What-If 0026: "Leap Seconds"

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What-If 0026: "Leap Seconds"

Postby ryzvonusef (1151717) » Tue Jan 01, 2013 11:45 am UTC

http://what-if.xkcd.com/26/

Every now and then we have to insert a leap second because the Earth’s rotation is slowing down. Could we speed up Earth’s rotation, so that we do not need Leap Seconds?

—Anton (Berlin, Germany)

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Chad Cloman
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Re: What-If 0026: Leap Seconds

Postby Chad Cloman » Tue Jan 01, 2013 11:56 am UTC

I'm thinking a much easier way would be to get rid of the Moon. Maybe we could put some really big rockets on it and send it far, far away. We might have to make some minor adjustments to the Earth's spin rate afterwards, but tidal forces would no longer be a factor.

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Re: What-If 0026: Leap Seconds

Postby mivlad » Tue Jan 01, 2013 11:58 am UTC

But what if we speed up the Moon to get Earth tidally accelerated?

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Re: What-If 0026: Leap Seconds

Postby Ehsanit » Tue Jan 01, 2013 12:55 pm UTC

What about the additional mass of the Baobab trees?

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Re: What-If 0026: Leap Seconds

Postby ebas » Tue Jan 01, 2013 1:09 pm UTC

I wonder why the obvious solution, getting rid of the moon, wasnt handled?

Also, if anyone reads this who can do anything about it, it still shows "WHAT IF IS ON BREAK FOR CHRISTMAS. SEE YOU NEXT TUESDAY!" on the What-If page.

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Re: What-If 0026: Leap Seconds

Postby geffuun » Tue Jan 01, 2013 1:21 pm UTC

couldn't we lower the moon to geostationary orbit (preferably over the middle of the pacific ocean) and speed it up to geostationary speed? Sure, we'll end up with some interesting tidal waves, and our clocks would Still be out of sync, but at least we could sync them up properly

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Re: What-If 0026: Leap Seconds

Postby Rzah » Tue Jan 01, 2013 1:36 pm UTC

Are the magnetic poles far enough away from the axis of rotation that an array of superconducting coils straddling the circumference of the planet would be able to impart a little force against the earth's magnetic field? Or is that a non starter?

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Re: What-If 0026: Leap Seconds

Postby AnticlimacticDervish » Tue Jan 01, 2013 1:40 pm UTC

How about moving vast amounts of mass from the equator to the poles, thereby changing earth's moment of inertia?

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Re: What-If 0026: Leap Seconds

Postby Klear » Tue Jan 01, 2013 1:52 pm UTC

The issue of spinning earth is mentioned here (number 5 on the list).

So... railguns. Would that work? I'm guessing it would take similar ammounts of matter as the asteroids approach, though.

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Re: What-If 0026: Leap Seconds

Postby floh » Tue Jan 01, 2013 2:15 pm UTC

An acceleration of the earth's rotation can be caused by moving mass toward the poles?

So why not move everyone and their pets into two giant skyscrapers, one on each pole...
a) It's 7*10^9 people against 6*10^24 kg earth, so just have everybody move their stuff with them to the poles.
b) The amount of stuff all the people need each day should be enough to offset any natural effect.
c) Those skyscrapers don't need windows, let's make the walls out of photovoltaic cells (The surfaces have the ideal angle)
d) Soon there is nothing left of earth, it's just one giant quader (two skyscrapers grown together).
e) As photovoltaic cells advance they soon absorb all light (the blackest material possible)
f) In a few million years the sun explodes and our perfect, black monolith home is hurled across space...

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Re: What-If 0026: Leap Seconds

Postby a123dv » Tue Jan 01, 2013 2:57 pm UTC

I think blowing up the moon would be more efficient.

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Re: What-If 0026: Leap Seconds

Postby webgrunt » Tue Jan 01, 2013 3:01 pm UTC

The solution is clear. We must move the moon into a geostationary orbit.

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Re: What-If 0026: Leap Seconds

Postby Klear » Tue Jan 01, 2013 3:16 pm UTC

webgrunt wrote:The solution is clear. We must move the moon into a geostationary orbit.


...or push it away from orbit altogether, possibly using some kind of laser.

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Re: What-If 0026: Leap Seconds

Postby tronic » Tue Jan 01, 2013 4:49 pm UTC

You are greatly over complicating this issue. To fix the problem of leap seconds being annoying for programers, you simply have to re-define the length of a second to be based on a table of known values / year on a going forward basis so the second can have varying lengths depending on what year it is.

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Re: What-If 0026: Leap Seconds

Postby keithl » Tue Jan 01, 2013 6:35 pm UTC

Rzah wrote:Are the magnetic poles far enough away from the axis of rotation that an array of superconducting coils straddling the circumference of the planet would be able to impart a little force against the earth's magnetic field? Or is that a non starter?


Still pushing on the handlebars of the bike. You've gotta couple force out into the rest of the universe, not back into something attached to the earth itself. Not to mention that the forces involved are way too tiny - this would be more like scowling at your handlebars.

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Re: What-If 0026: Leap Seconds

Postby keithl » Tue Jan 01, 2013 6:44 pm UTC

Stopping asteroids dissipates a heck of a lot of energy. Bouncing the asteroids doesn't. Imagine slowing down the asteroids in a big slingshot, storing the energy elastically, then slinging them back in the direction they came from. If we had the magic superelastic bands to build this slingshot, we would dissipate zero energy and double the momentum, needing half as many asteroids, and through the magic of orbital dynamics, returning the same asteroids (after a pinball course past jupiter, perhaps) to deliver more and more angular momentum as needed.

We could also do something like this to get rid of that pesky tide-making moon. However, about half the tidal effect is due to the sun, and getting rid of the sun is Just Not Done.

We don't have the big elastic bands, but we can do something like this with a LOT of magnetic coil guns (says the launchloop guy). Unfortunately, given real system efficiencies, we will still dissipate enough waste heat to melt the crust over time. But there's a better way, in the next post.
Last edited by keithl on Tue Jan 01, 2013 7:12 pm UTC, edited 1 time in total.

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Re: What-If 0026: Leap Seconds

Postby keithl » Tue Jan 01, 2013 6:51 pm UTC

For the third half of my reply, I suggest that instead of trying to maintain the earth's rotation rate, we simply build circular rails around the earth and mount civilization on them, moving eastwards about 15 millimeters per hour at the equator so the clocks line up. We could fix other things this way, too, shunting down side tracks to deal with precession of the poles, etc. Just think of how exciting leap days could be!

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Re: What-If 0026: Leap Seconds

Postby keithl » Tue Jan 01, 2013 7:32 pm UTC

And for the fourth half of my reply, a little story. Lynn Margolis was a proponent of Jame's Lovelock's Gaia hypothesis, that the biosphere of the earth is homeostatic. During a small meeting in Portland a few years back, she told us that the oceans are still here (rather than boiled away) because of the action of cyanobacteria, producing oxygen and participating in other environment regulation. Without those bacteria, no oceans. Without oceans, no large tidal coupling to the sun and moon. The moon's radius has increased over the eons because the Earth is feeding it angular momentum and energy through those tides.

"So," sez I to Dr. Margulis, "cyanobacteria are the solar system's first astro-engineers!" That floored her.

For extra credit: The Chixulub impactor had the particular effects it did, defining the transition from the Cretaceous to the Tertiary period (and us), because it landed in shallow water and sulfur deposits near the Yucatan. Landing on land, it wouldn't have been nearly as dangerous. Landing in deep ocean, it would have steam-cleaned the surface of the planet. If the Earth had been turned slightly differently, exposing deep ocean (likely) or a big landmass to the impact, the outcome would have been very different. The angle of the Earth exposed is the tiny residual of about a trillion rotations since the beginning of life, a number that is strongly dependent on the tidal coupling and the amount of ocean doing it. So ... how much water could you add or subtract to the ocean to move the angle by, say, 5 degrees, and change the outcome from wintry clouds of choking sulfuric acid to steam sterilization?

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Re: What-If 0026: Leap Seconds

Postby hamjudo » Tue Jan 01, 2013 7:34 pm UTC

It would be way less messy to reshape the earth. Move mass from the equator to the poles, until the Earth is the right shape to spin at the appropriate speed.

Compared to blasting the planet with 50,000 Little Prince sized rocks each second, it takes a trivial amount of energy to move enough rock to the North pole to create a new continent. It would take even less energy to refrigerate and thicken the ice sheet over Antarctica.

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Re: What-If 0026: Leap Seconds

Postby Wnderer » Tue Jan 01, 2013 8:55 pm UTC

The slowing of the earths rotation is not the issue at all with leap seconds. The problem is that the Earth's rotation varies unpredictably each year. If leap seconds could be added in a predictable way there would be no issue with coordinating the different time standards. Programmers could add the algorithm in the code. To coordinate the different time standards someone has to measure the Earth's rotation regularly and decide when a leap second is necessary.

This web page give an explanation.

http://www.ucolick.org/~sla/leapsecs/amsci.html

leap seconds.png

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Re: What-If 0026: Leap Seconds

Postby teelo » Tue Jan 01, 2013 9:55 pm UTC

What if we just got all the wizards/psychics of the world together and ordered them to accelerate the world a bit?

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Re: What-If 0026: Leap Seconds

Postby SlyReaper » Tue Jan 01, 2013 11:23 pm UTC

I've been saying it for years - what we need are flywheels on the north and south poles.
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Re: What-If 0026: Leap Seconds

Postby ijuin » Wed Jan 02, 2013 6:55 am UTC

tronic wrote:You are greatly over complicating this issue. To fix the problem of leap seconds being annoying for programers, you simply have to re-define the length of a second to be based on a table of known values / year on a going forward basis so the second can have varying lengths depending on what year it is.


Unfortunately, having seconds be of a variable length would be an even greater inconvenience than having to add extra seconds. You would need to have a "terrestrial second" that is synchronized with the Earth, while retaining the "scientist's second" that is invariant, and whenever you needed to make precise measurements for anything (e.g. calculating your location with respect to the GPS satellites, which requires a time-accuracy of 30 nanoseconds to get a location accuracy of 10 meters--our 0.8 milliseconds' difference per day accumulates to an error of 240 km per day), you would have to deal with converting one into the other.

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Re: What-If 0026: Leap Seconds

Postby sla29970 » Wed Jan 02, 2013 7:20 am UTC

ijuin wrote:You would need to have a "terrestrial second" that is synchronized with the Earth, while retaining the "scientist's second" that is invariant


Which is exactly what we do have now. POSIX requires that there be 86400 seconds in a day, and also that a day be a mean solar day of Universal Time. For all practical purposes of long-term counts this means that POSIX (IEEE 1003.1) requires the use of mean solar seconds while PTP (IEEE 1588) requires the use of TAI seconds. See the horror that results at http://www.ucolick.org/~sla/leapsecs/epochtime.html

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Re: What-If 0026: Leap Seconds

Postby ysth » Wed Jan 02, 2013 7:27 am UTC

Leap seconds exist so I get the pleasure of receiving semiannual emails headed "To authorities responsible for the measurement and distribution of time". The thrill is indescribable.

More seriously, I worry about leap seconds. I worry about the repeated attempts to get rid of them, apparently by people who don't actually believe that a net constant slow-down of rotation means a quadratic difference between apparant time and TAI. Sure, leap seconds isn't a permanent patch, but, when needed, going to monthly leap seconds extends our current timekeeping for quite a while.

Less seriously, I enjoy imagining the International Earth Rotation Service (the folks who track the Earth's rotation and decide on leap seconds) as a team of scientists lined up, all walking east or west as needed to regularize the Earth's rotation.

I do hope that someday soon we get a negative leap second - just to justify the support for it in the Olson tzcode.
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Re: What-If 0026: Leap Seconds

Postby Davidy » Wed Jan 02, 2013 7:41 am UTC

This whole discussion ignores the fact that the slowing of the earth's rotation by the tidal effects caused by the moon is also slowing down the moon in its orbit. The effect of this is that the moon is moving to a larger orbit. As this happens, the moon's affect on the earth is lessened and the slowing of the earth's rotation is proceeding at a decreasing rate. Eventually, the moon's affect on the earth's rotation and the necessity of leap seconds will dissappear entirely.
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Re: What-If 0026: Leap Seconds

Postby wking » Wed Jan 02, 2013 1:48 pm UTC

Typo in “Putting rocket engines on the Equator”. This line:

If the engines were somehow mounted above the atmosphere, they’d be able to slow the Earth…

should read:

If the engines were somehow mounted above the atmosphere, they’d be able to speed up the Earth…

(s/slow/speed up/)

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Re: What-If 0026: Leap Seconds

Postby Sandor » Wed Jan 02, 2013 1:49 pm UTC

ysth wrote:More seriously, I worry about leap seconds. I worry about the repeated attempts to get rid of them, apparently by people who don't actually believe that a net constant slow-down of rotation means a quadratic difference between apparant time and TAI. Sure, leap seconds isn't a permanent patch, but, when needed, going to monthly leap seconds extends our current timekeeping for quite a while.

But leap seconds cause problems all on their own, for example with calculating differences between future times, or with time synchronisation during (and shortly after) a leap second. I'm sure the people seriously advocating dropping leap seconds just believe they cause more problems then they fix. I think there is a US proposal to replace leap seconds with a kind of leap hour, with the first not expected to take place until many hundreds of years from now.

ysth wrote:I do hope that someday soon we get a negative leap second - just to justify the support for it in the Olson tzcode.

My impression is that this is unlikely, as long we don't experience any of the scenarios discussed in the what-if (major earthquakes, meteor strikes, etc.), so don't hope too hard!

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Re: What-If 0026: Leap Seconds

Postby sla29970 » Wed Jan 02, 2013 2:34 pm UTC

Sandor wrote:I'm sure the people seriously advocating dropping leap seconds just believe they cause more problems then they fix.

Yet those delegates have not acknowledged that there are other delegates representing countries whose position is that the word "day" should remain a concept that is related to the rotation of the earth, not quantum fluctuations in a cesium atom, so for over a decade no progress has been made in changing the situation.
Sandor wrote:I think there is a US proposal to replace leap seconds with a kind of leap hour, with the first not expected to take place until many hundreds of years from now.

The original US proposal included leap hours, and every other delegation ridiculed the notion. At that time the US delegates had to include the leap hour because without it the proposal would have violated the law of their own country they were representing.

This process of changing the international recommendation for radio broadcast time signals is one of finding a diplomatic way of satisfying the bureaucratic, legal, cultural and technical goals of all interested parties.

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Re: What-If 0026: Leap Seconds

Postby Klear » Wed Jan 02, 2013 3:53 pm UTC

sla29970 wrote:This process of changing the international recommendation for radio broadcast time signals is one of finding a diplomatic way of satisfying the bureaucratic, legal, cultural and technical goals of all interested parties.


...and I'm guessing it's quite impossible, so the status quo stands, right?

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Re: What-If 0026: Leap Seconds

Postby Ken_g6 » Wed Jan 02, 2013 4:05 pm UTC

Klear wrote:
webgrunt wrote:The solution is clear. We must move the moon into a geostationary orbit.


...or push it away from orbit altogether, possibly using some kind of laser.

Why use the lasers to push the moon? Why not just point them at the horizon along the equator? I wonder how much power that would take?

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Re: What-If 0026: Leap Seconds

Postby chretienorthodox » Wed Jan 02, 2013 4:15 pm UTC

You are greatly over complicating this issue. To fix the problem of leap seconds being annoying for programers, you simply have to re-define the length of a second to be based on a table of known values / year on a going forward basis so the second can have varying lengths depending on what year it is.


At "AmericanScientist" magazine I have posted a comment on the topic "The Future of Time: UTC and the Leap Second" July - August 2011. I have sent same proposal to ITU-R, SG-7A. In few words I propose a stepping in/de-creasing second for Civil Time scale. Second SI to be remained unit for atomic time scale and scientific purposes. GPS to continue implement atomic time for positioning or alternatively in/de-crement for second Civil Time to be inserted weekly in order to be less than one nanosecond.

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Re: What-If 0026: Leap Seconds

Postby samyewell » Wed Jan 02, 2013 4:52 pm UTC

Just thought I'd mention this essay about methods to move the Earth on the web at qntm.org/moving (can't post it as a link or the spam filter stops me... ). There's also a companion essay about destroying the Earth. Both are quite entertaining and worth the read. Of course it's talking about the Earth, not the Moon, but most of the points are still valid. (Personally I like the railgun method, mostly because it involves big guns.)

Then right after getting rid of the Moon, we'd have to also get rid of the Sun, which also exerts a tidal influence and contributes to the leap second problem. Hmmm.

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Re: What-If 0026: Leap Seconds

Postby Yupa » Wed Jan 02, 2013 7:52 pm UTC

After we finish fine tuning the rotation of the Earth, I'd like to work on adjusting the curvature of the universe, or at least our local patch of it, to make PI exactly 3.14175

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Re: What-If 0026: Leap Seconds

Postby rls » Wed Jan 02, 2013 8:07 pm UTC

Not surprisingly the discussion here has been more cogent than in many more august forums over the past dozen years. The issue is really the proposed redefinition of Coordinated Universal Time, not leap seconds per se. To read more than you might believe possible on this topic, visit futureofutc dot org (keeps calling it spam if I include the URL) and click through to the 2011 preprints and presentations.

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Re: What-If 0026: Leap Seconds

Postby Pfhorrest » Wed Jan 02, 2013 9:10 pm UTC

I think an interesting follow-up what-if would be: "What if we could adjust the orbits and rotations of the Earth and moon so that everything was nice even integer multiples of each other (e.g. exactly 12 lunar months of exactly 30 solar days of exactly 24 hours of exactly 3600 standard seconds in each tropical year of exactly 360 days)?" Both what would it take to accomplish that (and what the undoubtedly nasty side-effects of that process would be), but also, if we could just magically telekinetically change the orbits and rotations to accomplish that, what additional effects would there be from our new speed and position?
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Re: What-If 0026: Leap Seconds

Postby jamesprescott » Wed Jan 02, 2013 9:15 pm UTC

What are the relative magnitudes of tidal slowing and glacial rebound acceleration?

Could we speed up glacial rebound by melting what remains of the icecaps?

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Re: What-If 0026: Leap Seconds

Postby Eldin00 » Wed Jan 02, 2013 11:24 pm UTC

I'm surprised that nobody has mentioned the solution of placing one or more additional large satellites into an orbit where they provide a tidal acceleration effect, to counter the tidal slowing effect of the moon.

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Re: What-If 0026: Leap Seconds

Postby ghane » Thu Jan 03, 2013 2:38 am UTC

Ken_g6 wrote:Why use the lasers to push the moon? Why not just point them at the horizon along the equator? I wonder how much power that would take?


Please.

I stay on the equator, and having a BIG laser fired horizontally at me from next door is the kind of idea that makes kids go into science for the "Evil Scientist" trope.

We just need to adjust the definition of the metre once in a while (and maybe the kg, hoepfully not K), that way we can avoid leap seconds, and the asteroid barrage, the blowing-up-the-moon, the lets-all-move-to-next-town, etc.

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Re: What-If 0026: Leap Seconds

Postby ijuin » Thu Jan 03, 2013 6:54 am UTC

ghane wrote:
Ken_g6 wrote:We just need to adjust the definition of the metre once in a while (and maybe the kg, hoepfully not K), that way we can avoid leap seconds, and the asteroid barrage, the blowing-up-the-moon, the lets-all-move-to-next-town, etc.

Once again, changing the definition of units over time tends to introduce more problems than acknowledging the change-over-time of the things being measured. We will have to constantly convert old measurements into new ones--for example, looking at measurements for planetary orbits in the 1960s you would also need to remember how much a second and a meter would have been then as opposed to now.

A major early use of variable units can be seen in how the ancient Romans measured the day. The time from sunrise to sunset was divided into twelve equal hours, no matter what the time of year. This resulted in an hour being substantially longer in the summer than in the winter, and meant that "per-hour" measurements were useless without also knowing the date on which the measurement was taken. Using seconds or meters that are not of a fixed length would re-introduce this sort of problem. It may easily become a case of the cure being worse than the disease.


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