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Background:

In a setting similar to Roadside Picnic, non-man-made objects termed 'emitters' produce a periodic 'zone effect' of induced current, similar in effect to an EMP. This zone effect falls off in intensity over distance, and has a variable maximum strength depending upon the properties of the emitter itself.

The exact mechanism of action is unimportant and does not necessarily need to be an EMP; the intended effect is randomly induced current. Depending upon intensity, the result of exposure to zone effect ranges from minor computer errors to death from induced current in the brain.

Problem:

What I'm trying to figure out is a logical progression of EMP-like effects between those two extremes. To try to qualify it, I've broken the effects down into a series of levels to generally describe the effects at varying levels of intensity.

As a rule of thumb, I'm broadly characterizing electronics technology as 'simple' (vacuum tubes, basic circuits), 'complex' (transistorized, simple PCBs), and 'advanced' (microprocessor-driven). This is a gross simplification to characterize varying resistance to EMP-like effects.

The progression I have at the moment goes like this:

Level 1: Advanced electronics experience abnormal behavior. Bob's phone is restarting randomly.

Level 2: Advanced electronics temporarily stop functioning. Complex electronics experience abnormal behavior. Bob's phone won't turn back on, and now his radio is emitting random static, and the signal keeps fading in and out.

Level 3: Advanced electronics permanently burn out. Complex electronics temporarily stop working. Simple electronics experience abnormal behavior. Bob's radio has cut out entirely, and his flashlight is flickering.

Level 4: Complex electronics permanently burn out. Simple electronics temporarily stop working. The flashlight gives out. Nothing with a circuit is working.

Level 5: All electronics permanently burn out. The human brain starts to experience interference, manifesting as hallucinations and dementia. Bob sees things in the corner of his eye that aren't there when he turns to look. His cognition is slow, and his head hurts.

Level 6: Rapid incapacitation followed shortly by death. Bob falls unconscious and is dead within minutes.

Question:

Does this represent a plausible progression of effects due to increasing intensity of an EMP-like phenomenon? If not, how can it be altered to be more consistent with the effects of induced current in the real world?

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  • $\begingroup$ Almost every reasonably complex appliance you're likely to come across today is microprocessor-driven. That radio with a digital frequency readout or momentary-touch buttons for control (let alone touch control)? Almost certainly a CPU or more likely a microcontroller at its core. A moderate-vintage heater (kitchen stove or radiator) is likely to fit into your "complex" category. Any LED light definitely will. I'm not saying this invalidates, or for that matter confirms, your scenario; but it's something you will want to keep in mind if you want the effects to be realistic. $\endgroup$ – a CVn Aug 29 '17 at 17:42
  • $\begingroup$ @MichaelKjörling That's a valid point. One aspect of the context I didn't mention is that it's intended to be set in a developing nation, so there's more of a mix of technological levels than the everything-has-a-microprocessor standard of contemporary consumer tech. Plus, once the effect is understood, I would expect expeditions into the affected area to bring simpler electronic or purely analog gear whenever possible. Still, you have a very good point- off-the-shelf first-world consumer technology is going to be basically useless in an EMP-prone environment. $\endgroup$ – Catgut Aug 29 '17 at 18:23
  • $\begingroup$ I don't think that line of reasoning holds. There would be very little reason for a developing nation to use inferior, difficult-to-obtain technology with little application outside their borders. Taking vacuum tube tech vs solid-state, the former is hugely more power-hungry for the same or less useful results. Compare ENIAC with a modern-day smartphone. (Granted, ENIAC had other things going against it too, but look at some metric like, oh, I don't know, watt-hours consumed to calculate the square root of a number?) If anything, a developing nation would be incentivized to conserve power. $\endgroup$ – a CVn Aug 29 '17 at 18:26
  • $\begingroup$ @MichaelKjörling I'm not sure I follow. Having spent quite a bit of time in sub-Saharan Africa I can tell you for certain that there is a prevalence of decades-old consumer technologies in less developed nations. It's not a matter of going out of their way to get older, less efficient tech, it's more about using what they have, especially when they can't always afford or procure the latest and greatest. For a well-funded foreign expedition, that may not be the case, and if they're aware of the risks then logically they would seek out less vulnerable tech, right? $\endgroup$ – Catgut Aug 29 '17 at 18:54
  • $\begingroup$ An EMP effect over electronics would go from working as intended to irreversible damaged once the resistance threshold for only one component inside the circuit is reached. Since devices for normal consumers aren't design with the concept of redundancy. $\endgroup$ – Tridam Aug 29 '17 at 19:23
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The general pattern you have is sound, but you may be able to make it more accurate by accounting for what is actually happening when these pulses occur. If you have these in mind while you're writing, you'll be more inclined to give more interesting and vibrant effects rather than simply looking at a level of damage. For example, you might have some users notice issues quicker because the kind of thing they are doing magnifies the visibility of the lower level errors.

One fun detail you may want to pay attention to is that EMP is typically approached in terms of voltage, rather than current. We know the two always go hand in hand, but their relationship varies. In practice, it proves more reasonable to write the equations in voltage terms. For the rest of this, I'll assume that when you said "random current" you meant "random voltage," just for my own sake.

EMPs don't magically destroy electronics. What they do is expose electronics to environments that they may not have been speced to. The most common damage can EMP can do to electronics is to flip a bit. In our memory circuits, we carefully design them to hold onto little tiny charges to represent the 1's and 0's in our computer. By our designs, a 1 charge should never spontaneously change to a 0 charge. That would lose information. However, the designs typically assume a very low electric field around the chip. In an EMP, that field can get very high, and can induce voltages that actually change the charge on these little memory units.

The result is a spurious glitch. What that means is very much dependent on the software that's running. If the glitch is in the middle of the memory representing a video file, there might be a tiny flicker of an artifact generated by this corrupted bit, and no further issues. However, if the glitch is in the middle of something important, like operating system code, the results can be catastrophic. This generates a slow progression to what you labeled as level 1 and level 2. Some things are more affected by EMP than others. Often rebooting a machine fixes the problem because the media holding the data (like a hard drive) is more resilient to these fluctuations than the RAM, so the version on your hard disk is still pristine.

Eventually, as you raise the strength of the electric field, we see a different kind of effect, associated with levels 3 and 4. As you provide increasingly out-of-spec electric fields across the chip, it becomes possible to not only unintentionally flip bits, but to indeed cause current to flow in directions current wasn't supposed to flow. The insulator layers on many devices are very thin, and can easily be punched through by enough voltage. This is what permanently disables a device. As a general rule, the smaller the features on the device, the easier it is to disable, which is why you see a progression from levels 3 and 4 into 5.

As you start pushing into what you called level 5, we start looking at macroscopic effects of these electric fields in air. These electric fields are measured in V/m, and as they start to approach 33kV/cm, they start to approach the breakdown voltage of air, causing arcs between any two objects. This effect can be magnified by wires, which make it easy to quickly tie together 2 points in space with dramatically different voltages.

As for the failure of humans, that's much more complicated. It's known that high EMF can cause nausea, but in general we still don't understand all the things it does. A list of examples can be found on this site. Needless to say, humans degrade more gracefully than computers, so you can expect a much smoother process of degradation as the strength increases.

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    $\begingroup$ Two nits. (1) Bit flips in RAM don't "lose" information, they "corrupt" information. As you say, the effects of such corruption will vary. Much RAM is used in practice as cache, in which case it might not be noticed at all. Worst case is typically a system crash, as the system tries to make use of invalid code or data, but of course longer-term effects could be seen as well, particularly if corrupted data is persisted. $\endgroup$ – a CVn Aug 29 '17 at 21:01
  • $\begingroup$ (2) Some systems have ECC RAM, which allows for detection and in some cases correction of bit flips in RAM. Such systems typically handle single-event upsets (SEUs) better. OP could use that as a plot device, with some systems faring noticably better than others. ECC RAM is more common in environments where interference may be expected; you might expect to see a car-internal computer to use ECC RAM, but the average home or office PC won't. Servers most often do have ECC RAM. $\endgroup$ – a CVn Aug 29 '17 at 21:01
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    $\begingroup$ @MichaelKjörling I was using "lose information" in the information theory sense. You had information about something, and now you do not. That being said, you bring up a good point about ECC RAM. There would definitely be a visible difference in survivability between computers with ECC RAM and those that do not have it. I hadn't thought about cars using it... that would definitely create a flavorful distinction as the EMPs get worse, and the cars survive longer than other devices. $\endgroup$ – Cort Ammon Aug 29 '17 at 21:07
  • $\begingroup$ "I was using "lose information" in the information theory sense." Fair enough. "I hadn't thought about cars using [ECC RAM]..." A typical car is very noisy in RF. (Spark plugs, for one thing!) I suspect this would be mitigated with RFI-tolerant components, and ECC RAM with scrubbing at short intervals would be one of the easiest things to do that would help reduce susceptibility to RFI in the computers in a car. Of course not all computers in a car might use such techniques; I'd expect something like an entertainment system to be more susceptible than the engine control unit. $\endgroup$ – a CVn Aug 29 '17 at 21:14
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EMP is defined as a pulse, but we can ignore that. EM works as you describe, but it is a feeble effect. About 1955, the army used to send a half million watt radar unit to the county fair here, a tightly focused beam, and it only caused a buzz in the radio station's live coverage. On one occasion a news photographer's pack of flash bulbs were all ignited, so the army reduced the power to avoid PR disasters. So if your source has a half million watts of power, maybe you can set off a few old fashioned flashbulbs.

What you are talking about is a microwave oven. Your microwave runs only a thousand watts or so, and it is able to generate sparks in small conductors (such as a thin bit of plastic) or thin conductors in integrated circuits. But even in that case you only get damage in a very small space.

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