Dry Water

Summary
Dry water is the result of coating small water droplets in silica. It is a powdery substance like sugar and is composed of 95% water.

Dehydrated water crystals. Just add water!
(Photo: Taran Rampersad at Flickr)

Commentary
Jokes about dehydrated water crystals aside, this is a pretty impressive technique for collecting and containing water which has been around since 1968. In 2006, it was rediscovered as a potential way to absorb carbon gases and a host of other applications.

I've got to think back to other 8^th grade jokes to see what future technology will bring.


See Also

• “Dry water” could make a big splash commercially at the American Chemical Society where the announcement of this announcement was made at the 240^th meeting in Boston.
• Scientists Create 'Dry' Water Droplets at Scientific American
• Scientists create 'dry water' at The Telegraph
  

Reader Question: What does the furious brushing in curling accomplish?

This post is a response to a reader question. Please email your questions to metaist.blog@gmail.com. Not all questions will be answered.

Question
An anonymous reader asks: What does the furious brushing in curling accomplish?

From the little I've read, curling is a combination of darts and marbles. Sort of.
(Photo: andreassolberg on Flickr)

Summary
Curling is a 400+ year-old sport about which I know very little. Wikipedia saves the day again.

Explanation
Curling is played on level ice. However, droplets of water called pebbles are added which cause the stone (pictured above) to curl when it travels across the ice. According to Wikipedia, sweeping accomplishes two goals: to increase the distance the stone travels, and to change the amount of curl. The strategy of sweeping seems to involve figuring out when to sweep and how hard to sweep (apparently that has an effect on the amount of moisture created).

Overall, the point of sweeping seems to be to influence the curl of the stone by wearing down the pebbles.

Meta
Do you know more about curling than I do? If so, please post a comment so that I can update this post appropriately.

See Also

• Olympic Science: The Science of Curling at Fox News for a discussion of curling.
• Does sweeping in curling achieve anything? at Metafilter for a bunch of people talking about sweeping in curling.
• The Physics of Curling at the University of Toronto for an interactive description of how curling works.
• Curling at Wikipedia.

Wireless Electricity

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Summary
Wires are commonly associated with electricity. It is surprising, therefore, that people thought electricity would never be adopted widely if wires were required. Yet it was adopted, but we've only recently started to shed the wires.

(Video: TED)

Commentary
Earlier efforts focused on charging pads such by PureEnergy and SlashPower. The cleverness of MIT's technique is that it combines induction with resonance to achieve power at larger distances. That is, the resonance allows more of the power to be transmitted via induction to the receiver.

Meta
What are other potential uses of wireless electricity?

Electromagnetic Induction

Definition
From Wikipedia:

Electromagnetic induction is the production of voltage across a conductor situated in a changing magnetic field or a conductor moving through a stationary magnetic field.

In other words, magic.

One toroid to rule them all. Or not.
(Photo: Wikimedia)

Commentary
Induction is the principle behind generating electricity, most electrical motors, and some "smart" traffic lights. It's also how that little bit of foil gets attached to pill bottles and other containers.

More on this later.

See Also

• Concepts in Science: Electromagnetic Induction for an 80's video that's long, but informative.

Resonance

Definition
Resonance refers to a tendency of a system to oscillate more at certain frequencies than at others. Those frequencies are known as resonant frequencies.

(Photo: stevenduong on Flickr)

Commentary
An excellent example of acoustic resonance is shattering a wine glass with sound. Here's a quick explanation as to why the glass shatters:

1. The sound is being generated by a speaker. The speaker works by moving a small cone back and forth generating the appropriate frequency. You can sometimes see the movements.
   
   
2. Many frequencies make the glass vibrate, but only a handful make it vibrate so much that it cannot stay together. Those frequencies are the resonant frequencies-- they make the glass vibrate (i.e. oscillate) much more than the other frequencies.
   
   
3. Since the glass is insufficiently elastic, it shatters.

Meta
What other resonant systems have you encountered?