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eridanus-river

Eridanus is a large constellation which has been known since ancient times.   The constellation begins in the north (near Orion’s left foot) then winds south across the sky before snaking west towards Cetus the sea monster.  The river of stars which makes up Erdanus then doubles back east and eventually ends far to the south at the border with Hydrus, the water snake.  Because of its antiquity, there is some dispute as to where the name Eridanus came from:  second-century Greek astronomers believed the name indicated the sacred (mythical) river which Phaeton plummeted into after his unhappy attempt to drive the chariot of the sun.   Other etymologists, however, think that the name originated in ancient Mesopotamia where “the star of Eridu” was sacred to the primeval god Enki, lord of the abzu, a mythical abyss filled with all the fresh water in the world.  Eridu was the first known city of Earth, so the name may go back to the origin of civilization.

Enki in his watery home, the Abzu

Enki in his watery home, the Abzu

Whatever the origins of the name are, the constellation is the site of one of the strangest and most controversial objects in the heavens.  In 2007, astronomers using radio telescopes to survey the universe were astonished to discover nothing.  More specifically they discovered an immense and disconcerting amount of nothing—an enormous void in space time more than a billion light-years in diameter.  The Eridanus supervoid lies between six to 10 billion light-years away and its existence seems to be at odds with current cosmological models.

The Eridanus Supervoid (from an article by Bert Stevens)

The Eridanus Supervoid (from an article by Bert Stevens)

Cosmologists have several schools of thought concerning how the supervoid came into being and what its real nature is.  Because I am having trouble understanding any of these crazy theories, I have provided a rudimentary metaphor for each in blue (which would probably offend cosmologists, if they were reading my blog).

1)      Supporters of the standard model Big Bang theory say the region is colder because of dark energy, a hypothetical form of energy believed to permeate all of space.  If it exists, dark energy uniformly fills otherwise empty space yet interacts with none of the known forces in the universe (save gravity). The void is not empty but is filled with dark energy–which we do not yet understand: just like an empty room would seem empty to the Babylonians (despite being filled with air to us).

2)      A contrary theory proposes that the known universe orbits a supermassive black hole (in the same fashion that galaxies spiral around central black holes). This explanation would explain the “accelerating/expanding” universe as a sort of illusion: objects on the edge of the universe would be orbiting at a greater velocity than objects close to the black hole—a phenomenon which would affect their red shift relative to us.  Of course anything that got too close to the black hole in the void would be swallowed to an unknown doom into a black hole with the mass of another universe.  The universe is like an old vinyl record being spun around by a black hole in the center which is enormous beyond comprehension.  The expansion of the universe is an illusion caused by our limited perspective in such a scenario.   

3)      Laura Mersini-Houghton, a cosmologist who theorizes about the multiverse, believes that the supervoid is the imprint of another universe beyond our own.  Quantum entanglement has allowed us to see a shadow of this parallel universe in the form of the great empty spot located in Eridanus.  ??? Um, there are other universes out there which interact with our own in unknown ways which cause big holes (or maybe windows).

4)      Conservative astronomers speculate that the empty spot is an anomaly of the cosmic texture of the early universe.  Phase transition after the big bang resulted in heterogeneous distribution of matter. The universe is like a loaf of bread—sometimes it just has big holes in it because of the way it came into being.  

5)      The radiometric finding method by which the void was discovered is flawed.  The area only seems anomalously “cold” (in terms of EM emissions) because of a relatively hot ring of emissions surrounding it. The void doesn’t exist.  It was a mistake in observation.

6)      Something else entirely which we don’t yet comprehend and haven’t even imagined. Something else entirely which we don’t yet comprehend and haven’t even imagined.

I’ll be honest here.  Since I don’t have a radio telescope array or a degree in theoretical physics, these ideas are pretty hard to assay.  They are also wildly divergent.  I am therefore going to evaluate them aesthetically/emotionally (i.e. uselessly) in the following manner.  The first idea has the support of the astrophysics community, but is unsatisfactory until we have a more-than-theoretical understanding of dark energy (which could be forthcoming because of our discovery of the Higgs Bosun).  The second idea seems like it could be tested with mathematical modeling and astronomical observation (which so far seem to indicate there is no giant black hole in the middle of everything).  The third idea seems insane—and yet I have always intuitively felt that there are universes beyond this one (I’m sorry to be so guilty of such magical/hopeful thinking).  The fourth and fifth ideas seem quite plausible because they are boring (although why is the universe leavened like bread? Or why does it contain large relatively hot rings?).  The sixth idea is always applicable to everything.

Horses and Birds (M. C. Escher, 1949, wood engraving)

Horses and Birds (M. C. Escher, 1949, wood engraving)

Of course all this speculation may all be moot:  a more recent survey of the southern sky from a radio telescope in Australia suggests that there might be a much larger 3.5 billion light-year-wide void in the known universe.  That would certainly steer us back toward more conservative models of the universe, while at the same time leaving us with yet more questions.

In the impact crater of a giant meteor, an unknown ancient race built the largest snake effigy on the planet… Is this the beginning of a lurid sci-fi fantasy novel? No, it’s the description of an actual place.  This haunting structure which was built for unknown reasons by a mystery race can be found in deepest…um…Ohio!

The Great Serpent Mound is an ancient earthwork located in Adams County, Ohio.  Shaped like a snake devouring an egg, the mound is 410 meters (1,330 feet long) and a meter tall (3 feet).  The undulating form of the snake has been tied to astronomical phenomena but it is unclear why it was built or what purposes (if any) it served. It reminds me somewhat of the Rainbow Serpent, Wadjet, Nüwa, and other snake deities, but since there is no historical or ethnological record of its purpose, such connections are only airy speculation.

Possible Astronomical Significance of the Great Serpent Mound

An even greater mystery of the structure is who built it. Over the years scholars and archaeologists have variously posited that it was created by the Adena culture (1000 to 200 BC), or by tribes from the Hopewell tradition (200 BC to 500 AD), or by the Fort Ancient culture (1000 AD-1750 AD).  Of course the mound was known long before its “discovery” by European settlers. Unfortunately, the Native Americans of the region seemed just as confused about its provenance as anyone. For what it is worth, Native Americans of the Lenni Lenape (later Delaware) nation told missionaries that the mound was built by the Allegheny or Allegewi People, (who were also sometimes called the Tallegewi), a possibly mythical progenitor race who lived in the Ohio Valley in ancient times before 1200 BC.

The Great Serpent Mound from the Air

It is obvious that a date is thoroughly confused when it varies by as much as 3,000 years! Fortunately there are a few pieces of actual evidence associated with the mound. Adena graves were found and excavated near the Serpent Mound (Adena people were culturally and physically distinct from other peoples of the Ohio valley). Other Adena sites have revealed that these peoples built elaborate circular and winding earthworks and had a fascination with astronomical phenomena. The few pieces of Aedena art even seem to bear an aesthetic connection.

A Serpent Carved from Micah by the Adena or Hopewell

Frustratingly, carbon dating of charcoal taken from within the mound seems to indicate that it was built (or at least refurbished) long after the Adena culture declined and vanished. Conducted in the nineteen nineties, these tests indicated that parts (or all) of the Serpent Mound was built around 1070 AD.  The mound would thus have been made by people of the Fort Ancient Culture–but the Fort Ancient people do not seem to have evinced the same artistic and cosmological sensibilities as are reflected in the mound.  Additionally the mound was uncharacteristic of Fort Ancient culture in its lack of buried valuables.

A painting of Fort Ancient Civilization

Charcoal fragments are easily displaced by bioturbation and burrowing animals, so the carbon dating stands in question. The Fort Ancient people are known to have had contact with the intense pyramid building, city-dwelling (serpent worshipping) Mississippian cultures which were flourishing from Illinois down to the Gulf of Mexico. Perhaps outside cultural influences lead to the mound’s construction. Furthermore the Fort Ancient people got their name from the fact that they lived on huge earthworks built by the vanished Hopewell people (who are also potential builders of the Great Serpent Mound). Perhaps the Fort Ancient tribes also renovated and re-purposed the Great Serpent Mound from older Adena or Hopewell builders.  We simply are not certain about who crafted the Great Serpent Mound–but it is to be hoped that further evidence will clarify the issue.

By now space enthusiast readers are probably chaffing at all of this human history: in the first paragraph I mentioned that the Great Serpent Mound is located in a meteor impact crater. Waymarking.com relates how the crater was discovered by scholars studying the Great Serpent Mound:

After the mound was discovered it was noticed that the geology of the surrounding area differed greatly from that found elsewhere in Ohio. John Locke, who explored the area in the 1830’s noted that “a region of no small extent had sunk down several hundred feet, producing faults, dislocations and upturnings of the layers of the rocks.” At the time he thought the he had discovered a “sunken mountain.” Some of the areas look like they have slid straight down while others have risen almost 1,000 feet straight up. Over time more evidence has been found. Eventually in the 1970’s, core samples were taken from the crater area. Scientists have found iridium at levels up to 10 times that normally found in the Earth’s crust, soot from what may be scorched limestone, deformed grains of sand, and quartz with microscopic fractures. In addition “shatter cones” have been found from the surface down similar to those found in Nevada at nuclear weapon test sites.  

Such features are the smoking gun evidence of meteor strikes and scientists have since concluded that the crater is about 250 million years old (which was approximately the same era the Paleozoic came to an end). Over a quarter of a billion years the crater has deformed greatly, to such an extent that it is not immediately recognizable (unlike more contemporary strike sites such as Lake Lonar).

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