It is now a meme, a trope, a cliche that we are living in a post-truth world. The daily falsehoods of our president are a marquee case, but he is far from alone. In fact, substituting fiction for reality is a huge a burgeoning industry, as the fake news outlets he relies on demonstrates.

Once liars had to tell their own lies or publish them and they could be potent. “A lie can travel halfway around the world before the truth can get its boots on,” as Mark Twain said. Except that too is a lie. There’s no evidence Twain said it, though he should have. It’s pretty good.

Now media and the internet disseminate falsehood at the speed of light, and new technology is busy improving the techniques and platforms for deception. Russian security services, as we all know (except for those who get their fake news from Fox and like-minded friends on the right) used Twitter, Facebook and their ilk to further polarize the electorate in 2016. They seeded the battlefield with false narratives intended to suppress or misdirect votes, spread conspiracy theories, and tilt an election.

Still, the use of high tech for low ends only begins with election tampering. Jim Acosta of CNN recently had his pres pass taken away after Sarah Huckabee Sanders claimed he had laid hands on a White House intern, and she offered up video to prove it.

Unfortunately for her, the source was one of Trump’s usually unreliable manufacturers of bushwa — Infowars. The video had been doctored, as a comparison with the original made clear. But not every smear artist will be so inept.

Given the proliferation of body cams and CCTV for urban surveillance, how long till some rogue actor at a police department or other malefactor doctors video to make bad actors look innocent or the innocent look guilty?

“Afterimage,” a recent “New Yorker” article, describes the merging of AI and computer graphic capabilities to make it possible to create a video of a president, for example, saying words he never spoke through a process called image synthesis.

This creation of a synthetic reality is frankly terrifying, as instances form the piece demonstrated. A woman in a bitter divorce case, for instance, introduced as evidence a video of her husband reaching across a table and caressing another woman. It was a computer generated fraud, but it only came to light because forensic experts examined it.

We shouldn’t be surprised. Carrie Fisher has starred in two Star Wars sequels despite the impediment of being dead. Half of the movies we watch are computer generated imagery, not nature generated imagery. While this may be cool as entertainment, it is less fun when it invades our daily lives or the public square.

Cyber bullying is bad enough if a person’s secrets are revealed or private videos made public, but even worse if the videos are generated by an enemy out of thin air. Or if candidates for office or other public figures have to spend their lives refuting not just fake news of the “National Enquirer” variety, but fake audio and video.

Soon, we may all no longer believe what our lying eyes and ears are telling us. Sorting out truth and fiction is about to become exponentially more difficult. What happens when Trump doesn’t just claim a huge caravan is coming toward us made up of drug gangs and muslim jihadis, but has the video to “prove“ it? What happens when a slimy pol like Gov. Rick Scott doesn’t just claim his opponent for office has tampered with an election, but can offer video of Bill Nelson stuffing a ballot box with phony votes?

Capitalism has begun to come to the aid of capitalists via a start up called Truepic. It allows images to be verified as real and stored safely where they can’t be tampered with, but who will be able to afford this process, and for how long will it be reliable? Maybe only until another startup offers a way to outwit the protections of Truepic. Digital lying can easily turn nto an arms race.

Fact checkers are a lovely idea, but Juvenal, the Roman poet who lived at a time that taught him a thing or two about corruption and unreliability, coined this worrying warning: “Quis custodiet ipsos custodes?” That is, who will watch the watchers, or who will guard us against the guards?

Thus, who will check the facts the fact checkers checked? Who will prove the president apparently addressing us is really an actual person not a product of CGI? Who will vouch for the evidence offered in court or the videos supposedly showing a crime taking place? And if we get experts to testify, who will attest to their reliability?

Is this all too farfetched? Not really. This week Chinese state television announced that some of the anchor duties on its news shows will be turned over to robot anchorpersons, all but indistinguishable from the humans they will replace. They will work much more inexpensively and will be just as reliable. Or unreliable.

Is this a joke? Something put out by a satiric website like “The Onion?” And if it were, how would we know? And if it isn’t, how would we know? It begins to look as if we are all living in a Kafka novel where reality is imaginary and individuals can neither trust their own senses nor the powers of truth, justice and the American way. Any day any one of us may wake up to the same fate as Joseph K.

You recall in his case, “Someone must have been telling lies about Joseph K., for without having done anything wrong he was arrested one fine morning.” And those who came to get him didn’t even have the benefit of synthetic images, the better to frame him with. O, brave new world that has such technology in it.