In addition to the other points made, there is also theoretical calculations. The cesium fountain travels at a known dispersion of speeds (source of error) as well as known potential error in the tuning methods, so it's possible to estimate that the new design will have a lower error without actually having something to compare it to. >From: Hal Murray <hmurray@suespammers.org> >Date: 2006/07/16 Sun PM 12:28:19 CDT >To: Discussion of precise time and frequency measurement <time-nuts@febo.com> >Subject: Re: [time-nuts] New frequency standard, Mercury better than Cesium? >From the horses mouth: > > http://www.nist.gov/public_affairs/releases/mercury_atomic_clock.htm > > >This brings up a question I've been meaning to ask for a while. > >How do you tell how good your best clock is? I can figure out how good a >not-great clock is by comparing it to a better one. But what if there isn't >a better one? > > >-- >The suespammers.org mail server is located in California. So are all my >other mailboxes. Please do not send unsolicited bulk e-mail or unsolicited >commercial e-mail to my suespammers.org address or any of my other addresses. >These are my opinions, not necessarily my employer's. I hate spam. > > > > >_______________________________________________ >time-nuts mailing list >time-nuts@febo.com >https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts