> Has anyone measured the speed of light with GPS clocks in the same way that > neutrinos are measured - say between mountain tops?
I'm pretty sure that won't work very well. The problem is that air isn't vacuum. The index of refraction changes slightly with temperature. The subtle changes in the index of refraction are what causes mirages. The San Andreas fault (and friends) runs right down the middle of Silicon Valley. The USGS has a big research group here. There are two convenient mountains. They used to do laser ranging between the mountain tops to track the fault motions. In order to get good data, they had to run a helicopter along the beam to measure the air temperature. (Maybe they also measured other things like humidity. ??) I don't remember where I heard that story. It was a long time ago. These days, the USGS uses GPS. They don't need mountain tops. It's not uncommon to see them slightly off a highway. Maybe I'll remember to ask more at their next open house. For anybody in the area... The next open house in Menlo Park is May 19+20, 2012. http://openhouse.wr.usgs.gov/2012/index.html They have them every 3 years. Kids welcome. I always have fun. -- These are my opinions, not necessarily my employer's. I hate spam. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
