

Introducing the World’s Most Precise Clock - davidiach
http://spectrum.ieee.org/aerospace/satellites/introducing-the-worlds-most-precise-clock

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fmstephe
Can any wise person comment on the potential impact of this on distributed
systems? If they were cheap enough to pop in a server.

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burke
You still wouldn't be able to trust them.

Google's Spanner goes really far down this line of reasoning. Read the paper;
it's great.

Basically, highly-precise clocks in a machine-local context would
substantially reduce drift, but you can still never _really_ synchronize two
clocks reliably across a network (potentially asynchronous send and receive
times make it basically impossible)

Maybe there's some literature on this I haven't read, but I don't think it
would eliminate the kind of work you currently have to do to solve this
problem (ie. what Spanner has done), though it would certainly narrow the bars
on their TrueTime values quite a bit.

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darkmighty
I think a very basic reason it shouldn't be possible is that for _really_
accurate sync each device has an unkown bias (innacuracy) besides just high
std dev (imprecision) with relation to it's network/processing behavior. If
you average out a lot of samples you can get rid of all imprecision (albeit
very slowly), but you essentially need a very accurate clock to find the bias,
so it makes the whole network approach useless. I would guess you couldn't
even solve for bias with a clock once and then keep using the network, because
the bias should be time-varying.

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ctdavies
I'm confused by the use of "accuracy" and "precision" in this article.

From the IEEE article: "[ultranarrow lasers] will make it practical for us to
achieve an accuracy below 10^-18–more than 100 times the precision of cesium
clocks."

From
[http://en.wikipedia.org/wiki/Accuracy_and_precision](http://en.wikipedia.org/wiki/Accuracy_and_precision):
"accuracy is the proximity of measurement results to the true value;
precision, the repeatability, or reproducibility of the measurement."

Am I mistaken, or is the IEEE article conflating accuracy and precision?

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theoh
In this case, precision is a prerequisite for accuracy, so it's implicit that
higher accuracy involves greater precision.

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ctdavies
Ah I see. Thanks for clearing that up.

