A COUPLE of weeks ago, my laptop died. My stomach churned as I realized that a full day’s worth of work had vanished.

“Maybe I could just ask the National Security Agency for a copy of it,” I said to myself. “They have everything now.”

I didn’t know which surveillance bureaucrat to call, and that’s a shame. Because, let’s face it: The era of Big Data is upon us, and it turns out to be the era of Big Snooping.

In the business world, every corner-office visionary worth his M.B.A. is proselytizing about the miracle of data. Tech wizards comb Google searches and Twitter posts to find out what consumers want. That data is being used to sell stuff, everywhere. My bank statement now has ads for Burger King that show up next to the debit card purchase at Five Guys. When I do a Google search for old-fashioned wall phones, ads for old-fashioned wall phones start showing up next to my Facebook feed. Every company seems to have collected every bit and byte about me.