Today was a nice mixed day of climbing and flats traveling through the northern CA redwoods.  I had some serious issues with my derailleur, both rear and front.  One of my life goals is definitely to get to bicycle repair school; I'd love to know more about what's going on. 

Speaking of knowing more of what's going on, I kept thinking today about my little eTrex 10 GPS.  I spend so much time staring at the little numbers going up and down, both the distance and the elevation.  I was particularly curious about the elevation part - how does it know?  I had always had this erroneous idea that it used the coordinates to look up your elevation on a map but I realized today that would never work and it must work some other way.  And so I read the Wikipedia entries (side note: is any modern invention better than Wikipedia?) about GPS and how elevation works.  And, having read it, I have only this to say: science is basically incredible.  When you read how it works - and you should - you will basically say "no f'ing way".  Reading the description, it's like "that should never work".  But it *does*.  It works so well they can put it in a watch.  It works so well they can sell one for $50 that works within 13 feet.  It works so well that everyone has one in their cell phone.  But it's insanely complicated.  It relies on things like the speed radio signals travel in our ionosphere (whic, it turns out, changes all the time because of weather and god knows what else).  It relies on fractions of a nanosecond timing and the position of 4 out of 24 satellites hurtling through space 20,000 miles up.  If you start to think too hard about it your brain literally hurts, and yet it's one of the most reliable inventions of the modern age. 

It almost makes me want to work for a GPS company.