Dear Mr. Know-It-All I've always been proud of my scooter's great gas mileage. But a friend tells me its emissions make it no greener than a Chevy. Have I been deluding myself?

Your use of the word always implies that your scooter is rather aged. If that's the case, then your contrarian pal may be right. Older scooters with two-stroke engines emit far more smoggy pollutants per mile than their four-wheeled counterparts. True, you probably get double the fuel economy of a Chevy and can thus crow about your ride's smaller carbon footprint (and thus smaller contribution to climate change). But your tailpipe may also be belching out 10 to 15 times more smog (nitrogen oxide and hydrocarbons) than that Chevy, to the severe detriment of your city's air quality.

If you switched to a new, four-stroke scooter, you could pop your eco-jersey a bit more. New federal regulations on two-wheeler emissions kicked in for the 2006 model year, and they're slated to get even tougher for 2010. Look for a scooter with a catalytic converter — the emissions-scrubbing gizmos aren't required, but they are becoming more common.

My 10-year-old son wants to go trick-or-treating as Niko Bellic, the murderous antihero of Grand Theft Auto IV. Should I let him?

Your son's familiarity with Bellic indicates that he's an experienced GTA IV player. So if you put the kibosh on his costume, you're sending a mixed message — it's OK to play GTA but not to dress up as one of the characters.

If you're not prepared to bar Junior from exploring Liberty City, then a compromise may be in order. Let him don Bellic's gangster gear and (faux) facial hair, but strictly forbid the use of toy weapons — or any other pointy accessories, for that matter.

Granted, there's something distasteful about having your grade-schooler dress up as a drug-dealing, prostitute-beating, human-smuggling thug. But ask yourself: Is a werewolf or witch really morally superior? At least Bellic exhibits brief flickers of doubt about his chosen path. Werewolves, by contrast, never hesitate before eviscerating their prey.

Illustration: Christoph Niemann My ex-girlfriend recently posted one of my gooey love notes on her blog. I'd rather the world didn't know that I used to refer to this vindictive harpy as "babycakes." Can I compel her to delete the letter?

No doubt you intended your handwritten sweet nothings for babycakes' eyes only. But privacy, alas, just ain't what it used to be. If you claim copyright on that letter, your blogging former lover can argue that she's merely engaging in fair use. And odds are that most judges would take her side.

Your primary problem is that, by handing over the letter in the first place, you essentially published your writing — not in the conventional sense, perhaps, but in the eyes of the law. "When boyfriend gave the letter to girlfriend, he transferred ownership of the letter to the girlfriend," says Marc J. Randazza, an Orlando attorney and law professor who blogs at The Legal Satyricon. "This transfer of ownership is akin to you buying a book or magazine. That transfer, I think, is a publication, even though it was to just one person." So consider yourself a published writer. (Congratulations!)

Unfortunately for you, it's a lot harder for a plaintiff to win a fair-use argument when the work in question is published. According to Ned Snow, a professor at the University of Arkansas School of Law, courts that mull such cases are primarily concerned with whether the use impairs the market value of your work — be it letter, drawing, or photograph. You'd probably have a tough time convincing a judge that you intended to turn that love note into cash — especially since you presumably didn't keep a copy for yourself.

Courts can be fickle, of course, and you could pull off a miraculous upset. But do you really want to go to the mat on this one? The embarrassment seems minor, and steering clear of vengeful exes is always advisable. If it makes you feel any better, Mr. Know-It-All once fondly referred to a paramour as "peanut." You're certainly not alone.

Need help navigating life in the 21st century? Email us at mrknowitall@wiredmag.com.

Inspiration Point Walker frequently meets with the Walker Digital brain trust in the seating area of the library, hoping to draw inspiration from the surroundings. Artist Clyde Lynds (known for integrating fiber optics into his work) created the intricate illuminated glass panels and many other visual elements. Walker himself designed the Escher-like tile floor, modeled after a tumbling block pattern from the Victorian age. He bought the chandelier (seen in the Bond film Die Another Day) at an auction and rewired it with 6,000 LEDs. The open book on the table features watercolor illustrations for an 18th-century papal palace that was never built. The globe has special meaning for Walker: "It was a wedding gift Eileen and I received in 1982."

Reading Room In the foreground are several early-20th-century volumes with jeweled bindings—gold, rubies, and diamonds—crafted by the legendary firm Sangorski & Sutcliffe. On the table (first row, from left) is a 16th-century book of jousting, a Dickens novel decorated with the author's portrait, and (open, with Post-it flags) an original copy of the 1493 Nuremberg Chronicle, the first illustrated history book. Second row: the 1535 Coverdale Bible (the first completely translated into modern English), a medieval tome with intricate illustrations of dwarfs, a collection of portraits commissioned at a 17th-century German festival ("Facebook in 1610!"), a tree-bark Indonesian guide to cannibalism, and a Middle Eastern mother goddess icon from around 5000 BC.

Walker shuns the sort of bibliomania that covets first editions for their own sake—many of the volumes that decorate the library's walls are leather-bound Franklin Press reprints. What gets him excited are things that changed the way people think, like Robert Hooke's Micrographia. Published in 1665, it was the first book to contain illustrations made possible by the microscope. He's also drawn to objects that embody a revelatory (or just plain weird) train of thought. "I get offered things that collectors don't," he says. "Nobody else would want a book on dwarfs, with pages beautifully hand-painted in silver and gold, but for me that makes perfect sense."

What excites him even more is using his treasures to make mind-expanding connections. He loves juxtapositions, like placing a 16th-century map that combines experience and guesswork—"the first one showing North and South America," he says—next to a modern map carried by astronauts to the moon. "If this is what can happen in 500 years, nothing is impossible."

Gadget Lab A brand-new One Laptop per Child XO, far left, sits next to a relatively ancient RadioShack TRS-80 Model 100. In back, a 1911 typewriting machine and a 1909 Kent radio. The large contraption at center is the Nazis' supposedly unbreakable Enigma code machine. The book to its left is a copy of Johannes Trithemius' 1518 Polygraphiae, a cryptographic landmark. On the right is an Apple II motherboard signed by Woz. An Edison kinetoscope sits beside an 1890 Edison phonograph (along with three of the wax cylinders it uses for recording). Nearby is a faithful copy of Edison's lightbulb. The gadget with the tubes is an IBM processor circa 1960. In front of it stands a truly ancient storage device, a Sumerian clay cone used to record surplus grain.

Walker struggles to balance privacy with his impulse to share his finds with the outside world. Schoolchildren often visit by invitation, as do executives, politicians, and scholars. Last February, the organizers of the TED conference persuaded him to decorate their stage with some of his treasures. But he's never invited any press in to see the collection—until now.

Senior writer Steven Levy (steven_levy@wired.com) profiled sci-fi author Neal Stephenson in issue 16.09.

Don't trust anyone over 30. That's the prevailing wisdom in Silicon Valley, a land once again bestrode by millionaire CEOs who just learned to shave. Many people believe that the breakthrough ideas come only from the young. And why not? Media stories constantly recite the ages of a few famous founders: Bill Gates of Microsoft, 20; Mark Zuckerberg of Facebook, 20; the Google boys, 25; YouTube's Chad Hurley, 28. Tumblr founder David Karp is 21 — and on his second successful company.

Young people rule tech innovation, we tell ourselves, because they have several key advantages. They're fearless and naive, so they'll try anything. They can spy markets that elders, with their locked-in views, cannot. And without dependents or spouses, twentysomethings can work the sort of pyramid-building hours necessary for a startup. It's a kind of Logan's Run world: If you're ending a third decade, you're obsolete.

But hold on. A recent study has finally collected some data on age and high tech innovation and found that older geeks are just as successful as young Turks. What's more, the chronologically advanced are especially successful at solving problems we increasingly — and desperately — need solved.

In other words, the high tech future may belong to the over-30 set. The Ewing Marion Kauffman Foundation surveyed 652 US-born CEOs and heads of product development who founded high tech firms in the boom (and bust) years of 1995 to 2005. Both the average and median ages were 39 — far older than the mythic dorm-room visionary. Turns out those youthquake pioneers don't really represent the pack. They're outliers.

So why is our intuition wrong about this? Because young and old founders create different types of startups.

Mature entrepreneurs tend to launch startups that require huge amounts of capital — biotech companies, energy firms, outfits that make expensive hardware. Startup costs in these areas include tens of millions for research resources, large staffs, maybe a laboratory. Then, to take their invention to market, they have to navigate complex, entrenched industries, which requires connections. "You need to know how to run a company right off the bat and inspire confidence in investors," says Vivek Wadhwa, a Harvard Fellow who coauthored the Kauffman Foundation report.

In contrast, those sexy Web-service firms that have dominated headlines on and off for the past decade require almost no capital. The "social software" market also rewards people who intuitively understand new media experiences. "There's been social change, too," says Paul Graham, cofounder of Y Combinator, a seed-funding firm. "Ten years ago, it was bizarrely unusual for someone graduating college to launch a startup. Now almost everyone who gets a computer science degree at least thinks about doing it."

In essence, the high tech world divides itself: Young people create the way-kewl consumer software — the Twitters and the Loopts — and older folks tackle the heavy-industry stuff. Young founders hack information; old founders hack atoms.

But we're moving to a world where we need more and more of the latter. Think of some of the thorniest high tech challenges — solar energy, battery systems, plug-in cars. These all reside in the world of atoms. Whoever cracks the problem of carbon sequestration is going to reap a multibillion-dollar reward. But they'll have to solve some hellishly complex physics puzzles and then introduce the solution to an energy industry riddled with byzantine state-by-state regulations and run by an old-boy network of cigar-chewing gazillionaires. Not something easily accomplished in sweatpants.

When you look at it this way, the constant hype over social applications like Facebook or Tumblr can seem a bit misplaced. I'm not saying that Web 3.0 or 4.0 apps are going away (or that they'll stop being fun). But here's my bet: When we finally start solving our global energy and resource dilemmas, the next generation of media-feted tech CEOs will look more like your parents than your kids. Or, to put it another way: Don't trust anyone who wants to put an age limit on innovation.

Email clive@clivethompson.net.