[image: Hippolyte.jpg]
*Hippolyta:  * Amazonian Queen
To complete his ninth labor, Heracles was required to fetch the girdle of
Hippolyta, the Amazonian queen.  As was true with all preceding and
subsequent labors, this chore proved exceedingly difficult.   Consisting
entirely of females, the Amazons were a fierce race of warriors who not
only abjured the society of men, but hated them with a murderous
intensity.*    As he well knew of the detestation the Amazons felt for men,
the very masculine Heracles thought it prudent to have Theseus (also
overtly masculine) accompany him to the region surrounding the Thermodon
River where the Amazons had long before established a kingdom.     The two
men arrived braced for battle, but were received merely with cool hostility
by all except Hippolyta, herself, who smiled warmly at Theseus upon his
arrival.     Unbeknownst to Theseus, his matron goddess Aphrodite, who had
caused Aridane to fall in love with him just prior to his adventure in the
labyrinth, cast the same spell on Hippolyta. Aphrodite harbored a deep
affection for her devotee Theseus. She also had no love for the misandric
Amazons who spurned all men.   It was a pleasure for her to both do a good
turn for Theseus while simultaneously disrupting the rigid Amazonian
conduct code.  Hippolyta was enamored of Theseus at first sight and despite
the stringent rule prohibiting such behaviour, welcomed him and his cohort
to dine with her that evening.  Though deeply perturbed by their queen's
show of affections, the Amazons did not immediately interfere.      During
that evening's dinner, Theseus soon realized that his hostess was smitten
with him and pressed his advantage.      He professed to have been in love
with her and she delightedly assured him his feelings were requited.
Theseus took her hand and said, "Come with me to Athens. Together we shall
reign over the Athenians with wisdom, justice and strength. Relinquish your
girdle to us and be my queen."  Despite her deep love for Theseus,
Hippolyta had grave misgivings about abandoning the Amazons.     While she
sat silently contemplating Theseus' offer, a great commotion could be heard
outside her home.    The Amazonian warriors had surrounded Hippolyta's
domicile and were in a fury.  During the dinner, the goddess Hera, sworn
enemy of Heracles, had disguised herself as an Amazon.  She convinced the
others that Theseus and Heracles were plotting to kidnap the queen and
enslave the Amazons.      "You must act swiftly," she warned, "for they are
both devils and will ensnare your queen with their dark magic."   As soon
as Hippolyta stepped outside to address her subjects, she was pulled
violently away into the throng. The Amazons then rushed the house to attack
Theseus and Heracles, both of whom they underestimated.    Even though they
were vastly outnumbered, the two men slew many Amazonian warriors as they
fought their way through the crowd.       During the battle, Theseus found
Hippolyta and took her from her protectors.     Theseus and Heracles then
rushed out of the kingdom in possession of their queen and her girdle with
nary a scratch on them.         Heracles completed his ninth labor by
presenting the girdle to King Eurystheus, who then gifted it to his
daughter.      Theseus returned to Athens with Hippolyta, who became his
queen, either voluntarily or much against her wishes.    Theseus then led
the Athenian army against an all-out assault launched by the Amazons who
were attempting to regain their lost queen.       After a bloody battle,
the Amazons were vanquished and they never again tried to attack Athens
again.  Hippolyta soon thereafter gave birth to their son Hippolytus, whose
tragic tale we shall tell tomorrow.

*Once a year, the nubile Amazons mated with Gargarean men, inhabitants of
an adjacent kingdom.     The girls sired from these unions matured to
become Amazons, while the boys were either given to the Gargareans or
smothered at birth.

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2020-2021:  XXIV


THE DAILY ASTRONOMER
Monday, October 5, 2020
Remote Planetarium 102:  Relativity Questions

Honestly, Special Relativity is a mind bender.     Intuitively, we are
accustomed to thinking about space and time as rigid, absolute and
independent of each other.   A person runs around a track in three
dimensional space while time ticks along at a constant clip.     The track
distance remains constant as time's progression is inexorable and
unaffected by the runner's velocity.   And, indeed, in our lives, space and
time do seem rigid and distinct because we tend to move at low velocities
and, as we'll learn later this week, we inhabit a region of low gravity.
  However, when the speeds are high and the gravitational fields strong,
space and time behave in a wholly counterintuitive manner, as Albert
Einstein (1879-1955) explained with his two monumental theories, the
Special Theory of Relativity (1905) and General Theory of Relativity
(1916).    We devoted all of last week to Special Relativity and light.
 We'll begin this week by answering some intriguing questions people have
asked us about it.


*Has anybody actually proven that time dilation occurs?    It seems like it
couldn't be proven since we can't travel at relativistic speeds?   T.P.  *
Yes, physicists have conducted experiments to verify that time dilation
actually occurs in moving vessels.  Perhaps the most famous is the
Hafele-Keating experiment (1971).   Named for the two US Naval Observatory
physicists in charge of the experiment,  Joseph C. Hafele (1933-2014) and
Richard E. Keating (1941-2006), this test placed atomic clocks on
commercial airliners that then flew twice around the world.      They first
flew eastward and then westward to determine the time difference between
the airplane clocks and those on the ground.

They were testing for both gravitational time dilation effects (we'll
discuss later this week) and kinematic time dilation effects.       When
the plane moved eastward, it was traveling along the direction of Earth's
rotation and so the plane's velocity was greater than that of a Earth-bound
observer.      When the plane moved westward, it was moving against Earth's
rotational direction.  The Earth bound observer moved more quickly.
 Consequently, the eastward plane was expected to experience a time loss
while the westward plane should have experienced a time gain relative to
the Earthbound observer.

[image: hqdefault.jpg]
A graphic showing highly exaggerated clock differences related to both airplane
flights around the world during the 1971 Hafele-Keating experiment.

The measured time dilation amount for the eastward plane equalled -40
nanoseconds;  the westward plane's time gain equaled 275 nanoseconds.  Both
measurements were within 10% of the expected values.



*“If one twin is traveling and the other is not, there must be a reference
point by which to determine which twin is traveling and which is not. How
do we know which twin is stationary?”   -P.W. *
The twin paradox has been a tricky matter in Special Relativity.    We will
attempt to resolve the "paradox," (which isn't), to the best of our
ability.   Let's imagine a set of twins, Castor and Pollux, are standing on
Earth.  Castor, an inveterate wanderlust, decides to embark on a trip to a
distant star.  Pollux, more of a homebody type, decides to remain on
Earth.       Castor leaves at 95% light speed.   He reaches his destination
and then immediately returns.     When he disembarks, Pollux is present to
greet him.       Even though they're twins, Pollux is now much older than
Castor because the latter was moving quite quickly relative to Pollux.
 However, relative to Castor, didn't Pollux also appear to move at 95%
light speed and shouldn't he be the younger of the two?      This situation
isn't a paradox at all because Castor left Earth's reference frame and then
returned to it, while, in this example, Pollux always remained within
Earth's reference frame.      This statement is not to suggest that Earth
holds a special place in this situation.       The age difference would
occur if Castor and Pollux started on the moon, Venus, or on a space
station around Vega.     Castor becomes the younger twin by virtue of his
rapid departure away from Pollux's reference frame.



*"What is the basis for using the denominator 299,792,458 for the ratio
that creates the precise length of a meter?"   -J.V.*
The speed of light value is exact because the meter is defined in reference
to light speed.      A beam of light traveling through a vacuum moves
299,792,458 meters each second.    Consequently, when the meter was
re-defined in 1983 in reference to light speed, it was measured as the
distance that light travels through a vacuum at 1/299,792,458th of a
second.

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