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Comment by highcountess | Hacker News Reader

I agree with this theory even though I am not even sure it would require a specific modification like the mentioned heating wire, if you can simply use the existing circuit with some instruction to cause component overheating with the same effect.

Another reason I do not believe it was an explosive is that a clandestine explosive installation would have resulted in far greater damage and included shrapnel. Because why would you not install very high explosives and shrapnel in a shape charge that directed the explosion into the likely body of the wearer if you are taking the risk of intercepting and making a physical modification.

This is also less Stuxnet and more infiltrating insecure systems of vehicles to drive by wire accelerate cars into objects. There have been examples of this

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> a clandestine explosive installation would have resulted in far greater damage and included shrapnel

No and not much. The amount of explosion you get is proportional to the amount of explosives used. Small amount of explosives == small explosion.

Shrapnel is specifically engineered into explosive military weapons - it is not an innate property of explosive reactions. If you want a lot of shrapnel you have to design the case to fragment (e.g. grenades) or pack the area around the explosive with the stuff you want to become shrapnel (as with many bombers packing nails and screws and bolts etc., around their bombs). A small explosion in a mostly plastic device will result in a small amount of small pieces of plastic being scattered, which might harm bystanders but is by no means guaranteed or even intended to do so.

It would seem if they're going to all this trouble in the first place to design a substitute case of materials that had good shrapnel effects.

A shape charge would be pointless because you can't guarantee how the device is worn- one news article mentioned most people carry them in their pockets, so a shape charge would be blowing most of the energy away from the target in 50% of the cases.

A shaped charge need not be unidirectional. It could be focuses along an axis, resulting in a two-way explosion that would be more damaging than a symmetrical one. Two copper disks on either side of the charge would constitute a functional two-way shaped charged.

I think the grocery store security video supports the two directions idea. If you watch carefully it looks like a pressure wave away from the target and clearly something takes the target down. Perhaps a pressure wave in the opposite direction too.

With a pager you can be pretty sure the target will be holding it with one hand and looking at the screen. Reports indicate the pagers beeped shortly before they went boom. So if the blast is focused in the plane normal to the screen that would focus it into the hand and face of the target. No idea whether that's actually a good idea or not.

Doing much more damage 50% of the time might be more effective, if an undirected explosion is too weak to kill anyone but a directed (and lucky) one could.

I've seen some videos. Shattered hips, abdominal wounds, hands without fingers. I haven't seen any dead person, just maimed bodies. Mission successful I guess. Oh and one kid.

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