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I know that there exist nonnuclear EMP weapons, but these do not influence the entire world. Could someone build a device that creates an EMP that is powerful enough to make all mobile phones on the entire world stop working? How expensive would such a device be?

Riemann
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    It depends on the meaning of the phrase "make all mobile phones on the entire world stop working". If you mean "brick them", then I'm afraid there is no way to brick all mobile phones by means of a humongous EMP while not killing their owners. – AlexP Jun 25 '23 at 11:26
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    Only "mobile phones"? What you need are viruses more likely. – BMF Jun 25 '23 at 12:05
  • Yes, but not without...side-effects. Can you please shed some light on why this would be necessary? Maybe there's a less lethal alternative solution to the narrative problem. – biziclop Jun 25 '23 at 12:06
  • @AlexP I don't think this is true. The starfish tests managed to take out telephone exchanges in Hawaii 900 miles away without killing the people there, and the valve based electronics of the time was much more emp resiliant than todays technology. We know a nuclear explosion in space will take out every electronic device over a very wide area (1000s miles radius) whilst being far enough away to not kill the owners – camelccc Jun 25 '23 at 12:51
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    @camelccc: The Plain Old Telephone System (POTS) used looooong cables to connect the terminals to the exchanges. Long cables couple very well with EMPs. Mobile phones have very short wires in them and are most usually not connected to any cable. In fact, the user holding the phone is a two-meter-long conductor which will couple with the EMP about a hundred times better than the diminutive phone. This is why I asked what exactly is the goal, because, while bricking the phones is hard, simply disrupting communications by frying the transponders in the cell towers is a little easier. – AlexP Jun 25 '23 at 13:34
  • @camelccc: P.S. Most POTS exchanges in the day of the Starfish Prime test were actually electromechanical, with little in the way of valves or other electronics. – AlexP Jun 25 '23 at 13:36
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    An EMP that could disable all cell phones even in a 200 mile radius area would bring down the electrical grid and probably blow up propane distribution due to EM coupling onto long pipes not sufficiently grounded. It's kinda hard to justify taking out cell phones without taking a lot of the supporting infrastructure with them. – JBH Jun 25 '23 at 19:33
  • @camelcc the telephone network back then, though, used all-copper wiring (acting as an enormous antenna) and also probably carrier frequency lines (coax), which also probably had very sensitive receiving equipment (involving components rather more delicate than vacuum tubes). Modern communications networks use a lot of fibre optic lines - while the endpoint circuitry is certainly sensitive, you don't get any antenna effects.... – rackandboneman Jun 25 '23 at 23:44
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    @camelccc Sure, a powerful EMP attack on the world would only kill those trusting their lives to electronics (say, everyone in a jetliner) and probably a few freak incidents involving long wires, but if you blow the electronics it won't be long before almost everyone is dead anyway. It's a civilization-ending event. – Loren Pechtel Jun 26 '23 at 03:38
  • Not being brought up is EMPs are "line of sight" meaning that you could put an EMP high enough to knock out a wide range of targets, but you have that pesky "other Hemisphere" that is shielded by an entire planet worth of earth (During the cold war, the U.S. assumed that the first Soviet Nuke to explode would be a high altitude detonation above the geographic center of the lower 48 that would not cause any damage by the fire or overpressure wave, but would knock out all electronics not shielded in much of the North American continent. Then come the bombs meant to kill targets). – hszmv Jun 26 '23 at 17:55
  • An EMP that is experienced very regularly is lightning. Lightning can be pretty intense, many electronics have protection against lightning especially those that are expected to be outdoors. That is equipment such as telecommunications and power are protected to some degree from EMP. EG current transformers. – Gault Drakkor Jun 27 '23 at 21:37
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    @hszmv do you have a source for that? id love to read it – Seggan Aug 24 '23 at 20:59
  • @Seggan-OnStrike: https://en.wikipedia.org/wiki/Nuclear_electromagnetic_pulse Here you go. There's actually a graphic that helps with that. – hszmv Aug 25 '23 at 11:10

1 Answers1

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To take out all the mobile phones in the world, you would need multiple EMP explosions. The range of a single explosion is limited to the line of sight as the operative parts of the EMP are the gamma rays that strip electrons from the air molecules. (https://en.wikipedia.org/wiki/Nuclear_electromagnetic_pulse)

Secondly, the main way to take out mobile phones is to take out the base stations. These are far more vulnerable as they have antennas and a lot of wiring that can pick up the electrical pulse. They are also connected into the rest of the telco systems which are likely to stop working with an EMP. Without the base stations, you can't do anything with a mobile phone.

David R
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    Except that the base stations only serve to make the mobile phones work as telephones, which is by very far a minority of their uses. Most usually they are used as small computer terminals, navigation systems, media players etc. – AlexP Jun 25 '23 at 15:35
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    @AlexP True, but they still need the base stations in order to transmit data. The GPS is often augmented by cell tower data. – David R Jun 25 '23 at 20:54
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    @AlexP - For that matter, most "computer terminal" uses will require internet access. Media playing has largely moved to online streaming services. You might be able to receive a GPS signal, but besides any use of cell tower/wifi station signals for better triangulation, in almost all cases maps are downloaded dynamically. – Clockwork-Muse Jun 25 '23 at 22:50
  • While many cellphones can connect to a wired ethernet if connected to a suitable USB-C dock, this still makes them less mobile and assumes a still-working wired infrastructure (however, a lot of that is fibre optic based these days, so not as vulnerable as one might assume). – rackandboneman Jun 25 '23 at 23:37
  • And if the EMP was high enough, it could damage a lot of the satellites with radiation. While someone will object that the phone could still be used from a WIFI location, that assumes that the EMP didn't take out the phone network or the electrical grid. The electrical grid could take months to years to come back. – David R Jun 25 '23 at 23:39
  • So it is not possible with a single EMP? Is this also the case for nonnuclear EMP? – Riemann Jun 26 '23 at 15:26
  • @Riemann I like to describe EMPs (and the initial firestorm caused by a nuclear explosion) as operatating under "Mufasa Law": Everything the light touches will be fried. You could no more EMP all phones with a single EMP device (nuclear or otherwise) than you can get a sunburn at the Earth's equator at 0330 local time. The EM stands for "Electro-Magnetic" which is a fancy term for "light". You need a similar device, with a line of sight for the part that's on the dark side of the planet from the EMP. – hszmv Jun 26 '23 at 18:02
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    Also fun fact, if you have adequate warning of an incoming EMP, take your mobile phone and other devices, turn them off, put them into your microwave oven, close the door (DO NOT TURN THE MICROWAVE ON) and leave them there until the EMP burst happens. Microwaves use a portion of the EM spectrum (called a microwave) to heat water in food and cook the food. To keep the user from being cooked as well, the interior of the microwave has a faraday cage to prevents the microwaves from getting out... but it also prevents EMPs from damaging electronics inside the microwave. + – hszmv Jun 26 '23 at 18:08
  • You still have the problem of finding a signal for most mobile devise features and a power source for recharging phone batteries, but you can preserve it's use for momentary power ups, checks for signal, and power downs.
    • – hszmv Jun 26 '23 at 18:11