[LEAPSECS] Negative TAI-UTC
Tom Van Baak
tvb at LeapSecond.com
Sat Feb 4 12:22:36 EST 2017
Yes, of course. This is not the 1960's where saving a byte was an all-day decision. The spec is clear. Follow it.
While there's sufficient evidence the earth is slowing down over astronomical time due to tidal forces, it's also quite clear that the earth has been speeding up over the past 30 years. Therefore another ~7 year lull and even a negative leap second is likely within 10 to 20 years. And if that trend were to continue, then TAI-UTC will max out and head back down, to 37, to 10, to 0, and negative. All depending on how long this temporary speeding up lasts, of course. Or what happens with global warming.
So code and data structures must handle all cases of positive and negative leap second, as well as all cases of large and small, positive and negative TAI-UTC. Do it for the exercise, or as a robust example, if nothing else. To paraphrase Henry Spencer (see below) if you lie to a time scale it will get revenge.
----- Original Message -----
From: "Clive D.W. Feather" <clive at davros.org>
To: "Leap Second Discussion List" <leapsecs at leapsecond.com>
Sent: Saturday, February 04, 2017 8:41 AM
Subject: [LEAPSECS] Negative TAI-UTC
> Looking only into the future, not historical data, what do people think the
> probability is that TAI-UTC will ever be negative? Should data structures
> be designed to handle this case or not bother?
> Clive D.W. Feather | If you lie to the compiler,
> Email: clive at davros.org | it will get its revenge.
> Web: http://www.davros.org | - Henry Spencer
> Mobile: +44 7973 377646
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