John,
Thank you for this. It is very profound, if troubling.
Dave Hay
At 3/2/2014 07:05 AM, you wrote:
[
The subject line is the title of
a talk that Paul Borrill presented
at Stanford a few years ago. It's important for many issues
about
time that have been discussed in Ontolog Forum.
In particular, he emphasizes the complexities of time, the
difficulty
of defining time, and the disasters that have been caused by
treating
time as a Newtonian linear sequence.
The talk:
http://www.stanford.edu/class/ee380/Abstracts/091111-RethinkingTime.pdf
The slides are useful for an overview, but the talk is much richer.
It's packed with examples and stories that aren't on the slides.
Three of many examples:
1. For a multi-core chip, each core maintains its own clock. The
time
delays for signals passing across the chip make
it impossible to
keep the clocks exactly synchronized.
2. For GPS, even special relativity is not sufficiently
accurate.
People on earth are sitting in a deep gravity
well compared to the
satellites. GPS requires the corrections
of general relativity.
3. The disaster of the Challenger space shuttle, for which he
was
on the engineering team.
Borrill's conclusion: Simultaneity is a myth. Except for a
single
local observer, don't assume a linear time. In a distributed
system,
never depend on clocks to serialize anything.
I also like the slogan of his company: "Radical
simplicity."
That is his recipe for designing reliable systems.
His final slide is a quotation by Leonardo da Vinci:
"Simplicity is the ultimate sophistication."
John
_________________________________________________________________
Message Archives:
http://ontolog.cim3.net/forum/ontolog-forum/
Config Subscr:
http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/
Unsubscribe:
mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
Shared Files:
http://ontolog.cim3.net/file/
Community Wiki:
http://ontolog.cim3.net/wiki/
To join:
http://ontolog.cim3.net/cgi-bin/wiki.pl?WikiHomePage#nid1J
_________________________________________________________________
Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/
Config Subscr: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/
Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
Shared Files: http://ontolog.cim3.net/file/
Community Wiki: http://ontolog.cim3.net/wiki/
To join: http://ontolog.cim3.net/cgi-bin/wiki.pl?WikiHomePage#nid1J (01)