Tuesday, September 10, 2013

A Pitch Drop Contest

The Journal of Improbable Research is having some fun with the Pitch Drop Experiment.
"...in homage of John Mainstone, the 2005 Nobel prize winner for the longest experiment ever, [t]wenty competitors will have to prepare the slowest flowing mixture out of usual kitchen ingredients. All at the same time, they will place it in one of 30 funnels: the winning mixture will be the one that will release the first drop as late as possible, but before the Harvard Ig Nobel ceremony will end."
(You will recall that Prof. Mainstone recently passed away without ever seeing a drop fall in the Queensland Pitch Drop Experiment).

I'm not participating in the event (it's in Paris - I'm in Minnesota), but if I were, here's what I would try:

My first thoughts went to using cheese as an base, but I think it would be too sensitive to batch-to-batch variations to really work well. Some kind of paté would stand a good chance, but I don't have much experience in preparing such concoctions. I think it would have to be a reasonably soft paté too, but then there is the risk that it would start to separate with some of the low viscosity liquids migrating to the wall and lubricating them so that your drop slides out prematurely.

As for what I would work with, I'd start with
  • Gelatin. Plain of course, and a goodly quantity of it with water [*]. That will give you the backbone and the resistance that you want so that nothing drops for a long time.
But you don't just want a solid that doesn't flow over the 3 months or so of the experiment, so you need to cut the viscosity a bit. To achieve this, I would add some
  • Alcohol. The alcohol would actually serve 2 purposes. Beside lowering the viscosity, it would eliminate bacterial growth. The big question is how much to add (to the mixture, not the formulator). Someone with lots of experience with jello shots (not me!) would have an advantage.
Lastly, I'm concerned about water evaporation over the duration of the experiment, so I would also add a layer of
  • Honey. If permissible, I would also coat the gelatin with honey once it is in the funnel in order reduce water evaporation. An oil would not necessarily be a good alternative as it would preferentially displace the water and wet the walls of the funnel to lubricate them. In comparison, honey is very viscous and water-based so it would stay at the top of the funnel. An additional advantage is that it is not going to support bacterial growth.

Time a brief interlude. This is a far more challenging contest than most people realize - it is not about just getting the viscosity, density and other aspects of the rheology correct. You need to prepare your mixture from food, but remember that all human food is never food for just humans. There are plenty of microbes, both airborne as well as on all non-sterilized surfaces that will love to dine on your experiment while it is still running. They will have months to chow down on your mixture and in doing so, will alter the consistency of it most likely not in a good way.

And that brings me to a second option for the gelatin. Instead of fighting with biology, embrace it. Take your alcohol-free gelatin formulation and add
  • Sugar. This may seem to be an odd idea as it would have little to no direct effect on the viscosity, but the sugar suddenly gives you a third lever to play with. Gelatin and sweetened gelatin in particular are going to grow bacteria and mold, creating a colorful and odoriferous material without any redeeming organoleptic value, but it might, just might, get the gelatin's viscosity to decrease at just the right rate that it delightfully delivers a dramatic drop during the awards ceremony, ensuring your enduring fame for decades. For a consistent degradation, you would probably want to have bacteria throughout so inoculating the gelatin with mold from a lovely mountain gorgonzola cheese, or a yogurt with live bacteria would be a consideration. The former, being an anerobe would like be a more successful choice.
So there you have it. 2 paths - the traditional create-something-so-viscous-that-it-will-only-drip-really-slowly - and the other, a trifecta of physic, chemistry and biology that instead of fighting off bacterial growth, tries to take advantage of it. I like the second approach as it seems far more appropriate for The Journal of Improbable Research.

[*} I don't want anymore controversy like the last time I discussed mixing gelatin and water so let me be clear - heat the water, add the gelatin, stir and let cool. Adding gelatin to cold water will not create a gel of an appropriate viscosity for this contest.

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