Bob called me with rather interesting news.<p>It appears his experiment was a success. He worked at CMU
in Chemistry, specifically the area of supercooling things.<p>On a whim he decided that it would be interesting to supercool
something radioactive. That way he could study the subsequent
heating "in slow motion" atom by atom.<p>He needed something very stable but radioactive. The best option
seemed to be Uranium Hexafloride gas. Florine combines with anything
and is very stable so any defrosting would be very slow. The
radioactive Uranium would be easy to track.<p>The experiment was expected to last several years so he kept adding
more of the gas, cooling it and compressing it into a softball sized,
very dense solid. The whole experiment was put in the lab closet as
there was literally nothing to see.<p>He was very excited when he raised the temperature. The softball
stayed a solid all the way up to room temperature! This made the
measurement process much easier.<p>In April he built a measurement device in the corner of the lab.
It measured the radioactive gas released in great detail. In May
he found that the ball was ever-so-slowly evaporating. He estimated
that the process would take about a year.<p>Bob got a summer sabbatical to work at CERN. He would receive daily
reports from the experiment but was too busy to analyze them. But he
could see that the ball was slowly shrinking exactly as predicted.<p>One day the daily report showed no results. The video stream showed
that someone had opened the experiment and taken the sample. It seems
a grad student needed some of the measurement hardware for another
purpose and didn't know it was still an active experiment. The ball
was just left on a lab table and eventually thrown out.<p>When Bob finally analyzed the data he discovered that the Uranium
Hexafloride released from the ball only contained U238 atoms.
The U235 remained in the slowly shrinking ball.<p>This seemed like a great breakthrough for Uranium enrichment. Now the
centrifuges were no longer needed.<p>Unfortunately, as Bob pointed out, somewhere in the city there is a
ball of Uranium that is slowly shrinking, slowly enriching to pure U235.
And, at some point, it might reach a concentration sufficient for a
fissile yield explosion ... of several city blocks.