Ceyx and Alcyone: Dangerous terms of endearment.
The mythological Lucifer was nothing like the Lucifer with which most of us are familiar. Lucifer, whose name means "light bringer," was the son of Aurora, the dawn goddess and her lover Cephalus. Lucifer matured into the radiantly beautiful young man who often shone like a brilliant star* against his mother's ethereal light. Having been known as a demi-god who rarely strayed away from his adoring mother, Lucifer figured little in the mythological sagas. He is perhaps best known for having sired Ceyx, one half of the ill-fated couple Ceyx and Alcyone. Alcyone was the eldest daughter of Aeolous, the king of the high winds. One day as she was gliding along an early morning ocean gust, Alcyone caught sight of Ceyx, who was running along the east in full view of his adoring father. Alcyone had never before seen such a lovely young man. (He was nearly as radiant as Lucifer.) When Ceyx caught sight of her, he, too, was so enraptured that he stopped running and remained still merely to admire her. Without speaking a word, Ceyx and Alcyone approached one another and embraced. Within an instant, they fell passionately in love. Theirs was the unusual type of love that intensified with time instead of diminishing. Neither Lucifer nor Aeolous voiced any objection to the union. If they had had any misgivings, they decided it would have been pointless to have expressed them as Ceyx and Alcyone seemed to have one soul between them and could not be parted from one another.
Ceyx and Alcyone were soon married and lived happily together in Trachis, a region in Greece south of the River Spercheios. Keenly aware of both their exalted status and blissful marriage, they chose the loftiest terms of endearment possible. Alcyone often referred to Ceyx as "Zeus," and Ceyx, in turn, called Alcyone "Hera." When they came to learn of this practice, the real Zeus and Hera were incensed. (The other gods secretly thought it amusing that such a loving couple could have compared themselves to Zeus and Hera, whose marriage was -to be charitable- disastrous.) Zeus resolved to punish them both for their impertinence. For many nights, Ceyx dreamt of frightful monsters who had emerged from a chasm and devoured Alcyone. These night visions inspired such horror in him that Ceyx decided to travel to Delphi to consult the famous oracle. When Ceyx spoke to Alcyone of his intentions, she was terrified, for the journey would require sea travel, which most dreaded, "Let me accompany you, dearest husband," she pleaded. "I shan't be gone for long," Ceyx assured her, perplexed by her earnestness. "I need to seek out the oracle, something I need to do alone." Despite Alcyone's persistence and his own deep desire to have her accompany him, Ceyx did not relent. He felt that the trip might prove perilous and he did not want to jeopardize Alcyone.
Ceyx and Alcyone passed a sleepless night prior to Ceyx's departure. They were miserable at the prospect of being apart even for a brief time and spent the night locked in each other's arms. The next morning as Ceyx prepared to embark on the ship, he told Alcyone that he would return soon and, in the interim, would often visit her in her dreams. Alcyone begged one last time to accompany Ceyx,, but he refused to permit her to do so. Ceyx boarded the ship without another word. Soon after, the ship was making great progress due, in large part, to Aeolous' favorable winds. However, one evening a blinding lightning bolt ripped through the sky and struck the ship. The ship's crew panicked as they watched their vessel catch fire and rapidly sink. Ceyx, alone, remained calm. He yielded to death with stoic resignation, gladdened that Alcyone was safe at home, far away from danger. He uttered her name silently as the waves engulfed him.
To Alcyone, every day that elapsed without Ceyx passed as slowly as a year. She eagerly awaited each night, for she hoped to see her husband in her dreams. Yet, she never did. Her sleep was both disturbed and dreamless. Each morning she awoke and prayed to Hera, her matron goddess, to protect her husband and, in time, conduct him safely back to their home. Though like her husband, Hera, too, was displeased at the way Ceyx and Alcyone used their names, she was finally moved to pity. Ceyx had been dead for many days and Hera thought it time to inform his widow of what had transpired. She instructed Iris, the goddess the rainbows, to travel to the dark realm of Somnos, the god of sleep. Iris was to ask Somnos to tell his son, Morpheus, the god of dreams, to inform Alcyone of Ceyx's passing. That night, as Alcyone slept, Morpheus visited her disguised as Ceyx. Alcyone screamed at the sight of her husband covered in ocean water and seaweed. "I am dead, Alcyone," the dream Ceyx told her solemnly. "I perished many nights ago and even now my body floats along the sea surface. Weep for me so that I shall not pass into the underworld unmourned," As Ceyx reached out to touch her hand, Alcyone awoke. Though the sky was still dark, she rushed down to the same point along the sea shore where she had watched her husband depart. She sat there looking forlornly at the ocean water hoping in deepest earnest that Ceyx was still alive. Soon after the sun rose, she saw something floating on the water toward her. When the object came close to the shore, she saw that it was Ceyx's body. She wailed with grief and decided to dive into the ocean and end her life. However, before she touched the sea surface, her body was transformed into a kingfisher. Instead of swimming, she was gliding along the ocean surface. To her delight, she realized that Ceyx, as well, had also undergone a similar metamorphosis.
The two Kingfishers then ascended high in the air. They spent the day playfully chasing each other and calling to one another in a secret language only they could understand. Each year these Kingfishers conceived a brood of hatchlings over which Alycone maintained a constant vigilance for seven days around the winter solstice. During this week, all the water-disturbing winds subsided at the behest of Alcyone's father. The turbulent ocean was replaced by a sedate sea and for those seven days it seemed as though the entire world lay unperturbed. The hatching eggs would then shatter the tranquility, putting an end to that serene period around the solstice named for Alcyone and popularly known as the "halcyon days."
*The planet Venus
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THE DAILY ASTRONOMER
Monday, November 16, 2020
Remote Planetarium 124: Dark Energy I
We begin today with an extraordinary premise: the Universe expands. This expansion started just after the cosmic inception, approximately 13.8 billion years ago. Humanity has known of this expansion for less than a century. Prior to this time, we perceived the cosmos as either being stagnant or eternal without any beginning at all. Now, cosmologists widely accept that the Universe began in a single event -the Big Bang- and has been growing ever since.
The question then becomes, what is the Universe's fate? Will the expansion slow down and stop? Will the expansion slow down, stop and then reverse to cause a Big Crunch, the implosion of everything? Or, will the expansion literally continue forever? The answer to that question once seemed to depend solely on the material within the cosmos. Did the Universe contain enough matter to retard the expansion through gravitational breaking? Would this deceleration then cause the Universe to either stop (a flat Universe) or reverse course (a closed Universe)? Or, was it insufficient and the Universal expansion would persist indefinitely (an open Universe.) The entire issue was predicated on the assumption that the expansion rate would decrease with time. Cosmologists tried to ascertain if the Universe's density was less than, equal to, or greater than the critical density.
The three "fates." Once astronomers realized that the Universe was expanding, the only question remaining pertained to its fate. Would the expansion stop and precipitate a collapse? Would the expansion stop and cause the Universe to become static? Or, would the Universe continue to expand forever. The answer to that question was once believed to be related solely to Universe's material density: was the density sufficient to halt the expansion? With the inclusion of dark energy, we know now that the issue is far more complicated.
In the late 20th century, this fundamental cosmological question became far more complicated. A 1998 Survey conducted by two astronomical teams* showed that Type Ia supernovae which exploded when the Universe was about 9.2 billion years old (2/3 its current age) were much fainter than they should have been. The only conclusion to be drawn from this observation is that they had to be much farther away. Type Ia Supernovae occur when a white dwarf star draws so much material away from a larger companion that it exceeds its C-limit and explodes. (See the caption under the next graphic for more information.) Any Type Ia Supernova should be as bright as any other, which makes such supernovae useful to astronomers for distance determination. If one knows the object's intrinsic brightness, its distance can be readily determined by measuring its apparent brightness.
Type Ia Supernovae occur when a white dwarf strips material away from a much more massive companion. If it collects enough material, the whitre dwarf will explode to create a Type Ia Supernovae. To understand why this explosion occurs, we must first examine a white dwarf. A white dwarf is a dense remnant created when a low-mass star exhausts its core fuel reserves. It casts off its outer layers as a planetary nebula and leaves behind a highly dense white dwarf core. Despite the lack of internal energy pressure, this white dwarf doesn't collapse because of electron degeneracy: the electrons within it prevent further collapse due, in part, to electrostatic repulsion. (The electrons resist each other due to their like charges.) This electron degeneracy will withstand the white dwarf's gravitational compression provided the remnant's mass doesn't exceed the Chandrasekhar limit, equal to about 1.44 solar masses. (1.44 times more massive than the Sun.) If the white dwarf's tidal forces draw enough material onto it so that its mass exceeds the Chandrasekhar limit, it will collapse and explode as a Type Ia Supernova.
They concluded that the Universal expansion was accelerating, not decreasing, with time. The teams also realized that the expansion had decelerated for the first eight billion years after the Big Bang. Then, inexplicably, the acceleration started and still continues. The term applied to the force responsible for this phenomenon was called dark energy. Unlike "dark matter," in which the dark refers to a lack of light emission, the "dark" in dark energy refers to our ignorance of it. Scientists know very little about this mysterious force. They don't know how it can cause such an acceleration or if it will even continue.
It has been suggested that dark energy might be related to Albert Einstein's "cosmological constant." We recall that Einstein inserted this constant into his theory of General Relativity in order to counteract the expansion inherent within them. At the time of GR's formulation, Einstein considered the notion of an expanding Universe to be preposterous. He would later refer to the cosmological constant's introduction as the "greatest blunder of my life." Is it possible that this "fudge factor" might be real: that some anti-gravity force is pushing the Universe outward at a much greater velocity?
Though Dark Energy's nature remains unknown, cosmologists estimate that it comprises about 68% of the Universe. Since dark matter is thought to account for 28% of the cosmos, one can conclude that only four percent of the Universe consists of visible, baryonic matter such as stars and galaxies. A sobering return to the ancient days in which most of nature was relegated to the mystical realm.
Tomorrow, we continue this dark energy exploration by learning how scientists might be able to observe it or at least learn more about it.
*These teams included Saul Perlmutter, Adam Riess and Brian Schmidt, all of whom won the 2011 Nobel Prize in Physics for the discovery of the acceleration of the Universal expansion.
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