The Longest Day - Celebrating the Summer Solstice

Summer Solstice at Stonehenge

Since the beginning of mankind people of many cultures regarded the Summer Solstice or the longest day of the year as a major celestial event. This is the day that marks the triumph of light over darkness.

Mesmerized by the great power of the sun, civilizations all over the world have for centuries celebrated the first day of summer otherwise known as the Summer Solstice, Midsummer, the Saint John's Night, or Litha. The Chinese honored the Goddess of Light Li. The Slavs and the Celts celebrated the longest day of the year with dances and bonfires. 

Saint John's Night celebration in Poland

In Poland the Saint John's Night is celebrated as a magical feast of purification and fertility. Celebrations are rooted in ancient pagan rituals that honored the mystery of water and fire. To this day people all over the country dance and sing around bonfires until midnight. They make wreaths out of wild flowers and herbs and let them float on water after attaching candles to them. Young lovers set out in search of the magical fern flower that only blooms once a year during the Summer Solstice. The flower is supposed to bring great fortune to those who find it.

In England hundreds of people from all over the world typically gather at Stonehenge, the ancient megalithic circle in Wiltshire, to see the sun rise. The Heel Stone and the Slaughter Stone, set outside the main circle, align with the rising sun giving an incredible spectacle of light that affects people in the same way as it did thousands of years ago when the stone circle was first erected there.  

By Dominique Allmon

Image credit here and here

Timeless Universe

 The Frosty Leo Nebula

The underlying state of the universe is timeless. Before the first nanosecond of the Big Bang, there was only the potential for time in a dimension of all possibilities, after which quantum objects (energy, spin, charge, gravity), emerged. A potential doesn’t have a life span. It encompasses past, present, and future. The ground state of physics turns out to resemble the zero state of samadhi.

Once these timeless possibilities begin to collapse into space-time events, our connection to eternity seems lost. That is an illusion, though, fostered by our dependence on clock time. You have always been eternal; you still are. - Deepak Chopra in "War of the Worldviews: Science Vs. Spirituality"

Three thousand light-years from Earth lies the strange protoplanetary nebula IRAS 09371+1212, nicknamed the Frosty Leo Nebula. Despite their name, protoplanetary nebulae have nothing to do with planets: they are formed from material shed from their aging central star. The Frosty Leo Nebula has acquired its curious name as it has been found to be rich in water in the form of ice grains, and because it lies in the constellation of Leo.

This nebula is particularly noteworthy because it has formed far from the galactic plane, away from interstellar clouds that may block our view. The intricate shape comprises a spherical halo, a disc around the central star, lobes and gigantic loops. This complex structure strongly suggests that the formation processes are complex and it has been suggested that there could be a second star, currently unseen, contributing to the shaping of the nebula.

Protoplanetary nebulae like the Frosty Leo Nebula have brief lifespans by astronomical standards and are precursors to the planetary nebula phase, in which radiation from the star will make the nebula’s gas light up brightly. Their rarity makes studying them a priority for astronomers who seek to understand better the evolution of stars.

Image and description source here

Keep Looking Up

There is a fundamental reason why we look at the sky with wonder and longing - for the same reason that we stand, hour after hour, gazing at the distant swell of the open ocean. There is something like an ancient wisdom, encoded and tucked away in our DNA, that knows its point of origin as surely as a salmon knows its creek. Intellectually, we may not want to return there, but the genes know, and long for their origins - their home in the salty depths. But if the seas are our immediate source, the penultimate source is certainly the heavens… The spectacular truth is - and this is something that your DNA has known all along - the very atoms of your body - the iron, calcium, phosphorus, carbon, nitrogen, oxygen, and on and on - were initially forged in long-dead stars. This is why, when you stand outside under a moonless, country sky, you feel some ineffable tugging at your innards. We are star stuff. Keep looking up. - Jerry Waxman

Winter Solstice - The Shortest Day

Prehistoric Hohokam sun observation shrine in South Mountain Park,
Phoenix, Arizona

The winter solstice occurs exactly when the Earth's axial tilt is farthest away from the sun at its maximum of 23° 26'. Though the winter solstice lasts only a moment in time, the term is also a turning point to midwinter or the first day of winter to refer to the day on which it occurs. More evident to those in high latitudes, this occurs on the shortest day, and longest night, and the sun's daily maximum position in the sky is the lowest. 

The seasonal significance of the winter solstice is in the reversal of the gradual lengthening of nights and shortening of days. Depending on the shift of the calendar, the winter solstice occurs on December 21 or 22 each year in the Northern Hemisphere, and June 20 or 21 in the Southern Hemisphere.

Worldwide, interpretation of the event has varied from culture to culture, but most cultures have held a recognition of rebirth, involving holidays, festivals, gatherings, rituals or other celebrations around that time.
 

Decoding Andromeda

 Andromeda spiral galaxy

Andromeda Offers Clues Into the Formation of Galaxies Including Our Own 

By Michio Kaku

Astrophysicists know quite a bit about the life history of stars. In particular, they can be simulated by computer programs, since stars are basically gigantic hydrogen bombs and we know quite a bit about nuclear physics.

But astrophysicists, by contrast, know very little about the life history of galaxies since it is so difficult, even with our supercomputers, to calculate the motions and evolution of hundreds of billions of stars all at once. There is considerable uncertainty about how galaxies first formed and how they evolve. Ironically, the Milky Way galaxy comes out every night, clearly visible as a gigantic swath of light cutting across the entire night sky, but physicists are clueless about the precise way in which it formed and evolved.

One interesting piece of data, however, has come from analyzing our nearest galactic neighbor, Andromeda. The results of a five-year study of a very thick disc of older stars within the Andromeda Galaxy has yielded results that will essentially give us a greater understanding of how these galaxies form. The Andromeda Galaxy has often been referred to as Messier 31, M31 and even NGC 224 and is in fact the nearest spiral galaxy to our own at a distance of 2.5 million light years away or 1.46962495 x 10^19 miles. Last year, a team of astronomers reported that Andromeda was formed out of the collision of two smaller galaxies between 5 and 9 billion years ago. We now know that galaxies often collide and in fact cannibalize or devour smaller galaxies. It is believed, for example, that our own Milky Way galaxy will eventually collide and merge with the larger Andromeda galaxy billions of years from now, eventually creating a gigantic elliptical galaxy from the collision.

The Andromeda galaxy however is not alone and in fact is a member of the Local Group which is a group of more than 30 galaxies including the Milky Way and is about 10 million light years in diameter. It's estimated that over half (approximately 70%) of the total stars within the Andromeda Galaxy currently reside within the stellar disc. The stellar disc of Andromeda is relatively flat and surrounding the central bulge of the galaxy which is comprised of much older stars that formed billions of years ago. The generalized formation of these discs have in a sense been a mystery and otherwise not well understood even though we understand the composition and evolution of the galaxy itself.

Today, a team of astronomers utilizing the Keck Observatory in Hawaii have for the first time observed a thick disc in Andromeda. This is actually quite interesting because the findings and results will now give us a sneak peek into all of the processes in the overall formation of these types of galaxies including our own. According to the team, they "analyzed the velocities of individual bright starts within the galaxy and were able to observe a group of stars tracing a thick disc — distinct from those comprising the galaxy’s already-known thin disc - and assessed how these stars differ from thin-disc stars in height, width and chemistry." We already know that galaxies such as the Milky Way and Andromeda are composed of both thin and thicker stellar discs with the thicker one consisting of the older stars. Astronomers however were unable to study the thick disc of the Milky Way because we basically had a difficult time seeing it. But, the discovery of the disc within Andromeda will now give us a glimpse into how it and our own Milky Way has evolved into it's present form.

Michelle Collins, a PhD student at Cambridge University's Institute of Astronomy has led the research for this discovery. She recently stated, "The classical thin stellar discs that we typically see in Hubble imaging result from the accretion of gas towards the end of a galaxy’s formation. Thick discs, however, are produced in a much earlier phase of the galaxy’s life, making them ideal tracers of the processes involved in galactic evolution."

My webmaster, Michael Phillips was able to get in touch with Dr. Collins to learn more about the moment that the team made their discovery. Dr. Collins stated: "When we realized we had detected the thick disc in Andromeda we were really excited. Until now, our best chance of understanding the evolution of stellar discs was in the Milky Way, where we can't get a truly panoramic view of the component. So this disc in M31 presents us with a fantastic opportunity to better understand the nature of this structure. This is really important, because this kind of disc probes an earlier epoch of galaxy formation than the classical, thin stellar disc, so understanding it's formation and subsequent evolution will allow us to really get a handle on the way galaxies like the Milky Way and Andromeda have been assembled over cosmic time."

By studying Andromeda, hopefully, they hope to better understand how our own Milky Way galaxy formed about 10 billion years ago.

Article source here
Image source here

Tycho Brahe and Kepler

  Tycho Brahe demonstrating a celestial globe to Emperor Rudolph II by Eduard Ender, 1855

“Now it is quite clear to me that there are no solid spheres in the heavens, and those that have been devised by the authors to save the appearances, exist only in the imagination.” - Tycho Brahe

Tycho Brahe and Johannes Kepler are two colorful characters who made crucial contributions to our understanding of the universe.

Tycho’s observations were accurate enough for Kepler to discover that the planets moved in elliptic orbits, and his other laws, which gave Newton the clues he needed to establish universal law of gravitation.

Tycho built vast instruments to set accurate sights on the stars, and used multiple clocks and timekeepers. 

He achieved his goal of measuring to one minute of arc. This was a tremendous feat before the invention of the telescope. His aim was to confirm his own picture of the universe, which was that the earth was at rest, the sun went around the earth and the planets all went around the sun - an intermediate picture between Ptolemy and Copernicus.

Tycho himself was not a Copernican, but proposed a system in which the Sun orbited the Earth while the other planets orbited the Sun. His system provided a safe position for astronomers who were dissatisfied with older models but were reluctant to accept the Earth's motion. It gained a considerable following after 1616 when Rome decided officially that the heliocentric model was contrary to both philosophy and Scripture, and could be discussed only as a computational convenience that had no connection to fact. Tycho's system also offered a major innovation: while both the geocentric model and the heliocentric model as set forth by Copernicus relied on the idea of transparent rotating crystalline spheres to carry the planets in their orbits, Tycho eliminated the spheres entirely. 

He was aware that a star observed near the horizon appears with a greater altitude than the real one, due to atmospheric refraction, and he worked out tables for the correction of this source of error.To perform the huge number of products needed to produce much of his astronomical data, Tycho relied heavily on the then-new technique of prosthaphaeresis, an algorithm for approximating products based on trigonometric identities that predated logarithms.

Johannes Kepler (1571-1630) believed in Copernicus’ theory. Having been raised in the Greek geometric tradition, he believed God must have had some geometric reason for placing the six planets at the particular distances from the sun that they occupied. He thought of their orbits as being on spheres, one inside the other. 

One day, he suddenly remembered that there were just five perfect Platonic solids, and this gave a reason for there being six planets - the orbit spheres were maybe just such that between two successive ones a perfect solid would just fit. He convinced himself that, given the uncertainties of observation at the time, this picture might be the right one. 

However, that was before Tycho’s results were used. Kepler realized that Tycho’s work could settle the question one way or the other, so he went to work with Tycho in 1600. Tycho died the next year. Kepler stole the data, and worked with it for nine years. 

The death of Tycho Brahe was more than suspicious and some people even consider that Brahe might have been murdered by Kepler. At the age of fifty four, Brahe was considered to be a very healthy person, but one day in October 1601, after attending a banquet, he suddenly fell ill and died within ten days of the event.

For a long time it was normally assumed that Brahe had died either from uremia, or from a burst bladder. But a forensic analysis of his hair that was conducted in the 1990s, shows an elevated amount of mercury in Brahe’s body short before his death. This discovery would rather confirm the old suspicion that Brahe was poisoned. There is a suspicion that Kepler poisoned Brahe. The two man had a very difficult relationship and Kepler was known for his unbecoming personality, but could Kepler really kill Brahe? But who wouldn't kill for knowledge and fame?

Brahe was not only a great astronomer, but like most scientists of his time, a great alchemist although he wasn't really trying to transmute base metals to gold, but rather develop medicines. Some of his potions contained mercury and it is a known fact that he took some of his preparations to cure minor discomforts. The amount of mercury in his medicines, however, was much too small to produce such a surprising forensic result. Brahe simply could not have overdosed. 

The high amount of mercury in the analyzed hair sample actually suggested two separate poisonings: The first, that most probably occurred at the dinner party, where he had suddenly fallen ill. The second, the night before his death, when his condition had seemed to improve at first. A spike in his calcium level a few hours before his death also suggests that the poison was most certainly administered in a glass of milk.

Although Kepler makes a perfect suspect, there is no definite proof that he murdered Brahe. Brahe's death may forever remain a mystery although a new team of scientists under the leadership of Danish archeologist Prof. Jens Vellev certainly hopes to solve it with the help of the modern technology.

Article sources here, here & here 

The Birth of Our Universe

 By Michio Kaku

Up until just a few hundred years ago most people thought that the Universe was a stable, static place that had been here forever and would continue forever. Today we know that nothing could be further from the truth. In reality, we know that the Universe is a violent and continually changing place that was born in a mere nanosecond of time in the spectacular event we call the Big Bang. You may have heard the Big Bang referred to as the mother of all explosions but it wasn’t an explosion so much as an expansion. From a space that was infinitely small, the entire Universe expanded and continues even to this day -13.7 billion years later.

Lots of people wonder how we even arrived at that number and how we originally calculated the age of the Universe in the first place. It started with some educated guesswork and later got refined through some sophisticated technologies. A remarkable astronomer, Edwin Hubble was really one of the very first to make a reliable calculation of the age of the Universe. When Hubble was at Mount Wilson in the 1920’s, astronomers still believed that the Universe was static and not moving. But when Hubble looked at the very distant galaxies through a large new telescope, he began to notice that light was a bit distorted. The yellow galaxies appeared to be slightly redish and he wondered if the color change might be due to something called the Doppler effect. According to Wikipedia, the Doppler effect is commonly heard when a vehicle sound a siren or horn approaches, passes and then recedes from an observer. The same Doppler effect happens with starlight which becomes distorted and changes color. Hubble was then able to estimate the distance to certain stars and soon realized that they were receding and moving away from us. This meant that the Universe wasn’t static at all and was in fact actually expanding and had been for billions of years. Hubble’s work was a monumental discovery and changed everyone’s view on the way they looked at the Universe.

As hard as this is to fathom, at the very beginning, just at the instant of the Big Bang, the entire universe was infinitely smaller than an atom and we call this infinitely tiny point a singularity. This also raises the question of what was going on before the Big Bang. The problem we have is that standard mathematics just don’t apply before the Big Bang. There are of course beautiful animations of what we think may have happened during this bang but the fact is that the explosion took place in a time that is so short that it simply cannot be comprehended. The Universe expanded not into space but as space. In other words, matter did not simply explode but space expanded. It grew from a dot infinitely smaller than an atom to an area billions of light years across in a mere fraction of a second.

The Big Bang expanded as it cooled and as it cooled different kinds of matter began to condense out. For example, atoms began to condense about 300,000 years after the Big Bang. We still have lots of questions and there is still lots to learn but machines like the Large Hadron Collider are bringing us closer than ever before. With every successful experiment - we are closer to understanding the birth of our Universe.  

Article source here

Size Matters: The Key to Cosmic Perspective

The ancient Egyptian god Nun, the great unknowable and indescribable source of all the other gods, was sometimes portrayed associated with a serpent or even as a serpent. 

There is something about the image of a serpent that has led many cultures to associate it symbolically with the creation of the world and the unity of all things, especially when the serpent is represented as swallowing its own tail. In ordinary speech the word “serpent” is sometimes used interchangeably with “snake,” but a snake is an animal, while a serpent is the symbolic, mythic, sometimes dreamlike representation of that animal. Snakes do not actually swallow their tails, but serpents can do anything humans can imagine. Adapting an idea of Sheldon Glashow, 1979 Nobel laureate in physics, we turn to the multi-thousand year-old symbol of the serpent swallowing its tail and give it a modern interpretation. “Uroboros” is the ancient Greek word for a serpent swallowing its tail. We will call the symbol pictured above the “Cosmic Uroboros.” The tip of the cosmic serpent’s tail represents the smallest possible size scale, the Planck length, and its head represents the largest size scale, the size of the cosmic horizon.

The Cosmic Uroboros represents the universe as a continuity of vastly different size scales. As the image above shows, the diameter of the earth is about two orders of magnitude (10-2) smaller than that of the sun. About sixty orders of magnitude separate the very smallest from the very largest size. Traveling clockwise around the serpent from head to tail, we move from the maximum scale we can see, the size of the cosmic horizon (10-28 cm), down to that of a supercluster of galaxies, down to a single galaxy, to the distance from Earth to the Great Nebula in Orion, to the solar system, to the sun, the earth, a mountain, humans, an ant, a single-celled creature such as the E. coli bacterium, a strand of DNA, an atom, a nucleus, the scale of the weak interactions (carried by the W and Z particles), and approaching the tail the extremely small size scales on which physicists hope to find massive dark matter (DM) particles, and on even smaller scales a Grand Unified Theory (GUT) . The tip of the tail represents the smallest possible scale, the Planck length.  Human beings are just about at the center.

Let’s get oriented on the Cosmic Uroboros.  Most of the time we humans are conscious only of things from about the size of ants to the size of mountains. This range of sizes corresponds to the bottom of the Cosmic Uroboros – if it were a clockface, it would fall approximately between 5 o’clock and 6:30, just about the middle. This is humanity’s native region of the universe, our true homeland.  This is the “reality” in which common sense works and normal physical intuition is reliable. It’s not a geographical location: it’s a point of view. We will name this range of size scales “Midgard,” a name for Earth borrowed from the Norse creation myth, the Edda, in which the world of human beings was seen as midway between the land of the giants and the land of the gods. For much the same reason, the ancient Romans named their sea the Mediterranean, literally “middle of the earth.”  We have chosen the name Midgard for our human-scale homeland in the modern universe not because it is between heaven and hell or any other spiritual dualities, but because it is midway between the largest and smallest sizes. This turns out to be the only size that conscious beings like us could be.

Smaller creatures would not have enough atoms to be sufficiently complex, while larger ones would suffer from slow communication – which would mean that they would effectively be communities rather than individuals, like groups of communicating people, or supercomputers made up of many smaller processors.

Different physical forces control events on different size scales. Electrical and magnetic (electromagnetic) forces control what happens from atoms up to mountains, even though gravity also plays a role.  But around the size scale of mountains, gravity starts to gain the upper hand.  The maximum size of mountains is determined by a competition between electromagnetism and gravity. The electromagnetic force is the glue of the chemical bonds that hold together the atoms that mountains are made of, and the strength of the glue is the same everywhere, regardless of the size of the planet.  But the strength of the gravitational force grows with the increasing mass of the planet or of the mountain.  When the mountain becomes big enough, its gravity overcomes the electromagnetic forces that hold mountains together, and the roots of the mountain flow or break, causing earthquakes. The smaller the mass of the planet, the weaker the gravity pulling the mountain down.  Consequently, mountains can be much higher on smaller planets like Mars than they are on Earth. Since the strength of gravity continues to grow with mass, once we reach that part of the Cosmic Uroboros where gravity controls, all larger scales are also controlled by it and all other forces become less important.

Moving counterclockwise from Midgard up into the larger size scales means adjusting our conscious focus, zooming out to encompass vaster regions, where gravity has counteracted the headlong expansion of the universe by collecting matter in those regions that in the early universe happened to be slightly denser than average. Gravity eventually stopped the cosmic expansion in those regions, and gravity has ever afterward shaped and held everything in the region together in a beautiful, dynamic, yet stable structure – a galaxy, in which stars and planets formed and evolution has had time to work its wonders. The largest structures astronomers see are the great sheets of galaxies known as superclusters. In the old Newtonian view, there was no known object larger than a star, and stars were randomly distributed forever. But in the new cosmology not only are there galaxies, each containing hundreds of billions of stars, but there are superclusters of tens of thousands of galaxies, which astronomers have been mapping since the mid 1980's. That, however, appears to be the end of the line. We see no structures larger than superclusters. On scales much bigger than superclusters, the universe becomes increasingly smooth. If each supercluster were a dot, the visible universe would look much the way Newton expected. He was right about the universe being essentially uniform, but on the wrong scale: he thought the stars were scattered more or less evenly, but instead it’s the superclusters.

Moving clockwise now on the Cosmic Uroboros, zooming way inward past Midgard to the very small, we reach the size scales of subatomic particles.  This is the region controlled by what are called the strong and weak interactions. These forces are active only on scales smaller than atoms. Gravity is of no importance at all on these scales. In fact, gravity’s power fades out at the small end of Midgard. It can’t hurt a mouse. You can drop a mouse down a thousand-yard mine shaft and at the bottom, as long as the ground is soft, it will walk away. Gravity plays virtually no role in the life of bacteria, which are at about 7 o’clock on the Cosmic Uroboros. From there until about 12 o’clock, gravity is completely irrelevant.

But then a strange thing happens. As we continue along the Cosmic Uroboros to the very tip of the tail, gravity becomes extremely powerful again. The reason is that gravity’s strength increases as objects get closer to each other, and at the tip of the tail distances between particles are almost unimaginably small. The Cosmic Serpent swallowing its tail represents the possibility that gravity links the largest and the smallest sizes and thereby unifies the universe. This actually happens in superstring theory, a mathematically beautiful idea which is our best hope for a theory that could unify quantum theory and relativity. In string theory, sizes smaller than the Planck length get remapped into sizes larger than the Planck length.

The latest breakthrough in particle physics was the realization in the 1960s and 1970s that the strong and weak forces are closely related to the electromagnetic force. In the very successful “standard model” of particle physics based on this, elementary particles are treated as if they are points with certain properties. But the standard model cannot be the final word on the subject, since it cannot explain why, for example, electrons and other elementary particles have the masses and other properties that they do. So physicists have been trying for several decades to go beyond the standard model.

The very speculative but promising physics of string theory suggests that not just electrons but all elementary particles might just be the ways a single kind of tiny looped string can vibrate, and in that case an electron would be just a way a string vibrates. An identical string vibrating in a different way would be a different particle. Just as only certain shapes of electron clouds are allowed in atoms, only certain sorts of vibration (and thus of particles) are possible.  An electron is a special sort of vibration: it is the lowest mass vibration having the property of electric charge.  String theory has striking mathematical elegance: it might even be true, and it’s so powerful that it might eventually allow physicists to understand the reason for quantities like the masses of elementary particles. However, string theory only works if you assume a world with ten dimensions – one time and nine space dimensions. No one has figured out what string theory implies for the world of one time and three space dimensions that we actually experience – not only with our senses but with our most sensitive scientific instruments.

Consequently, this beautiful theory has not made a single testable prediction yet (except possibly for the existence of supersymmetric particles like the WIMP dark matter particle), so we don’t yet know how to evaluate its claim that particles are “really” vibrating superstrings.

There is a second meaning to tail-swallowing that may seem strange at first. Swallowing may have existed before the serpent.  At the beginning of the Big Bang, if our present understanding of the laws of physics is right, there was nothing but the head of the Cosmic Uroboros with the tip of the tail in its mouth. There was little of the body because there was little difference between the smallest scale and the largest scale.  The smallest scale is fixed by the constants of nature, and the largest scale, the size of the cosmic horizon, was only a little larger than that because the universe was so young and had not yet had time to expand. The body filled in later as the universe expanded and evolved. Thus tail-swallowing may express a fundamental aspect of the evolution of an expanding universe.

The Cosmic Uroboros represents not only a way to structure the universe but also a dream that has been an underlying personal motivation for many scientists. “What I’m really interested in,” Einstein said, “is whether God could have made the world in a different way; that is, whether the necessity of logical simplicity leaves any freedom at all.” This question is still open. The universe could possibly have been organized in many ways and just happened to end up the way we find it. But it is also possible that there was only one way everything could have worked together. The dream of physicists is to find the theory that answers such questions and ties everything together – a “theory of everything.”

The Cosmic Uroboros swallowing its tail thus symbolizes the dream of a theory of everything, which will tie together our understanding of the universe. Through this dream, physicists are expressing a desire perhaps even more ancient than the uroboros symbol: to feel coherent and at home in the wholeness – to experience reality as One.

Even if there is no success in that quest for years to come, the Cosmic Uroboros can help us right now to appreciate our extraordinary place in Midgard. The centrality of Midgard on the Cosmic Uroboros has nothing to do with the units we choose to measure length. Whether measured in centimeters or light years, Midgard would always fall in the middle. Midgard, as we have said, is not a special location in space – it is a special size scale, and it is everywhere in the universe.

As a serpent, the Cosmic Uroboros is much more than a circle, because every point on it is unique.  There is a head and a tail, and therefore every point in between has a relative position. There is a beginning and an end, even though they overlap and are interdependent and inseparable. On a circle, all points are identical. On the Cosmic Uroboros every point has its own meaning. The uroboros has been used to represent the continuity of whatever universe a tribe or people perceived themselves to be living in.

Something about the serpent swallowing its tail has resonated in the human imagination for thousands of years. We humans are not yet able to explain the perennial attraction of this symbol, and it may be deeper than our conscious understanding. The serpent’s exceedingly simple and flexible body has been endlessly twisted and artistically embellished. It has been seen as both goddess-like and evil, fascinating and repulsive, finite and infinite, yin and yang. None of this rich history would have been implicit in a circle. The uroboros symbol as we interpret it here is capable of representing the modern universe at least as completely as it represented the universes our ancestors imagined. The Cosmic Uroboros resurrects an ancient symbol whose possibilities are by no means exhausted. 

From "The View from the Center of the Universe"