[Phys-L] leap seconds +- critical thinking

[John Denker <jsd@AV8N.COM>]

A "balanced" article in the Washington Post:
   http://www.washingtonpost.com/wp-dyn/content/article/2005/12/25/AR2005122500496_pf.html

[A]
> Some experts think the leap second should be abolished because the periodic, but random,
> adjustment of time imposes unreasonable and perhaps dangerous disruptions on precision software
> applications including cell phones, air traffic control and power grids.
[B]
> Others, however, argue that it would be expensive to adjust satellites, telescopes and other
> astronomical systems that are hard-wired for the leap second, and besides, people want their
> watches to be in sync with the heavens.
....

This is at least tangentially on-topic because it shows how some rather
fundamental physics can affect real-world activities.

====

It may also be worth explaining to students that there is no "debate"
about the physics;  there is only a debate about the public-policy
implications of the physics.  This is more like engineering than like
fundamental physics.  The question is, which is cheaper and more
convenient:  leap seconds or no leap seconds?  That's an engineering
question.

===================

Note that I called the Post article "balanced".  Alas, balance is not
always a good thing.  Churchill said he would not stand impartial between
the fireman and the fire.

There's a rule in the courtroom that says that if one side relies on
falsified evidence to make their case, it suggests that they don't
have any good evidence.  This is not a law of physics, but it is often
a helpful guideline.  At the very least, it serves a useful purpose by
penalizing people for introducing false evidence.

Alas, this rule is not very useful in the present debate ... because
almost all of the evidence cited by *both* sides (as in paragraphs [A]
and [B] above) is complete garbage.

This might make a useful exercise for teaching healthy skepticism and
critical thinking to physics students:  construct simple tests to decide
whether each bit of evidence in the article has any chance of being
trustworthy.
  -- Is there really any chance that an intercalary second will cause
   a dangerous disruption of the air traffic control system?
  -- Is there really any chance that an intercalary second will cause
   a dangerous disruption of the power grid?
  -- Is there really any chance that the lack of an intercalary second,
   or even 20 years worth of intercalary seconds (at the present slip
   rate) will disrupt the operation of telescopes?
  -- Et cetera.

These questions are super-easy for me to answer, because I know a thing
or two about air traffic control, power grids, et cetera.  Students don't
know this stuff off-the-cuff, but they could find out.

These are definitely not plug-and-chug questions.  These are definitely
not ACT "science reasoning" questions (i.e. 40 question in 35 minutes).
It's gonna take the average student a fair while (more than a minute,
but less than an hour) to figure out how the power-grid does timekeeping,
how air traffic control does timekeeping, et cetera.

=====

As a very important higher-level lesson, this demonstrates just how easy
it is to inject completely bogus facts into public-policy debates.

False evidence is a bad thing.  As D.P. Moynihan said:  Everybody is
entitled to their own opinion, but they're not entitled to their own
facts.
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