In this question, I asked what would happen if a supernatural EMP hit an urban-fantasy Earth. The answers pointed out a flaw in my assumption: an EMP, supernatural or otherwise, would not likely have the effects I need. Oops!

Therefore, assuming a modern urban fantasy setting (thus, the world is "ours" in the present time, with the known continents, cities, technology, and general environment), what kind of singular event could do all the following, without also wiping out life as we know it?

a) Disable or destroy all manmade satellites (and thus a lot of communication);

b) Take down the power grid for weeks;

c) Render communication via cell phones and computers virtually impossible for the forseeable future;

d) Other effects optional!

Assuming my bad guy successfully triggers this event, whatever it is, what would be the effect on the following systems in particular?

a) How would cars - from old, non-computerized models up to the Tesla - react? Would they be disabled, and if so, for how long?

b) How would hospitals react? Would an event capable of knocking out power on this scale temporarily or permanently disable their backup generators, or would they be able to switch over with little to no disruption?

c) Are there any other major side effects, either on manmade structures or on the environment?

The event can be a one-off phenomenon, such as a solar flare or EMP detonation; or it can be some kind of ongoing thing (like fluctuating magnetic fields or something). The main goal is to achieve those three primary effects all via a single mechanism. (If the answer is, "no known real-life event can do all those", that's fine too! The bad guy has Magic(tm) so I can fudge a little; I'm just hoping to ground the magic effects in as much science as possible for realism's sake.)

  • $\begingroup$ In one of my favourite modern/urban fantasy series - Mark Chadbourn's Age Of Misrule books - the cause of the problem ties in to the fantasy side rather than the modern side; a great and ancient spell has been unleashed that has overthrown the age of reason and released ancient powers to walk the world again. Given that you are wandering into that area already, it's not too big of a stretch. $\endgroup$
    – glenatron
    May 27, 2015 at 13:59
  • $\begingroup$ @glenatron Yeah, I'm hoping to mix magic and science with this event. I just want to ground the effects of the magic in science, so it's not like "this evil sorcerer cast a spell that perfectly disabled everything because magic", but rather, "this evil sorcerer cast a spell that piggybacked on $known_scientific_phenomenon to get the effect he wanted rather than creating it all from scratch." $\endgroup$
    – thatgirldm
    May 27, 2015 at 14:27

7 Answers 7


Coronal Mass Ejection

It will knock down communications as well as potentially knock down satellites and power grids. A CME would not prevent diesel, coal, or wind turbines from generating power; the issue would be the blown transformers. The CME could literally change the orbit of satellites as well as ionize them, potentially making them unable to adjust their courses. Enough charged particles hitting radio antennae could potentially fry their circuits as well.

Weaponized EMPs

This can cause some havoc, but not really knock down satellites. It is speculated that an EMP would disrupt electronics, essentially frying circuits or wiping all electronic memory. It is easily countered, however, because a Faraday Cage would protect all electronics from any damage. EMPs are not "as destructive" as a coronal mass ejection because they cannot cover the same area.

The Reactions

  • Cars: cars don't care if they don't have electronics. Most modern cars do have electronics, however, and many rely on them for their increased performance. Knocking out the computers on a modern car would render it useless, especially if it does not rely on mechanical structures, like clutches. In any case, the general rule here would be that older cars would be more likely to function, as they have less electronics in them.

  • Hospitals: I foresee hospitals doing just fine, at first. They have backup generators, but it's unclear how long those generators would last; my source says a hospital can stay working for 8-24 hours. If a hospital has an abnormally good supply of diesel, the generator could work longer. After that initial time period, panic would set in. People would likely die, because a hospital without power cannot do surgery or use fancy things x-rays, CAT scans, and so on.

  • $\begingroup$ Out of curiosity - how would a nuclear detonation in orbit, rather than on/near earth, go down? Would we be able to control the grid sans satellites (after all the debris acted like ASATS + EMP from the detonation)? $\endgroup$
    – pavja2
    May 26, 2015 at 23:38
  • $\begingroup$ @pavja2 I don't know how it would go down. I imagine the US power grid does not rely on satellites for essential services, but I'm afraid I do not know about this subject to give a good answer. I do know a nuclear blast produces an EMP, but that the effects of the EMP generally pales in comparison to the actual blast and radiation. Maybe someone else can give you a better answer? $\endgroup$
    – PipperChip
    May 27, 2015 at 0:09
  • $\begingroup$ A single nuclear detonation in orbit almost certainly won't give you enough debris - space is big and satellites are widely distributed. Grid control is surprisingly manual but completely dependent on telecoms. Without comms you can't really organise grid repairs, so that's likely to go down and stay down. $\endgroup$
    – pjc50
    May 27, 2015 at 8:33
  • $\begingroup$ Nice answer, but all non-classic cars/trucks would be disabled by an EMP, and hospitals by extension. All (American, at least) cars made since the mid-70's have used electronic ignitions, so none hit by EMP would start without repairs/retrofitting. Some could probably be hotwired, but fuel injection is generally controlled by onboard CPUs, so they'd run very inefficiently if at all. Hospitals would lose power after 72 hours to a week without trucks to deliver fresh diesel for the generators. $\endgroup$ May 27, 2015 at 17:26
  • 1
    $\begingroup$ A CME strong enough to do this actually hit Earth during the Carrington Event of 1859. It lit night skies up enough to see unaided and electrified the telegraph grid (enough to fry many machines and electrocute some telegraph operators). If a similar event happened now, our power grid would suffer widespread collapse and many (if not most) unshielded satellites would fail. (Most satellites are unshielded.) It probably would take over a decade to repair the damage. $\endgroup$ Jun 24, 2016 at 16:12

The other answers have been pretty scientific. I'd suggest something more magical.

Mass transmutation

The bad guy casts a spell that continuously transmutes all monocrystalline silicon into gold. Useless, worthless gold. Boom, goodbye transistors. Goodbye microchips.

a) Disable or destroy all manmade satellites (and thus a lot of communication);

All existing satellites use microchips, so yep, they'd be disabled.

b) Take down the power grid for weeks;

While the raw generators would work, the control circuitry will be inoperative, leading to either clean shutdowns or the things ripping themselves into pieces. Eventually vacuum tube based systems would be built and designed, but indeed, there wouldn't be any power. Not even photovoltaic solar power.

Some sufficiently low-tech power generators might work.

c) Render communication via cell phones and computers virtually impossible for the forseeable future;

Definitely no computers. Eventually you'd get the re-emergence of old fashioned WWII era radios. But yes, we're basically resetting to WWII.

No bad biological effects, because crystaline silicon is not found in nature.


The very simple way is just to bomb all The world's power plants. Admittedly this is rather difficult since they have high security measures preventing people breaking in and bombing them.

The next way, which has already been said, is to figure out the computer systems. Most power plants are computer controlled so if you hack the system you can shut it down.

EMP is a viable method but you need a very big EMP to cover the entire planet, or you need some form of outside influence to create the EMP. Coronal mass ejections can do this, or gamma-ray burst from a quasar or black hole. If you get hit by GRB from a black hole though you're probably too close to it.


A mass takedown of the world's computers would achieve these goals. A clever hacker might be able to do quite a bit of damage, but there are still a lot of systems that aren't connected to anything else and thus difficult to hack. A more plausible way would be through a remotely-triggerable hardware backdoor.

For instance, your bad guy may have been planning this for a while, and over the years has secretly bribed, blackmailed, and extorted the world's major chip fabrication companies to secretly add extra circuitry to the chips that they produce. The bad guy could activate this extra circuitry by broadcasting a specific signal (for example), and the circuitry would effectively cause permanent, fatal damage to the chip. This would allow him to destroy the vast majority of the world's electronic infrastructure at will. Continuously broadcasting the signal would effectively make all spare parts worthless, as they would self-destruct as soon as they were powered on.

Assuming that you want something that a single bad guy can trigger at will, this seems like the option that would involve the least amount of "magic" (such things are already possible today). The only thing that you might need to fudge on is the specifics of the activation mechanism.

With something like this, any vehicle with a computerized engine wouldn't work at all. Older, purely mechanical cars should continue to run normally, provided they can find a non-computerized gas pump.

Since this is strictly focused on electronic devices, it should have no direct effect on the environment or on non-electronic things like buildings, books, or roads. There will undoubtedly be indirect effects caused by the sudden lack of computer control, such as a dam no longer being able to regulate water levels and causing floods downstream, or an entire generation of the population finding themselves unable to coherently communicate with others without autocorrect and spell checkers.

  • $\begingroup$ There will be some major environmentally effects caused by nuclear power plants being uncontrollable. Apart from that, i like the general idea of your answer. Even if it takes a fairly large quantity of handwavium(tm) to explain that enormous influence on chip producers. But... what if the villain himself was the world's largest - or maybe only - microcontroller producer? Some decades of intrigue, bribes, and other ways of eliminating competition, just to make sure his backdoor-infested chips are planted everywhere? $\endgroup$
    – Burki
    May 27, 2015 at 14:36
  • $\begingroup$ @Burki if the sorceror had the ability to manipulate chaotic energy or chaotic entities ( maybe tiny tadpole size demons! ), their spell could consist of purely flipping random bits in every memory chip and magnetic data drive on the planet. It wouldn't take very much to crash all the computers and corrupt all the data they had stored. If the effect - some kind of chaotic resonance - was to persist, then there wouldn't be much way to build working chips from then on. $\endgroup$
    – glenatron
    May 27, 2015 at 14:46
  • $\begingroup$ @glenatron sure, that would work... but as far as i understand the question, the OP would prefer an answer that was as nearly scientific as possible. $\endgroup$
    – Burki
    May 27, 2015 at 14:54
  • $\begingroup$ Sadly, it's probably easier than you think to explain a villain having heavy influence over a large number of chip manufacturers. This is actually a real-world security concern at the moment. Most of the world's chips are manufactured by a small handful of companies, and security-paranoid people (governments, militaries, etc) are concerned that a rival nation or a criminal element could secretly insert security backdoors at the factory without the chip designer's knowledge. A combination of bribes, hacks, and perhaps a man or two on the inside could do it. $\endgroup$
    – bta
    May 27, 2015 at 22:08
  1. Coronal Mass Ejection could maybe provide the answer if the evil mage possesses the power to seriously mess with the sun to provoke repeating ejections. Otherwise it would just hit once, so computer chips would be disabled (see bottom of answer) for a few minutes to hours, or in the case of satellites maybe longer. Plus it's a phenomena which isn't really understood yet, so you risk being outdated by newer findings.

  2. One EMP would rather kill everyone than disable communications, but it's still mentioned in several answers here. By adding enough magic you could have lots of small EMP bursts inside each system you want to destroy. If you have some analytical magic to find all semiconductors and then change the electromagnetic field inside those semiconductors drastically (preferably several times back and forth for alternating current) then you would induce current which could melt any electronics and which wouldn't do much to natural occurrences of semiconductors (wouldn't conduct enough, while there are always low resistance paths in computer chips). But that wouldn't be a single event, that would be billions of events, for each occurrence of semi-conductive material. Would result in destruction of computer chips, see bottom of answer.

  3. The mage could just switch on and off the magnetic field of Earth, without directly affecting electrical ones. Initially I thought this was a good idea, but now I think it would be similar to EMP. By just switching Earth's field you would just achieve a temporary effect (disabling chips) and by doing it with a stronger field you would also kill everything by starting to ionize practically everything. But you could have the mage keep switching the field on and off for as long as you like to disable computer chips. Would also kill some birds relying on the magnetic field to navigate, probably. You could also do it with a switching electromagnetic field instead of just magnetic (wouldn't help the birds).

  4. Not a single event: Computer viruses could disable computer chips in theory (in some cases destroy, for satellites which can change their course and maybe some industrial systems). Enough of them are networked to make this effective given some preparation time for the virus to spread. Needs lots of analytical power (math and computer science). If the mage could summon some ultra intelligent being, or a life-form which lives in electromagnetic fields or something...

Consequences of disabling or destroying computer chips:

disabling: Only a few chips would break completely, most could be restarted once the phenomena disabling the chips stops breaking: The phenomena destroys all chips, so the parts about rebuilding them applies

  • wouldn't kill anyone directly
  • would destroy modern cars but some percentage of older ones would survive
  • would destroy the stuff controlling the power grid, taking it down without destroying the generators and other infrastructure
  • would destroy lots of vital systems in hospitals (not the power, there would be lighting over the emergency generators unless it was LEDs, but /lots/ of stuff wouldn't work, they would essentially be thrown back like 50 years in their capability)
  • would leave stuff like generators, power lines or (non-LED) light bulbs themselves intact
  • wouldn't be a complete apocalypse, infrastructure would be undamaged, within a few months to a year production of new computer chips could probably start and society could rebuild.
  • $\begingroup$ Disabling earth's magnetic field would kill everyone eventually: without the van Allen radiation belts, solar wind would strip the atmosphere, although probably not before everyone died of cancer from the huge upswing in ionizing radiation making it in from space. $\endgroup$ May 27, 2015 at 17:21
  • $\begingroup$ I suggested toggling the field on and off. Just toggling it off wouldn't lead to the desired effect (maybe indirectly through what you describe). Toggling it on and off would reduce effective average power, but not necessarily by a lot - you could just switch it off and back on almost without time in between, wait 5s, repeat. Or you could reverse it's polarity every couple of seconds, that would also work without any reduction in power. As long as you can permanently turn it on again once you are done messing with it... $\endgroup$
    – Nobody
    May 27, 2015 at 19:19

Another option that presented itself to me is if an Artificial Intelligence goes rogue.

Computers are used in just about everything, so any modern power stations are suddenly fed the wrong instructions and cause massive destruction. It wouldn't work on some older power stations, and Germany would suddenly be doing fantastic with its solar power, but most first world countries would be pretty bad off.

  • $\begingroup$ Hi Steve, and welcome to Worldbuilding. We want these questions and answers to have lasting value, so don't worry about answering old questions if you feel that there is something new that you can contribute in an answer! Particularly if you do answer old questions, just take care to ensure that the answer actually brings something new to the existing answers as well as meeting our criteria for how to write good answers. $\endgroup$
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    Jun 23, 2016 at 10:58
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    – user
    Jun 23, 2016 at 11:00

In the book Starbound, by Joe Haldeman (one of the most influent scifi writers ever), the Earth is at odds with a much more powerful civilization. The other civilization has reached technological singularity, which means that by Clarke's third law, all their technology seems like pure magic to us.

At some point, the aliens get relly mad at humanity. At some point, they turn off the electricity. No devices that require electricity work. Not even wrist watches. They let biochemical processes that use or produce electricity work, though, so people don't drop dead because their brains stop working.

A few seconds prior to pulling the plug, the aliens broadcast this message to humans, which I think is the most awesome way to turn the grid off in a fictional world:

All this energy that you call 'free' comes to you at the expense of a donor world in a nearby universe. You are donors now.

So, you could have it like this: due to some quantum law that we don't know about with our current understanding of physics, all the electricity we use comes from another world. This is not far-fetched: Nikola Tesla believed that all forms of energy ultimately came from the Aether (a concept later dropped by modern scientists). Your bad guy can then reverse the process, making your fantasy world provide the power to some other plane of existence instead of drawing power from it.


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