About time

About Time
OLLI/RISE Class – Fall 2015
Jim Isaak
HTTP://is.gd/Abouttime
2- Culture 3 Measuring 4 Cosmic 5 Future

What is Time?
• Past (memory) – Now – Future
• Second Law of Thermodynamics (Entropy)
– Heat dissipation – hot item loses heat to environ
[physic’s ‘non-reversible’ process]
– 1st
- conservation of energy (you can’t win)
– 3rd
–entropy approaches zero as temperature
approaches zero
• the indefinite continued progress of existence and events in
the past, present, and future regarded as a whole.
• Natural “periods”, defined “periods”
11/17/15 http://is.gd/Abouttime 2

Topics for our Consideration
• Time – The only show in town
– How and why humans started to keep time
• Cosmic Time – where were you 13.8 billion
years ago (on the night of Feb. 29th
?)
• Geological Time
• The drive for accuracy – what is “on time”
• Cultural Variations
• Relativity and Time
http://is.gd/Abouttime11/17/15 3

Time – The only show in town
• Once upon a time, long, long ago, before TV,
radios, clocks, sundials … people lived in
caves, or temporary shelters migrating with
game and seasonal vegetation
• The evening activities were limited … stories
by the campfire, ceremonies, … and then
watching the sky

So what is Time – way back when?
• Days --- pretty obvious
– Big yellow thing comes up, crosses sky, goes down
– Seems to be warm
– Sometimes it’s not as warm as other times
• Folks farther from Equator notice cold white stuff
– The cold/warm sequences seem to match animal
and vegetation changes
– All of this seems to repeat
• And some smart character notices the stars!

http://www.space-exploratorium.com/big-dipper-clock.htm

Then there is that big white thing

28 Days
• And the Days and Moon
seem to be related
– Full moon 29.530589 days
• For those close to the
ocean, particularly those
feeding on low-tide
creatures, or on fish that
spawn on Spring Tides
(grunion)

So the smart one(s) - observe
• Shaman’s – “one who knows”
– Perhaps “count the days” (marks on the wall)
– Realize that the Moon Cycle and Year are not
quite “right”
– 12 Lunations = 354.37 days
– Year is sort of 365 days
– And the shadows move, get longer/shorter

People like Stories and Predictions
• When will winter come?
• When will the high tide / low tide come
• When will the monsoon’s start
• When will the birds return, the bison leave
• The moon and stars seem to hold the answers

Astrology
• Is a natural attempt to relate the apparent
relationship between the events that govern
man’s life (and women as well) – and
synchronize with the motions of the heavens

First step to becoming a Shaman
• “Gnomon” is also a term for one who knows

Attach it to a piece of cardboard
• Spread your wings – it is stronger that way
– Ideally the angle of the “back” will be 42 degrees”
(our latitude) – but close is good enough
• It will take more than a 9” x 9” piece to have
all of the shadow “on the cardboard”
• Align your Gnomon North (point)/South
• Start marking the hours

If you have a big open yard

Vertical Gnomon
• Track the “top shadow” at noon (true noon) at
least once a month
• Note the sun-rise/set points for
– Equinoxes (first day spring/fall)
– And Solstices (winter/summer – longest day)
Does the sun set In the West or North on June 22?

Cultural Variations

Cultural Variations
• What’s Important?
– Herd migrations
– Tides
– Storm patterns
– Annual floods
• “natural” periods (days, moons, years)
– Breaking daylight into “hours” is a contrivance

Lunar Calendars
• Babylonians stuck with a lunar calendar,
knowing it did not yield a solar year –
discovered the 19 year “Metonic” cycle
– Alternated 7 years of 13 months, and 12 of 12
• Variations persist today
– Hebrew calendar follows this model
– Muslim – “star and crescent” allows the months
to flow independent of the years

73 is a prime number
• And so is 5
• Which means that 365 (=5x73) is not easily
divided into parts
• Consider “perfect” numbers (6, 28) which are
the sum of their factors (1+2+3=6…)
lots of choices for factoring … primes have
none, and products of primes just two
• i.e. for math oriented cultures, it is hard to
divide the year (even if it were exactly 365)

• If a Lunation were exactly 28 days
• And the year were exactly 336 days
– 336= 12 x 28 = 2x6x28
Every culture would have lunar calendars and six
day weeks (28 and 6 being perfect numbers)

Egypt (26° N Luxor –30 ° N Cairo)
• Flood driven 3 seasons – and good
observations yield a 365 day calendar
– 12 months of 30 days plus 5 ‘new year days’
– 36 ten day weeks + 5 [36 key stars]
• Driven by the helical rising of Sirius
(mid flood season)
• Wandering ‘year’ has 1460 year cycle
• 12 ‘decans’ of the night – asterisms rising

Heliacal rising
For a given position, the star always rises at the same
point
And at the same time for a given day

Babylonians (33° N Bagdad)
• Enamored of “60” divided the circle into 360 degrees, then 60
minutes and 60 seconds
(base 60 arithmetic)
– 5 “elements” and sacred “12”=>60
– But also “Fists above horizon”
• This was transferred into time-keeping
• And, prior to the introduction of “zero” (from India) decimal
arithmetic did not exist as we know it.

But wait, there’s more
• Introduced 7 day week (perhaps 4/moon cycle?)
– Adopted by Jewish calendar, including names
aligned with 7 days of creation
• Alexander the Great embraced their calendar &
propagated it
• Creation cycle is 600 x 3600 years (2.16 MY)

India (8-36° N New Delhi @ 28° )
• Not homogeneous – religion, language, geo
• Days into 60 Ghati (24 min), into 60 Pala (24 sec) into
60 vipala (.04 seconds)
• Months tied to timing of earth’s elliptical orbit – we
spend longer in Gemini (31.6 days) than Sagittarius
(29.4 days)
• Knew about polar precession, but ignored it
6 seasons named for weather, now off by 6 weeks
• 4.32 million year cycles of creation/destruction
last one started 18 Feb 3102 BC in this case

Jaipur Observatory 17th century

Greeks (Athens at 38° N)
• Influenced by both Babylon and Egypt
• 36 star “decans” – source of “decimal”
– Each with 10 degrees of separation in circle
• Caught up in “geometric” models of the
cosmos, rather than observational reality

Jewish Calendar
(Jerusalem at 31.7° N – 35.3° E)
• Lunar, with adaptations to align with years
• Starts 7 Oct. 3761 BC
– (compare to Bishop Usher’s
6 pm on 22 October 4004 BC)
• Calendars designed for
– Religious holidays (Holy days)
– Civil administration (collecting taxes)
– Agricultural cycles (etc.)

China (Beijing at 39.9° N)
• The Emperor demonstrated his mandate of heaven
by his calendar – an imperial secret/right
• Jesuit’s brought clocks as gifts, lingered in
detention, but established credibility with the
solar eclipse of 21 June 1629
• Three divisions of the day:
– 12 ‘hours’ (double hours)
– 100 Ke (about 15 minutes each)
– 5 night watches
–

Astrology
• In China, the critical “time” is the point of
conception, not birth
• The Emperor rotated concubines and wives on
a defined schedule so that the “Empress” had
the two nights (exclusively) of the full moon.
• The ‘vermillion pens of the ladies secretarial”
recorded each liaison (since typically nine
concubines or secondary wives were present)
so subsequent birth’s would have accurate
data

Apparent star motion
Where is the center of the universe?

Mayan (Tikal at 17° N)
• Mayan: 260 day cycles
– Perhaps influenced by human gestation
– Or planting cycles, or cycles of Venus
• Solar year: 18 – 20 day periods with 5 “outside” days
• And no significant division of the day into parts
• Tracking eclipses was important, and did trigger
additional calculations/observations
• Cycle: 52 years (52x365=73x260)

Aztec
(Mexico City
at 19.4° N)
• 5 Suns:
– Jaguar – destroyed
– Wind – some saved as monkeys
– Fire-rain – some saved as birds
– Water – some saved as fish
• We are now in the 5th
: “movement”

Stonehenge (51.2° N)
• Sits at a unique latitude
• Primarily aligned:
– Summer Solstice Sunrise
to Winter Solstice Sunset
Orthogonal to
Winter solstice Sunrise
& Summer Solstice Sunset

Inca (Cusco at 13.5° S)
• Aligned primary city on astronomical guides
– sun viewed over 328 “huaca” pillars from center
– Used “dark constellations” in sky view
• Milky way (river) as path for departed to
come/go
– The “door” closed due to precession of axis, an
event apparently predicted in Inca mythology
• June 9 (now) agra-calendar reset with Pleiades
– But with 37 “no time” days to make up for 365

Inuit (69 ° 22’ N)
Month names for Igloolik
1. Sun is Possible
2. It gets higher
3. Premature birth of seal pups
4. Seal Pups
5. Bearded Seal Pups
6. Caribou Calves (image below)
7. Eggs
8. Caribou hair sheds
9. Caribou hair thickens
10. Velvet peels from antlers
11. Winter starts
12. Hearing
13. Great Darkness
•Different villages, different month names
•“Aagjuuk” (Altair/Tarazed) is not recognized as asterism until mid-winter
•5 day & 5 night variable time divisions
•Associate activities with star/sun positions, not dawn/dusk
•Track years, moons, landmarks (births, deaths)

Rome (42° N) introduces finer
divisions
• AM/PM; then
• Morning, forenoon, afternoon, evening
• Then asserting 12 “temporary” hours during
daylight, and 12 at night (variable length)
• Water timers were used to limit speakers in
the senate or the court (we should be so wise)

Gregorian Calendar

One other take on Cultural Time
• In Germany show up on time
• In Spain if you arrive at the hour suggested
you may embarrass your hosts who may not
be prepared
http://www.culturegrams.com/ (subscription)

Telling Time (and why)

Who Owns Time?
• Compare Inuit (family time) to Roman (court time)
• The emperor, king, Inca, pope, …
– If someone controls your time …
• And how do you measure it?
– Why do you measure it?
• We move from AM/PM to hours to minutes…
• Religious observations is a leading factor

Early Time
• Stars: Identify Meridian, when this star crosses
meridian then… (or appears above peak)
• Sun Dials
Shadow Clock, Egypt 1500 BCE
• Water Clocks (problem with variable hours)
as early as Egypt 1500 BCE
• Candles, oil, incense, .. Burn at given rate
Korean Examples (2 min)

A Note on Incense
• Can be made to burn at constant rate
• Different ‘smells’ at different points on stick
(“it smells like 10PM” – no need to light the candle)
• Clock burns through
strings, balls drop
• Stick it between
your toes to wake up
• Partial sticks as
pill reminders

Clock Requirements
Repeatable – ideally in terms of cycle measured
Measures useful increments
We think “fixed hours”, but not so with early
clocks (which was a problem since equal hours
is a bit easier)
Display result

Mechanical Clock #30
• In the “Top 101 inventions of all time”
• 8- fire
• 7-Computer
• 6- Lever
• 5- Transistor
• 4- Steam Engine
• 3- Light Bulb
• 2- Printing Press
• 1- Wheel
History Channel Shoiw with
Judges from Popular Mechanics
Your mileage may vary

Su Sung Clock
1088 CE. a water-driven escapement
(circa 725 CE.)
a bronze power-driven armillary
sphere for observations, an
automatically rotating celestial
globe, and five front panels with
doors to view manikins which rang
bells or gongs, and held tablets
indicating the hour or other special
times of the day.

Korean Water Clock
• Animation
– 2 min
• Striking
– 20 sec

The drive for accuracy – what is “on time”
• Early divisions of the day
created laments about the
intrusion of the hours,
dissecting one’s day
• Religion has played a
significant role with
expectations of prayers at
Dawn, Sunrise, Mid-morn,
noon… (Catholic)
or towards Mecca (Islam) 5
times a day

Galileo & the Pendulum
• Recognizes the constant period of pendulum
based on length
• Suggests it might be used to keep time (1641)
• Applies knowledge to measure increments of
time --- determining the rate of fall of objects
• 13th
century early clocks existed
• 1656 - Huygens Pendulum Clock
• 1675 wall clocks – from ±15 Minutes to ±15 Seconds

17th
Century
• Era of massive innovation & discovery
– Telescope, and Galileo’s “Starry Messenger” (1610)
– (Sidereus Nuncius)
• Introduces “observational” science
displacing “dialog among experts”
• Observatories across Europe in last half
• But also – emergence of capital
– Caput (head) – Capital (cattle, and chattel)
(mercantilism economics based on fixed wealth: 1500 -1800)

Time – By Jupiter!
• Best seen via binoculars … need wide field

1707 the Wreck of the Fleet
• 4 Royal Navy vessels sank
• 1550 sailors lost (including Admiral of the fleet)
• In ability to determine longitude (East West position)
• Triggered “Longitude” prize
• And 60 years of work to create and prove the first
marine chronometer by John Harrison
(some Commissioners of Longitude were competing
for the prize as well, or held pet theories – lunar
observation, Jupiter's moons..)

The Equation of Time
• The difference between Solar Mean Time
and clock time ±16 minutes
• Sundial’s are ahead on Nov. 4th
(16 min)
and behind of Feb 12 (15 Min)
Earth’s Tilt yields “long” axis of figure 8
Rotation of earth each day -> loops
the diurnal day > sidereal day (4 min)
Earth’s motion in orbit -> Asymmetry
and a key variation in “solar time”

Marshmallow (sidereal) Time
• You are the Sun!!
• The room is the celestial sphere (fixed stars)
• The marshmallow is the Earth (toothpick axis)
• Angle the axis so the upper point faces the
screen – it will maintain this orientation even
as it spins and orbits (23.439 °)
• Spin in place; now try a quarter orbit with a
full earth spin – notice it is not facing you!

To Scale
• ½ inch Marshmallow
• Sun is 4.5 feet in diameter
(spread out your arms)
• And it’s 490 ft away!
(stretch real far!)
• Ask about what
causes the seasons!!

Why do seasons happen?
Daylight hours Heat spread over larger area

The Analemma
2006 Greenwich Eng (51.48°N )
Width distorted to show

Why Measure Time?
• Daily religious observances
• Change of “watch”
• Galileo – scientific analysis, and related skills
like cooking, brewing, etc.
• The devices are delightful works of art
• Church Chimes – call to worship, and more
• The clock “eliminates the tyranny of the Sun”
But ….

Emergence of “paid” work
• Industrial Revolution
– Factories want to start/stop on time
– Massive water driven mechanisms (or coal…)
– Perhaps even shifts of workers
(if sufficient light)
– For this, you want agreement (and conformance)
to “Local” time (noon is when sun crosses meridian)

But – is this any way to run a railroad?
• Sandford Fleming – Canadian Railroad, unity advocate
– misses train in 1878
• Advocates universal 24 hour time at 1884 conference
• But concept of 15 degree time zones, while not
formally adopted is implemented by 1929
• Until Time zones
every station/town
had it’s own time
(sun passes our
meridian at noon)
No actual riots occurred

Day light Savings Time
• An early advocate, Benjamin Franklin
(perhaps poking fun at his French hosts)
• First adopted by Germany April 30, 1916
– To improve war productivity
• US adopted in 1918 for the same reason
mostly repealed until 1942
• US Time Zones labeled “Eastern War Time” …
• But not uniformly adopted until 1966!
(expanded 1974 to conserve oil & in 2005)

A “foot note” on the (North) Pole Star
• This week it
is Polaris
• And it will
be again in
26,000
years …
• The Earth
precesses
on it’s axis

Cosmic Time

Cosmic Time
• Bill Bryson
– A Short History of Nearly Everything

Creation
• Greek/Roman “thema mundi”: starting configuration
• Aboriginal “dream time” – serpent shapes land
• Asmat of New Guinea – creator kills to create life
young man is given fresh skull in coming-of-age ritual
• Balance of, often violent, competing forces are
foundation of creation – Mesopotamia, Navaho,
Hindu Vishnu
• Time is often a synonym for both creator and
destroyer of all things

How Old is “Everything”?
• If there are stars everywhere, then we should
have light from all of them on earth – a ‘white
sky’
• Unless it takes time for light to reach us, they
are far away, and the intensity diminishes with
distance ….
• So the speed of light becomes a key way to
measure the age of the universe

Speed of Light
• 1600’s folks considered how to measure it
Galileo – 1638 “purty darn fast”
• First estimates Romer, 1676 based on Jupiter
Moon eclipses tied to Earth’s position in orbit
• 1800’s getting to a fairly accurate estimate
“a hair under” 300k meters/second
• Newton determined same speed for all colors
• 1860’s ID’d as Electromagnetic wave
• 1887 Michelson/Morley fail to detect aeather
•11/17/15 http://is.gd/Abouttime 72

Henrietta Swan Leavitt
• A computer at Harvard College Observatory
• 1912 “A straight line can readily be drawn among
each of the two series of points corresponding to
maxima and minima, thus showing that there is a
simple relation between the brightness of the
variables and their periods.“ (Cepheid variables)
• Later shown to be a result of helium isotopes
“containing” heat/light->expanding star
->condensing helium ->releasing light ->shrinking
star – i.e. – the stars pulse at a predictable rate

Parallax and Red Shift

Hubble discovers Galaxies
• 1922 Edwin Hubble identifies Cepheid
variables that must be outside of the Milky
Way
• In 1929 he uses red-shift data to demonstrate
that “they further away the faster they
recede” (Hubble’s law)
• Implies “big bang”

Distance => Minimum Age
• Between Parallax, Cepheid variables, and Red
Shift – distances can be determined
• If a star is 15 light years away, it must be at
least 15 years old …
if a billion light years away, at least a billion
years old
• Furthest observed star/galaxy is
EGS-zs8-1 lies 13.1 billion light-years away

Beyond the Galaxies
• The Cosmic Background Radiation
• The accidental discovery in 1964 by Arno
Penzias and Robert Wilson resulted in the
1978 Nobel Prize
• 2014

13.8 Billion Years

Geological Time

Stratigraphic Layers
• Lyell – Darwin’s
Colleague
• (for Grand Canyon)
– Earliest rocks date
back 1.8 billion years
– Vishnu layer named
for the initial
documenting of this
layer in India

Fossils

Carbon Dating
Carbon 14 providing
dating back 60,000
years max
Other elements can
provide mechanisms
that go back billions
of years

And the beat goes on…
Uranium-thorium -a twofer
U234 80k yr half life
U235 34.3 k yr half life
U238 4.5 billion yr half life
Samarium-neodymium
1000 billion yr half life
Potassium-argon dating method - 50
Billion yr half life
Rubidium-strontium
1.3 billion yr half life
Others:
argon-argon (Ar-Ar)
iodine-xenon (I-Xe)
lanthanum-barium (La-Ba)
lead-lead (Pb-Pb)
lutetium-hafnium (Lu-Hf)
neon-neon (Ne-Ne)
rhenium-osmium (Re-Os)
uranium-lead-helium (U-Pb-He)
uranium-uranium (U-U)

Scientists use “BP”
• Vs the “BCE, CE” – ‘current era’ euphemism
• BP = “Before Present” – i.e. Jan. 1, 1950
• Why that date?
– Radio carbon dating introduced Dec. 1949
– Atmospheric nuclear testing after 1950
– Aligned with then current Astronomical Epoch
(as of 1984, moved to Jan 1, 2000– “J2000”)

The Tale Tell Magnets
• Every 100k to 1M years
the magnetic poles
decide to swap
• With occasional hiccups
(41k years ago a 450
year decline/switch and
return – 75%+
reduction in field ->
more radiation -> more
carbon 14…)

local magnetic fields sway as well
• Leaving imprints in ponds and other
sedimentary collections (that can be dated by
other means)
• And then in the pottery made from that mud
– Allowing locality of clay to be identified
– And also dating of the pieces
• A field called “microarcheology” dating objects
within decades vs. centuries….
(See “Witness to Armageddon”, Nov. 2015 Discover
Magazine)

The Future of Time
Relativity and Time

Einstein 1905
1. how to measure the size of molecules in a liquid
2. how to determine their movement
3. light comes in packets called photons—the
foundation of quantum (Nobel Prize)
4. special relativity (not fully accepted till after his death)
5. pointed that matter and energy can be
interchangeable at the atomic level: E=mc²

Einstein
• 1905 – thought experiments
The speed of light is fixed for all observers
therefore time & measurements are relative

Einstein’s Dream’s
(Alan Lightman –MIT)
• Short fictional scenarios exploring alternate
perspectives of time
– Circular – all things repeat – exactly
– Stream with eddies, some folks displace backwards
– Multiverse with every decision branches
– Live forever, or just one day, or known end
– Absolute everywhere, frozen at center, different
rates for different persons
– Flows backwards, visible dimension, only local…

Time Travel
• In theory going faster than the speed of light
(superman movie), Startrek IV, etc …
runs the clock backwards
But – approaching the speed of light mass
increases approaching infinity -> ergo infinite
energy required to get to speed of light…
• BUT – since space/time is a continum
a worm-hole may connect one time to
another
• BUT - perhaps a different multi-verse … so ..

Big Bang
Generally the laws of physics can be reversed
Entropy seems to be an exception
the one that defines the “arrow of time”
There are indications that the direction of this
arrow was a random aspect of the big bang
Prior to the big bang there was no time,
which is to say this statement starts with a
meaningless concept

Hawking – A Brief History of Time
• Three Arrows of time (at least)
– Entropy (disorder, heat dissipation)
– Psychological – memory and perception
– Cosmological – expanding universe
• Psychological follows from the experience of
entropy in action (cups break, they don’t assemble)
• The anthropomorphic principle implies ‘if the arrow were
reversed, no intelligent creatures would exist to observe & ask
the question of why things were getting more ordered’

A new take on time’s arrow
• Science News, 25 July 2015
• “Janus point”

SciNews: Clocking in the Brain
• Different time keepers in the brain
– short term memory
– speed up recording -> slow motion with “high
octane” experiences,
– chemical modification
– disease impact (.2 sec for most folks, up to .4 for
persons with schizophrenia )
– sight merger at 24 frames/second vs
sound integration at 44000 cycles/second.

SciNews – Life’s Cycles
• circadian time, in critters, but also in cells
• many life forms have 24 hour cycles, perhaps
to avoid oxygen (anti-oxidant cycles)
• some are lunar, some tidal
• many instances, no apparent single “mother”

Time seems to slow down
• Extreme events seem to slow time down
an apparent illusion
The mind records more “frames per second”,
so in retrospect, things seem to have been
moving slower
• But, the difference between the .2 second
reaction time and .4 awareness time is the
critical element of mastery – pre-wired
responses
• (PBS Brain show and July Science News Issue)

A very good PBS series (2015)
The Brain with David Eagleman
1. What is reality?
2. What makes me?
3. Who is in control?
4. How do I decide?
5. Why do I need you?
6. Who will we be?
Addresses some aspects of perceived time

Time Paradox (Book and TED talk)
• Philip Zimbardo – psychology of time
– Time is the medium in which you live
“No man ever steps into the same river twice,
for it’s not the same river and he is not the same
man” (Heraclitus)
• “Remember that time is money” B. Franklin
• ‘Only during the last thousand years have we
had “discretionary time”, and only in the last
hundreds have substantial segments of us
enjoyed it.’

Pace of life
Walking speed, bank teller speed, talking speed:
- Fastest cities: Boston, NY and Northeast
- Slowest cities: South and West, LA as slowest
So what:
• Returning a pen someone ‘accidently’ dropped
• Helping a blind person across the street
• Donate to United Way
• More coronary disease
Rochester NY most helpful; LA not so good

Future oriented/Now oriented
• The Marshmallow test
– Kids who resisted scored 250 points higher on SAT
better students, less trouble, self confident
• Time Perspective – individual, cultural…
– Present oriented – past positive/negative
– Past oriented - hedonist/fatalist
– Future oriented – life goal/ transcendental
RSA sketch talk on cultural time zones
but also revolution in time – affects kids/future

Ideal Time Perspective mix
Past
Your Roots – Identify
Family, grounding
High on past positive Always low on
past negative
Present
Energy – explore people,
places, self
Hedonism - moderate Always low on
Present fatalism
Future
Your wings – soar to new
destinations & challenges
Moderately high
Develop the discipline to shift time perspectives based on situation is key

Downside of excess
• Futures sacrifice family, friends, etc for
success
live for work, achievement, control
• Understanding your time perspectives, and
those of others, can facilitate resolution of key
interpersonal issues, but also addressing social
challenges such as drug abuse, PTSD, etc.

Useful
• Money is time … given enough money, you
are free to do what you want with your time
(and insufficient money means others
dominate your time)
• “There is no present like time”
(Second Best Grand Marigold Hotel)

The Long Term
• http://longnow.org/ fostering long term
thinking – sponsors:
• Long bets: http://longbets.org/
– 2+ year bets that will affect society
must have “both sides”, with explanations
– Money goes to winner's charity of choice
• http://www.10000yearclock.net/
Jeff Bezos & friends

Questions
If we have enough time!

About time

More Related Content

Similar to About time

More from Jim Isaak

Recently uploaded

About time

Editor's Notes