Bouldering (not Boulders or Boulder), Exoplanets, and the Thermodynamics of Ice Cream

1) How to boulder! The lab went bouldering* today, which reminded me just how much fun climbing stuff is, and also *exactly* how out of shape I am (pretty out of shape, but not hopelessly so). 

* Bouldering is like gym-style rock climbing, but less tall and without the safety lines. Instead, they just have super plushy mats that you fall onto. Falling and rolling out is the most fun part, imho.

2) NASA is holding a press conference tomorrow detailing the latest results from the Kepler Space Telescope, which searches for Earth-like planets in other star systems. The fact that they're having a press announcement, and not just publishing their results like normal scientists, may be a sign of very juicy details about to come to light. Stay tuned!

3) How *not* to make ice cream by hand. The usual method is to put your cream into essentially a thermos with the vacuum part replaced by a slurry of ice and salt, which rapidly cools the interior. Then you turn a crank that scrapes ice crystals off the sides. What you might be tempted to do is to add your ice and salt to the thermus bit, then fill the rest with water to increase thermal conductivity between the ice and the inside container. That would be wrong. It turns out that the cooling is mostly from the enthalpy of fusion of the ice, which is a technical term for the heat that is absorbed by ice as it melts, which it does very quickly because of the salt. The enthalpy of fusion absorbed (is this the right term? Chemists help me out) from melting is much stronger than the effect of conduction from ice-cold water, and adding water just gives you a huge heat source to draw from instead of the interior container, ergo slower cooling of the interior and longer crank times.

Now, this begs the question in my eyes -- what if you fill the thermos bit with saltwater, freeze it (using a -20 freezer, presumably), let it warm until it starts to melt, then add ice cream and start cranking? It seems like that would give you the benefits of both enthalpy of fusion of ice and maximal thermal conductivity.

...or you could just use liquid nitrogen. (http://tinyurl.com/plk5n53 -- note the last step)