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To: one_less who wrote (3680)	11/29/2006 10:39:47 PM
From: average joe	Respond to of 5290

Mysteries of computer from 65BC are solved Ian Sample, science correspondent Thursday November 30, 2006 The Guardian A 2,000-year-old mechanical computer salvaged from a Roman shipwreck has astounded scientists who have finally unravelled the secrets of how the sophisticated device works. The machine was lost among cargo in 65BC when the ship carrying it sank in 42m of water off the coast of the Greek island of Antikythera. By chance, in 1900, a sponge diver called Elias Stadiatos discovered the wreck and recovered statues and other artifacts from the site. The machine first came to light when an archaeologist working on the recovered objects noticed that a lump of rock had a gear wheel embedded in it. Closer inspection of material brought up from the stricken ship subsequently revealed 80 pieces of gear wheels, dials, clock-like hands and a wooden and bronze casing bearing ancient Greek inscriptions. Since its discovery, scientists have been trying to reconstruct the device, which is now known to be an astronomical calendar capable of tracking with remarkable precision the position of the sun, several heavenly bodies and the phases of the moon. Experts believe it to be the earliest-known device to use gear wheels and by far the most sophisticated object to be found from the ancient and medieval periods. Using modern computer x-ray tomography and high resolution surface scanning, a team led by Mike Edmunds and Tony Freeth at Cardiff University peered inside fragments of the crust-encased mechanism and read the faintest inscriptions that once covered the outer casing of the machine. Detailed imaging of the mechanism suggests it dates back to 150-100 BC and had 37 gear wheels enabling it to follow the movements of the moon and the sun through the zodiac, predict eclipses and even recreate the irregular orbit of the moon. The motion, known as the first lunar anomaly, was developed by the astronomer Hipparcus of Rhodes in the 2nd century BC, and he may have been consulted in the machine's construction, the scientists speculate. Remarkably, scans showed the device uses a differential gear, which was previously believed to have been invented in the 16th century. The level of miniaturisation and complexity of its parts is comparable to that of 18th century clocks. Some researchers believe the machine, known as the Antikythera Mechanism, may have been among other treasure looted from Rhodes that was en route to Rome for a celebration staged by Julius Caesar. One of the remaining mysteries is why the Greek technology invented for the machine seemed to disappear. No other civilisation is believed to have created anything as complex for another 1,000 years. One explanation could be that bronze was often recycled in the period the device was made, so many artefacts from that time have long ago been melted down and erased from the archaelogical record. The fateful sinking of the ship carrying the Antikythera Mechanism may have inadvertently preserved it. "This device is extraordinary, the only thing of its kind," said Professor Edmunds. "The astronomy is exactly right ... in terms of historic and scarcity value, I have to regard this mechanism as being more valuable than the Mona Lisa." The research, which appears in the journal Nature today, was carried out with scientists at the National Archaeological Museum of Athens where the mechanism is held and the universities of Athens and Thessaloniki. guardian.co.uk

To: one_less who wrote (3680)	12/24/2006 12:37:31 PM
From: LTK007	Read Replies (1) \| Respond to of 5290

Did a search to see if anyone else on SI picked up on this as majorly important and mindbending photo in photographic history. r-c-g you are the only person on SI that brought attention to this other than myself It is times like this i sense the basic shallowness of most all on SI and iHub. i doubt very much that more than 5% on these threads give a bloody damn about this first confirmation of "dark matter" (i prefer, "missing mass" or "the otherness":). My original post on this was on iHub( my handle there "otraque") ************************************************** <<Posted by: otraque In reply to: otraque who wrote msg# 1213 Date:8/23/2006 8:05:10 PM Post #of 1599 Astronomers: 'Dark matter' exists Tuesday 22 August 2006, 5:39 Makka Time, 2:39 GMT english.aljazeera.net "Dark matter" is invisible Astronomers have said they have found the best evidence to date of "dark matter" the mysterious invisible substance that is believed to account for the bulk of the universe's mass. Using a host of telescopes, researchers focused on the collision between two galactic clusters. They found that most of the gravitational pull from the aftermath of the encounter comes from a relatively empty looking patch of sky, a strong suggestion that there is something more there than meets the eye. Doug Clowe, a research astronomer at the University of Arizona, said: "This provides the first direct proof that dark matter must exist." His colleagues used NASA's Chandra X-ray observatory, the Hubble Space Telescope and several ground-based observatories to examine the "bullet cluster", a clump of galaxies that formed over the last 100million years from the violent collision of two smaller galactic clusters. The object gets its name from a bullet-shaped cloud of super hot gas on one of its sides. Bullet cluster Most of the visible mass in the bullet cluster is concentrated in that cloud and another near it. But using a technique known as gravitational lensing, Clowe and his colleagues show that the force of gravity is actually stronger in a part of the cluster that appears to be emptier. They will publish their results in a future issue of Astrophysical Journal Letters. Sean Carroll, a university of Chicago physicist, said: "This is really exciting", adding that the observations demonstrate the existence of dark matter "beyond a reasonable doubt". (edit: i remind "dark matter" is a term that now should be understood as that which simply can not be seen, and has no proven explanation. max:) Astronomers have used dark matter for 70 years to explain various observations about the universe's behaviour. They have shown that rotating spiral galaxies would fly apart if it were not for the gravitational pull of undetectable matter in addition to their stars. Other observations show that the expansion of the universe is being held back by a force greater than the gravitational pull of visible matter alone. Alternative theories Though dark matter clearly provides the best explanation for such observations, Clowe said, "astronomers have long been in the slightly embarrassing position" of having to appeal to some mysterious, unobservable material in order to make things fit together. Some physicists have even proposed that it is not the amount and type of matter in the universe that needs to be adjusted, it is the law of gravity itself. They have suggested alternative theories that boost the strength of gravity on galactic and intergalactic scales in order to do away with the need for dark matter. Carroll said: "It's always possible that there's some modification of gravity going on as well. "No matter what you do you're going to have dark matter."(edit: again i wish they would just kill that 70 year old term, and stick with the one that is being used more and by others, and that is simply " the missing mass" that it does not emanate a light that interacts with the stuff we are made and in that sense only is it "dark"--as in we can NOT see it--wild say what??:)max)>> AP >>