FiO/LS 2011 - The Tech

  I took some time off during the Wednesday sessions, as I was having information overload and need some time to recharge my brain for another few rounds of information dump. To chill out, I visited The Tech which is a science museum with an emphasis on technology and interactivity. It was very nicely done, and I had a good time - if I were a kid again you'd have a really tough time getting me out! I was only able to spend a couple of hours in the museum, but there's certainly enough there for a full day.

  One of the first exhibits I encountered on the top floor was this nifty robot arm. You could get your picture taken at a station nearby, and the arm would then draw your portrait.
  Another nearby robot would re-arrange wooden letter blocks until you asked it to spell your name, when it would kindly oblige.

  Around the top floor, they also had some nice exhibits on digital logic and programming microchips (we are in Silicon Valley after all). These consisted of a Mr. Potato Head whose clear head showed off his microchip brain, in a room with lights, fans, thermometers, etc. that you could control. By placing labeled blocks in slots you created a logic chain that would cause Mr. Potato Head to perform some action. For instance, the chain could read "Light is on" "and" "Mr. Potato Head is hot" then "Speak". You then sent these commands to the PIC brain, and he would execute them if the conditions were right. So if the light was on and the fan was off, the temperature would rise, and Mr. Potato Head would start talking.

  They also had nice DNA exhibit, the best part of which was a functioning wet lab. Of course, I had to test it out. I was quite impressed, they had the ingredients (e. coli? and gfp? plasmids) nicely laid out, a how-to video which you followed at your own pace, and included the proper safety procedures; goggles and gloves. They walked you through the entire process of getting the bacteria to uptake the genes by heat-shocking them. Since the bacteria need some time to grow, you incubate overnight and then can check back on them via their on-line interface.

My two bacterial colonies!

A double helix of books

The nerve center.

  Speaking of the online interface, it was well done; the events had barcode scanners that would scan your ticket, and you log in to their website using a number from your ticket. Once online you can check back on the exhibits, and items you may have 'collected'. Admittedly from a review point, I should probably have taken more advantage of this, but at the time I wasn't that interested, so I only scanned the bacteria station above. Those electronic looking racks to the left are the servers.

I think I'm in the monitor at the lower left...

  This was one of the best - it was a remote controlled submarine. They had three in a tank and had them returning video feeds, so you could see things through the sub camera you otherwise would not be able to see. A perfect demonstration of why this tech is used. The pic is an attempted self-portrait, but I was having difficulty keeping the sub stable with one hand.

  Also on the lower level was an awesome demonstration of NASA's Extravehicular Mobility Unit (powered space suit). A chair had several compressed air jets to levitate it, and then a few more for control. Excluding the minor friction I noticed (which may have had something to do with the fact that I'm about a hundred more pounds heavier than their target 7 year old), it was a good demonstration of what the astronauts have to deal with to maneuver in space.

Tracks of flights across the globe.

  The photo on the left is of another exhibit that I quite enjoyed. The globe shows the track of planes as they traverse the globe. It was part of a station that showed how we monitor global weather, of which planes play a part.

  Overall this was a fantastic museum: I was only able to spend a couple of hours here, but one could easily loose a day or two in these very interactive halls.

FiO/LS 2011 - Tuesday Sessions

    Wow! Today was absolutely packed and quite exciting. First off I just invented my "Most Amusing Talk" award so I could give it to John Dudley, whose talk (slides available here) was very entertaining. He started off with a case of how he was wrong, then moved into a recount of how he was observing super continuum generation (where you get white light from almost single color laser light using special optical fibers) as a solution to the nonlinear wave equation and couldn't get it published anywhere (Science, Nature, and on down the food chain), but eventually got it into Applied Optics. Now these types of results make the cover of Nature Photonics! He suggested they start the journal "Nature Reinterpretations" which got a good chuckle from the audience.
    This was mixed with a recount of how the first nuclear weapon design (gun type) was not actually tested, but the engineers who were building it had a good idea it would work, so while the physicists were busy testing their bomb (implosion type), the engineers just dropped theirs! I really have no idea how this fit in, but interesting trivia anyway. Another good quote; "Fluid dynamicists were divided into engineers who observed things that could not be explained and mathematicians who explained things that could not be observed …" (Sir James Lighthill). I can think of some other fields, where this is true.
    Finally, he ended by showing just why science is exciting - the solutions they were seeing in their nonlinear optics experiments should have been possible in water (where the equations the optics people used were first developed). Despite searching, no-one had been able to produce the effect in water until the optics folks showed the way. And now we have rogue wave type solitons in water;

    The best part of the day, however, was going by the '"Mission: Optical" Student Chapter Competition'. The goal was to build a project for under $25 (US) that demonstrated an optics principle. So many good and fun ideas - I'll definitely be stealing many of these! My favorites were a balloon stretched across the end of a tin can, the other end was cut off so you could speak into it. A laser pointer was then attached pointing at a mirror (or CD) that was glued to the balloon. When you spoke into it, the balloon drum would vibrate, and the reflected spot would trace out a pattern on the wall. A great way of 'visualizing sound', and much easier, more direct and more robust than having motors drive mirrors to deflect the laser beam. Another group used legos, LED's, CD's and some ingenuity to build a 3D stroboscopic viewer. It almost worked. But it was enough of an ingenious idea, that I'd really like to give them credit for it.
    Other groups used just a bucket of water, sugar and milk to demonstrate as many different optical principles as they could: Reflection and refraction, the later of which changes with the addition of sugar to the water, total internal reflection in the bucket and the addition of milk for scattering. And another had a great setup that really made it easy for students to get into the scientific principle (just don't tell the kids that). They had kids split into groups and try different ways to heat water. Yet another demonstration of just why I think these conferences are awesome - I never would have thought of some of these ideas on my own, but now I can use them to teach others about optics.

Oobleck!

Here's a hands-on experiment that even the kids can try*.

  Oobleck (or corn starch in water) is a "Non-Newtonian fluid". When something tries to move through the oobleck, it tends to stiffen, and make it even more difficult for that object to move through. In the video below, sound waves from the speaker apply little pulses of pressure to the ooblek. Let's see what happens.

  When each pressure pulse (sound wave) is applied, the oobleck stiffens, and then relaxes when the pressure stops. This gives rise to the "fingers" of oobleck forming, then slowly wiggling around and breaking off. Look again at the video and watch the oobleck at the edges of the speaker. When the pieces break off and land on the part of the speaker that is not vibrating they stop stiffening and look almost like a normal liquid.

  Don't forget about the oobleck that's dripping off the edge too! It almost looks like a very thick syrup, similar to molassas. The same physics is happening here as well. As the oobleck slides down itself there's a force that causes it to stiffen up.

  Compare this behavior with plain water in a speaker cone (not responsible for musical tastes):

  Unlike oobleck, water doesn't get stiffer in the same way that oobleck does. If you have a bathtub full of water and you pull your hand through it it's difficult. That's the drag of water resisting you. Now if you drag your hand twice as fast it's just about twice as difficult. That's a Newtonian fluid, for those of you more advanced, it means that the drag of the water is linear in the rate of shear (how fast it flows over your hand).

   If we were to take our bathtub and fill it with oobleck (hypothetically, I wouldn't recommend doing this), we could pull our hand through it as well. Now if we were to drag our hand through it twice as fast, it resists us much more than twice as much. That is to say it gets stiffer as we increase the rate of shear, people call this dilatant.

  Alternatively we could imagine a material where if we were to pull our hand through twice as fast, it would actually be easier! This type of liquid gets softer as we go, or you may hear it as "shear thinning" or pseudoplastic.

  Oobleck is really a fantastically fun recipe and one that's so incredibly simple I really encourage you to do on your own: Mix 1 part water to 1.5 or 2 parts corn starch. Add some food coloring if you'd like. That's it!

  Another do-at-home non-Newtonian fluid recipe is that of Flubber.

*Always exercise caution when working with exposed electrical wiring, such as that which can be found in speakers, subwoofers, and other audio electronics. Children should always be supervised around electricity.