Kevin in Bentonville, Arkansas, wrote in to ask this question: "Why do you hear the ocean when you put a seashell up to your ear?"
All right, first things first: no matter how much it may sound like the rolling waves, it's not actually the ocean you're hearing in a shell.
Now that we've got that out of the way, what exactly is it that you're hearing? In a word, noise; the ambient noise that's being produced all around and inside you, which you normally don't hear or pay attention to because it's too quiet.
To amplify this noise so you can hear it clearly, you need a resonator. Want to make one on the cheap? Form an O shape with your mouth and flick your finger against your throat or cheek. You should hear a note. Make a smaller or larger O, or change the shape of your mouth, and you'll get different notes. Sort of like this. What you're doing here is letting your mouth fulfill its potential as a Helmholtz resonator, where sound is produced by air vibrating in a cavity with one opening. Different pitches can be coaxed out by changing the shape of the resonating cavity.
The seashell you're listening to—the inside of which has many hard, curved surfaces great for reflecting sound—is essentially doing the same thing you just did with your mouth. The ambient noise mentioned before—the air moving past and within the shell, the blood flowing through your head, the conversation going on in the next room—is resonating inside the cavity of the shell, being amplified and becoming clear enough for us to notice. Just like the various shapes we make with our mouths will produce different pitches, different sizes and shapes of shell sound different because different resonant chambers will amplify different frequencies.
The fact that all shells sound just a little bit like the ocean is purely coincidental. Holding any sort of Helmholtz resonator to your ear will produce a similar effect, whether that object is associated with the ocean or not. Put an empty glass over your ear or even cup your hand over it, and the sound you hear will be just about the same.
Could Game of Thrones's Dragons Really Fly? We Asked Some Experts
BY Nicolas Rivero
August 25, 2017
Game of Thrones is a show that requires a serious suspension of disbelief. It exists in a universe where the dead can rise from their graves, humans can see through the eyes of animals, anyone can travel between Dragonstone and Eastwatch at or near the speed of light, and Jon Snow can hold an unbroken frown for seven straight seasons.
Still, as we basked in the fiery glow of this season’s high-budget dragon action—cowering each time Drogon hovered in midair to pour a throatful of flame over one of Daenerys Targaryen’s enemies, we started to wonder: Could a beast that big really maneuver through the air like that? Fortunately, two scientists who have dedicated their lives to studying flying creatures agreed to clear that up for us.
Kevin McGowan, a Cornell ornithologist who specializes in crows, says there’s one major problem with dragon flight: physics. “They’re just so damn big,” he says. “Way too big to ever get off the ground.”
For comparison, there's the albatross, which weighs around 25 pounds and needs a 10-foot wingspan in order to heave itself into the air. And birds don’t scale up easily. McGowan says that as a bird gets heavier, its wingspan has to grow exponentially to keep up: “If you need a 10 foot wingspan for a 25-pound bird, what would you need for a 2000-pound dragon?” (Last season, one eagle-eyed engineer estimated that Drogon weighed around three tons and flew with a wingspan under 60 feet—and the dragons are even bigger now.)
In the real world, bird species generally stay small to avoid having to grow their wings exponentially. Those that do grow large wings, like the albatross, can travel long distances—but pay the price in maneuverability. Birds with smaller wings can maneuver in tighter spaces, but have to expend much more energy to stay aloft. “Birds make a lot of compromises to fly,” McGowan says, “and dragons just aren’t doing that.”
Still, there is some hope for letting our dragon-sized fantasies take flight. Michael Habib, a paleontologist and assistant professor of Clinical Integrative Anatomical Sciences at the University of Southern California's Keck School of Medicine, studies the flight mechanics of extinct animals, including giant pterosaurs once thought to be too big to get off the ground. He also works with film studios like Disney, Marvel, and Lucasfilm to design believable flying monsters like griffins, hippogriffs, and pegasi. There are three tricks, he says, for plausibly scaling up fantasy flying creatures.
First, you want to give them the right wing type. Like modern day bats, pterosaurs—which lived from 228 to 66 million years ago—had membrane wings, made of skin stretched over a series of elongated fingers. These are good for slow, maneuverable flight, and they don’t have to be as large compared to the body as a bird’s feather wings. Habib tells Mental Floss that a dragon with a good pair of wings would be able to sustain flight easily once it was in the air—but it could only get there “if it came with a catapult for takeoff.”
Second, a dragon needs to have the right skeletal structure. Their bones should be strong enough to withstand the massive mechanical forces involved in flight without getting too heavy. Hollow bones are best; they're actually stronger than a very dense bone with a similar mass. Habib explains that’s because the bone’s ability to withstand the strain of flight depends on its diameter—the wider it is, the more force it can take. A hollow, air-filled bone can be much wider than a dense bone full of marrow, and it will still weigh less than the dense bone.
Third, and most importantly, a dragon needs to have as much power available for takeoff as possible. Habib says that almost every animal that takes flight, from birds to flying squirrels to winged snakes, gets into the air by jumping, not flapping its wings.
“What birds get stuck on is they only have two hind limbs available for jumping power,” Habib says. “Bats do better—and pterosaurs did, too—because they walk on their wings and they can jump off of all four limbs.”
That makes a big difference, especially because most of a bird’s strength is in its wings. While birds take off with less than half their bodies’ muscle power, bats and pterosaurs launch themselves with everything they’ve got. That’s what allowed the largest pterosaurs to grow into 550-pound behemoths, while the heaviest-ever flying bird—the extinct Argentavis magnificens—maxed out around 150 pounds.
The dragons in Game of Thrones do have membrane wings, and they could conceivably have hollow bones. Back in season three, WIREDreported that the show’s animators based the dragons on a cross between an eagle and a bat. (Their strenuous, flappy hovering certainly takes after fruit bats.) Although the dragons walk around on their wings like bats, they don’t seem to jump off of them during takeoff. Throughout the series, we see them dive from cliffs and glide into flight, leap off their hind legs after a running start, and sometimes just flap their wings and leave the ground.
Habib says even if a dragon followed all of his specifications, it could only grow up to about 1000 pounds without grounding itself—not several tons, like Daenerys’s children.
“They’re probably beyond the flight limit for any anatomy,” Habib concedes, “unless they’re secretly made out of carbon fiber and titanium.”
“Maybe they’re full of hot air,” suggests McGowan, “or maybe it’s just magic.” To him, though, how the dragons fly doesn't really matter: “I think all day. When I go home, I don’t want to think anymore. I can just say it’s magic. I don’t care.”
Batman has the Batcave, Superman has his Fortress of Solitude, and Scrooge McDuck has his money bin. For 70 years, the maternal uncle of Disney’s Donald Duck has been portrayed as a thrifty—some might say miserly—presence in cartoons and comics, a waterfowl who has such deep affection for his fortune that he enjoys diving into his piles of gold and luxuriating in them.
It’s a rather gross display of money worship, but is it practical? Can anyone, including an anthropomorphic Pekin duck, actually swim in their own money, or would diving headfirst into a pile of metal result only in catastrophic injury?
According to James Kakalios, Ph.D., a professor of physics at the University of Minnesota and author of the recently-released The Physics of Everyday Things as well as 2005’s The Physics of Superheroes, the question really isn’t whether someone could swim in a mass of gold. They could not. It’s more a matter of how badly they’ll be injured in the attempt.
Diving into a gold pile the Scrooge way—hands first, prayer-style, followed by your head—is the most efficient way to begin breaking bones. “Keeping his arms stiff and his elbows rigid, he’s definitely going to break his wrists,” Kakalios tells Mental Floss. “Gold is a granular material like sand, a macroscopic object. You can’t swim through sand or dive into it easily.” Launch yourself off a diving board from 3 or 4 feet up and you will meet a solid surface. Landing with your feet, a far better bet, is unlikely to result in injury—provided you try to bend your knees.
In that sense, diving into gold is not dissimilar from “diving” into a concrete floor. But with gold being granular, it might be possible to break the surface and “swim” if the friction were low enough. “A ball pit is a good example,” Kakalios says. “The balls are lightly packed and have low friction relative to one another. The key is to have objects in front of you move out of the way in order to advance.”
Despite being a fictional character, McDuck hasn’t totally ignored the impossible physics of his feat. His creator, Carl Barks, has written in repeated references over the years to the implausibility of using his money vault as a swimming pool and has depicted the villainous Beagle Boys trio as getting hurt when they tried to emulate the stunt. Scrooge smirked and said there was a “trick” to making the gold dive.
That’s led to one fan theory that McDuck has used his fortune to coat the gold coins in some kind of lubricant that would aid in reducing friction, allowing him to maneuver inside the vault. Ludicrous, yes. But is it possible? “You would need a massive amount of lube to slide your body past the coins with minimal effort,” Kakalios says. “The ball pit is easier because the weight of the elements is low. Gold is a very dense material.” Diving and swimming into it, even with lubricant, might be analogous to trying to shove your hand into a deep bowl of M&Ms, he says. “M&Ms have a low friction coating. Continuing to move is really the problem.”
Presuming McDuck could somehow maneuver himself deeper into the pile, his delicate duck bones would almost surely succumb to the crushing weight of the gold above him. By one estimate, diving under one of his 5-foot-tall gold piles would put 2492 pounds of pressure on his bill.
We'll see if he tips his top hat to any further gold-diving tricks—or if he's in a full-body cast—when Disney XD relaunches DuckTales this summer.