It's either a heartfelt appeal or a cleverly crafted publicity stunt, or maybe both. When viewers arrive at theaters to watch Snowden, Oliver Stone's latest movie, they'll be greeted by a public service announcement in which Stone himself (who directed such hits as Wall Street, Platoon, and JFK, among many others) urges them to turn off their smartphones.

There's a growing crop of ever-more-creative PSAs urging people to silence their mobile phones during movies as a courtesy to other movie-goers. But Stone has a lot more in mind: He advises that we all turn off our smartphones permanently because of the privacy threat they represent. 

Yes, they can be great for watching videos of kittens, he acknowledges--and he even shares a kitten video with the audience. "That's not all it does," he warns. "It allows certain parties to track your every move every time you send a call, send a text. We are giving them access. The information you put out into the world voluntarily is enough to burn your life to the ground."  

"Think I'm being dramatic?" he asks. If so, you can ignore his advice he says--but please do turn off your phone for the duration of the movie.

Well, yes, Stone certainly is being dramatic. But he's not exaggerating and he's certainly not making things up. Edward Snowden, the famous whistleblower and the subject of Stone's film, has long maintained that smartphones strip us of all privacy. US government bodies such as his former employer the National Security Agency, foreign powers, both allies and enemies, and even hackers can gain control of ordinary citizens' smartphones by simply sending an encrypted text. He told the BBC that the NSA and the British Government Communications Headquarters had both invested "heavily" in smartphone tracking technology. They can turn on a phone when it's off and then use its microphone to listen in and its camera to watch what's going on around the phone.

Can you stop the spying?

What can we do to protect ourselves? Snowden, in partnership with a hardware expert, has proposed a specially-designed smartphone case that would alert the phone's owner to "unusual activity." (Here's a full description of the spy-blocking phone case.) 

But all that will do is alert you to possible spying, not prevent it. If you want to completely avoid being eavesdropped on via your smartphone, one of your only options is to use a Faraday Box which blocks the radio signals smartphones and most other devices use to communicate. Of course, you won't actually be able to use the phone unless you take it out of the box.

You could go back to using land lines--which of course can also allow eavesdropping, and pinpoint your location even more accurately than smartphones do. Or, you could do what most of us will likely do and ignore Stone's and Snowden's warnings. And hope that no one out there really cares about anything we have to say.