-aim may, but the basic function will not). So you will need to craft a scenario to eliminate these 'antiquated' weapons. Or someone has an antique gun as memorabilia that will be used to turn the tide in the climax.

As for futuristic beam weapons in space battles, I think their effectiveness is overestimated. According to science nerds (http://www.projectrho.com/public_html/rocket/spacewardetect.php), space battles are likely to be fought from millions of miles/kms apart. As fast as light beams are, it will take them a while to arrive at the targets, which may have moved a few kms away by then. And light beams can't turn. So chances are the gunner will have to guess (based on trajectory) the enemy's projected position in a few minutes before pulling the trigger. OTOH, you (or your pirates) can use an ultrafast missile armed with active sensors to chase down and hit the victim's ship, and upon striking the hull, generate EMP burst (or sleeping gas) from inside--if the victim ship hasn't disintegrated yet ^_^.

lizmonster
01-10-2019, 06:44 PM
As for futuristic beam weapons in space battles, I think their effectiveness is overestimated.

Not to derail too much, but this is one of the things I think The Expanse (TV show) does quite well. There's a lot of waiting involved until you get up close, and then you're shooting actual solid projectiles at each other (which gets very messy!). I haven't fact-checked their work, but I do know they have a reputation for working to get the science right, so it might be a place to start.

Bing Z
01-10-2019, 07:15 PM
Not to derail too much, but this is one of the things I think The Expanse (TV show) does quite well. There's a lot of waiting involved until you get up close, and then you're shooting actual solid projectiles at each other (which gets very messy!). I haven't fact-checked their work, but I do know they have a reputation for working to get the science right, so it might be a place to start.

Yes, that's true. I especially like how they tackle artificial gravity.

As for the waiting game, I also concur. Space warfare is actually quite like submarine warfare. Everyone tries to hide their existence, while silently searching for the enemies. There are three stages in engagement:

a) Detection - you detect something out there, say 100 million km away. You don't know what or who they are. (This stage is to the pirate's benefit. They know whoever they are, it is either an enemy or a target, never a friend, so 'load your weapons and sharpen your axes, boys.')

b) Identification - say, at 50 million km away, you identify them. You know who they are. "OMG, it's the pirates, what do we do now?????" or "Hey, it's a Cinderella class cruise. Unarmed. We're gonna be rich!!!!!"

c) Targeting - say, at 10 million km away, the pirates have resolved the target's coordinates. Their weapons system has the cruise locked. They are ready to fire at the target.

It could be a few minutes or a few hours from a) to c). Meanwhile, the prom queen on the cruise may decide to marry the broke janitor (who is trying to sell his antique gun without success) before she dies (or gets kidnapped or abused) and the captain may have succumbed to pressure & anxiety, leaving the cruise in total chaos.

efreysson
01-10-2019, 08:23 PM
So you will need to craft a scenario to eliminate these 'antiquated' weapons. Or someone has an antique gun as memorabilia that will be used to turn the tide in the climax.

My way around this logical issue is that future body armour has an easy time of stopping solid projectiles.


As for futuristic beam weapons in space battles, I think their effectiveness is overestimated. According to science nerds (http://www.projectrho.com/public_html/rocket/spacewardetect.php), space battles are likely to be fought from millions of miles/kms apart.

I know. But I'm going with fun, retro space fantasy la Star Wars. But I do concern myself with internal logic and I want to avoid using a real-life issue in the wrong way, which is why I created this thread.

ironmikezero
01-10-2019, 09:40 PM
For a pragmatic perspective on EMP, check out this link . . .

http://www.futurescience.com/emp/emp-protection.html

Thomas Vail
01-12-2019, 03:21 AM
So, how exactly does an EMP work, why does it shut down electronics, and can I somehow semi-justify one being produced by a futuristic beam weapon or special grenades? And could one theoretically design an electrical system that isn't immune to an EMP, but does recover after a little while rather than being destroyed?
Hardening a system against EMP is not hard to do. As is mentioned above, how it disrupts electronics is that suddenly you have things conducting electricity that aren't used to conducting energy in that amount and direction. Beefier construction, ability to dump current overloads, discharge channels or grounding to try and route it somewhere safer, etc. et. al. If the setting makes it easy to do something offensively, then people are going to be working very hard to find defensive counter measures against it. A 'lightning' beam or an emp grenade would both be eminently plausible ways of generating an EMP in most sci fi settings.

And of course, much like Mr. Grenade when the pin is pulled, EMP is nobody's friend. Something as directed as a lightning gun might be safe for the firer, but the hypothetical grenade will not. The user might be using equipment that is appropriately hardened to be generally safe from whatever EMP weapon they're using, but if they have protection from it, it stands to reason that their opponents might have equivalent or some other form of compensation as well.

Wesley_S_Lewis
02-04-2019, 03:29 AM
This thread is a bit old, but I spent a lot of time researching this many years ago, so I'll share my understanding of electromagnetic pulse (EMP).

A classic electrical generator works by passing a magnet around coils of wire, thereby aligning the electrons in the wire and creating an electrical current. An electromagnetic pulse basically operates the same way: A wave of electromagnetic energy travels at the speed of light, creating an electrical charge in any metal it passes. The larger the metal, the larger the charge.

On earth, this can cause problems in a couple of ways. First, our electrical grid is thousands upon thousands of miles of electrical wire, which means that an EMP from space (either from a solar flare or from a nuclear blast) could create a massive overcurrent in these wires, which would fry pretty much anything connected to the grid (e.g., anything plugged into a wall outlet). Second, solid-state electronics (i.e., semiconductors) are extremely sensitive to overcurrent (that's why a new hard drive comes in a static-proof bag that includes a warning about grounding yourself before opening the bag). The small amount of overcurrent an EMP could potentially cause in the circuits and connecting wires of solid-state electronics could be enough to fry the electronics. That's why an EMP can theoretically fry your cell phone even if it isn't plugged into a wall at the time.

One of the things that determines whether a certain device is affected by an EMP is the wavelength of the EMP. (NOTE: This is where the subject gets far enough from my own limited education on the matter that I have only the flimsiest grasp on the material.) This is my understanding: An EMP from a powerful solar flare would have a long enough wavelength that it probably wouldn't affect solid-state electronic devices not plugged into the grid (but probably would affect the grid and anything plugged into it). On the other hand, a nuclear detonation in low Earth orbit would create an EMP with a much shorter wavelength, which very likely would impact many solid-state electronics not plugged into the grid (e.g., your cell phone).

There are two ways of defending against an EMP: shielding and hardening. Shielding is relatively simple; hardening is relatively complex. The simplest form of shielding is a Farday cage, an enclosure of highly conductive material (i.e., some sort of metal) around the device you want to shield. When the device is completely encased in a highly conductive material, the electrons inside the enclosure will realign themselves to neutralize the effect of the electromagnetic wave outside the enclosure. This type of shielding is pretty simple if your goal is to protect a bunch of hard drives that contain redundant backups of important government records. However, this isn't really an option if you want to protect an F-35 fighter jet.

If you want to protect something that can't be encased (e.g., a fighter jet), the problem gets a lot more complex and (as I understand it) involves high-speed circuits designed to redirect the overcurrent away from sensitive circuits. (NOTE: This is way above my area of expertise, so this is as detailed as I can get without just talking out of my hindquarters, which I hope I'm not already doing.)

I believe you can protect a running computer with a combination of shielding, hardening, and grounding (the computer itself is shielded with a grounded Faraday cage, and the power and network connections are hardened), but as I said before, this is a complex process that I don't fully understand.

One thing to keep in mind about EMP is that when an EMP fries a circuit, that circuit is dead; it doesn't come back on after a few minutes like in Ocean's Eleven. Also, an EMP affects electronics plugged into the power grid and solid-state electronics; it doesn't affect simple internal combustion engines (e.g., lawnmowers, chainsaws, most motorcycles, and old cars) or simple circuits like flashlights and electric toothbrushes (though, a powerful enough EMP might fry the "bulbs" in LED/CREE flashlights, but again, that's beyond my area of expertise).

I believe it is possible, however, for an EMP to be powerful enough to disrupt a computer but not actually fry the solid-state circuitry (though I'd think this would be a very fine line to walk). One of the things debated about an EMP from a high-altitude nuclear detonation is whether it would knock out automobiles that contain solid-state circuitry (which most cars built since about 1980 do). It's difficult to replicate the effect of an EMP from a high-altitude nuclear blast, but the testing that has taken place has demonstrated mixed results (some cars work, some don't), and it has been claimed that some of the cars that stopped working were later restarted by disconnecting the batteries and allowing the onboard computers to reset.

There are several competing schools of thought on how devastating an EMP attack utilizing a high-altitude nuclear blast would be. Some people argue that such an attack against the U.S. would knock out all communications and transportation within the country and result in the deaths of 90% of Americans (mostly from starvation) within the first year. Others argue that the primary damage would be to the power grid and that, although devastating, the attack wouldn't be nearly as devastating as theorized in the aforementioned worst-case scenario.

How this translates to science fiction, I can't honestly say, but I hope this information is helpful for anyone researching the topic.