NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: what is a second?
From: Peter Fogg
Date: 2006 May 9, 23:49 -0500
From: Peter Fogg
Date: 2006 May 9, 23:49 -0500
A quick Google reveals:
"The unit of time, the second, was at one time considered to be the fraction 1/86 400 of the mean solar day. The exact definition of "mean solar day" was ..."
www.bipm.fr/en/si/base_units/second.html
"second n. ( Abbr. sec. ) A unit of time equal to one sixtieth of a minute. The time needed for a cesium-133 atom to perform 9192631770 .."
www.answers.com/topic/second
"Definition. The second is the duration of 9 192 631 770 periods of the ... The definition of the second was later refined at the 1997 meeting of the BIPM to ..."
en.wikipedia.org/wiki/Second
and so on. The consensus seems to be that a second started as an interval within a mean solar day, but lately has been redefined with reference to the known decay of radioactive elements. Bit like the story of time itself.
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---
"The unit of time, the second, was at one time considered to be the fraction 1/86 400 of the mean solar day. The exact definition of "mean solar day" was ..."
www.bipm.fr/en/si/base_units/second.html
"second n. ( Abbr. sec. ) A unit of time equal to one sixtieth of a minute. The time needed for a cesium-133 atom to perform 9192631770 .."
www.answers.com/topic/second
"Definition. The second is the duration of 9 192 631 770 periods of the ... The definition of the second was later refined at the 1997 meeting of the BIPM to ..."
en.wikipedia.org/wiki/Second
and so on. The consensus seems to be that a second started as an interval within a mean solar day, but lately has been redefined with reference to the known decay of radioactive elements. Bit like the story of time itself.
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---
