They've got chocolate. The latest news on hallucinogenic drugs. Espionage, jazz, and weathered gravestones. Plus video games for autistic kids.

Where else but the third annual Philadelphia Science Festival?

The 11-day extravaganza starts Thursday, with 110 events aimed at all ages, many in locations not normally associated with science. At restaurants, branch libraries, and even cemeteries, people can examine dinosaur fossils, gaze at the stars, build rockets, and learn about the science of beer, cheese, or honey.

"One of the things we're dedicated to doing is meeting people where they are," said festival director Gerri Trooskin, who works at the Franklin Institute.

Science festivals are multiplying like bacteria in a petri dish. Before Philadelphia's event was first held in 2011, there were perhaps half a dozen such affairs nationwide, said MIT Museum official Ben Wiehe, who manages the nonprofit Science Festival Alliance. Now there are more than three dozen, and organizers share what they have learned.

Education and entertainment are always on the agenda, but also these events tend to have corporate sponsors - in Philadelphia's case, Dow Chemical Co. - with an interest in an educated workforce.

Dow's foundation contributed $100,000 to the event last year, and plans to announce Thursday that it doubled that amount for this year, fulfilling a pledge to match gifts from other donors. The overall festival budget exceeds $500,000, not including untold contributions from volunteers, said Franklin Institute president Dennis Wint.

It all begins Thursday night with an adults-only party at NextFab Studio, the high-tech workshop on Washington Avenue. Guests can listen to music, watch "live science" shows, and sample the festival's official beer from Yards Brewing Co. Geek humor alert: it is called Pythagorean Beerum.

That shindig costs $15, but most of the 11-day festival is free.

The headliner event is Saturday's Science Carnival on the Parkway, from 11 a.m. to 4 p.m. More than 130 exhibits are planned on the streets surrounding the Franklin Institute, which leads a broad group of local institutions organizing the festival.

Many events have an interdisciplinary vibe. At 7 p.m. Tuesday in Drexel University's Mandell Theater, a jazz combo will play while a funky graphic display gyrates to reflect the timbre and pitch of the instruments. One of them is an unusual piano modified by Drexel engineers so that the strings are vibrated with electromagnets.

"It's opening my ears up from a math perspective to really understand the harmonics and how they work," said avant-garde jazz pianist Marc Cary after trying it out this week.

Other highlights:

At 2 p.m. Saturday at the Franklin Institute, Mars Inc. research fellow Ed Seguine tells how he tastes chocolate for a living. Don't be too jealous - it's mostly unsweetened.

Monday at 6 p.m., at the Stratus Rooftop Bar and Lounge, retired CIA case officer Martha Peterson describes how spy technology has advanced since the late 1970s, when she worked in Moscow before being arrested and sent home by the KGB.

At 5 p.m. Wednesday at the University of Pennsylvania Museum of Archaeology and Anthropology, scientists from various museums will demonstrate the value of conserving art and artifacts. Among other activities, guests can create their own works and use infrared light to peer at underlying layers of paint.

Before and during the Phillies game April 25, patrons can explore more than a dozen sports-related topics in the stadium concourse, such as the physics of baseball and why it's smart to wear a helmet.

At 7 p.m. April 26 at the Mütter Museum, ticketholders can work with forensic scientists to solve a pretend murder mystery, while swilling cocktails and sampling high-end hors d'oeuvres.

As for the hallucinogens, no illicit behavior is in store. At the Frankford Hall restaurant at 4 p.m. Sunday, Matthew Young, a neuroscience Ph.D. student at Penn, talks about psychedelic substances throughout history, and how they have reemerged in the last decade as potential treatments for mental illness.