Fans will no doubt complain about a scientific inaccuracy tonight. The production crew wouldn’t let me bring real rocket fuel for the episode and instead used water. Apparently Warner Brothers has some rule against bringing hydrazine and nitrogen-5 onto their sets.
Hydrazine has a long history in the rocket world as a propellant. Its first use was for the German rocket-propelled military aircraft, the Messerschmitt Me 163 Komet. To date, the only such aircraft ever in regular operation.
When mixing the hydrazine with solvents, the Germans called the fuel “B-Stoff”. Today hydrazine is used for more peaceful purposes, such as adjusting the orbits of satellites and as auxiliary power for the International Space Station.
The hydrazine reaction was on tonight’s boards so it was a kind of spoiler for those paying attention.
The concept the writers explained to me was that Leonard’s mistake was that something didn’t scale. They wanted that what would work for a real rocket, would not scale to the small amount of fuel he brought. The hydrazine reactions happen faster by exposure to the element iridium. The word chemists would use, is to say the reaction is “catalyzed” by iridium. A catalyst accelerates a reaction but is not used up. This is what the platinum does in a car’s catalytic converter and was the reason for the ‘iridium flask’.
By what is now the season’s third application of the square-cube law, the full amount of hydrazine would be exposed to a relatively small surface area of iridium. In Leonard’s small container, a far greater fraction of hydrazine is exposed to iridium, and as Sheldon realizes, becomes highly explosive as shown on the boards above.
We added some “Nitrogen-5”, or pentanitrogen, to sweeten the mixture. That was a fuel that was being developed in 2003, and would likely have some secret aspects Leonard should not discuss.
Not everything on the boards relates to rocket fuel. Recall it is 2003. Drs. Abrikosov, Ginzburg and Leggett had just received the Nobel Prize in physics
for pioneering contributions to the theory of superconductors and superfluids.
Their theoretical work is laid out on the boards as well, as something Sheldon would have been thinking about.
The whiteboards star the show once again. I don’t know why the director keeps letting the actors walk around and upstage them.