[LEAPSECS] Letters Blogatory

[Tom Van Baak]

Brooks,

> Overall he seems to make a good philosophical argument why solar time is 
> good for humans. But his conclusion seems confused.

Quite correct. Solar time is good for humans. That's why no one except the United Kingdom can use UTC for their daily activities. Every other nation has a way to circumvent UTC and use their own local time instead.

UTC, with or without leap seconds, is still solar time -- plus or minus a couple of hours, plus or minus a couple billion people, plus or minus a thousand years. Noon at 12:00 is an extremely loose assumption.

I would not worry or argue what happens beyond 1,000 years or 10,000 years. Knowing what little I do about earth dynamics, and how science, technology, culture, and politics [d]evolves, it would be irresponsible for anyone in the year 2000 to dictate the details of atomic or civil time in the year 2500 or 3000.

> 
> "... let the airlines and the Internet companies use TAI".

Ok, let's say the airplane runs on TAI. What about the pilot's watches? Their navigation iPads? Then what about ATC? Do you really want the plane running TAI and the tower running UTC? And just big planes but general aviation too? Crop dusters should also run TAI then? And not just one ATC tower but every tower in the world. What about collision avoidance systems? What about the employees of ATC. Should they use local time or UTC while the planes use TAI? What about the weather reports. Or emergency services? Or their wall clocks? Should the ticket reservation system run TAI then too? How about the entire airport ground infrastructure? Do you want fuel and baggage and security running a different timescale as ATC and pilots and planes? What about realtime telemetry? Or in-flight WiFi? Should all contracts involving the airplane industry be tied to TAI instead of UTC? Where does this lawyer draw the line? What is and isn't an "airline"?

The entire purpose of UTC is to provide a single timescale for all human-related activity. That includes transportation.

You can run through the same thought experiment for "internet companies". Do we want ATT to use TAI? All time-stamps going into and out of ATT are TAI. While Verizon uses UTC? What about Google? Or Microsoft? Should Facebook use TAI or UTC? Should local time be based on a hour offset from TAI then? Should all routers be required to use TAI instead of UTC? Where does this lawyer draw the line? What is and isn't an "internet company"?
 
The entire purpose of UTC is to provide a single timescale for all human-related activity. That includes the internet.

It sort of doesn't matter what that timescale is. Or where its midnight Meridian is historically located. It works extremely well to have one timescale for 99.9999% of human activity. Yes, there are some 0.0001% niche timescales for highly specific scientific purposes. But UTC runs the world. This must not change. Fortunately, neither the pro/con arguments for leap seconds propose a change in UTC's role in this regard. What is scary is when a lawyer jumps into the 15-year game and propose a third alternative: that certain major technology sectors of the planet switch to TAI, as a way to "solve" the leap second issue.

/tvb