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To protect your electronics during a huge Electromagnetic Pulse in the RF range, all one needs is a Faraday shield for the most part.

On the other hand, what do you do when you are near an acoustic shock wave/sonic boom? Obviously you no longer care about electronics, your hearing itself can be destroyed depending on the circumstances.

There isn't an acoustic version of Faraday shields, but it should be possible to make a shield that does transmit the sonic boom and is simultaneously livable, I think phys.se owes it to the world to come up with a solution. What solution is there?

From https://io9.gizmodo.com/a-suprisingly-clear-photo-of-an-explosions-shock-wave-1691631397

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    $\begingroup$ The answers below indicate that "shock wave shielding" can probably be done, but they seem to have limited practicality. Is there a known practical way to shield against shock waves? In other words, is there a device that a person could enter that doesn't require a lot of extraneous equipment and "set up" time? (e.g., it takes time to pull a vacuum in the space between concentric spheres). $\endgroup$
    – David White
    Commented Jun 12, 2018 at 16:00
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    $\begingroup$ @DavidWhite I recall a few Mythbusters episodes where they looked at dumpsters, cars, thin walls, thick walls, etc at various distances from the source. They also looked at getting underwater. Basically anything can block the shockwave at some distance -- that distance depends on what you use to block it. $\endgroup$
    – tpg2114
    Commented Jun 12, 2018 at 19:55
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    $\begingroup$ Bombs are used to rip apart and destroy things, so it's unlikely that one can build a chamber that can withstand a direct impact. The vacuum chamber below is a cute idea, but if the outer layer is punctured, it would render the whole idea moot. Given that the likelihood of having an impenetrable outer layer is near zero, I would not bank on that idea. $\endgroup$
    – honeste_vivere
    Commented Jun 13, 2018 at 13:58
  • $\begingroup$ @Qmechanic It seems this question is thought to be off-topic. I checked the help center but didn't see why this can't come under "experimental design". In any case, is there a stackexchange that can actually answer this question then? $\endgroup$
    – KF Gauss
    Commented Jun 13, 2018 at 14:58

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Yes, it's called a bomb shelter. you build it under the surface of the ground so most of the shock wave passes it by, and you make it deep enough under ground so the mass of the overburden is sufficient to inertially clamp it against the shock impulse.

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  • $\begingroup$ Could you elaborate some more? I have never heard of the term "mass of the overburden" before $\endgroup$
    – KF Gauss
    Commented Jun 12, 2018 at 17:24
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    $\begingroup$ that's just the mass of the earth above the underground shelter (engineering jargon). the mass has two beneficial effects: 1) it tends to reflect shock and acoustic (subsonic) waves and 2) being crumbly, it tends to dissipate the energy of an impinging shock through friction, thereby protecting the shelter from damage. the design of bomb shelters is a well-developed art. $\endgroup$
    – niels nielsen
    Commented Jun 12, 2018 at 18:21
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The acoustic farday cage

There isn't an acoustic version of Faraday shields...

That's not strictly true. Sound waves (including sonic booms) require a medium to travel in. Remove the medium, and you create an impenetrable barrier to sound. For example:
enter image description here

Two concentric shapes with the intervening space pumped to a few torr would do the trick. The inner shape still needs to be suspended, and some sufficiently dampened springs would do. I would imagine something like the gas pistons large trucks use to suspend their cargo (called "air-ride"?).
The details are engineering related; the point is it is certainly possible to achieve arbitrary levels of isolation from a shock wave.

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  • $\begingroup$ I'm not really familiar with shock wave propagation in materials, but I would guess that it would propagate through the spring into the inner room and still hurt you. Is that incorrect? It seems the key physics here is hidden in those springs $\endgroup$
    – KF Gauss
    Commented Jun 12, 2018 at 14:10
  • $\begingroup$ There's also the question of how you get into that box in the first place if it is only connected via springs. $\endgroup$
    – KF Gauss
    Commented Jun 12, 2018 at 15:27
  • $\begingroup$ Very well -- used dampened magnetic levitators if you so wish instead of something 'mechanical'. As far as a door, again that's an engineering constraint: two doors, one that can withstand vacuum on one side and another door that can withstand a shock wave are already things that currently exist. I've shown you a conceptual drawing that is sound (hah) from the perspective of physics, not a detailed schematic. $\endgroup$
    – cms
    Commented Jun 12, 2018 at 16:25
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    $\begingroup$ this may sound very stupid, but wouldn't even magnetic levitators be vibrationally coupled? If the bottom magnet moves rapidly wouldn't the top also pick that up in response, and transfer the shock wave across through a rapid change in the positions of the magnets? $\endgroup$
    – KF Gauss
    Commented Jun 12, 2018 at 22:21
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I don't know about shock waves specifically, but of course there are approaches to manipulating sound/pressure waves in general. For instance, a cursory search yields the following:

  1. Farhat, Mohamed, et al. "Broadband cylindrical acoustic cloak for linear surface waves in a fluid." Physical review letters 101.13 (2008): 134501.

  2. Brun, Michele, Sébastien Guenneau, and Alexander B. Movchan. "Achieving control of in-plane elastic waves." Applied physics letters 94.6 (2009): 061903.

  3. Zigoneanu, Lucian, Bogdan-Ioan Popa, and Steven A. Cummer. "Three-dimensional broadband omnidirectional acoustic ground cloak." Nature materials 13.4 (2014): 352.

Note that these are mostly for in-plane waves, or 2D problems. They are analagous to the so-called 'invisibility cloaks' that use metamaterials to 'bend' certain frequencies of light around objects, that were all the rage in the popular science articles a few years ago.

By analogy I could imagine using layers of concentric steel cylinders to at least attenuate the effect of the shock wave. I haven't run the number's but I imagine the massive pressure gradients associated with shock waves would lead to difficulties with this approach (concrete pillars would't work because they could shatter, I'm assuming here steel would bend). I don't know whether this would work better than just hiding in a large solid steel safe, so it's not very practical. As I said, I don't think these methods are necessarily applicable to shock waves, but perhaps it's a good starting point.

Here's a popular article about such an approach (again two dimensional) to 'hide' ocean waves from tsunamis.

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