[LEAPSECS] Letters Blogatory

Thu Mar 12 09:45:21 EDT 2015

My post was not to suggest that circadian cycles will be affected by leap
seconds or their absence as much as to point out that Mr. Folkman's
argument is a better argument against mean time than an argument in favor
of keeping the leap second.

Getting rid of the leap second will probably have no affect on circadian
biology.  We already mess that up quite thoroughly with artificial lights
and UTC with leaps.

What getting rid of leap seconds will eventually do is create confusion in
the existing biological literature because biologists are generally not
attuned to the difference between clock time and environmental
cycles--they too often confuse the measure of time with the timing
phenomenon observed.  So within a century, field primatologists might
start challenging the (silly) claim that baboons are active from 9 to 5.
The claim is silly because baboons do not tie their activity to clock
time, but cycles of daylight, but the literature emphasizes clock time.

As to the level of precision applicable to biological processes, since the
fastest neural processes are in milliseconds, for complex behaviors, like
response to a stimulus, we're probably talking about 10ths of seconds, but
this is only applicable to short-term timing mechanisms, not circadian
ones.  The circadian system is remarkable for its ability to tolerate
changing periodicity of light due to weather and variation in Earth's
rotation.  

With regard to cross-continental travel, there was a very interesting
study done on win/loss records of professional baseball teams on
cross-continental road trips.  It actually matters.  That study is:

RECHT, LAWRENCE, LEW, ROBERT A., SCHWARTZ, WILLIAM J.  1995. Baseball
teams beaten by jet lag.  Nature 377:583

I do not know of any students that examine N/S travel across latitudes
during mid-winter or mid-summer.

Cheers,

Kevin

Kevin K. Birth, Professor
Department of Anthropology
Queens College, City University of New York
65-30 Kissena Boulevard
Flushing, NY 11367
telephone: 718/997-5518

"We may live longer but we may be subject to peculiar contagion and
spiritual torpor or illiteracies of the imagination" --Wilson Harris

"Tempus est mundi instabilis motus, rerumque labentium cursus." --Hrabanus
Maurus

On 3/11/15 4:53 PM, "Tom Van Baak" <tvb at LeapSecond.com> wrote:

>Thanks, Kevin, for your interesting biological perspective. I think the
>two vocal astronomers on the mailing list, Rob and Steve, will be happy
>to add your conclusive scientific, .edu-validated, biological expertise
>to their pro- leap second knowledge base. As you know, I am neither pro
>or con, but as someone with many cesium clocks along with some mammals
>(wife, kids, dogs) in my home I wonder, though, if milliseconds per day
>(~2e-8) or milliseconds per day per century (~5e-13), have measurable
>effect on biological systems.
>
>I always thought that biological systems were more resistant or more
>adaptive than parts per billion changes.
>
>One could explore the effect of cross-continent seasonal migrations, or
>even cross-country college road-trips. An interesting experiment might be
>to change local time by an entire hour once or even twice a year and see
>how long or how quickly humans and domestic pets can adapt. The effect is
>non-zero. The "Q" value of that impulse would provide useful support to
>your conclusions. Or not. The other experiment is to go to Hawaii or
>Alaska for a week and see the effect that changes in latitude have on
>diurnal cycles. Having been to both in the past year, I can say it was
>quite profound and easily measurable at the 10% or maybe (with careful
>instrumentation and multiple runs by multiple people over many years) at
>the 1% level.
>
>The issue of leap seconds, OTOH, is sort of at the 1e-8 to 1e-9 level. So
>I wonder if the biological effects you're talking about are perhaps a
>million times below noise?
>
>/tvb
>
>----- Original Message -----
>From: "Kevin Birth" <Kevin.Birth at qc.cuny.edu>
>To: "Tom Van Baak" <tvb at leapsecond.com>; "Leap Second Discussion List"
><leapsecs at leapsecond.com>
>Sent: Wednesday, March 11, 2015 11:59 AM
>Subject: RE: [LEAPSECS] Letters Blogatory
>
>
>Solar time is good for humans, but as everyone on this list knows, solar
>time is not the same as mean time or UTC.
>
>From a chronobiological perspective, mammals have a small cluster of
>neurons at the base of the hypothalamus called the suprachiasmatic
>nucleus (SCN).  There are two parts to this structure.  The medial
>portion has a robust free-running rhythm of around 24 hours plus or minus
>about 15 minutes.  The two ventral portions connect to the optic nerve
>and have no strong rhythm.  Instead, the ventral portions work to reset
>the dorsal part so that the @24 hour rhythm always anticipates the next
>sunrise regardless of seasonal variations in the length of the daylight
>period (or the equation of time).  One could say that the SCN is an
>evolutionary adaptation to Earth's foibles.
>
>The SCN then operates quite differently from representations of solar
>time, mean or apparent, which chart the rotational day.  In fact, the SCN
>works much like some old forgotten systems of timekeeping like Bohemian
>or Italian time, which reset every day.
>
>The features of UTC that we celebrate--continuity, uniformity and
>standardization--are features that are useful for measuring biological
>cycles but warp our understanding of those cycles if we begin to think of
>those cycles as having the same features of uniformity as UTC.  This is
>true whether or not there are leap seconds.  One of the shortcomings of
>modern chronobiology and psychophysics of time perception is that as they
>move more and more into laboratory settings from field settings the
>cycles are clock controlled, i.e., uniform.  As a result, a lot of
>current biological science of timing is actually studying how well
>organisms adapt to humanly created time cycles rather than environmental
>cycles tied to the Earth's rotation and weather conditions.
>
>Since many human activities are now structured by UTC and not circadian
>rhythms, many of those activities are, in fact, unhealthy.  In a sense,
>with regard to what Folkman worries about in his blog, the horse has left
>the barn and galloped to the border, cleared customs, and now is in
>another country and most people still don't know the barn door is open
>much less the horse is gone.  The disconnect between social rhythms,
>human biology, and apparent solar time began hundreds of years ago when
>preference in timekeeping shifted in favor of mean time and 24 hour days
>beginning at midnight, and this disconnect has been exacerbated by
>artificial lighting.
>
>Cheers,
>
>Kevin
>
>
>
>
>
>
>
>________________________________________
>From: LEAPSECS [leapsecs-bounces at leapsecond.com] on behalf of Tom Van
>Baak [tvb at LeapSecond.com]
>Sent: Wednesday, March 11, 2015 2:04 PM
>To: Leap Second Discussion List
>Subject: Re: [LEAPSECS] Letters Blogatory
>
>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
>_______________________________________________
>LEAPSECS mailing list
>LEAPSECS at leapsecond.com
>https://pairlist6.pair.net/mailman/listinfo/leapsecs
>_______________________________________________
>LEAPSECS mailing list
>LEAPSECS at leapsecond.com
>https://pairlist6.pair.net/mailman/listinfo/leapsecs