On 12/28/2011 12:09 AM, [email protected] wrote: > Danny Mayer <[email protected]> wrote: >> On 12/27/2011 8:48 PM, [email protected] wrote: >>> Danny Mayer <[email protected]> wrote: >>>> On 12/24/2011 8:10 PM, [email protected] wrote: >>>>> John Hasler <[email protected]> wrote: >>>>>>> The open sky nearest the OPERA detector is straight up through 1400m of >>>>>>> rock. >>>>>> >>>>>> Jim Pennino writes: >>>>>>> And the easiest open sky to get to is horizontally down the tunnel to >>>>>>> the entrance which is next to a freeway. >>>>>> >>>>>> Yes, the entrance is next to a freeway. The entrance to the LNGS >>>>>> facility where the OPERA detector is located is near the middle of the >>>>>> 10 km long Gran Sasso highway tunnel. >>>>> >>>>> The bottom line is that the only thing that is relevant is how easy it is >>>>> to get to a GPS antenna with an open view of the sky. >>>>> >>>>> Everything else is bloviation. >>>> >>>> GPS is not used for this kind of thing, they are too inaccurate, so it >>>> doesn't matter. They use atomic clocks. >>>> >>>> Danny >>> >>> How do you measure distance with an atomic clock? >>> >>> >> >> That's a complex question. GPS (even the military version) is not >> accurate enough. >> >> Danny > > No, it is not complex; you can't measure distance with an atomic clock. > > An atomic clock is used to measure time intervals. > > As for GPS, it is pretty trivial these days to determine an absolute location > to parts of a centimeter for a fixed location. >
There's no such thing as an absolute location. See Einstein. Danny _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
