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The Ouroboros (APOD 28 Jul 2008)

Posted: Mon Jul 28, 2008 2:32 pm
by neufer
http://apod.nasa.gov/apod/ap080728.html

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http://en.wikipedia.org/wiki/Ouroboros

<<The Ouroboros, also spelled Ourorboros, Oroborus, Uroboros or Uroborus, is an ancient symbol depicting a serpent or dragon swallowing its own tail and forming a circle. It has been used to represent many things over the ages, but it most generally symbolizes ideas of cyclicality, unity, or infinity. The ouroboros has been important in religious and mythological symbolism, but has also been frequently used in alchemical illustrations. The name ouroboros (or, in Latinized form, uroborus) is Greek ουροβóρος, "tail-devourer". The depiction of the serpent is believed to have been inspired by the Milky Way, as some ancient texts refer to a serpent of light residing in the heavens
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Plato described a self-eating, circular being as the first living thing in the universe — an immortal, perfectly constructed animal.

"The living being had no need of eyes when there was nothing remaining outside him to be seen; nor of ears when there was nothing to be heard; and there was no surrounding atmosphere to be breathed; nor would there have been any use of organs by the help of which he might receive his food or get rid of what he had already digested, since there was nothing which went from him or came into him: for there was nothing beside him. Of design he was created thus, his own waste providing his own food, and all that he did or suffered taking place in and by himself. For the Creator conceived that a being which was self-sufficient would be far more excellent than one which lacked anything; and, as he had no need to take anything or defend himself against any one, the Creator did not think it necessary to bestow upon him hands: nor had he any need of feet, nor of the whole apparatus of walking; but the movement suited to his spherical form was assigned to him, being of all the seven that which is most appropriate to mind and intelligence; and he was made to move in the same manner and on the same spot, within his own limits revolving in a circle. All the other six motions were taken away from him, and he was made not to partake of their deviations. And as this circular movement required no feet, the universe was created without legs and without feet."
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In some representations the serpent is shown as half light and half dark, echoing symbols such as the Taijitu, which illustrates the dual nature of all things, but more importantly, that these opposites are not in conflict. In alchemy, the ouroboros symbolises the circular nature of the alchemist's opus, which unites the opposites: the conscious and unconscious mind. It is also often associated with Gnosticism, and Hermeticism.

The Ouroboros often represents self-reflexivity or cyclicality, especially in the sense of something constantly re-creating itself, the eternal return, and other things perceived as cycles that begin anew as soon as they end (See Phoenix (mythology)). It can also represent the idea of primordial unity. The Jungian psychologist Erich Neumann writes of it as a representation of the pre-ego "dawn state", depicting the undifferentiated infancy experience of both mankind and the individual child.[2]

The ouroboros has several meanings interwoven into it. Foremost is the symbolism of the serpent biting, devouring, eating its own tail. This symbolises the cyclic Nature of the Universe: creation out of destruction, Life out of Death. The ouroboros eats its own tail to sustain its life, in an eternal cycle of renewal.

The Ouroboros could very well be used to symbolize the closed-system model of the universe of some physicists. The organic chemist August Kekulé claimed that a ring in the shape of Ouroboros that he saw in a dream inspired him in his discovery of the structure of benzene. As noted by Carl Jung, this might be an instance of cryptomnesia.
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. Historical representations

The Ouroboros is one of the oldest mystical symbols in the world. The serpent or dragon appears in Aztec, Middle East, and Native American mythologies, among others. "Coiled dragon" forms have been attributed to the Hongshan culture (4700 BC to 2900 BC). One in particular, in the shape of a complete circle, was found on the chest of the deceased.The notion of a serpent or dragon eating its own tail can be traced back to Ancient Egypt, circa 1600 BC. From ancient Egypt it passed to Phoenicia and then to the Greek philosophers, who gave it the name Ouroboros ("tail-devourer").

. Norse mythology

In Norse mythology, it appears as the serpent Jörmungandr, one of the three children of Loki and Angrboda, who grew so large that it could encircle the world and grasp its tail in its teeth. In the legends of Ragnar Lodbrok, such as Ragnarssona þáttr, the Geatish king Herraud gives a small lindorm as a gift to his daughter Þóra Town-Hart after which it grows into a large serpent which encircles the girl's bower and bites itself in the tail. The serpent is slain by Ragnar Lodbrok who marries Þóra. Ragnar later has a son with another woman named Kráka and this son is born with the image of a white snake in one eye. This snake encircled the iris and bit itself in the tail, and the son was named Sigurd Snake-in-the-Eye.
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. Hinduism

It is also present in some Hindu folk-myths, as a snake ( Adisesha) circling the tortoise Maha kurma that supports the eight elephants which support the world on their backs. However,the snake does not bite its own tail as usually thought, but instead is calling itself into being through, what some literary theorists have called a performative speech act, its telling of the tale of its tail, rendering the propriety of its inclusion in this article questionable.>>
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Re: The Ouroboros (APOD 28 Jul 2008)

Posted: Mon Jul 28, 2008 4:58 pm
by Case
neufer wrote:Ouroboros
Although I must have seen the symbol earlier, I remember looking up ouroboros when the tv series Millennium aired, as it had the symbol in the opening credits.

OBapod: Maybe it's my imagination, but the computer reconstructed image of the blue background galaxy looks like three galaxies close together...

Re: The Ouroboros (APOD 28 Jul 2008)

Posted: Mon Jul 28, 2008 5:58 pm
by apodman
Case wrote:image of the blue background galaxy looks like three galaxies
It doesn't look much like a single galaxy to me.

I think the projection by the gravitational lens is not one-to-one with regard to what configuration of matter can produce the image we see. I think there are many configurations of matter that can produce a like image. And that's if the mass of the foreground galaxy is known - if not, we have a variable to deal with.

So I think the reconstruction method has to make some assumptions and choices, and maybe that's why the result looks the way it does.

Posted: Tue Jul 29, 2008 5:43 pm
by emc

Re: The Ouroboros (APOD 28 Jul 2008)

Posted: Tue Jul 29, 2008 9:00 pm
by henk21cm
Dag Kees,
Case wrote:Maybe it's my imagination, but the computer reconstructed image of the blue background galaxy looks like three galaxies close together...
Yes, it looks like three spiral images. Is it real or an artefact of the image reconstruction? If you look closer at the the SLACK collection, most of the foreground galaxies look quite elliptical or nearly spherical. Nevertheless part of the fainter regions of the foreground galaxy is blurred or outradiated by the background galaxy. Allthough i can not prove it, it seems that the colours are not real. In all images the background galaxy is blue, although the redshift is quite large: ranging from z=0.4 to z=1. The number of realy blue galaxies featuring here at APOD, is rather limited. The great galaxy in Can. Ven. is one i know. So my suggestion is that the redshift is used to identify foreground and background.

apodman questions the validity of the gravitational reconstruction. Assumptions must have been made. If you would have to tackle such a problem, you should start with a spherical symmetric foreground galaxy. Judging the fraction of the full perimeter of the foreground galaxy, one can make an assumption for the alignment of both galaxies. From the expected luminosity and the distance (redshift) the mass can be estimated. Then, with the deformation of space around the fore ground galaxy, you can track down each possible ray of light (or pixel) and reconstruct its origin. The latter part: deformation of space, is still an object of further study for me, although a little out of reach of my ability to comprehend physics.

My question is: are those three seemingly spiral galaxies the net result of an optimalization sequence of did Slack stop when the most obvious facts -like mass, shape and alignment- were used?

Posted: Wed Jul 30, 2008 4:41 pm
by emc
Astronomers ability to measure and differentiate these lensed and lensing objects is amazing. The caption under the subject Hubble image states the background objects are enhanced in blue. I suspect this enhancement is a computer algorithm.

It would be marvelous to be able to understand the parameters that are used to make the foreground and background distinction. I am blown away by the details that astronomers and engineers are able to extract from tiny points of light.

Re: The Ouroboros (APOD 28 Jul 2008)

Posted: Thu Jul 31, 2008 8:50 am
by neufer
Case wrote:OBapod: Maybe it's my imagination, but the computer reconstructed image of the blue background galaxy looks like three galaxies close together...
What do you make of NGC 5216 then?