links for 2008-03-06

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News: Major Decisions - Inside Higher Ed "For 15 broad categories of majors, such as engineering, physical science, and business, the report explores the median and quartile pay, the percentage of the major comprising women and minorities, and the percentage of individuals from that major who went…
The Edublogs Magazine : Who Are the Top Edubloggers? "Aseem Badshah has created a listing of the Top Education Bloggers or edubloggers based upon Technorati's rankings." This page reviews some of them. (tags: blogs education academia) The Other Side of Graduate Admissions | Cosmic Variance How…
In Grad Admissions, Where Is Class? :: Inside Higher Ed :: Higher Education's Source for News, Views and Jobs "A study just published in PS: Political Science and Politics suggests that in graduate departments, class may be nowhere to be found in admissions decisions." (tags: academia class-war…
Bad Baby Names - A Boy Named Sue, and a Theory of Names - John Tierney - New York Times "During his 1969 concert at San Quentin prison, Johnny Cash proposed a paradigm shift in the field of developmental psychology. " (tags: kid-stuff psychology science society culture music) Gen Ed Reform --…

The Twin Paradox is cleaned up by triplets. Three identical clock kit boxes. Each clock will have a little on-off toggle switch. Two space ships, one home base.

Space ship L goes waaaay to the left, space ship R goes waaaay waaay to the right of home base H. Each spaceship accelerates to a large fraction of lightspeed aimed at skimming home base, then coasts with zero acceleration for the remainder of the experiment. All three observers proceed to build their clocks from parts after acceleration is zero, toggle them off, and set them to zero elapsed time.

Space ship L skims past home base and the toggles touch (locality!). Clocks L and H are on. Space ship L and space ship R pass each other, toggles touch. Clock L is off, clocks R and H are on. Space ship R skims home base, toggles touch, all clocks are off. Both space ships radio their elapsed times to home base. Home base compares L+R to H elasped time. Not equal!

It's not acceleration or even the clocks, it is the inertial reference frames. They have different relative mixes of spacetime even though none of them accelerated after the clocks were built.