[time-nuts] List of time synchronization hardware and software

Magnus Danielson cfmd at bredband.net
Tue Jan 17 13:15:41 EST 2006

From: "Poul-Henning Kamp" <phk at phk.freebsd.dk>
Subject: Re: [time-nuts] List of time synchronization hardware and software
Date: Tue, 17 Jan 2006 18:52:59 +0100
Message-ID: <60347.1137520379 at critter.freebsd.dk>


> >> Even better, pulsars. They have a period that is usually the same order
> >> of magnitude as a second, and some of them are regular enough that they
> >> are similar in stability as an atomic clock (how many of us have
> >> cesium beam tubes that will last for billions of years, hmmm?)
> Pulsars were considered for timekeeping several times in the past, and in
> every instance the winning argument was "You want to base our timekeeping
> on some cosmic phenomena we don't even know what is ?".
> I guess we think we know what they are now, but the argument is
> still pretty powerful as we don't know how stable we can expect
> pulsar rates to be in the long term.


We should expect a long term continous frequency drift, since it is
transmitting quite alot of energy and thus should be loosing mass (E=mc^2
anyone?) and thus the rotational speed of the phenomena should change over
time. That assuming fairly Newtonian physics with only a dash of Einstein on
top of the composition. The loss of mass should surely change the gravitational
pull and thus shift the pulsars sense of time and then naturally the expansion
of the Universe changes the relative speed between us and the pulsar. That was
only the simple stuff that me as a non-astronomer and non-physics guy cooked
up in a few minutes. No fancy stuff like dark matter and dark energy in the

However, it may be stable enought for tau in the range of 1 Ms to 1Gs or so,
and that is still usefull.

Let's get these frequency comb-thingies working instead. Sounds promessing.


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