BERKELEY — Baxter Wood is one of Hubert Dreyfus' most devoted students. During lectures on existentialism, Wood hangs on every word, savoring the moments when the 78-year-old philosophy professor pauses to consider a student's comment or relay how a meaning-of-life question had him up at 2 a.m.
But Wood is not sitting in a lecture hall on the UC Berkeley campus, nor has he met Dreyfus. He is in the cab of his 18-wheel big rig, hauling dog food from Ohio to the West Coast or flat-screen TVs from Los Angeles to points east.The 61-year-old trucker from El Paso eavesdrops on the lectures by downloading them for free from Apple Inc.'s iTunes store, transferring them to his Hewlett-Packard digital media player, then piping them through his cabin's speakers. He hits pause as he approaches cities so he can focus more on traffic than on what Nietzsche meant when he said God was dead, then shifts his attention back to the classroom.
"I'm really in two places at once," he said. "The sound of chalk on the chalkboard makes it so real."
By making hundreds of lectures from elite academic institutions available online for free, Apple is reinvigorating the minds of people who have been estranged from the world of ideas.
For several years universities have posted recorded lectures on their internal websites, giving students a chance to brush up on their classes or catch ones they missed.
But 28 colleges and universities, including the Massachusetts Institute of Technology, Stanford and Yale, now post select courses without charge at iTunes.
The universities want to promote themselves to parents and prospective students, as well as strengthen ties with alumni. Some also see their mission as sharing the ivory tower's intellectual riches with the rest of the world.
"It was something we couldn't easily do before the digital age," UC Berkeley spokesman Dan Mogulof said.
These unofficial students, invisible to their instructors, won't earn degrees for listening. Some professors won't even respond to their correspondence. But they relish the explosion of free lectures.
Retirees in Long Beach and Weaverville, Calif., halibut fishermen in Alaska, data entry clerks in London, casting agents in New York -- all separated from the classroom by age, distance or circumstance -- are learning from some of the world's top scholars.
"Something revolutionary is happening," said UC Berkeley professor Richard Muller, whose Physics for Future Presidents class airs on iTunes. "A large number of people around the world want more education. They thirst for understanding and knowledge." One e-mail Muller received came with the subject line "Thank you from a grateful sailor in Iraq."
Apple began working with Duke University in late 2004 to broadcast classes from its website using iTunes software and has expanded the service to other schools. Separately, some universities started putting lectures on the iTunes store in the form of podcasts, which are free video or audio recordings that anyone can download to their computer or iPod.
The downloads have surged since May, when Apple began featuring lessons on the iTunes home page under the heading iTunes U. For example, the 86 courses UC Berkeley offers are now being downloaded 50,000 times a week, up from 15,000 before Apple's promotion.
Analysts say Apple foots the bill for storing and cataloging the recordings to create goodwill with universities, which are big buyers of its Macintosh computers. It has another motive: Podcasts drive demand for iPods.
For their part, universities are experimenting to see what works. Mogulof said UC Berkeley had no plans to charge for the podcasts but acknowledged that the benefits were unclear.
"We know there's oil under the ground," he said. "People are punching a lot of holes, and no one is sure what will come up as a big gusher."
The courses on iTunes U may not be the stuff of Casey Kasem's "American Top 40." But they are ranked nonetheless, and some become surprise download hits. One recent week, popular iTunes U podcasts included Modern Theoretical Physics from Stanford, Elementary Greek from Concordia Seminary in St. Louis and Intro to Biology from MIT.
It's a stretch to say that professors compete for iTunes popularity, but many are eager to know how many people tune in and see whether the university can benefit.
Dreyfus has cracked the top 20. He's the iTunes U equivalent of an indie rocker with a cult following.
Fans of his podcasts have trekked to his office in Moses Hall to meet him. Many have sent the university money, generally between $5 and $500, to show their appreciation for him and other podcasting professors, said Benjamin Hubbard, a co-manager of webcast.berkeley, which produces Berkeley's online courses and events.