Feb12

## Putting Picos In Perspective

Fast Fission Podcast #23 – Download mp3 Here Ever thought about how many zeros there are there in a “pico” something? Remember back in grade school when we learned the metric system of measures?  We started out with units that are easy to visualize: meters get 1000 times bigger and become kilometers; meters get 1000 times smaller and become millimeters.  We understand these intuitively because we have a frame of reference and can visualize each of those unites of length and distance.  Units of mass are the same way; we know a gram is a small unit of mass – we can hold a gram of almost any material in the palm of our hand.  For example, a penny weighs 2.5 grams. Stack up 400 pennies and you have a kilogram, or 1000 grams.  Cut a thin copper shaving off a penny and you have a milligram, or one 1,000th of a gram.  Again, these are things we can see, and that makes it easier to understand. As our schooling progressed we learned about very large and very small numbers, exponents, and scientific notation.  We put these principles to use in science and learned there are other units of measure larger than a “kilo” and smaller than a “milli”.  These are harder to visualize because we have to think in terms we can’t see.  For example, the mass of Mount Everest,  is 3E18 grams, or 3 “exa-grams” and the mass of the planet earth is 6×10^24 kg, or 6E27 grams (6,000 “yotta-grams”) (see note below). On the opposite end of the scale is the prefix “nano” or 1E-9 of a unit. A nanometer is 1E-9 meters, and a nanosecond is 0.000000001 seconds.  I had a hard time visualizing a nano second of time until I learned that it takes about 1 nanosecond for a beam of light to travel one foot.  That kind of puts a nano into perspective, doesn’t it?  The newest computer chips, for example have transistors with a thickness of 45 nanometers!  We can only see things that small with powerful electron microscopes. A “pico” is even smaller than a “nano” , 1000 times smaller!  “Pico” means there are 12 places behind the decimal point.  Even for a person like me who deals with engineering and science all the time, it can be difficult to visualize a “pico” of something.  A pico is so small that even a million picos is still very small amount. It takes a million, million pico grams to make one gram.  If you have a million pico-curies in a liter of water, it would take one million liters to provide a...