So I was in the grocery store this morning buying three rolls of toilet paper and a bottle of seltzer with a credit card, as I am wont to do. (It was on my way back from the gym and I had brought a credit card just for this purpose. I didn’t have any cash, I don’t like to bring my wallet to the gym, and I don’t like to have to futz with lockers).

After I swiped my card, I watched as a blue bar status bar creeped across the cashier’s screen. After a good 30 seconds, it said something like “failed to create an ip connection.” They tried again, and at another register, with the same results. We all shrugged our shoulders and made fun of the internet.

The casher said of the credit card machine, “When it works, it’s great, but when it doesn’t…pfft.”

We’re being trained to forgo cash because credit and debit cards are supposed to be more convenient. But what do in a world where most people don’t carry any cash around whatsoever, and the systems break down? What if they failed on a massive scale, like a nuclear or electromagnetic attack? Your $20 bill is never going to give you a connection error.

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