The Future of Time: UTC and the Leap Second 235
rlseaman writes "UTC ("Coordinated Universal Time") is very close to being redefined to no longer track Earth rotation. Clocks everywhere — on your wall, wrist, phone or computer — would stop keeping Solar time. 'American Scientist' says: 'Before atomic timekeeping, clocks were set to the skies. But starting in 1972, radio signals began broadcasting atomic seconds and leap seconds have occasionally been added to that stream of atomic seconds to keep the signals synchronized with the actual rotation of Earth. Such adjustments were considered necessary because Earth's rotation is less regular than atomic timekeeping. In January 2012, a United Nations-affiliated organization could permanently break this link by redefining Coordinated Universal Time.'"
PDF version (Score:5, Informative)
Re:Membership Required (Score:5, Informative)
The Download: PDF Only link on the right hand side of the first linked page (Cornell) gives you a PDF of the same article [arxiv.org].
How long is year anyway? (Score:4, Informative)
We say 365 days.
We observe 365.25.
The tropical year (equinoxes+solstices) is closer to 365 solar days, 5 hours 49 minutes 19 seconds
The sidereal year is 1.0000385 tropical years (365.256363004 ) (20m24.5128s longer than tropical year)
So may times...
Re:It's about time (Score:5, Informative)
Seriously this has been an issue for along time - GPS time does not include leap seconds and I am tired of having to write software that let's user adjust for the variable amount of leap seconds - nobody really cares if the earths rotation is synchronized with " UTC"
Those who doesn't care about synchronisation already have the option to use TAI. They should use that instead of redefining UTC.
What would be the point of UTC, then? (Score:4, Informative)
If UTC would be redefined to no longer be adjusted to Earth's rotation, then what would be the point of having UTC at all? We already have a time scale that counts seconds without adjusting to Earth's rotation: TAI [wikipedia.org]
It's been done. (Score:5, Informative)
(GMT hasn't been in use for a long time, although most people use the term interchangeably with UTC).
Re:Copypasta (Score:2, Informative)
Because we can't read the actual article unless we're a paid subscriber to the journal/magazine - that's why.
As others have mentioned, it is available - follow the first link and look for a link to the article PDF in the right sidebar. I agree that the /. summary could've mentioned that.
three pictures to explain it, and a solution (Score:2, Informative)
The situation can be explained in three pictures [ucolick.org].
Using already-deployed code, here is one way to solve the problems [ucolick.org].
Re:Metric Time (Score:5, Informative)
The metric system is originally based upon an earth derived measurement called the meter. 1m ~ 1/10,000 the distance from the equator to the poles, 1g = the weight of 1cc of pure water at STP, etc. That all the measurements are base 10 is not what makes it "metric", it's that they're derived from the (originally) earth centric meter. Our time system is also derived from earth centric measurements, called day and year.
Base 10 time would be a huge adjustment for society. While using a 100,000 "MetSec" day and a 100 "MetSec" "MetMin" would produce units fairly close to the existing second and minute measurements, a "MetHour" would be much longer or much shorter than an hour, either 14.4 minutes (100 MetHours/day), or 2.4 hours (10 MetHours/day). And that doesn't do anything to address the leap second issue, nor does it alter the ~ 365.25 MSD year.
The bottom line is that as long as we maintain the concept of a day and year and all the associated stuff (seasons, equinoxes, solstices, etc.), all of which are critical to agriculture and survival, there has been no system of time keeping proposed that is significantly better than what we have. The universe is not going to arbitrarily adapt it's cycles to make it easy for our minds and computers to keep track of time.
And that's without considering relativistic time dilation. While most people never have to worry about time dilation effects, the atomic clocks that create UT1 and GPS satellites have to compensate for relativistic differences caused by differences in local gravity and speed, both of which are affected by altitude.
Perhaps Douglas Adams said it best, "Time is an illusion, lunchtime doubly so."