Universal Properties and Similarities
Cells and organismsIn an interesting Nature article (*) from August 2003, Paul Nurse concludes that "new approaches are needed to determine the logical and informational processes that underpin cellular behaviour". He writes that "Many of the properties that characterize living organisms are also exhibited by individual cells. These include communication, homeostasis, spatial and temporal organization, reproduction, and adaptation to external stimuli. Biological explanations of these complex phenomena are often based on the logical and informational processes that underpin the mechanisms involved." The similarities between the individual cell and the aggregation or group of cells are interesting. Although the individual cell and the cell-group are quite different, certain properties and features seem to be invariable or invariant.
These invariant properties are some of the basic properties of complex adaptive systems and systems subject to evolution: Adaption, Feedback, Growth, Reproduction & Replication, Specialization & Cooperation,.. Cells communicate with each other as large organisms do. They adapt themselves to the environment and keep the internal conditions constant in a changing environment : Homeostasis is reached by negative feedback control, in organisms and cells. They specialize themselves in different directions like larger organisms, and they reproduce themselves like their larger counterparts. Cells specialize themselves by activation of certain genes and producing certain proteins (which in turn may regulate other genes). According to Kauffman, a cell type corresponds to an attractor in the gene regulatory network. Organisms specialize themselves by activation of certain behaviors and selection of certain actions (which in turn modulate and influence other behaviors). Already Aristotle knew : We are what we repeatly do.
(*) "Understanding cells", Paul Nurse, Nature, Vol. 424 No. 6951 (2003) Page 883
the Nine Planets website. If this is boring, you can look at the milky way. The position of our solar system can be found in this map of the milky way.
Or you can discover the cosmos with the Apod site. From the night side of saturn to the pleiades star cluster, each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer : the Astronomy Picture of the Day website
Moons of Uranus
Did you you know that fifteen of the Moons of Uranus are named after characters in Shakespeare's plays ? Four take their names from The Tempest : Ariel (airy sprite), Caliban (Prospero's slave), Sycorax (a witch) and Miranda (Prospero's daughter). Three moons are named after characters in A Midsummer Night's Dream : Oberon (the King), Titania (the Queen), and Puck (the elf). Except some moons, the rest are named after Shakespearean heroines. There are Desdemona (the wife of Othello), Ophelia, who killed herself in Hamlet and Cordelia, the beloved but rejected daughter of King Lear. One moon is named after Bianca, Cassio's courtesan from the same play, one after Portia from the Merchant of Venice and one after Rosalind from As you like it. Finally there is a moon named for Juliet, but not for Romeo, and one for Cressida, but not for Troilus.
( from The Bedside, Bathtub & Armchair Companion to Shakespeare, Dick Riley & Pam McAllister, 2001 )
Supernovae explosions and the remains of exploded stars
Catastrophes and complexity, extinction and emergence, demise and life, death and birth are closely connected. They go hand in hand with each other, and one is not possible without the other. The ultimate catastrophe is the destruction of a whole star, not an artificial end through a Star Wars 'Death Star' or a Star Trek rocket from a mad scientist, an end through natural "cosmic" forces. The most spectacular ways for a star to die are: to be gobbled up by a black hole, or to explode in a supernova. Both are spectacular events, at least from a safe distance.
Supernovae were named because they were objects that appeared to be 'new' stars, that hadn't been observed before in the well-known heavens. The name is a bit ironic, since supernovae are actually stars at the end of their lifecycle.
A type Ia supernova shines for a few days as bright as a billion suns (see here for an explanation of type Ia/II supernovae) If it would happen near us, let us say only a dozen lightyears away, a shockwave from a billion nuclear bombs would hit the earth, a new second sun brighter than everything else would appear at the sky, and the earth would be fried.
If a black hole gobbles up a star, the results are similar. The chandra site says about Tidal Disruptions in the Milky Way: "If our Galactic Center's black hole were to tear a star apart, the resulting X-ray source would easily outshine every other X-ray source in the sky besides the Sun, frying the instruments aboard Chandra and XMM! The center of the Milky Way would become a hundred billion times brighter in X-rays than it is now."
Fortunately, the only supernova we have observed so far are a vast distance away. Observing the shockwave of a supernova at 100,000 lightyears aways is like watching a nuclear bomb detonate in extreme slow motion, but in fact the explosion causes a shockwave which is a "40-million mile per hour sledgehammer blow".
A smaller catastrophe are the events and fusion processes in a star itself. We usually don't think the sun is the subject of an infernal catastrophe. But this is only due to the fact that we watch it from a large and safe distance. The energy released in nuclear bombs gives a small clue how infernal the processes at the sun really are. Yet these ongoing catastrophe is responsible for the construction of elements.
Gravitational force vs. radiation pressure
(Fusion of elements lighter than iron in Stars)
All of the elements in the Universe that are heavier than hydrogen and helium are created either in the centres of stars during their lifetimes or in the supernova explosions that mark the demise of larger stars. The star can not live without fusion and vice versa, without star no stellar furnace and without fusion no radiation pressure. If the enormous gravitational force is not balanced by the radiation pressure of the fusion, the star collapses and dies in a Supernova.
"Stars of all masses spend the majority of their lives fusing hydrogen into helium. When all of the hydrogen in the central regions of a star is converted into helium, the star will begin to "burn" helium into carbon. However, the helium in the stellar core will eventually run out as well; so in order to survive, a star must be hot enough to fuse progressively heavier elements, as the lighter ones become exhausted one by one. Stars heavier than about 5 times the mass of the Sun can do this with no problem: they burn hydrogen, and then helium, and then carbon, oxygen, silicon, and so on... until they attempt to fuse iron.[..] Nuclear fusion in the core of very massive stars produces elements all the way to iron. Once the mass of the iron core exceeds a certain threshold, it collapses and causes a titanic explosion, a supernova." (from http://curious.astro.cornell.edu/supernovae.php)
The material of our planets (the gas-giants Jupiter and Saturn, the inner planets Mars, Earth, Venus, Merkur and the outer planets Uranus, Neptun and Pluto) once was made in stars. The planets and the earth were formed from leftover material of the disk around the proto-sun. This material in turn was the star ash from many different stars and has been dispersed by Supernovae from the interstellar neighbourhood. We (and everything else on earth) are made of star dust.
Build-up/Fusion vs. Break-Down/Dispersion
(Supernova in stellar/cosmic evolution)
The tremendous explosion of a supernova is the ultimate and perhaps greatest catastrophe with profound and far-reaching effects (on the left the remnant of a star that exploded about 300 years ago in the Cassiopeia constellation). It destroys complete stars and planetary systems, threatens everything in a distance from hundred lightyears, and creates shock waves which propagate through the interstellar medium. At the same time a supernova is a powerful generator of complexity. The great catastrophe is the motor of cosmic evolution and goes hand in hand with greater complexity. The shock waves they produce are vital to the process of star formation, causing large clouds of gas to collapse and form new stars. No supernovae, no new stars, and no heavier elements or complex life-forms. Elements heavier than iron are only formed in supernova explosions. And they are distributed by them at the same time. Supernovae enable the Build-up and fusion of heavy elements, and they disperse the results accross the universe.
"Galactic clouds spawn clusters of stars, only a few of which (the more massive ones unlike the Sun) enable other, subsequent populations of stars to emerge in turn, with each generation's offspring showing slight variations, especially among the heavy elements contained within. Waves of "sequential star formation" propagate through many such clouds like slow-motion chain reactions over eons of time - shocks from the death of old stars triggering the birth of new ones - neither one kind of star displaying a dramatic increase in number nor the process of regeneration ever being perfect. Those massive stars selected by Nature to endure the fires needed to produce heavy elements are in fact the very same stars that often create new populations of stars, thereby both episodically and gradually enriching the interstellar medium with greater elemental complexity on timescales measured in millions of millennia; such rising complexity, further promotes planetary systems that act as advantageous abodes for life as we know it." (p. 161) (Cosmic Evolution, Eric J. Chaisson, Harvard Univ. Press, 2001)
Eric J. Chaisson says in his book "Cosmic Evolution" (Harvard University Press, 2001) : "Interestingly enough, the pancake shape, the spiral-arm structure, the distribution of energy, the differential rotation pattern, and many other morphological characteristics of hurricanes bear an uncanny resemblance to those of spiral galaxies [..] even the "eye" in a hurricane conjures up the purported "hole" (black or otherwise) in the cores of most galaxies."
How galaxies form is still one of the unsolved questions and a hot topic of research. How typhoons and hurricanes form is better understood, since their development is faster and much easier to observe. Hurricanes require a complex combination of atmospheric processes. Like stars, they have a certain lifetime, they grow, mature and finally die, disappear or vanish.
In hurricanes, contraction or attraction is caused by low pressure inside the core. Expansion is caused by the rotation of the earth and the inertia of the air masses. Furthermore, we have at the core an interaction between cool air from the troposhpere at the top and warm tropical water at the bottom.
A hurricane is a low-pressure area in which winds spiral heavily inward. Cold air from above (from the troposhpere 15 to 20 km above the surface) sinks into the calm cloud-free eye (4). At the bottom it collides with the hot moisty air and the rain bands from the surface (2), which causes the moisture to condense into drops and to form more clouds. The condensation releases additional energy and more heat, and the warm air spirals upwards at the eyewall (3). As the warm air rises, the air pressure at the surface drops. The large difference in pressure between the center and the surrounding field causes the strong winds and sucks more air into the core. At the top, the air spreads out over the storm (1). (picture from accuweather.com website).
This impressive photo below from the eye of Hurricane Isabel was taken by Astronaut Ed Lu from the International Space Station on September 2003. ( Image published from NASA Earth Observatory on this website, Image courtesy of Mike Trenchard, Earth Sciences & Image Analysis Laboratory, Johnson Space Center, NASA).
Like a Hurricane which arises in it's early stages from an unorganized cluster of thunderstorms, a galaxy arises from several unorganized cluster of stars. Many factors contribute to the birth of a hurricane. Hurricanes form and intensify over tropical oceanic regions. They require sea-surface temperatures of at least 26°C (80°F) and the influence of the earth's rotation to initiate a spinning circulation. The four main factors are the following conditions :
Similarly, we can expect several conditions for the birth of Galaxies. The birth of Galaxies and Stars is much more complex and a topic of research (see for example http://origins.jpl.nasa.gov/index.html ). As far as I know, up to date, all attempts at theoretical modeling of the spiral structure of galaxies by purely analytic methods have failed. The Structure and Evolution of the Universe (SEU) is not completely understood. The rough picture looks like this (Source : NASA, http://universe.gsfc.nasa.gov/lifecycles.html ) :
Black Holes, remains of ancient stars
In the Dark Side Edition of science from 20th June 2003, Mitchell C. Begelman argues that there are maybe much more black holes than you think. According to Begelman, a Professor in the Department of Astrophysical and Planetary Sciences of the University of Colorado, a common galaxy is full of small black holes, the remains of ancient stars. And these small, invisible black holes maybe the cause of the mysterious dark matter.
So probably there is not only a black hole in the core of the galaxy, but many small invisible black holes in the inner and outer regions. All these tiny or small black holes together contribute to the invisible dark matter. Although a galaxy in our common imagination is circled by bright stars, there are maybe a lot of small black holes revolving around the core of each galaxy as well.
Maybe black hole mergers played an important role in the formation of a galaxy itself.
Evidence for Black Holes
Mitchell C. Begelman;
Science (2003) vol. 300, no. 5627, p. 1898-1903
Gravity's Fatal Attraction: Black Holes in the Universe
Mitchell Begelman, Martin J. Rees
W H Freeman & Co., 1998
For more information about Hurricans, read
NASA Satellites Extract Ingredients in Hurricane Recipe to Improve Forecasts
Hurricane Fabian's Trail
Sea Surface Temperatures in Hurricane Alley