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- كاتب الموضوع nina-6
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[FONT=ARIAL, HELVETICA][SIZE=+4]Nuclear Warfare[/SIZE][/FONT]
[FONT=ARIAL, HELVETICA][SIZE=+4]Nuclear Warfare[/SIZE][/FONT]
[SIZE=+1]Nuclear weapons have profoundly changed the way war is fought. Along with more powerful bombs have to come control and countermeasure considerations. The way in which the world thinks about war has changed. The development of nuclear weapons started rather innocently as a physical phenomenon but has become a source of constant terror among many. How did it all start? What can be done about the spread of nuclear weapons? [/SIZE]
[FONT=Arial, Helvetica][SIZE=+2]An Overview of the History[/SIZE][/FONT]- [SIZE=+1]The discovery that it is possible to release the energy within the atomic structure of certain elements has led to the manufacture of weapons of unprecedented destructiveness. Such weapons present a great danger as they are capable of causing damage on an immense scale and possibly killing hundreds of millions of people while destroying the basis of civilized life over wide areas. In the 19th century, the rapid advance of modern technology and industrial organization greatly increased both the destructive power of armed forces and the capacity of societies both to resist and to recover from an attack. In the present century, these advances have already resulted in two massively destructive world wars. These experiences led many to question whether modern war on a large scale remained a practical--let alone a morally justifiable--way to achieve political purposes. Nuclear weapons carry the possibilities of destruction to a new level for[/SIZE]
[SIZE=+2]Nuclear weapons are able to inflict far greater damage within a few hours than previously resulted from years of warfare![/SIZE]
- [SIZE=+1]This not only makes the consequences of war worse but also raises new concerns about controlling such a destructive process. Fearing the consequences of losing control, the nations possessing nuclear weapons, have, therefore, become extremely cautious in managing these dangers and in their dealing with each other. A more in depth view of the history of nuclear warfare is on the nuclear past page.[/SIZE]
- [FONT=Arial, Helvetica][SIZE=+2]Nuclear Deterrence[/SIZE][/FONT]
[SIZE=+1]Over the past few decades, ways of living with nuclear weapons have evolved, creating political systems that everyone hopes will prevent such weapons from ever being used. The main feature of these systems is known as nuclear deterrence. Quite soon after the destructive power of nuclear weapons was realized, people understood that an active defense, such as shooting down bombers, was impossible. But a passive defense (building air raid shelters, evacuating peple, etc.) would not do much good either. Safety could only come from persuading potential attackers not to attack at all. This could best be done by convincing them that they would suffer an equally bad attack in return. This threat of retaliation, therefore, would perhaps serve to deter the possible aggressor.[/SIZE]
[SIZE=+1]While deterrence is not a new idea, what is new about nuclear deterrence is, first, that it may be the only defense possible and, secondly, that a well-designed nuclear force could create retaliatory threats so great that no leader would ever act to bring about such destruction deliberately. Consequently, whatever its other military policies, each of the nuclear powers has tried to develop a nuclear retaliatory force that could--even if its enemies struck first--deliver in a second strike a blow that would result in unacceptable damage to the aggressor. That is the principle behind nuclear deterrence.[/SIZE]
[SIZE=+1]It can be argued that nuclear deterrence is effective because no nuclear weapons have been used in warfare ever since 1945, but a world of nuclear deterrence has several obvious drawbacks:[/SIZE]- [SIZE=+1]Because nuclear weapons continue to exist, there is the permanent danger of catastrophe, and the system might produce catastrophe rather than stalemate.[/SIZE]
- [SIZE=+1]The system requires that nuclear powers regard each other as possible enemies, keeping calculating military balances against each other, and watching nervously for signs that others have found ways to break the stalemate in their favor and engage in nuclear blackmail, or even an attack.[/SIZE]
- [SIZE=+1]While, theorectically, deterrence could be maintained by only a few nuclear weapons, the kind of suspicion and uncertainty that exists tends to drive nuclear powers to heavy expenditures in order to increase or improve their arsenals. This, in turn, reinforces mutual suspicion.[/SIZE]
- [SIZE=+1]As such suspicions illustrate, simple nuclear deterrence is based on the assumption that there is no adequate defense yet. In recent years, however, this assumption has been undermined in two ways:[/SIZE]
- [SIZE=+1]First, ways of intercepting bombers and missiles have been much improved. Although any adequate defense against a large-scale nuclear attack in the near future seems unlikely, would-be deterers have to worry about possible defense against their retaliation. This, however, can increase suspicion and competition. [/SIZE]
- [SIZE=+1]Secondly, missiles have become more accurate. While early intercontinental missiles typically missed targets by a mile or two, they can now achieve accuracies of a few hundred feet and will soon be able to arrive within a few yards. Therefore, it might be possible to seek defense by destroying an enemy's retaliatory force before it could be used. The possibility of such a counterforce strike against enemy forces rather than against cities or industry could be combined with active defenses against the weakened surviving retaliatory force.[/SIZE]
[SIZE=+1]For all these reasons, deterrence cannot be assured simply by possessing a few nuclear weapons. The weapons also have to be effective against an agressor's range of countermeasures. Such a situation creates an arms competition that would be expensive at best and, at the worst, might produce tensions and uncertainties that could lead a nuclear power to believe that attacking was the only way to avert or minimize an attack on itself.[/SIZE]
- [FONT=Arial, Helvetica][SIZE=+2]Early-warning Systems[/SIZE][/FONT]
[SIZE=+1]The destructiveness of nuclear weapons, and the danger of escalation to higher levels of warfare if even one or two were used, makes governments possessing nuclear weapons anxious to guarantee their use only when absolutely necessary. Consequently, great care has been taken to perfect the systems that control nuclear weapons, and systems for Command, Control, and Communication, or C[/SIZE][SIZE=-1]3[/SIZE][SIZE=+1]. [/SIZE]
[SIZE=+1]Closely connected to this system for controlling forces are the systems used to determine the size and capabilities of potentially hostile forces and to provide warning of an impending attack. Most of these activites are now performed by the many kinds of sensors carried by space satellites and by ground-based radars such as the three U.S. Ballistic Missile Early Warning Systems (BMEWS) that are located in Alaska, Greenland, and England.[/SIZE]
[SIZE=+1]The systems for preventing unintended use of nuclear weapons can be divided into three categories:[/SIZE]- [SIZE=+1]safety devices to prevent accidental explosions or launching of weapons[/SIZE]
- [SIZE=+1]laws and military discipline for making sure that people obey orders[/SIZE]
- [SIZE=+1]devices to prevent people from acting without authority[/SIZE]
[SIZE=+1]While military discipline is nothing new, the special dangers of nuclear weapons have inspired ingenious physical controls. Weapons are being guarded with electronic locks that require the insertion of a code number before operators can act. These are often supplemented by devices that will make the weapon unusable if anyone tries to bypass the locks.[/SIZE][FONT=Arial, Helvetica][SIZE=+2]Surveillance Satellites[/SIZE][/FONT]
[SIZE=+1]Satellites provide their owners with much information about the activities of other countries and also provide useful reassurance that nothing too dangerous is happening or that an atttack is not imminent. If nuclear war were tragically to occur, satellites could help to control it by providing reliable information about what was actually happening and therefore, could reduce the typical confusion that is often referred to as the "fog of war." [/SIZE][FONT=Arial, Helvetica][SIZE=+2]Antimissile Weapons[/SIZE][/FONT]
[SIZE=+1]It takes only a very few of the larger nuclear weapons to create great destruction. Power nuclear warheads are now only a few feet in length so they can be delivered by ballistic missiles, which cannot be stopped by traditional air defenses. For many years, it was thought that no defense was possible against ballistic missiles, but now the situation has changed. This is an important development because the revolution created by nuclear weapons would be significantly reversed if effective defenses against missiles were to be developed.[/SIZE][FONT=Arial, Helvetica][SIZE=+2]Star Wars [/SIZE][/FONT]
[SIZE=+1]In the past, developments in rocketry and in electronic guidance made it possible for one rocket to intercept another and destroy it. But while it was possible to intercept single test rockets, catching all of a numerous incoming attack still seemed impossible. As it only took a few penetrations to cause a disaster, U.S. experts did not think building a defensive network was worth the great expense. A further reason to be doubtful about ballistic missile defenses then was the probable ease with which an attacker could make the defender's job more difficult. Although the most expensive, the simplest way would be to buy more offensive missiles to "saturate" the defense. Cheaper ways would be to equip reentry vehicles with devices such as chaff and decoys--lightweight imitations that acted like the real thing while outside the atmosphere--to confuse the defensive radar.[/SIZE]
[SIZE=+1]There are also broader arguments against ballistic missile defenses, and one is that such defenses could accelerate an arms race such as the Cold War mentioned in the nuclear past section. Many people believe that if all parties in a nuclear balance of power know they have no defense, they will be cautious and content with fairly small attacking forces. But if an attacker faced with defenses, tries to get through by increasing the size of its attack, the result might be more rather than less destruction if the defenses failed. On the other hand, if one side were confident in its defense, it might be more tempted to use its own offensive forces. It was this kind of thinking that led to the U.S. and the Soviet Union signing the Anti-Ballistic Missile (ABM) Treaty of 1972. That treaty limited each side to one defended area. The Soviet Union has one around Moscow, but the United States has yet to build the system permitted by the treaty.[/SIZE]
[SIZE=+1]Although the challenge of intercepting a reentry vehicle was technologically mastered in the 1960s, it still seemed impossible to offer a really worthwhile defense to a full-scale sttack. By the 1980s, however, a variety of technological advances had made such a defense seem possible. Because space operations played such an important role in these efforts, the U.S. program, officially called the Strategic Defense Initiative (SDI), became known as Star Wars.[/SIZE]
[SIZE=+1]Many differeny technologies contributed to this new optimism. Radars had become more efficient, and computers were much more capable of rapidly processing the information they received. Interceptor rockets could more quickly meet attacking warheads and, where earlier systems had to rely on nuclear explosions to destroy hostile reentry vechiles, more accurate interception made it possible to employ non-nuclear kill methods such as conventional explosions and shrapnel-like clusters of solid projectiles, or kinetic kill. the most Star Wars-like idea was to use laser beams from the ground or from satellites to damage offensive vehicles. As rockets rose slowly and vulnerably from the ground with all their later-to-be-dispersed multiple warheads aboard, they might be destroyed by kinetic or laser deviecs in satillites over enemy launch-sites. These ideas offered the possibility of a layered defense, whereby the offensive force would be attacked during all three stages of its flight: the boost phase, the mid-course phase, and the reentry, or terminal, phase. Thus, the defense would have several chances to attack and could enjoy a good overall performance, even if each phase had been only partially successful.[/SIZE]
[SIZE=+1]There are still many difficulties with a layered defense, however, and many of the necessary devices are still in the experimental stage. It is particularly difficult to get the necessary energy for lasers into space because the atmosphere has the effect of shielding the ground. Moreover, the attacker can use countermeasures such as decoys and can "harden," or strengthen, its weapons against lasers. It can also increase the acceleration of its boosters to permit the separation of the warheads while they are still within the atmosphere, which will give them some shielding from lasers. They enemy can, of course, also nicrease the attack by aircraft or cruise missiles, which means the defender must also have a good antiaircraft system.[/SIZE]
[SIZE=+1]Once an option becomes technologically possible, its usefulness always depends on the cost. for instance, can an attacker afford to maintain the effectiveness of its attack? Most experts belive it will be a long time, if ever, before a "leak-proof umbrella of defense" can be built. But before then, defenses may become efficient enough to reduce an attacker's confidence in success and thus promote deterrence.[/SIZE]
- [SIZE=+1]So far in this nuclear age, nuclear weapons have been in the possession of only very few nations. While the danger of an increasing number of countries gaining possessiong of these powerful new weapons has long been recognized, much less attention has been given to the possibility that private groups might gain access to a nuclear weapon. In an age of widespread terrorism, it is not difficult to imagine the attraction that such a terrifying instrument might have for those seeking power for coercion or blackmail. In theory, terrorists might either seize an existing weapon or set up a secret organization to make one. [/SIZE]
[SIZE=+1]On the whole, obtaining nuclear weapons by unauthorized individuals or groups seems unlikely because nuclear materials are difficult to acquire and to handle. Military weapons and nuclear power stations and manufacturing facilities are closely guarded, often by special police forces or by technological devices. Also, nuclear weapons often contain mechanism that not only prevent accidental explosions but also disable the weapon if an unauthorized person tampers with it.[/SIZE]
[SIZE=+1]Radioactive material is so dangerous, however, that it might not be necessary for terrorists to obtain a weapon. Instead, they could create immense fear and panic if they were only suspected of possessing a nuclear bomb and threatened to release radioactive material. As the amount of radioactive waste in the world increases, this might offer one of the easier methods for terrorists.[/SIZE]
- [SIZE=+1]The detonation of nuclear weapons has a number of very powerful effects. Chief among them are the immediate release of X-ray energy followed by thermal radiation, atmospheric blast and the subsequent movement of longer-term radiation, which is carried in dust from the bomb and residue from any crater. These longer term aftereffects depend on the design of the weapon and how it was used--whether on the earth's surface or below the ground or in or above the atmosphere. The weather is also a factor. Wind can cause long-distance travel of particles, and fog can shield against thermal radiation.[/SIZE]
[SIZE=+1]The explosive nuclear components of a typical weapon instantly rise to temperatures of several million degrees and create a massive fireball of heat and radiation, usually culminating in fallout. An explosion in the atmostphere also causes a shock wave of compressed air that travels at about one-half mile in two seconds. This causes over-pressure. Here the first wave meets a reactive reflection. Thermal radiation also occurs, and animals up to some 12 miles from where the bomb detonated can be burned. Buildings will suffer damage chiefly from explosion and fire. Buildings are also destroyed by fires caused by the thermal radiation. Although people are usually injured by the collapse of buildings rather than by the over-pressure, the various forms of radiation also kill people, either quickly or slowly.[/SIZE]
[SIZE=+1]Of course, there are also many medical effects on humans from radiation. For more information on that, consult the radiation effects on humans page.[/SIZE]
- [SIZE=+1]There are many arguments both for and against abolition, disarmament, and arms control. Everyone has his or her own idea about how best to tackle the intensely serious problem of nuclear weapons. Some will work for their abolition, which is the declared ultimate goal of most world leaders. The difficulties of achieving this are very great, however, and careless or overeager efforts to achieve this goal might actually be harmful. While nuclear weapons are a great danger, they exist because the nations that own them think they provide some protection against serious threats to their security, some of which are also nuclear.[/SIZE]http://library.thinkquest.org/3471/nuclear_warfare.html
[SIZE=+1]Most statesmen, therefore, believe that the day for abolishing nuclear weapons is far off and, meanwhile, nations must find safe ways to live with them. In effect, this is an arms control outlook that can be pursued both by trying to have cautious strategies and controllable weapons, safe from accidents, and by agreements about arms control. Under such an arrangement, governments would undertake to reduce the number of weapons and abolish dangerous ones and keep each other informed and reassured about situations that might otherwise cause countries to take hostile action.[/SIZE]
[SIZE=+1]While no single action will guarantee success, everyone seems to realize that failure would be catastrophic for everyone--everywhere--on this earth.[/SIZE]
or
http://en.wikipedia.org/wiki/Nuclear_warfare
3-
http://www.iiasa.ac.at/Research/CAT/research.htmlhttp://en.wikipedia.org/w/index.php?title=Special:Search&search=natural+catastrophes
or
http://www.swissre.com/rethinking/natcat/
هذا واش لقيت من الحاج قوقل يصلح
واذا حبيتي حاجة اخرى اختاه نحن في الخدمة بحول الله
"hichemjsk"
http://www.iiasa.ac.at/Research/CAT/research.htmlhttp://en.wikipedia.org/w/index.php?title=Special:Search&search=natural+catastrophes
or
http://www.swissre.com/rethinking/natcat/
هذا واش لقيت من الحاج قوقل يصلح
واذا حبيتي حاجة اخرى اختاه نحن في الخدمة بحول الله
"hichemjsk"
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