Wednesday, February 22, 2012

Google Doodle - Heinrich Hertz

Google Doodle, 2/22/2012
Today's Google Doodle is an animated gif celebrating the birthday of Heinrich Hertz .  Writing this post probably won't hurtz me much.  Hertz.  The SI unit of frequency in cycles per second is named after him (hertz, Hz) in honor of his research on electromagnetics - specifically the existence of free-space propagation of EM waves at radio frequencies.  He also established the photoelectric effect  (PE) after noticing changes in the charge of objects illuminated by UV light.  The PE effect was later explained by Albert Einstein.   Hertz also experimented with "cathode rays" and showed they could penetrate thin sheets of aluminum. 

Frequency (or more precisely temporal frequency)  is a fundamental physical idea.   All kinds of objects vibrate , more or less, periodically -  leaves flutter in the wind,  hollow tubes whistle,  trees sway,  balls bounce. etc. etc.    Surface waves  move water up and down and move foward and backward.   The frequency spectrum  of a time-domain function is a unique transformation (the Fourier transform).  Time and frequency are dual variables related through an analytic duality.   Here is a list of dualities.  The one of interest here is  Pontryagin duality .


Monday, February 13, 2012

Speedskating Trip To The Netherlands

Yesterday,  I skated about 80 km of canal ice in Friesland,  in the north-eastern part The Netherlands.   My plan was to skate the entire 200 km Elfstedentocht route.   However, I was waylaid by several Frisian pirates on the icy canals and forced to drink Beerenburg.  The sun was going down and I was advised that  canal skating tipsy and in the dark was not a good idea.  So we skated tipsy until sunset.  I started at Leeuwarden, skated to Sneek, then IJlst, Workum, Bolsward, Witmarsum and Harlingen.


View Larger Map
 It was great fun.  It's been 15 years since the last really deep freeze in Friesland when an official Elfstedentocht was held.

Here is a photo link to my trip album (click to enlarge).


And also a video link.

Enjoy.

Utility Pole Replacement in Cambridge (Riverside)

Last night a wooden  utility pole  cracked at the base and fell toward the neighboring pole across the street. This caused the wires to d...