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Suppose there's an earth-like planet, perhaps even modern day earth itself - and at one point in time, it began to be bombarded by a continual stream of Electromagnetic Pulses.

For the sake of simplicity let's say that the EMPs are coming from a set of cloaked alien satellites orbiting the planet, and all areas are being hit at least once every few seconds.

The EMPs are just strong enough to ruin a modern-day power grid and make modern-day electronics inoperable outside Faraday cages.

The question is both about the society's coping mechanism (assuming they have hundreds of years to adjust) and the environmental effects, but I'm far more interested in the latter.

I believe computers can be redeveloped using Fluidics or something to the effect, and until long range communication can be re-established most of the world will find itself divided into city-states connected by steam-powered trains. I have not found any evidence indicating that such EMPs will be harmful to humans, but there's barely any info on how it would affect the rest of the environment.

Is this scenario feasible, or did I miss some fundamental change here?

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  • $\begingroup$ I think that any alien species capable of travelling all the way to us, then deploying cloaked satellites which our technology can't detect at all, would have a lot more to throw at us than a measly EMP weapon. $\endgroup$ – AndreiROM Nov 21 '15 at 21:20
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    $\begingroup$ It's not to fight humans, it's to put them in an awkward situation and study the effects :P "FOR SCIENCE!" as they say $\endgroup$ – Parson's Phone Nov 21 '15 at 21:25
  • $\begingroup$ In that case consider testing not with EMP's, but by instigating international conflict, or releasing subtle hallucinogens into target populations, etc. I think our world would be more susceptible to psychological manipulation rather than just taking our fancy toys away. Also, keep in mind that such EMP attacks would give their presence away, and that most military equipment is build to withstand EMP attacks. We might actually fight back at that point. $\endgroup$ – AndreiROM Nov 21 '15 at 21:29
  • $\begingroup$ @AndreiROM They already did that first experiment (as is apparent). $\endgroup$ – PyRulez Nov 22 '15 at 0:55
  • $\begingroup$ "For the sake of simplicity let's say that the EMPs are coming from a set of cloaked alien satellites orbiting the planet, and all areas are being hit at least once every few seconds."- Real simple. This is a good question! $\endgroup$ – Quiquȅ Nov 22 '15 at 1:33
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If you're not concerned with the aftermath of the initial attack, the answer is fairly simple: Electronics would all be shielded by then. In fact, the new smartphones and other portable electronics would probably be charged by induction loops leeching off the EMP.

It should not have much effect on the environment, except possibly some migratory birds getting a little lost.

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    $\begingroup$ Excellent idea for charging. $\endgroup$ – Samuel Nov 21 '15 at 22:26
  • $\begingroup$ Accepting this one because it's concise, clear, and inspirational. Gary's answer is really good, I'd accept both if it were possible, but since I have to choose, I'll go with the one that offers insight into how humans would take advantage of this. $\endgroup$ – Parson's Phone Nov 21 '15 at 22:54
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    $\begingroup$ Woohoo! Free Electricity! $\endgroup$ – timuzhti Nov 22 '15 at 2:35
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Damaging the grid is considerably easier to do than the level requiring a Faraday cage to protect electronics.

The grid is so susceptible to EMP because of the long transmission lines. EMP is a pulse where you measure the strength in volts / meter, i.e., the longer the run, the higher the voltage available to do damage. The grid can be protected at a reasonable cost by installing high speed switches that dump the pulse to ground to protect major components. The estimated cost to protect the most of the US grid is about $20 billion. Also note that the US grid is partially protected against EMP, it is not an all or nothing approach. Other nations are better protected or less protected than the US grid.

The US military protects their grid and electronics just fine using both published and classified methods. A friend of mine works on some of the classified methods for protecting electronics and that is all I know about it, it is classified. I assume other national military are similar in this regard.

Electronics tend to be susceptible because the voltage require to damage them is quite low and even a tiny fault typically ruins the device. However, since the devices are small, a weak EMP is often fails to destroy electronics since voltages are also low. Vacuum tube based systems are generally unaffected as voltage the spikes simply overheat the active components for a short time, but not enough to damage them significantly.

A Faraday cage is effective protection and not expensive. So electronics would be used and installed inside Faraday Cages. There other ways to protect electronics too, these methods would be also used.

So, in a world where EMP was a daily occurrence, things would simply be designed to survive the typical EMP. In our world, since EMP is rare, we often don't protect against EMP.

EMP levels required to damage humans and other life directly would have to be extremely massive as the field levels are non-ionizing. In theory you could make an EMP strong enough to harm people directly, but the power levels would be insanely high. Remember that humans and animals have been exposed to very high level of EMP by close proximity to nuclear weapons without harm (from EMP) and we routinely expose humans to high magnetic fields in MRI scans without harm.

At the level of EMP you propose, wider environmental harm is nonexistent. Solar flares have the same effect and the general environment is not affected by large solar flares. The Carrington Event would be a pretty major disaster today because so much of electronics, etc. is unprotected. But such events are thought to occur on the average of once per 500 years. Note that no biology or environmental damage was noticed in 1859. There are no unexplained problems during earlier historical natural EMP events either.

I just remembered a humorous account relating to very strong magnetic fields. Andre Geim won the Ig Nobel prize for levitating frogs in a magnetic field the field strength was 10 Tesla - this is nearly 1 million times the strength of Earth's magnetic field (25-65 microTesla). The frog was mot harmed.

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    $\begingroup$ Thank you for explaining that, surprise, EMPs are not like the movies make them out to be. $\endgroup$ – Samuel Nov 21 '15 at 22:26

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