Messages récents

Pages: 1 ... 6 7 [8] 9 10
71
Discussions Générales / Re : Online essays service
« Dernier message par Wive1934 le 12-09-2019 13:18:50 »
By coming online essay, The work of students is very easy and simple. You can also make your career in this field by writing online essay by yourself. It the best place to getting help and also doing help of anyone.
72
Discussions Générales / Où jouez-vous à klondike solitaire?
« Dernier message par ravka le 12-09-2019 12:46:57 »
Dans mon temps libre, je joue à klondike solitaire. J'ai même fait attention quand je vais au bureau de quelqu'un au travail, là aussi, presque tout le personnel joue au Klondike solitaire. Et où ne pas aller, partout vous pouvez dire que les gens jouent klondike solitaire. Ça surprend comme ça. Mais ce jeu est vraiment addictif. Quand je l'allume, je ne remarque pas comment cela passe plusieurs heures. Comme si une minute était passée. C'est probablement pourquoi partout les gens qui travaillent à l'ordinateur jouent à ce jeu. Ils tuent leur temps de travail. Vous faites ça aussi? Où jouez-vous à klondike solitaire?
73
Discussions Générales / Evolving Universes
« Dernier message par ravka le 12-09-2019 12:43:58 »
To many it seems unlikely that a universe could spring into being from chaos, and achieve a level of organization advanced enough to allow for life—let alone intelligence. After all, if an electron were only twice the size that it is, chemistry as we know it couldn’t exist. If the Strong and Weak nuclear forces were out of proportion, stars mayn’t work. Over the centuries a number of theories have cropped up to try to explain life, the universe, and everything, but almost none propose to explain how it all came together. As with many problems that are too grandiose to grapple, however, sometimes it’s best to start on a smaller scale.

Evolutionists and naturalists have long observed Earth’s “natural selection” where most creatures create offspring with slightly different characteristics than their own. Those with characteristics better suited to the environment will thrive, procreate, and pass on their heritage; whereas offspring less suited will wither, reproduce less, and their traits will fade and vanish.

Theoretical physicist Lee Smolin looked at the simple, functional elegance found in the the theory of natural selection, and thought that maybe such a concept could be applied on a universal scale. Thus the theory of Cosmological Natural Selection was born.


In order to tackle how complexity came into being, most scientific theories postulate that there are an infinite number of universes, and each of them are host to its own set of physical laws. Some would therefore have laws where chemistry cannot function, and thus are home to nothing more complex than a vast field of hydrogen. Some would have to be like ours: rife with complexity where a star larger than 1.44 times the size of ours can collapse into a black hole. And the black hole is the point where Cosmological Natural Selection begins.

Many people mistakenly attribute the concept of the Black Hole to Albert Einstein, however the earliest proposition of the Black Hole (called a “dark star” at the time) was presented by a fellow named John Michell in 1784—a hundred-forty years before General Relativity was published. Nevertheless, it was Einstein who refined the idea into its modern incarnation. According to General Relativity, when an object achieves enough mass, it crushes down to an inconceivably small point called the singularity. It is so weighty that the escape-velocity from it is greater than the speed of light, and since nothing exceeds the speed of light …

As good as it sounds, it’s been found that Einstein’s work doesn’t function so well when one starts exploring items smaller than the atom. Modern acolytes of Quantum Physics and String Theory have suggested that it’s highly unlikely that there’s a singularity in there at all. Instead they propose a 4-dimensional tube opens to a new region of space/time. The introduction of the black hole’s material in this virgin space/time is analogous to a Big Bang—the genesis of a new universe.


Here, at the dawn of a new universe is where Smolin’s theory fits. He postulates that the new universe’s laws are influenced by those of the parent. Thus, our universe which has complexity and is therefore very successful at creating black holes/new universes is spawning universes that also have complexity, and will pass that trait onto their progeny … much like evolution. However, unlike evolution, there are no known universe-predators culling the ill and unfit universes from the multiverse, therefore “Cosmological Natural Selection” might be a less apt name than “Fecund Universes”; it’s not a race for survival, just reproduction.

Some sectors of science dismiss the notion, calling it inherently untestable. There is no way to peek into other universes to see if they are related to their parent … yet. Smolin responds by asking that his peers to seek out any natural law that shows that our universe isn’t adapted to easily create black holes. After all, if there is a basic principle that inhibits the formation of black holes it would be a pretty big hole in the idea.
74
Discussions Générales / Operation Acoustic Kitty
« Dernier message par ravka le 12-09-2019 12:43:35 »
At the height of the Cold War, the US Central Intelligence Agency was willing to try just about anything to gain an advantage over the dreaded Communists. The agency considered using exploding cigars or seashells to remove Cuban leader Fidel Castro; they employed psychics to attempt “remote viewing” of Russian military secrets; and the CIA even put the Soviets on the business ends of clairvoyant minds to attempt mind-control.

One of the CIA’s most bizarre Cold War efforts was Operation Acoustic Kitty. In declassified documents from the CIA’s super-secret Science and Technology Directorate, it was revealed that some Cold-War-era cats were surgically altered to become sophisticated bugging devices. The idea was that the cats would eavesdrop on Soviet conversations from park benches, windowsills and garbage containers. The cat was meant to just stroll up to the sensitive conversations, completely unnoticed. The clandestine cat’s electrical internals would then capture and relay the audio to awaiting agents.

The project was funded and work began in 1961. Former CIA officer Victor Marchetti recounts the story of the Acoustic Kitty:

“They slit the cat open, put batteries in him, wired him up. The tail was used as an antenna. They made a monstrosity. They tested him and tested him. They found he would walk off the job when he got hungry, so they put another wire in to override that. Finally, they’re ready. They took it out to a park bench and said, “Listen to those two guys. Don’t listen to anything else – not the birds, no cat or dog – just those two guys!”

After several surgeries and intensive training, the cyborg cat was ready for its first field test. The CIA drove the cat to a Soviet compound on Wisconsin Avenue in Washington, D.C., and let him out of a parked van across the street. The cat ambled into the road, and was struck by a taxi almost immediately. Five years of effort and over $15 million in spending were reduced to roadkill in an instant. Shorty after its demise a CIA operative returned to the accident site and put the cat’s remains into a container to prevent the Soviets from getting their paws on the sensitive and expensive listening devices.
75
Discussions Générales / The Dark Tale of Colliding Superclusters
« Dernier message par ravka le 12-09-2019 12:43:19 »
For all that mankind has learned through science, the Universe has so far managed to keep most of its secrets. For instance, we don’t know where the Universe came from, what its fate will be, or even its most basic composition.

But over the last few decades, tantalizing clues and some very intelligent guesswork led astronomers to an astounding hypothesis: the ordinary matter that stiffens our bones and fuels our suns plays only a bit part in the grand epic of existence. Astronomers now believe that for every kilogram of normal matter like atoms, electrons, and quarks there are five kilograms of dark matter.

Very recently, astronomers announced what many had thought impossible, the direct observation of the existence of dark matter. Billions of years ago, two galactic superclusters collided. The collision occurred at a relative velocity of over a million miles per hour. Not since the Big Bang itself has the known universe experienced so violent an event. The aftermath of this collision offered what may be a once-in-Creation opportunity to finally “see” dark matter itself.

Ordinary matter is organized into structures from scales as small as the nucleus of an atom to those that span much of the Universe. The same four physical forces that bind protons to neutrons and hold our feet to the ground cause suns to organize into galaxies, galaxies to group into clusters, clusters to gather as superclusters, and superclusters to form structures astronomers call simply filaments, bubbles, and sheets.

Filaments of Galaxies Simulated with a Supercomputer
Filaments of Galaxies Simulated with a Supercomputer
Superclusters can contain millions of galaxies in relative close proximity. The stars within these superclusters remain bound to their native galaxies, but most of the gases are diffused throughout the cluster and heated to millions of degrees in the process. These gases make up most of the mass of an individual galaxy, and about 90% of the visible mass of the supercluster.

Astronomers have long been aware that superclusters do not contain enough visible matter to explain their existence. The hot gases and galaxies orbit the cluster so quickly that the gravity of the visible mass is insufficient to hold the matter together. Thus the theory of dark matter was born. The theory suggests that dark matter interacts with normal matter via only one of the four fundamental forces: gravity. Calculations and computer simulations show that clumps of dark matter lie at the centers of all large structures in the Universe, even the Milky Way.

When two clusters collide at high speeds, the visible galaxies and dark matter pass right by each other as if nothing happened. But the gases smash into each other with enough force to slow them down considerably. Thus most of the visible matter in the clusters is stripped away leaving two remnant clumps of dark matter behind. This is exactly what astronomers believe happened billions of years ago in cluster 1E0657-56, also called the bullet cluster.
76
Discussions Générales / The Bridle on the Neck of the Sea
« Dernier message par ravka le 12-09-2019 12:43:01 »
This article was written by Zack Jordan, one of our shiny new Damn Interesting writers.

In the grand old year of 1492, Christopher Columbus set out from Spain with a fleet of three tiny ships. His journey began in August of that year, but it was March of the next before the Old World heard from Columbus again. Time taken: nearly eight months.

Over a century later, in September of 1620, the Mayflower departed England on its historic voyage to the New World. In May of 1621, it returned, bearing news of a (relatively) successful mission. Total time taken: more than nine months.

Over two centuries after the Mayflower, in 1850, the western world was in a state of dynamic change. The Industrial Revolution was in full swing, and the world was optimistic. The first railroads had been operating profitably for over a decade, steamships plied the rivers and coasts of America and Europe, and a network of telegraph wires had spread across territory on both sides of the Atlantic. Where once it had taken weeks to transmit news across hundreds of miles of land, it now took minutes. The world, it seemed, had shrunk. And between the two continents, where once it had taken months to deliver news, it now took… months. Nineteenth-century communications had hit a brick wall; the fastest way to get a message across the Atlantic was still floating and steam-powered, and it looked like things were going to stay that way unless someone was willing to take some huge risks.

As well-connected as Europe and America were internally, they were still cut off from each other just as effectively as they had been for centuries. Even with the advent of the steam ship, Atlantic crossings were still risky and of unpredictable length. Fortunately for the mid-eighteenth century, there was one man who not only saw the possibility of instant trans-Atlantic communication but was willing to put his formidable assets to work to make it happen.

Cyrus Field
Cyrus Field
Cyrus Field was the embodiment of the Victorian American dream. He was a self-made man with a taste for business, and one of the wealthiest men in New York City. He also had the benefit of nearly limitless charisma, drive, imagination, and— some would say— blockheadedness, all of which proved to be indispensable for the project. If you can imagine a cross between Andrew Carnegie and Donald Trump (substitute a chin curtain for the comb-over), you’ll have a good picture of Cyrus Field- he was that rare example of a brilliant businessman/salesman with a philanthropist’s heart.

Fortunately, both sides of his personality saw the benefit of trans-Atlantic communication. Of course there was plenty of money to be made, but Field knew that good communication could solve many of the problems between distant countries. For example, the bloodiest battle of the War of 1812, while technically an American victory, was fought two weeks after the Treaty of Ghent had been signed; this event and others like it offered proof that news in the nineteenth century simply couldn’t travel quickly enough. Armed with his notable charisma, Cyrus was able to collect enough investors to begin the project by 1854. Initially, the sum of $1.5 million dollars was pledged to the project. In contrast, the entire budget of the United States that year was under $60 million.

This monumental feat of engineering required technology that was not only in its infancy- it was derived from technology barely into its toddler years. No one knew if it was even possible to send a signal through more than two thousand miles of cable. The concept of resistance, while known, had not yet been scientifically defined. No one knew how much an armored electrical cable weighed, or whether any ship in the world had the payload capacity to carry its entire length.

Fortunately, Cyrus was ignorant about all of this. He hired the best minds in the world- including Samuel Morse and William Thomson, later known as Lord Kelvin- and told them to make it happen. Field’s small group of engineers would soon learn that a well-armored nautical cable weighs over one ton per mile- resulting in a total weight of nearly 2,500 tons to span the Atlantic. Adding to this problem was the fact that no ship currently in existence had a payload of 2,500 tons.

For the first three attempts, steps were taken to reach a compromise between cost and quality. Corners were cut during the construction of the cable, and two ships began the massive undertaking of laying it. Unfortunately, the results were not encouraging. During the first two attempts, the cable snapped due to machinery inadequacies which were heightened by rough weather. The third attempt was a technical success, but the cable stopped working less than a month later. This failure was blamed on an operator who upped the potential to several hundred volts, blowing a hole in the cable somewhere in its two-thousand-mile length.

The Great Eastern
The Great Eastern
For the fourth and fifth attempts, Cyrus Field was able to purchase a ship- and not just any ship. Cyrus purchased the largest ship in the world, the recently-built Great Eastern. And if this in itself does not seem impressive, consider that this massive vessel held the distinction of being five times the size of the next biggest ship in the world. This was the nautical equivalent Spruce Goose, dwarfing all other seagoing craft and weighing in at 32,000 tons. The extra weight of the cable was a drop in the bucket of this Leviathan.
77
Discussions Générales / The Atomic Automobile
« Dernier message par ravka le 12-09-2019 12:42:40 »
During the 1950s, much of the world was quivering with anticipation over the exciting prospects of nuclear power. Atomic energy promised to churn out clean, safe electricity that would be “too cheap to meter.” It seemed that there was no energy problem too large or too small for the mighty atom to tackle during the glorious and modern Atomic Age.

It was during this honeymoon with nuclear energy— in 1957— that the Ford Motor Company unveiled the most ambitious project in their history: a concept vehicle which had a sleek futuristic look, emitted no harmful vapors, and offered incredible fuel mileage far beyond that of the most efficient cars ever built. This automobile-of-the-future was called the Ford Nucleon, named for its highly unique design feature… a pint-size atomic fission reactor in the trunk.

Ford’s engineers imagined a world in which full-service recharging stations would one day supplant petroleum fuel stations, where depleted reactors could be swapped out for fresh ones lickety-split. The car’s reactor setup was essentially the same as a nuclear submarine’s, but miniaturized for automobile use. It was designed to use uranium fission to heat a steam generator, rapidly converting stored water into high-pressure steam which could then be used to drive a set of turbines. One steam turbine would provide the torque to propel the car while another would drive an electrical generator. Steam would then be condensed back into water in a cooling loop, and sent back to the steam generator to be reused. Such a closed system would allow the reactor to produce power as long as fissile material remained.

Using this system, designers anticipated that a typical Nucleon would travel about 5,000 miles per charge. Because the powerplant was an interchangeable component, owners would have the freedom to select a reactor configuration based on their personal needs, ranging anywhere from a souped-up uranium guzzler to a low-torque, high-mileage version. And without the noisy internal combustion and exhaust of conventional cars, the Nucleon would be relatively quiet, emitting little more than a turbine whine.

William Ford alongside a 3/8 scale Nucleon model
William Ford alongside a 3/8 scale Nucleon model
The vehicle’s aerodynamic styling, one-piece windshield, and dual tail fins (which are absent in some photographs) are reminiscent of spacecraft from 1950s-era science fiction, but some aspects of the Nucleon’s unique design were more utilitarian. For instance, its passenger area was situated quite close to the front of the chassis, extending beyond the front axle. This arrangement was meant to distance the passengers from the atomic pile in the rear, and to provide maximum axle support to the heavy equipment and its attendant shielding. Another practical design aspect was the addition of air intakes at the leading edge of the roof and at the base of the roof supports, apparently to be used as part of the reactor’s cooling system.

Ford’s nuclear automobile embodied the naive optimism of the era. Most people were ignorant of the dangers of the atomic contraption, as well as the risk that every minor fender-bender had the potential to become a radioactive disaster. In fact, the Nucleon concept was often received with great enthusiasm. Some sources even claim that the US government sponsored Ford’s atomic car research program.

The Nucleon’s silent, sleek, and efficient design was poised to secure its place in the American lifestyle of the future. It seemed inevitable that the internal combustion engine would fade into obscurity, becoming a quaint relic of a pre-atomic past. But the Nucleon’s design hinged on the assumption that smaller nuclear reactors would soon be developed, as well as lighter shielding materials. When those innovations failed to appear, the project was scrapped due to conspicuous impracticality; the bulky apparatus and heavy lead shielding didn’t allow for a safe and efficient car-sized package. Moreover, as the general public became increasingly aware of the dangers of atomic energy and the problem of nuclear waste, the thought of radioactive atomobiles zipping around town lost much of its appeal. Atoms had broken their promise; the honeymoon was over.

The Ford Nucleon concept car with optional tailfins
The Ford Nucleon concept car with optional tailfins
Ford never produced a working prototype, nevertheless the Nucleon remains an icon of the Atomic Age. In spite of the Nucleon’s flaws, its designers deserve a nod for their slapdash ingenuity. Their reckless optimism demonstrates that one shouldn’t consider a task impossible just because nobody has tried it yet— some ideas need to be debunked on their own merit. With today’s looming energy crisis and slow migration to alternative fuel sources, we may not have seen the last of the atomic automobile concept. A safe atomic vehicle may not be entirely beyond our reach, as the US Navy has demonstrated with its perfect record of nuclear safety. Perhaps one day fossil fuels will wither under the radioactive glare of the mighty atom, and our highways will hum with the steam turbines of mobile Chernobyls. It could be a real blast.
78
Discussions Générales / Gsm Reparatie sint truiden
« Dernier message par james039 le 12-09-2019 12:26:03 »
MMSTORE sint truiden is de beste gsm-reparatiewinkel in België. We hebben veel tevreden klanten in Sint Truiden en in België.
79
Discussions Générales / Essay Writing Service Cheap
« Dernier message par james039 le 12-09-2019 12:23:47 »
Essaywritingservicescheap is the best essay writing service in USA.We have writers who will write a good essay for you.Essay writing services provided by our writers is the best unique and high quality.Our writers write plagiarism free content for you.
Pages: 1 ... 6 7 [8] 9 10