Provided

Shimon Edelman contemplates a spoon, à la "The Matrix."

President Obama watched Navy SEALs raid the house where Osama bin Laden was killed in "real time," news outlets reported. Gamers spend their time immersed in fantasy. Our cell phone calls and Skype video chats send us real-time images and sounds that re-create a simultaneously occurring reality.

What if realities we take for granted are not, in fact, real?

In a new paper surveying work on questions of perceived reality, Shimon Edelman, professor of psychology, ranges from cryptography and computing to mathematics and Descartes. The paper is published in the peer-reviewed, open access journal Frontiers in Theoretical and Philosophical Psychology.

"This is a metaphysical question that goes back to ancient thinkers, yet there are new things to be said that come from cryptography and from statistical testing for intruders in a communications network," Edelman said. "The very same algorithms used by your cellular carrier can be brought to bear on the question, What is real? How do you know who you're talking to? But only up to a point."

The idea of virtual worlds is at the center of the "Matrix" films and more recently "Inception," which confuses a dream world with reality. Reality is an ongoing concern in Eastern philosophies but in the West, except for occasional arguments, doubting reality pretty much petered out with Cartesian skepticism until about a decade ago, when Oxford philosopher Nick Bostrom took up the question, said Edelman.

By incorporating developments in computer science, Edelman said his paper describes "a new synthesis. Minds are computational. I'm a computational psychologist, so one central premise to this is the possibility of simulating an entire reality with minds that don't realize they are simulated."

The idea for the paper arose in a class discussion with his students, when Edelman asked how they would feel about living in computer-generated reality. "Some were completely complacent," he said. "I appreciate the equanimity of one guy who was particularly unperturbed by this idea. I find [the promise of alternative realities] on balance more intriguing and exciting than threatening."

Edelman said, "The bottom line is that there are things to be said that go beyond the existential doubt that Descartes is famous for, also beyond Descartes' acceptance on faith that God is benevolent and would not deceive him [Descartes]. Both those considerations can be set aside on the strength of new developments in computer science in the last 20 years."

Edelman concludes in his paper that unless the designer of a virtual reality is omnipotent, computational constraints would apply. "Which is really a big deal because people who are not of theistic predisposition, if they think at all about the possibility that reality is constructed by a game designer in another, containing reality, it is subject to the same laws of mathematics and computer science," he said.

Edelman's synthesis incorporating computer science into the discussion of reality is "a bit of progress, even if it's a very small step," he said, adding that it represents one of the few developments "on this issue since Descartes."