*[image: bouguereauphilomelaprocne.jpg]*
*Procne and Philomela:  The Sisters' Revenge*
(Note: Though I tried to soften details as much as my limited abilities
enabled me to do so, I must preface this famous mythological tale with a
clear warning:  *Discretion is advised.)*

Athenian king Pandion and Thebian king Labdacus were in constant
conflict over the boundary dividing their adjacent kingdoms.   Naturally,
each king wanted to enlarge his respective domain at the expense of
the other.  Initially, this dispute was limited to the odd skirmish at
different points along the demarcation.     In time, the dispute devolved
into a full blown war. Knowing that his army was inferior to that of
Labdacus, Pandion sent emissaries to Daulis, a nearby city ruled by King
Tereus.     As the son of Ares, the god of war, Tereus had earned a
reputation for being a fierce taskmaster in charge of a truly
formidable army.    As Tereus had experienced his own run-ins with the
troublesome Thebian king, he was quite willing to ally himself with
Pandion.  Together, they easily defeated the Thebians and killed Labdacus.
   Pandion was so grateful to Tereus for his invaluable assistance, he
offered to marry Tereus to his elder daughter Procne.     Tereus was
delighted by this arrangement for Procne was kind and beautiful in equal
measure.  Though the marriage was not of her choosing, Procne was happy to
become Tereus' wife as he was strong, handsome and uncommonly kind,
especially considering the nature of his father.    Her only regret was
having to leave her home and Philomela, her beloved younger sister.
Though deeply saddened at her elder sister's departure, Philomela remained
calm and cheerful as Procne and Tereus prepared to leave for Daulis. After
Procne and Philomela embraced, the latter handed her an ornately designed
shawl.   A gifted weaver, Philomela had sewn many happy scenes from their
childhood along it.  "And this," Philomela said as she turned over a
corner, "is the moonstone of Morpheus. I wove it into the webbing. On full
moon nights, sleep with it under your head and we shall be together in your
dream."      With the shawl wrapped around her, Procne left with Tereus at
her side.   Philomela smiled at her sister as she rode with her husband
into the distance. The smile was genuine for  Philomela's sorrow was
leavened by the vicarious joy she derived from her sister's bliss.  Procne
and Tereus lived in Daulis.   Early in their marriage they welcomed a
child: a beautiful young boy named Itys, who bore a striking resemblance to
his father.    His presence intensified the love the couple bore to one
another: a love they bestowed generously onto their one son.    Procne was
deliriously happy for each full moon night she slept with the amulet and
was reunited with her distant sister for a few moments in a dream.
During each encounter they laughed and ran together as they did when they
were young girls.     Unfortunately, these gatherings were fleeting and
details of them remained vague in Procne's awakened recollection.   One
day, about five years after their wedding, Procne confided a secret sorrow
to her husband. "I miss my sister dearly.    Though I am very happy here
with you, I long to see her again.   The amulet's dream encounters are not
sufficient.    Dear husband, could you not bring her to live with us?    I
ask only this one favor.  If fulfilled, I shall never ask another."
 Tereus assured her that he would leave the very next day to bring
Philomela back to Daulis.    True to his word, Tereus sailed across the
Gulf of Corinth and then continued over land until reaching Athens.
Pandion greeted him warmly on his arrival at the palace.   They embraced
like father and son and spoke for a long time about Procne, the marriage,
and, of course, little Itys.      "Procne 's heart is heavy," Tereus said
sadly. "For she misses Philomela and greatly desires to have her live with
us in Daulis, provided, of course, that you give your consent."
Pandion gave his consent gladly.  "She shall leave tomorrow with her for
Daulis!  My daughters' will be delighted to be together again.    Pray,
stay here while I bring forth Philomela."       A few minutes later Pandion
returned accompanied by Philomela.   Tereus was stunned.    The last time
he saw his sister in law, she was little more than a child.   After the
passage of five years, she had grown into a ravishingly beautiful woman.
Philomela ran forward to embrace and kiss Tereus, for he had proven to be a
devoted husband who had brought much happiness to Procne.     'Yes, I shall
travel with you tomorrow, dearest brother in law.    I cannot tell you how
happy I shall be to live with you and my sister in Daulis."     Tereus
disengaged from the embrace and said nothing in return.     The next day
Tereus and Philomela departed.    While Philomela spoke cheerfully about
her sister and her deep gratitude to Tereus for bringing to her Procne,
Tereus remained uncharacteristically laconic.  Interpreting Tereus'
reticence as a longing for his wife, Philomela resolved to lighten the mood
with frequent chatter and the occasional show of Platonic affection.
 After having crossed the Gulf of Corinth, Tereus stopped his chariot at a
small house.    Philomela looked confused.  "Why have we stopped here?
Certainly this cannot be your palace!" she said laughingly.     "No,"
Tereus replied, stepping down. "This is a small cottage I own.  Procne and
I stay here at times when we travel. It is our resting stop for now.  The
Sun will be down soon and we have a great distance yet to travel.  We must
rest and allow the horses to do the same."    Philomela shrugged and left
the chariot happily, not knowing that they were only three miles from
Tereus' home.   "How long shall we remain here?" Philomela inquired as they
approached the door.      "Just the evening," Tereus assured her.  "At dawn
we ride again and will likely reach Daulis by afternoon."    As they
entered the cottage, Philomela clasped Tereus' hand and kissed it.  "I
cannot wait to see my sister.  Thank you for this."     Tereus squeezed her
hand in return before closing the door.      It is said that within
everyone in the mythological world -as well as our own- there resides a
shadowy antechamber in which the impurest thoughts, darkest desires and
most bestial impulses are stowed.    Most people leave it shut tightly as
they fear what lies hidden within.  (Gods, living with blissful impunity,
open theirs frequently.)   Soon after they arrived at the cottage, Tereus
yielded to his lust and, after drawing his dagger, had his way repeatedly
with his sister-in-law without her consent.  The deep sisterly affection
she harbored for Tereus was quickly transformed into a visceral hatred. By
the next morning, Philomela was shouting imprecations and pleading with the
gods to avenge the assaults.    "My sister shall know what a vile beast her
husband truly is!" she spat at him.   "You shall say nothing to your
sister," Tereus replied calmly as he removed her tongue with his dagger.
 Tereus then chained her ankles and left her in the cottage.  He would have
remained longer had he not realized that the moon was going to be full the
following night.       He sped home as fast as his chariot could carry
him.  Procne was waiting outside when Tereus arrived.       Procne's
countenance, at first bright with anticipation, darkened as she noticed
that her husband had been crying.    She embraced him warmly.  "What is the
matter?  Where is Philomela?"  Tereus wiped his eyes.  "She is dead, my
dear.   I went to your father's palace to retrieve her only to learn that
she perished less than a month earlier of a fever.  And, my dearest, your
father died of grief at her loss soon after.   These tears I have shed
constantly during my return. Forgive me for bearing these tidings."  Procne
dissolved in tears and clasped onto Tereus tightly.   They entered the
house where the young Itys joined them in their grief.   The three of them
embraced and remained together the entire afternoon except for the brief
period when Tereus arose and said that he had to attend quickly to a few
matters, but would return quickly.       Their once happy home was suddenly
mired in grief.   Procne, in particular, was the most distraught,
especially when she realized that her shawl was lost.   The night after
Tereus' arrival she had sought it out.  She thought, perhaps, that the
moonstone would allow Philomela's shade to infiltrate her dream.    Yet,
despite frantic searching, it was nowhere to be found.    Even though her
sorrow deepened, Procne came to think that perhaps the shawl's
disappearance was for the best and that the dead are best left
undisturbed.  During the following months, Procne grew ever closer to her
husband and son, the only  family she had left. Tereus made frequent
clandestine trips to the cottage, where he indulged himself joyfully on
Philomela.    Fearing that she would kill herself, Tereus made her
accommodations as comfortable as possible.  He removed the ankle chain,
preferring instead to make the cottage into a prison.    He brought her
ample stores of food, wine and a weaver's loom and ample thread.     These
amenities, scant compensation for the outrages on her dignity, did nothing
to diminish Philomela's loathing of Tereus.  Though powerless to speak, she
glowered at him with a hateful intensity that would have petrified most
men.   Tereus seemed strangely delighted -and aroused- by her animus.
Philomela was determined to somehow let her sister know what was happening
to her, even though she was confined and during the last two full moons she
didn't see Procne in her dreams.   Philomela decided to employ her weaving
skills to create a tapestry on which she would weave the sordid tale of
what transpired between her and her brother-in-law.  She worked on it
assiduously whenever Tereus was away.  A few months later, around the time
that Philomela had completed the tapestry, Procne was wandering outside
while Itys played in the dirt.   She noticed that her son had unearthed a
shimmering object and approached it.  Procne quickly recognized it as the
Moonstone of Morpheus.  She dug beneath it and discovered the remains of
her shawl, now moldy and dirt-encrusted.      She couldn't understand how
the shawl could have been  buried in the dirt or why.    What she did know,
however, was that the moon would be full within a few days. "Say nothing of
this to your father," Procne told her son sternly. before she reburied the
shawl and hid the stone away in her pocket.    Later that week, on the
night of the full moon, Procne slept with the moonstone under her pillow.
   Philomela appeared to her in a dream.  Elated, Procne rushed forward to
embrace her sister.  Philomela shied away from her, looking morose, almost
mournful.   "Alas," Procne said, "I had forgotten,  You have died."
 Philomela suddenly looked perplexed and angry.  She shook her head.  "Are
you not dead?"   Philomela shook her head again and tried to speak, only to
produce a jumble of incoherent sounds.  "Why can you not speak?"  Procne
asked.  Philomela opened her mouth to reveal the tongue stump.  Horrified,
Procne screamed, "What happened to you?!"    Philomela unfurled the
tapestry and showed it to her sister.  To her terror, Procne saw a series
of images showing Philomela and Tereus from the time they left Pandion's
palace to the time they arrived at the cottage.    When Philomela turned
the tapestry over to reveal the next image, Procne turned her head away and
shrieked.   However, she soon forced herself to look back and study the
other images.  She saw everything, including her husband's repeated
visits.      Ashen-faced, Procne asked, "Are you at our cottage still?"
 Philomela nodded.  Procne then awoke with a start.   She looked over and
noticed her husband stirring slightly.    She quietly arose from the bed,
dressed and promptly ran with all speed to the cottage.   On arriving, she
noticed that it has been fortified, almost like a prison.   A large log
blocked the door.  With great difficulty, she managed to hoist it away,
open the door and rush inside.  Philomela greeted her with sobs and they
embraced tightly.  Throughout the night, Procne managed to extract the
entire story from her sister by asking a series of questions to which
Philomela responded with a nod or shake of the head.       "He told me he
had to visit the cottage often to renovate it.  'We'll make it a second
home for us and Itys,' he said."    At this, Philomela broke down into
convulsions.   Procne firmly grabbed her hands and kissed them.  "We shall
be avenged, my dearest sister, and at once.   Come with me."
         When Tereus awoke the next morning, he found Procne already
dressed and seated next to the bed.     "You slept late, dearest husband,"
she said smilingly.   "Do you not have kingly matters to which you must
attend today?" Tereus started when he noticed the Sun's high angle in the
sky  "Indeed I do. I must have been tired to have slept so late."   Procne
reached over and caressed his face.   "No doubt your exertions of late have
exhausted you.  Make haste, though.   The day is growing old."    Tereus
hastily dressed and, after hugging his wife, left.      The day proved so
busy that he returned home only after the Sun had set.    To his delight,
Procne awaited him. She was dressed in the finest raiment she possessed.
By the torchlight, Procne looked particularly radiant and alluring.    "My
dearest Tereus," she sighed. "I have missed you.   You must be so tired
after your day."   Tereus smiled warmly. "Tired and hungry," he replied.
Procne gestured to the table,  "Dinner is prepared.  Itys has already eaten
and is now resting.    That leaves just you and I to dine together."     As
Tereus sat down, he whispered "I am happy for that, my love."    Tereus
feasted on bread, wine and meat stew.  So engrossed was he in the delicious
meal that he didn't notice his wife casting furtive glances on occasion
toward the bedroom.     "You're not eating much," Tereus observed between
bites.  "I ate some earlier and am nearly satiated," Procne answered.
 Tereus shrugged and continued eating.  When he had completed the meal, he
leaned back and sighed.  "Thank you, my dear.   I, too, am satiated."
Procne arose from the table and went over to her husband.  She stood behind
him and massaged his shoulders.  "You are truly satisfied, my love?"
Tereus stretched his arms,  "Immensely.   A fine meal, dear wife."   Procne
laughed.  "It should have been.  I used the most savory meat I could
find."  She then violently pivoted his chair to one side so that he could
see Philomela standing before him holding a sphere under a cloth.     Her
face was contorted with the deeping hatred and loathing.   As he sat aghast
at her presence, Philomela removed the cloth.     Tereus lurched forward
and retched.  "He really did look exactly like you, didn't he?"   Procne
asked gleefully.      Tereus smashed the table with rage and unsheathed his
dagger.  Procne and Philomela fled from the home with Tereus in murderous
pursuit.  Just before Teresus could reach the sisters, Ares transformed
each of them into birds.  Procne became a swallow; Tereus a hoopoe and
Philomela a nightingale.    It is said that though its music is more
melodious than any sounds mortals are ever likely to hear, no nightingale
has ever been able to sing even a single note in the kingdom of Daulis.



THE SOUTHWORTH PLANETARIUM
207-780-4249   www.usm.maine.edu/planet
<http://www.google.com/url?q=http%3A%2F%2Fwww.usm.maine.edu%2Fplanet&sa=D&sntz=1&usg=AFQjCNHulkHuLP13bOG2PkNrPazsGWFs2A>
70 Falmouth Street   Portland, Maine 04103
43.6667° N                   70.2667° W
Altitude:  10 feet below sea level
Founded January 1970
Julian Date: 24591137.16
2020-2021:  XXX


THE DAILY ASTRONOMER
Wednesday, October 14, 2020
Remote Planetarium 108:  General Relativity IV:  Gravitational Red-Shifting

Today's lesson focuses on the way that gravity affects light.    To
understand these effects, we should first quickly review some of what we
already know about light.  Every light photon, be it gamma ray or radio
wave, travels at light speed.    If photons lose energy, they will not slow
down.  Instead, their frequency will decrease.      In the visible light
band -a minute part of the EM spectrum- the colors are separated into
violet, indigo, blue, green, yellow, orange and red.  The energy level
decreases from the high energy violet toward the low energy red.

[image: wavelength-nm.jpg]
The "visible spectrum."  This band includes all the light we can directly
observe.  The wavelengths are measured in nanometers, which equals one
billionth of a meter.

A photon of light must expend energy whenever it moves away from a
gravitational field.      As the light cannot slow down, its energy level
or its frequency must decrease.       The decreased frequency results in an
increased wavelength.  The light is "red-shifted," meaning that its energy
is reduced, not that it is necessarily turning red.

[image: Gravitational_red-shifting2.png]
In this highly exaggerated diagram, blue light loses energy as it moves
away from a highly massive body.  As a consequence, the light's frequency
is decreased and shifted toward the red end of the spectrum.

Though gravitational redshifting is a real phenomenon, and has been
confirmed, the actual shifting amount is quite small in most situations.
For instance, imagine a white dwarf star such as Sirius B.*  This small,
dense body is 100,000 times more gravitationally powerful than the Sun.
 However, the photons leaving its surface would be red-shifted by less than
one part in 30,000.   A meager shifting.

The gravitational red-shifting from the surface of a neutron star or around
a black hole will tend to be much greater.

[image: main-qimg-8592cf282e48bf83bd1026f89ffee3d6.webp]

When a light source is too close to a black hole, the light is infinitely
red-shifted, meaning that it cannot escape from the black hole's
gravitational pull.    For this reason, the region is "black," or devoid of
light.

If a light beam approaches a massive body, it will experience a "blue
shift," or an energy increase.   This increase will prove negligible around
most massive bodies.  Around a black hole, the light will be infinitely
blue shifted and will be similarly trapped within the event horizon.

Yesterday, we learned how Eddington proved that light bends around a star,
  Surprisingly, light will also lose energy around one.

Tomorrow, more surprises!

*Remember that a white dwarf star is not a star, but is, instead, a stellar
remnant left behind after a solar mass star perishes as a planetary nebula.

To subscribe or unsubscribe from the Daily Astronomer:
https://lists.maine.edu/cgi-bin/wa?SUBED1=DAILY-ASTRONOMER&A=
<https://lists.maine.edu/cgi-bin/wa?SUBED1=DAILY-ASTRONOMER&A=1>