Further to the subject of retrocausality, my dad, John Cramer, emailed to say:
From the article:
Over the next few years, some experiments hold out a chance of finally being able to show whether or not time can move backward as well as forward. Theoretically, at least, it might be possible for the future to influence the past, said John Cramer, a physicist at the University of Washington. He and his colleagues plan to try just such an experiment next year.
Cramer acknowledged that the concept of retro-causality doesn't seem to make sense, "but I don't understand why not."
Both Greene and Cramer know the science as well as the fiction side of the time-travel issue: Greene is the author of "The Elegant Universe," a best-selling book on string theory — but he also played a cameo role in "Frequency," a time-travel movie released in 2000, and served as a scientific consultant for "Deja Vu."
"It was a kick to be in the room with [producer] Jerry Bruckheimer and [director] Tony Scott and the writers, talking about special relativity and general relativity and wormholes," he told MSNBC.com.
Cramer, meanwhile, has done research into ultra-relavistic heavy-ion physics at CERN and Brookhaven National Laboratory — but he's also written two science-fiction novels and pens a regular column for Analog magazine called "The Alternate View." If his experiments show that retro-causality is a reality — that one event can determine the outcome of another event taking place 50 microseconds earlier — it could lend support to the ultimate alternate view of quantum physics.
"It opens the door to doing all kinds of really bizarre things," he said.