Rusty Kennedy, Associated Press Peyton Sundin, 10, of Houston, selects a question at the National Historical Park's Light of Liberty yesterday in Philadelphia. The CMU-designed interactive exhibit can literally answer thousands of questions for vistors in the virtual persona of Ben Franklin. Click photo for larger image.

If President Bush could ask Benjamin Franklin's advice about flagging opinion poll numbers regarding the Iraq war, what might he say?

"There never was a good war or a bad peace," perhaps?

Or maybe: "We must all hang together, or, most assuredly, we shall all hang separately."

No one can know exactly what Old Ben might say, of course. But an exhibit developed by Carnegie Mellon University's Entertainment Technology Center and now open in Philadelphia at least gives the illusion that the founding father can still keep up his end of a conversation.

Called "Ben Franklin's Ghost," it is open across the street from Independence Hall in the visitors center for the Lights of Liberty Show, a sound-and-light walking tour after dark through Independence National Historical Park.

Using a Carnegie Mellon-patented technology called Synthetic Interview, visitors can ask questions of Franklin, either by choosing from 160 prepared questions or typing in their own questions based on a list of key words.

Computer software then calls up the most appropriate of about 800 possible answers as performed by actor Ralph Archbald, who has portrayed Franklin in hundreds of appearances in the Philadelphia area over the past 25 years. These digitally recorded images are then displayed using a 150-year-old illusion known as Pepper's Ghost, which makes Archbald's image appear to float in front of the visitor like a ghost.

"It's the closest people will come to being able to speak to Benjamin Franklin," said Ann Meredith, president of Lights of Liberty. It's been used steadily since Carnegie Mellon researchers worked out the final kinks last Friday and likely will get a heavy workout from July Fourth crowds this weekend.

"Kids love it," she said, noting they typically spend between five and 20 minutes with the exhibit. "My son is 10 and he was here yesterday and he just couldn't stop."

Jessica Trybus, edutainment director at the Entertainment Technology Center, said she hopes this type of interactive exhibit might become the basis of a new tourism-and-education product, one that makes use of the center's unique combination of writers, actors and hard-core computer scientists.

A South Side health information firm, Medrespond, already is using Synthetic Interviews for Web-based medical advice applications, she said. But Ben Franklin's Ghost is the first public exhibit to use the technology.

The Synthetic Interview, patented in 1999, was invented by Scott Stevens, a senior systems scientist at Carnegie Mellon's Human-Computer Interaction Institute, and Michael Christel, senior systems scientist in the School of Computer Science. One of the first pilot projects involved an interview with Albert Einstein.

The Franklin project was initiated last summer after Gov. Ed Rendell visited the Entertainment Technology Center, which trains students in developing video games and other amusements that employ computers. He suggested that the exhibit for Lights of Liberty, which he initiated while mayor of Philadelphia, might serve as a test case for a broader statewide proposal by center officials.

"It was a good hit for us," said Meredith, noting Philadelphia is gearing up for Franklin's Tercentenary, or 300th birthday, in January. About 50,000 people attend the Lights of Liberty show each year, but as many as 250,000 people go through the free visitors center, where Franklin's Ghost now appears.

Trybus said the Pittsburgh Film Office helped bring the parties together, with the state providing a $150,000 grant and both the university and Lights of Liberty making undisclosed contributions.

Meredith said the development included gathering questions from a variety of sources, including elementary school classes and at the Pittsburgh Children's Museum.

The questions range from the obvious -- "Did you know George Washington? Did you fight in the Revolution?"---- to the irreverent -- "Did you have children out of wedlock? Did you own slaves? Why are you fat?"

J.A. Leo Lemay, a Franklin biographer from the University of Delaware, is a consultant on the project.

More than 100 hours of video of Archbald playing Franklin were recorded in Pittsburgh and Philadelphia -- providing fodder for hundreds of possible answers to questions.

In the exhibit, the video of Archbald/Franklin is reflected on an angled pane of glass in front of the exhibit guest, making the image appear to float on the other side of the glass -- the so-called Pepper's Ghost illusion.

Visitors to the exhibit can choose from 160 prepared questions.

"The problem with open-ended questions," Trybus said, "is that they don't know what to ask. They get in front of Ben Franklin and ... what do they do?"

But the adventurous can type in their own questions, constructed from a set of key words.

"If it's a wild question or doesn't make sense, [the synthetic Franklin] has plenty of answers" so he can sidestep gracefully, she added.