> -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Jean-Louis Oneto > Sent: Wednesday, August 19, 2009 2:42 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] time-nuts Digest, Vol 61, Issue 77 > > I also remember that one of Digital Equipment Corp. (DEC) VMS Operating > System was defined in microfortnight... > > ----- Original Message ----- > From: "Mark Sims" <[email protected]> > To: <[email protected]> > Sent: Wednesday, August 19, 2009 8:18 PM > Subject: Re: [time-nuts] time-nuts Digest, Vol 61, Issue 77 > > > > > > Alas, yes, the RCH is no longer politically correct. It's slightly > more > > acceptable cousin is now the RPH. > > > > I have a friend that does monomolecular / monoatomic layers. His > > definition of a thin film is a gnats ass spread over the Rockies...
Hmm. 50 microns (=1 GA) out of 5000 meters (Height of Rockies) is 10 ppb. A monolayer of oil on water is on the order of 1 wavelength of light (0.5 micron = 10 mGA), but that's a very thick layer as thin films go. Let's look at the layer of aluminum on a crystal. I think these are in the few tens of nm range (usually given as hundreds of Angstrom), and are deposited on a slice of quartz a few mm thick (I think.. others on this list know a LOT more about this than I do), or roughly 1 ppm thickness. But, to relate to our GPS timing question, what should the basis be? Orbital semidiameter of the satellites? Radius of Earth? A wavelength of the carrier frequency? _______________________________________________ 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.
