the GPS myth almost mythbusted
On Aug 21, 2:58*am, Koobee Wublee wrote:
On Aug 20, 7:37 am, Jerry wrote:
Unless the satellites' clocks are synchronized with ground clocks
via the GR correction, there is simply no feasible way for them
to distribute time around the globe.
This is an absolute myth. *Well, He has had enough with these
bull****s from someone who does not even understand Snell’s law.
You've avoided answering me on the proper thread. If that's how
you insist on behaving, I will copy over my thought experiment
from the Sobral 1919 thread.
Your claim is that a pure gradient refractive index lens, with
no distinct surface, will not focus light, but instead will
merely displace an incident beam without changing its direction.
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Here is a thought experiment for you.
Walk out on a moonless night into the clear dark country skies of
Oklahoma. The land is flat for miles around.
Jupiter has just risen above the horizon! I train my telescope
on the planet, but the atmospheric turbulence near the ground is
too great for me to make out anything. Patience. I have to wait
an hour before Jupiter is high enough above the horizon to make
it worthwhile to use a telescope.
Indeed, geometrically, Jupiter is half a degree BELOW THE HORIZON!
Atmospheric refraction allows me to see it two minutes before it
has actually risen above the horizon in the geometric sense.
Quick! Turn around 180 degrees from Jupiter! What star do you see
on the horizon, just about ready to set? Not star. STARS! The
Pleiades! I'd recognize that cluster anywhere!
Geometrically, however, the Pleiades already set a couple of
minutes ago. In a geometric sense, the Pleiades are actually half
a degree below the horizon.
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In the above thought experiment, trace a line leading from Jupiter,
to you, and on to the Pleiades. That line is bent a total of about
a degree.
Earth's atmosphere does not merely displace light. It BENDS light
rays skimming its surface by up to a degree.
Earth's atmosphere represents a pure gradient refractive index
lens.
Jerry
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