The science of leap time

Gene Hays, West Covina, CA — Fri, 29 Feb 2008 00:32:59 GMT

This sure is a very technical subject... I'm just thankful that I get a birthday every four years!!

The science of leap time

James Vaughn — Fri, 29 Feb 2008 01:13:38 GMT

Wait a second!

The science of leap time

john doe seattle wash — Fri, 29 Feb 2008 01:17:40 GMT

thank u for telling uuuuussssssss

The science of leap time

Brett, HCMC, VN — Fri, 29 Feb 2008 01:26:58 GMT

Why don't they consider a time alternative that just has visual objects of realistic position? Time something else like an atomic count and link it to the visual references of our position in the universe, galaxy, solar system and personally on the planet. Why keep up the prediction necessity? Then we could celebrate our birth moment!

The science of leap time

Todd — Fri, 29 Feb 2008 02:22:25 GMT

Awesome stuff. You rock Alan!

The science of leap time

Anthony Cupo — Fri, 29 Feb 2008 02:40:30 GMT

So what is the measure of time that is less than seconds? I mean by definition. Because it does exist. I always thought it was interesting to see how basketball games , for example, keep track of that time in between the seconds. So now we get aglimpse of the pre-buzzer lesser than a count time. Time travel is becoming increasing possible as time goes on. But you know since it could be possible that would mean someday it happens and those time travelers are already here. Peac be with you.

The science of leap time

Thomas Ashby, Calgary — Fri, 29 Feb 2008 04:15:02 GMT

Does anybody really know what time it is?

The science of leap time

Greyrider Martinsburg, WV. — Fri, 29 Feb 2008 09:13:14 GMT

Keep it up, and they will resolve Zeno's paradox, only the other way around!

The science of leap time

Brian Taylor, Brooklyn, NY. — Fri, 29 Feb 2008 11:24:00 GMT

Why not just add the leap seconds together so that as the leap year comes by just add them in there?

So this year for example you would have one extra day and 5 seconds added to February. And as the problem increases just increase the seconds accordingly so that when we are adding 4 extra seconds a year it would come out to one day and 20 seconds.

Great article btw.

The science of leap time

Glen, Albany NY — Fri, 29 Feb 2008 13:30:50 GMT

I think the concept of time is interesting, but its nothing more than Man's attempt to define change in the world/universe. There will always be a need for leaps so long as humans continue to "cement" time into defined calendar years (and weeks, and days, and so on). Time is not meant to be cemented in place. It is relative, as we all know. It constantly changes.

The science of leap time

TimeBandit, Denville, NJ — Fri, 29 Feb 2008 13:44:16 GMT

Time and Alan both rock!

The science of leap time

Greg — Fri, 29 Feb 2008 13:59:17 GMT

This seems like a debate between people who want to base time on a unit (a precise second) vs people who want to make sure time is measured in the how often the earth spins on its axis and how often it rotates around the sun. The year based on our orbit was needed for farmers and such waaaayyyyy back in the day. Now it seems moot, it really is similar to the idea of day light savings time. Realisitically time to humans is nothing but a measure of change. Be it in the Earth position around the sun or what have you. Celelbrating a birthday or New Years is almost crazy when you think about it; hoooray, its been X number of rotations around the sun since you were born.

The science of leap time

Guy S. Newell — Fri, 29 Feb 2008 14:05:55 GMT

So, on my home planet, we use the time between seconds to contimplate our own contributions to the universal collective soul.

The science of leap time

Brian Woods, Worcester, Mass — Fri, 29 Feb 2008 14:12:01 GMT

I seem to remember a slightly different take on the real world/calendar application of the leap year system from, of all things, an episode of "Ripley's Believe It or Not!" from the 1980s (when Jack Palance was the host) and there was a factoid that every 400 years, we were supposed to get a 2nd Leap Day to balance things out (so that we'd actually get a February 30th that year, believe it or not). Obviously, that didn't happen, but does anyone know what the rationale behind the concept was (I'd always been taught that one revolution around the Sun is 365.26 days, so to me it made sense that the .25 portion was dealt with every 4 years, leaving a cumulative .01 discrepancy annually needing to be addressed eventually)? That version of the show doesn't re-run these days, and I don't think it's been released on DVD/video, so I've not been able to find out. Thanks!

The science of leap time

CB, Concord, NH — Fri, 29 Feb 2008 14:56:12 GMT

It doesn't matter what time/date a clock/calendar shows as long as everyone's clock/calendar shows the same thing.

The science of leap time

Drew — Fri, 29 Feb 2008 15:53:47 GMT

"on my home planet, we use the time between seconds to contimplate our own contributions to the universal collective soul"

Classic!! Laughed 'til I cried!!!

The science of leap time

Denise, Ringwood, NJ — Fri, 29 Feb 2008 16:06:09 GMT

I'd always heard that the concept of time was a human invention. Figures!
And while we're at it, leap day aside, exactly why DOES February have only 28 days when some months have thirty one? What was the rationale behind that?

The science of leap time

Barry U. Headinsand, Lakeland, Florida — Fri, 29 Feb 2008 16:12:30 GMT

The solution to this "leap second" problem is obvious: we need to adjust the speed of the earth's orbit around the sun &/or speed of the earth's rotation so it will more precisely coincide with our atomic clocks' measurements of time. A few well-placed gigantic rocket engines would do the trick, & it's existing technology, so we know it'll work.
Every day I've got these incredible brainstorms, but do they ever give ME a Nobel Prize? NOOOOOOO!

The science of leap time

David, Rochester, NY — Fri, 29 Feb 2008 16:21:45 GMT

Re: second Leap Day. Actually the rule of 400 is just the opposite. Century years (1800, 1900, and 2000) are NOT leap years unless they are divisible by 400. Thus 2000 was a leap year, 1900 was not.

The science of leap time

Bonnie Goren — Fri, 29 Feb 2008 16:26:19 GMT

Facinating information! An interesting read...

The science of leap time

Alan Boyle — Fri, 29 Feb 2008 16:44:57 GMT

Denise, back in Roman times (pre-Julius Caesar), February was the last month of the year. The calendar year began on March 1. So February tended to get the short end of the stick. Whenever someone needed an extra day to beef up their favorite month (July for Julius Caesar, August for Augustus Caesar), they'd steal a day from February. The Romans apparently considered odd numbers to be luckier than even numbers, and that's why the Caesars saw a benefit in making their favorite months 31 days instead of 30. Originally, the leap day was inserted somewhere around Feb. 24, and the day was considered to be especially unlucky. That idea of an unlucky leap day has persisted in some areas of the world, and it's considered unlucky to be married on leap day.

http://www.timeanddate.com/date/leap-day-february-29.html

The idea of adding extra days to the end of the year still comes up every once in a while with regard to calendar reform. Over the centuries, overly sensible folks have come up with various schemes for a universal, unchanging calendar ... which usually inserts out-of-the-ordinary leap days at the end of the year, or smack-dab in the middle. I wrote about one such scheme a couple of years ago, developed by a Johns Hopkins professor:

http://www.msnbc.msn.com/id/6699413/

This scheme would periodically insert a whole week between June and July, called the Newton mini-month. Under this so-called C&T system, today is not Feb. 29, but Feb. 5, 2008. Next year, the day we call July 1 would be called Newton 4 instead.

The science of leap time

Kathy A. Lake Forest, CA — Fri, 29 Feb 2008 16:45:42 GMT

I would love to know how they figured out that there was a discrepancy between the 365 day calendar and the seasons getting out of sync. Where can I go to learn more?

The science of leap time

Bruce Wyshak, Northboro, Mass. — Fri, 29 Feb 2008 16:53:41 GMT

I don't think I have time for this ....

The science of leap time

Earl Stratton, SLO, CA — Fri, 29 Feb 2008 16:55:12 GMT

Brian Woods, the year is closer to 365.2422 days, not 365.26. You are essentially correct that we add 1 day every four years to get the .25 days. But now there is an excess of .0078, so every 100 years we SUBTRACT one day -- or rather, eliminate leap day that year. But then, there will a .0022 deficit, so every 400 years we add back the leap day. Now, there is only .0003 days excess every 400 years. I don't know if the calendar specifies what to do about this excess, but note that it amounts to an extra day every 3,000 years. Also, my number 365.2422 days per year is also only an approximation, and the exact answer itself varies due to gravitational influences of other planets (speeding and slowing Earth in its orbit) and that Earth's daily rotation varies and slows (as the article pointed out).
.
In the end, our technology and social structure require certainty and predictability, but the Earth's environment cannot provide this -- time to leave the nest...

The science of leap time

Alan Boyle — Fri, 29 Feb 2008 16:55:56 GMT

Kathy, the ancients put great stock in the lunar cycle as well as characteristics of the solar cycle (equinoxes and solstices, etc.). That was the motivation behind ancient observatories such as Stonehenge. So they devised various ways of keeping track of those dates. The Babylonians had a lunar calendar, but found they had to add extra months to get the calendar back in sync with the seasons. Even before Julius Caesar, the Egyptians figured out that you had to add a day every four years:

http://encarta.msn.com/encyclopedia_761560321/Calendar.html

I found this discussion of calendars through the ages to be pretty interesting:

http://webexhibits.org/calendars/calendar-ancient.html

The science of leap time

Martin — Fri, 29 Feb 2008 17:14:31 GMT

As long as it's 5 o'clock somewhere...

The science of leap time

Kathy A, Lake Forest, CA — Fri, 29 Feb 2008 17:29:33 GMT

Thank you, Alan. At least it's Friday today, Martin.
:-)

The science of leap time

Mike, Earth — Fri, 29 Feb 2008 17:33:46 GMT

Time flies like an arrow. Fruit flies like a banana.
--Groucho Marx

Great article. Makes sense to me. But you have to consider my perspective. I'm diagonally parked in a parallel universe.

The science of leap time

Matt McHugh, NJ — Fri, 29 Feb 2008 17:46:45 GMT

Very interesting. In a less technical vein, looks like I was one of the misinformed who confuses "Leap Day" with "Sadie Hawkins Day":

http://www.leapyearday.com/February29isNOTSadieHawkinsDay.htm

- mm

The science of leap time

Joe Wetzel, Dunnellon, FL — Fri, 29 Feb 2008 17:47:07 GMT

Nice work, but I think you will find that in 1582 Gregory XIII corrected an error of 10 days, not 11. He did this by declaring that the day after Friday, October 4, 1582, would be October the 15th. Whereas, 11 days were corrected in 1752, when Britain and the Colonies switched, Parliament declared that the day following September 2 would be September 14. So, that day George Washington's birthday went from February 11 (Old Style) to February 22 (New Style).

[Alan adds: D-oh! I've fixed the reference. Thanks for setting me straight, Joe!]

The science of leap time

Ed Kyle, Oxford, MI — Fri, 29 Feb 2008 18:07:46 GMT

I still like the description of a second as being the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom (Machinery Handbook, 9th Edition, 1974). That should impress the ladies.

The science of leap time

Mississippi, Lake Charles LA — Fri, 29 Feb 2008 18:12:03 GMT

wow, some really in-depth discussions...that I totally didn't understand. I feel it's better to just be happy with the leap year and not know the "inner workings".

Just goes to show that not even time can be controlled

The science of leap time

S.B. Stein E.B. NJ — Fri, 29 Feb 2008 18:17:38 GMT

It would have been interesting to compare that to the types of calendars from around the world. The Jewish calendar adds a leap month on occasion including the current year of 5768; there is some formula the rabbis came up with that I can't recall that works things out so that holidays are in the proper time. I recall that there were various calendars from South America that are different than the Gregorian. As I recall, the Muslim calendar doesn't correct itself. That explains why their holidays don't appear in the same time every year compared to the Gregorian calendar.

The science of leap time

Loren, SF Bay Area, CA — Fri, 29 Feb 2008 18:25:12 GMT

Time is what keeps everything from happening all at once. Space is what keeps it all from happening in the same place.

The science of leap time

Mark, Panama City, Florida — Fri, 29 Feb 2008 18:31:55 GMT

You think you have problems...I was 1 second late for work and almost got fired. I've got to bone-up on this leap second thing so this doesn't happen again.

What is my job...I update sundials!

The science of leap time

EB, Illinois — Fri, 29 Feb 2008 18:36:39 GMT

I'll bet those darn republicans caused this whole mess, just so they can start an extra hurricane every 22.6 years!

The science of leap time

Samuel W. Fields, Lawrence, Kansas 66044 — Fri, 29 Feb 2008 18:39:50 GMT

Even time has been corrupted by man imperfect thought.

The science of leap time

Rick — Fri, 29 Feb 2008 18:51:16 GMT

Forget the antiquated system of time measurement we currently use. What Stardate is it?

The science of leap time

CB, Albuquerque, NM — Fri, 29 Feb 2008 19:21:06 GMT

Didn't the Mayan calendar have this all figured out already? Why not follow their calendar??

The science of leap time

RH, Mahopac New York — Fri, 29 Feb 2008 19:33:27 GMT

Maybe these time experts can help me solve another problem that I have. My dog was born on Feb. 29th. How do I figure out her age?

The science of leap time

JB, Kenmore, WA — Fri, 29 Feb 2008 20:13:54 GMT

September of 1752 brought some interesting debates to Parliament...would landlords be charging a full month's rent for only 19 days? Would investments that pay per month dole out a full portion?

The science of leap time

Dawson Lewis, Pierre South Dakota — Fri, 29 Feb 2008 20:18:01 GMT

Great article, but about the leap second. It is not that the earth slows by .6 seconds per year. It is that the atomic clocks and the actual rotation differ about that much. The Naval Observatory website has an explanation (http://tycho.usno.navy.mil/leapsec.html). The earth has actually slowed approximately 2 MILLSECONDS between 1820 and 1999. If it was .6 seconds per year the day would have lengthen by 1 minute and 40 seconds since 1820. The .6 is not the rate of slowing, it is the difference between the hyper accurate atomic clocks and the messy real world.

The science of leap time

Karen Jo, Broken Arrow, OK — Fri, 29 Feb 2008 20:39:47 GMT

"..time comes by virtue of motion and because mind is inherently aware of sequentiality. From a practical viewpoint, motion is essential to time.....we do not know the absolute limits of space, but we do know that the absolute of time is eternity."
(from the Urantia Book 12:5.1,2)

,,,And the beat goes on, la-da-da-da-dee...

The science of leap time

John, Murray KY — Fri, 29 Feb 2008 21:03:18 GMT

I agree with Martin - at least somewhere, in some continuum it is 5:00 o'clock and the sun has passed over the yardarm - so let us raise a glass of our favorite beverage and make a toast to "The Syncopated Clock"

The science of leap time

DW, Modesto, CA — Fri, 29 Feb 2008 21:24:30 GMT

Ahh, Luke, I sense a disturbance in the Force.

The science of leap time

Alan Boyle — Fri, 29 Feb 2008 22:39:52 GMT

Dawson, you're correct as far as it goes. I hope I didn't imply that the discrepancy is approaching 0.4 seconds (not 0.6 seconds) per year. Rather, 0.4 seconds (as of next month, see below) is the accumulated discrepancy since the last leap second was added, back in 2005:

http://www.msnbc.msn.com/id/8476418

This excellent Web page helps to explain the leap second issue and also shows that as of yesterday, the discrepancy was 330 milliseconds, plus or minus 5 milliseconds (the UT1-UTC value will reach 400 milliseconds in March):

http://tf.nist.gov/pubs/bulletin/leapsecond.htm

When you get down to the subsecond scale, Earth's rotation is indeed messy. I couldn't get this into the original item, but the length is affected by such factors as the amount of snowfall in the Northern Hemisphere (which affects angular momentum). And it's possible that the difference between atomic and astronomical time could be basically revised in the other direction if Earth's rotation sped up.

The trend in rotation can be uneven. However, the general trend is toward a slower rate of rotation and a longer day, as explained in the story linked above. Earth's transfer of rotational momentum to the moon is one of the factors behind this.

http://en.wikipedia.org/wiki/Orbit_of_the_
Moon#Tidal_evolution_of_the_lunar_orbit

You've provided a great link to the USNO site in your own comment ... and that pretty much supports what I tried to say:

"The length of the mean solar day has increased by roughly 2 milliseconds since it was exactly 86,400 seconds of atomic time about 1.79 centuries ago (i.e. the 179 year difference between 1999 and 1820). That is, the length of the mean solar day is at present about 86,400.002 seconds instead of exactly 86,400 seconds. Over the course of one year, the difference accumulates to almost one second, which is compensated by the insertion of a leap second into the scale of UTC with a current regularity of a little less than once per year. Other factors also affect the Earth, some in unpredictable ways, so that it is necessary to monitor the Earth's rotation continuously. "

Sorry about any confusion I may have caused.

The science of leap time

Dennis, West Fargo, ND — Sat, 01 Mar 2008 04:24:59 GMT

So, on what day of what year does the year slow to a complete stop?

The science of leap time

Dennis Lokken, West Fargo, ND — Sat, 01 Mar 2008 04:29:50 GMT

So, on what day of what year does the earth slow to a complete stop?

The science of leap time

JD Smith, Louisville, KY — Sat, 01 Mar 2008 08:12:02 GMT

I was wondering about what effects global geological occurrences have on the speed of the earth's rotation. I thought I read that the earthquake that hit Indonesia in 2004 had perhaps slowed the earth down by an undetermined amount. If so, has anybody calculated the amount of rotational speed lost or gained by such an event yet? What effect on the earth's rotation has: the rise of a volcano mount, the rise of sea levels, the erosion of mountain chains, or even human-built structures like skycrapers or China's Three Gorges Dam? Is there an organization that measures and correlates rotational speed gain or loss from such events? I know I won't notice a difference, but people keeping track of time in ten decimal places will. Just curious, that's all.

The science of leap time

Mark Bloomer, Caribou, Maine — Sat, 01 Mar 2008 09:46:12 GMT

Only time has a one way sign
while everything else seems unconfined
time is evolution through integration
toward a great epiphany of celebration

Time kisses the bud which allows it to open
yet curses the blossom and sends it to seed
but the seed is the being which gives time its true theme
of all possibility that comes from eternity

Each season comes new through a progressing spiral
yet returns from last year a helix all the while
like water that flows and moves onward and down
but with waves that will grow and keep coming around

The past will give way to only the future
but the present breaks through to touch the eternal
each moment with memory that holds a potential
through seminal lines that will reach the eventual

Nostalgia is fantasy lost under the bridge
yet hope a reality across the wide rivers width
and memory a map of some things which have been
but anticipation wheels that on your road spin

Time is supported only by rhythm
yet rhythm will answer to nothing but time
without having either there would have been neither
but with both together they dance on forever

The temporal can never become the eternal
but has no beginning and will never end
like the surface of earth which is not infinite
yet with no boundaries and without an edge to it

Outside of time is the nest of eternity
which yearns to create the seeds of temporality
as chronological infinity cradles all time
crystalizing creation out from the sublime.

The science of leap time

Frank Glover Rochester, NY — Sat, 01 Mar 2008 18:45:56 GMT

"I'd always heard that the concept of time was a human invention. Figures!
And while we're at it, leap day aside, exactly why DOES February have only 28 days when some months have thirty one? What was the rationale behind that?"

Just as the time taken to orbit the Sun (a year) need not be an intergral multiple of the time it takes Earth to do one complete rotation (a day), there's no reason for the time it takes the Moon to orbit the Earth (essentially a month) to fit neatly into an Earth year, either. You gotta tweak something...!

(Besides, gravitational/tidal interactions between Earth and Moon have been VERY gradually slowing Earth's rotation and will continue to do so. A Lunar month and an Earth day were once both much shorter. This has been confirmed by the laser retroreflectors left on the Moon during Apollo missions.)

The science of leap time

no one , nowhere — Sat, 01 Mar 2008 19:34:49 GMT

interesting.. i clicked a link marked "inside the human body" and it took me to something about the changing of the times.

how accurate.

[Alan adds: How untimely! There was an incorrect link that has since been fixed. Sorry about that...]

The science of leap time

Eric, St. Paul, MN — Sun, 02 Mar 2008 02:51:36 GMT

I think we should update the definition of a second. I vote for a new clock/calendar that has 10 months in a year, 10 hours in day and 100 minutes in an hour. The current definition of a second is 'x' amount of rotations of 'y' atom. Change the atom, change the number of rotations and voila!

The science of leap time

Brandon — Mon, 03 Mar 2008 09:33:26 GMT

"Didn't the Mayan calendar have this all figured out already? Why not follow their calendar??"

Because acording to the Myans the world ends in 2012

The science of leap time

Andrew Pruett, Rochester, MN — Mon, 03 Mar 2008 18:35:37 GMT

Great Article. I am going to use it in my Social Studies class!

The science of leap time

The Kona Slacker — Mon, 03 Mar 2008 20:58:56 GMT

If 10 days were added on a Thursday, was the next day a Friday or a Sunday?

The science of leap time

Don Spencer, Alpena, Michigan — Wed, 05 Mar 2008 01:03:35 GMT

So, on what day of what year does the earth slow to a complete stop?- Dennis West Fargo ND. Dennis, I believe that would be either on a Friday afternoon at 4:30pm on a holiday weekend, OR anytime during a Sunday sermon.

The science of leap time

Delmar Fairchild, Barron, WI — Thu, 06 Mar 2008 22:40:45 GMT

Maybe Al Gore has it all wrong. If the Earth is slowing down, the sun hits an area more and therefore warms it. As the Earth slows down, the evaporation rate will slow down too and thus we don't cool off as much.
I too, like Barry from Lakeland, Florida, would like a Noble Prize for figuring this out.

The science of leap time

Don Stockstill, Ozark. Missouri — Tue, 09 Dec 2008 06:32:15 GMT

I am a scientist as a result of my education and training and therefore have an appreciation of what is stated in the article. However, considering that the average person in this world lives less than 100 years, even adding 1 second every year would not have any significance in their lifespan. Although the article is interesting in itself, it does not really mean much to the average person or report anything that has any real effect on people's lives.