>electricity
If we're hit with EMPs or the solar equivalent and all our shitty consumer electronics are fried, copies of the block chain will still be saved and running. Your precious jew crypto wouldn't go "poof". Danger is irrecoverable network segmentation habbens, in which case the effect would tend to be a hard fork the longer the pockets of crypt transactions occur in isolation. And it's to your advantage. You won't lose your jewcoin, you'd be able to spend in more than once from region of isolation to region of isolation.