User:Chetvorno/work4
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[edit] For Schrödinger's Cat
Schrödinger's cat, often described as a paradox, is a thought experiment devised by Austrian physicist Erwin Schrödinger in 1935. It illustrates what he saw as the problem of the Copenhagen interpretation of quantum mechanics being applied to everyday objects, by considering the example of a cat that may be either alive or dead, according to an earlier random event.
[edit] Description of experiment
One of the strangest ideas in quantum mechanics is the concept of 'superposition'. When a quantum scale event, such as the decay of a particle, can have several possible outcomes, the wave function representing the particle 'splits' and each outcome unfolds simultaneously. A 'superposition', broadly speaking, is the totality of all the possible locations for the particle. This is one of the most firmly established principles underlying quantum mechanics, and these superpositions are encountered on an atomic scale, as an 'interference pattern' indicating that a single particle is in several places at once. However, when an experiment is done to see which of the alternative states the system is in, it always finds, in conformity with common sense, only one or another state, not a 'superposition'.
The traditional explanation for this behavior in the 1920s, called the Copenhagen interpretation, was that a superposition lasts until an 'observer' , At that point it collapses, and somehow one of the alternative states is randomly 'chosen' to be reality. What constituted an 'observer' was not well defined.
Schrödinger conceived his thought experiment to show that the Copenhagen interpretation could have results which went against 'common sense' when superpositions grew to large scales. Perhaps a particle can be in two different states at once, he thought, but certainly not a large object like a cat. He imagined a case in which a quantum event can result in two very different outcomes inside a box. A cat is put in a box, with a tiny amount of radioactive material, a geiger counter, and a flask of poison, and the box is closed. If the geiger counter detects radiation, the flask will be broken, killing the cat. So whether the cat is alive or dead at any later time depends on a quantum event; whether a radioactive atom has decayed or not. The Copenhagen interpretation implied that since the fate of the cat is dependent on ('entangled' with) the fate of the atom, until it is opened the box will contain a superposition of separate realities, containing either a live cat or a dead cat. In effect, the cat is simultaneously alive and dead.
When the box is opened, only one of the outcomes, a live or a dead cat, will be found; this isn't at issue. Any attempt from outside to determine the state inside the closed box will distroy the superposition, again finding only one outcome. So the dead cat - live cat superposition seems to be unobservable, leaving the question of whether it actually occurs open to different interpretations of the mathematics.
Schrödinger did not wish to promote the idea of dead-and-alive cats as a serious possibility; quite the reverse: the thought experiment serves to illustrate the bizarreness of quantum mechanics and the mathematics necessary to describe quantum states. However, others have taken this possibility quite seriously, and other interpretations of quantum mechanics besides the Copenhagen interpretation have been put forward in an attempt to resolve the paradox. How they treat it is often used as a way of illustrating and comparing their particular features, strengths and weaknesses.
[edit] For Jewel bearing
Jewelled bearings serve two purposes in a watch. First, they reduce friction, which can increase accuracy. Slight variations in the force applied to the balance wheel can cause variations in the rate of timekeeping. Reducing the friction level of the going train reduces these variations. Second, they increase the life of the bearings. Before jewelled bearings, the pivots of the watch's wheels just rotated in holes in the plates supporting the movement. The force on the gears caused more friction on one side of the hole. As the wheels rotated they slowly wore the holes into an oval shape.
In bearings, jewels are used in two different ways. Sleeve bearings are used for most of the wheels. However, In bearings where friction is critical, such as the balance and escape wheel shafts, a capstone is added at each end of the axle. In the escapement, jewels are used for the parts that work by sliding friction: the impulse pin and the pallets.
The number of jewels used in watch movements increased over the years as jewelling grew less expensive and watches grew more accurate. The only bearings that really need to be jewelled in a watch are the ones in the going train - the gear train that transmits force from the mainspring barrel to the balance wheel - since only they are constantly under tension and constantly in motion. The wheels that turn the hands, and calendar works, are not under tension, The most friction occurs in the wheels that move the fastest, so they benefit most from jewelling. So the first mechanism to be jewelled in watches was the balance wheel. As more jewelled bearings were added, they were applied to slower moving wheels, and jewelling progressed up the wheel train toward the barrel.
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| 11 jewel watch - adds: |
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| 15 jewel watch - adds: |
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| 17 jewel watch - adds: |
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| 21 jewel watch - adds: |
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| 23 jewel watch - adds: |
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[edit] Jewel inflation
Experts doubt whether adding jewels in addition to those listed in the box above is really useful in a watch. It doesn't increase accuracy, since the above wheels, the going train, are the only ones that have an effect on the balance wheel. Most of the other wheels in a watch either have little force applied to them, or move so slowly or so seldom that friction is unimportant. But consumers have learned to equate more jewels with more quality in a watch, so watch manufacturers have an incentive to increase the jewel count.
Around the 1950s, a 'jewel craze' seized the public, and watch manufacturers catered to it by making watches with 53, 75, or even 100 jewels. Many of these additional jewels were totally nonfunctional; they never contacted moving parts, and were included just to increase the jewel count. For example a Waltham 100 jewel watch consisted of an ordinary 17 jewel movement, with 83 tiny pieces of ruby mounted around the automatic winding rotor. In 1974, the International Standards Organization (ISO) in collaboration with the Swiss watch industry standards organization NIHS (Normes de l'industrie Horlogre Suisse) published a standard, ISO 1112, which generally prohibited manufacturers from including such nonfunctional jewels in the jewel counts in advertising and sales literature.
This put a stop to the use of totally nonfunctional jewels. However manufacturers have continued to inflate the jewel count of their watches, by adding
