[Caveat for the easily offended: today's blog post is mildly NSFW.] The Time Lord is off gallivanting in Avignon with his fellow cosmologists, leaving Jen-Luc Piquant and me to fend for ourselves in terms of ferreting out interesting science topics. Today's inspiration comes courtesy of The Late Late Show with Craig Ferguson, specifically, his April 13 monologue in which he riffed on the NHL playoffs and various national obsessions (or lack thereof) with hockey; Canada takes their hockey very seriously indeed, while Los Angeles… not so much. He mentioned one game in particular that was delayed when fans from Sweden tossed all manner of rubber sex toys onto the ice — presumably in celebration, or to cheer on their team, or… well, who the hell knows why they did it? Those Swedes love their sexy fun time. The point is, Ferguson wondered whether tossing a rubber dildo onto the ice, and the ensuing change in temperature, would result in what has been immortalized on Seinfeld as "shrinkage." And this, people, is a physics question. Oh, yes, it is.
Rubber, and rubber bands, are of great interest to physicists, being an example of a "deformable material," and a terrific means for studying elasticity under varying conditions (temperature, yes, but also response to electrical current). This fascination dates back to 1880, when Wilhelm Roentgen — yes, the guy who discovered X-rays — attached a rubber band to an apparatus and dangled an unspecified "mass" from the other end, then zapped it with electrical current to see what happened. The result: the rubber band changed in length in response to the current. (Fill in your own off-color quip here.) This was the first electroactive polymer. By 1945, scientists had figured out that collagen wires would expand or contract when dipped in acidic or alkali solutions, respectively.
So electrical current and alkali solutions cause "shrinkage" in rubber bands and collagen fibers. What about cold or heat? I can think of no better expert to comment on the amazing physical properties of rubber bands than the great Richard Feynman:
Feynman Physics Lectures: Rubber Bands by FeynmanPhysicsLectures
As Feynman says, "The world is a dynamic mass of jiggling things if you look at it right." So if heat drives the rubber band, what happens when rubber gets cold? If you're like the students who have asked this question online, you'll have a hard time getting a straight answer unless you're very, very specific about your chosen parameters for the experiment. It's hard to get a straight answer out of a scientist, not because they're deliberately being difficult, but because they know so much about the subject that they can think of innumerable variables that might affect your outcome. That said, in general, when rubber gets cold, it gets harder — but not in a good way. It loses its elasticity and becomes increasingly brittle, and if it gets cold and brittle enough (we're talking very cold, like liquid nitrogen temperatures), it might even shatter if you drop it.
Probably the best example of the catastrophic failure of rubber at cold temperatures comes courtesy of Feynman again. Shortly before he died of cancer, he testifed before Congress in the wake of the Challenger disaster, memorably demonstrating — with a simple cup of ice water — that the rubber O-rings failed on the space shuttle because of the unusually cold conditions on the launch pad that fateful day. Specifically, the rubber lost its elasticity; it didn't go back to its original shape like it was supposed to, a property that was critical to maintaining sealing on the spacecraft.
Feynman Physics Lectures: Challenger Crash O-Ring by FeynmanPhysicsLectures
Yeah, okay, so that's a very bad thing. But there's good news for the sex toys tossed into the hockey rink: they likely didn't get anywhere near cold enough to become brittle and shatter on the ice. Frankly, even if they did get a little cold, it would be very easy to re-heat them using friction — and friction, to put it delicately, is kind of inevitable during the traditional uses for these items. Zap them with electricity or dip them in alkali, and it might be a different story, depending on the kind of polymers used to make them. And here you thought physics had nothing to offer that could be relevant to your sex life!
Scientists are still interested in rubber bands. Last year, a team of physicists from MIT and Ecole Polytechnique in Paris decided to study how a rubber band "deforms" as it rolls around, of particular interest because it is elastic — and I'm using that term in the technical sense to describe something that regains it shape after being deformed by an outside force (like one of those squeezable stress balls, for example, or a sponge). The problem: have you ever tried to "roll" a rubber band down an inclined surface, a la Galileo? "It would have taken several meters to get the loops rolling fast enough to deform, and that was larger than the size of our room," team member Cristophe Clanet told Science. Apparently lab space is at a premium these days.
The solution: put the rubber band loops into a big steel drum and spin it, like a makeshift centrifuge, so you can control the conditions of the experiment. Then you'll see, as the researchers did, that the faster the rubber band spins, the more squashed it gets. Frankly, this doesn't strike me as especially surprising, but that's because I don't know very much, and it's not my job to measure and describe as precisely as possible what's going on at a deeply fundamental level. In contrast, the scientists created intricate mathematical models for the rubber band "system" and the various forces that were acting upon it.
"They combined equations for the effects of gravity, bending forces, centrifugal forces, and internal stiffness to explain the loop's movement. Initially, the rubber band's natural stiffness balances with gravity to keep it in shape. As the rolling begins, gravity works to help the loop keep its shape. But at higher speeds of rotation, the other forces overwhelm gravity, and the loop begins to collapse."
Just this past week, rubber bands (or rather, dielectric elastomers of the sort Roentgen discovered) were back in the news, with the announcement that scientists at the Auckland Bioeningeering Institute have used them to create "wearable energy harvesters" that can convert your movement as you walk down the street, for example, into electrical energy to re-charge your cell phone. (Not surprisingly, Sminton Comics had a bit of fun with this concept relating to prophylactics.)
These "dielectric elastomer generators" are more commonly known as "artificial muscles," and are of great interest in the field of robotics, since they make terrific sensors and actuators that together can ably mimic the behavior of real muscles. I'll bet these things would also make terrific materials for dildoes, which have their own kind of underlying physics, apart from the materials from which they are made. Just think, you'd never need to replace the batteries in your vibrator! When it comes to the physics of the device's operation, it's all about oscillations, resonances, and strategic dampening of vibrations, according to the lustily curious folks over at the Physics of Sex blog:
In battery-powered models, vibrations generally come from an electric motor attached to a rotating disk, with its weight placed off-center. The principle is the same thing that causes unbalanced washing machines – which are some, other, people's favorite lovers – > to buck violently when more of the laundry is on one side of the washer drum than the other. The faster the motor turns, the higher the vibrator frequency. …
Some dildos have a cavity that allows you to insert vibrators into them. The softer and heavier the dildo, the more it will dampen the vibrations and slow the resonance. Many manufacturers of plug-in vibrators offer soft sleeves and attachments to allow you to dampen oscillations in the same way. Damping is the reason that vibrators are more comfortable when used in the anus or vagina than on a hard penis or clitoris. A rigid clitoris or penis has much less damping than softer and more enveloping anal and vaginal tissue. The vibrational motion, and resulting energy, is transmitted at full intensity to sensitive nerves in a small area where the vibrator makes contact with the rigid tissue. In the vagina and anus, the energy is distributed to more tissue and nerves, which feels less intense.
Ahem. I just report the science news, people, I do not make this stuff up. That said, I'm delighted to finally have an excuse to post this hilarious British TV appearance by particle physicist Brian Cox, who shows himself to be quite the broad-minded good sport when host Jonathan Ross presents him with a mini-scale model of the Large Hadron Collider — built entirely out of sex toys, including a vibrating butt plug. I'd wager Cox knows his oscillations from his resonances.