On Tuesday, October 24, 2017, Antoine Pitrou <solip...@pitrou.net <javascript:_e(%7B%7D,'cvml','solip...@pitrou.net');>> wrote:
> On Tue, 24 Oct 2017 09:00:45 +0200 > Victor Stinner <victor.stin...@gmail.com> wrote: > > By the way, you mentionned that clocks are not synchronized. That's > another > > revelant point. Even if system clocks are synchronized on a single > > computer, I read that you cannot reach nanosecond resolution for a NTP > > synchronization even in a small LAN. > > > > For large systems or distributed systems, a "global (synchronized) clock" > > is not an option. You cannot synchronize clocks correctly, so your > > algorithms must not rely on time, or at least not too precise resolution. > > > > I am saying that to again repeat that we are far from sub-second > nanosecond > > resolution for system clock. > > What does synchronization have to do with it? If synchronization > matters, then your PEP should be rejected, because current computers > using NTP can't synchronize with a better precision than 230 ns. >From https://en.wikipedia.org/wiki/Virtual_black_hole : > In the derivation of his equations, Einstein suggested that physical space-time is Riemannian, ie curved. A small domain of it is approximately flat space-time. >From https://en.wikipedia.org/wiki/Quantum_foam : > Based on the uncertainty principles of quantum mechanics and the general theory of relativity, there is no reason that spacetime needs to be fundamentally smooth. Instead, in a quantum theory of gravity, spacetime would consist of many small, ever-changing regions in which space and time are not definite, but fluctuate in a foam-like manner. So, in regards to time synchronization, FWIU: - WWVB "can provide time with an accuracy of about 100 microseconds" - GPS time can synchronize down to "tens of nanoseconds" - Blockchains work around local timestamp issues by "enforcing" linearity > > See https://blog.cloudflare.com/how-to-achieve-low-latency/ > Regards > > Antoine. > > > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: https://mail.python.org/mailman/options/python-dev/wes. > turner%40gmail.com >
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