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& 周五植树:栽一棵“海森贝格“树

(2008-01-06 10:47:58) 下一个
海森贝格的“观察者效应”论点
http://en.wikipedia.org/wiki/Observer_effect

蜂鸟注:至今,此论点的中文的百科译本尚未出现

Observer effect
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For the Star Trek: Enterprise episode, see Observer Effect.

The observer effect, or observer bias, has any of various context-specific meanings, some of which are related.
Contents
[hide]

* 1 Use in science
* 2 Use in information technology
* 3 Use in the social sciences
* 4 Observer bias
* 5 See also
* 6 References

[edit] Use in science

In science, the term observer effect refers to changes that the act of observing will make on the phenomenon being observed. For example, for us to "see" an electron, a photon must first interact with it, and this interaction will change the path of that electron. It is also theoretically possible for other, less direct means of measurement to affect the electron; even if the electron is simply put into a position where observing it is possible, without actual observation taking place, it will still (theoretically) alter its position.

In physics, a more mundane observer effect can be the result of instruments that by necessity alter the state of what they measure in some manner. For instance, in electronics, ammeters and voltmeters need to be connected to the circuit, and so by their very presence affect the current or the voltage they are measuring. Likewise, a standard mercury-in-glass thermometer must absorb some thermal energy to record a temperature, and therefore changes the temperature of the body which it is measuring.

A common lay misuse of the term refers to quantum mechanics, where, if the outcome of an event has not been observed, it exists in a state of 'superposition', which is akin to being in all possible states at once. In the famous thought experiment known as Schrödinger's cat the cat is supposedly neither alive nor dead until observed — until that time, the cat is both alive and dead (technically half-alive and half-dead in probability terms). However, most quantum physicists, in resolving Schrödinger's seeming paradox, now understand that the acts of 'observation' and 'measurement' must also be defined in quantum terms before the question makes sense. From this point of view, there is no 'observer effect', only one vastly entangled quantum system. A significant minority still find the equations point to an observer; Wheeler, who probably worked more deeply on this subject than any physicist thus far, devised a graphic in which the universe was represented by a "U" with an eye on one end, turned around and viewing itself, to describe his understanding.

The Heisenberg uncertainty principle is also frequently confused with the "observer effect". The uncertainty principle actually describes how precisely we may measure the position and momentum of a particle at the same time — if we increase the precision in measuring one quantity, we are forced to lose precision in measuring the other. Thus, the uncertainty principle deals with measurement, and not observation. The idea that the Uncertainty Principle is caused by disturbance (and hence by observation) is not considered to be valid by some, although it was extant in the early years of quantum mechanics, and is often repeated in popular treatments.

There is a related issue in quantum mechanics relating to whether systems have pre-existing — prior to measurement, that is — properties corresponding to all measurements that could possibly be made on them. The assumption that they do is often referred to as "realism" in the literature, although it has been argued that the word "realism" is being used in a more restricted sense than philosophical realism[1]. A recent experiment in the realm of quantum physics has been quoted as meaning that we have to "say goodbye" to realism, although the author of the paper states only that "we would [..] have to give up certain intuitive features of realism" [2] [3]. These experiments demonstrate a puzzling relationship between the act of measurement and the system being measured, but it is unclear if they require a conscious observer or not.

[edit] Use in information technology

In information technology, the observer effect is the potential impact of the act of observing a process output while the process is running. For example: if a process uses a log file to record its progress, the process could slow. Furthermore, the act of viewing the file while the process is running could cause an I/O error in the process, which could, in turn, cause it to stop.

Another example would be observing the performance of a CPU by running both the observed and observing programs on the same CPU, which will lead to inaccurate results because the observer program itself affects the CPU performance (modern, heavily cached and pipelined CPUs are particularly affected by this kind of observation).

Observing (or rather, debugging) a running program by modifying its source code (such as adding extra output or generating log files) or by running it in a debugger may sometimes cause certain bugs to diminish or change their behavior, creating extra difficulty for the person trying to isolate the bug (see Heisenbug).

[edit] Use in the social sciences

In the social sciences and general usage, the effect refers to how people change their behavior when aware of being watched (see Hawthorne effect). For instance, in the armed forces, an announced inspection is used to see how well soldiers can do when they put their minds to it, while a surprise inspection is used to see how well prepared they generally are.

In parapsychology, the observer effect refers to the situation of an experiment subject's expectations creating the experiment's results. The phrase was coined by two friends performing an experiment wherein they set up a number of volunteers who had to press the button when they felt they were being watched by the experimenters.[citation needed]

[edit] Observer bias

The related social-science term observer bias is error introduced into measurement when observers overemphasize behavior they expect to find and fail to notice behavior they do not expect. This is why medical trials are normally double-blind rather than single-blind. Observer bias can also be introduced because researchers see a behavior and interpret it according to what it means to them, whereas it may mean something else to the person showing the behavior. See subject-expectancy effect and observer-expectancy effect.

[edit] See also

* Anthropic bias
* Double-slit experiment
* Uncertainty principle

[edit] References

1. ^ Norsen, T. Against "Realism"
2. ^ Quantum physics says goodbye to reality
3. ^ An experimental test of non-local realism

* Observer Effect in the social sciences (Association for Qualitative Research)
* The observer effect (usage of the term in the computer industry)

Retrieved from "http://en.wikipedia.org/wiki/Observer_effect"

Categories: All articles with unsourced statements | Articles with unsourced statements since February 2007 | Philosophy of science | Types of scientific fallacy | Cognitive biases

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维尔纳·海森贝格
维基百科,自由的百科全书

维尔纳·海森贝格

出生
1901年12月5日
德国维尔茨堡
逝世 1976年2月1日
德国慕尼黑
研究领域 物理
著名事务 测不准原理、量子力学
国籍 德国
居住地 德国
研究机构 格丁根大学
哥本哈根大学
莱比锡大学
柏林大学
圣安德鲁斯大学
慕尼黑大学
母校 慕尼黑大学
导师 阿诺尔德·佐默费尔德
学生 费利克斯·布洛赫
爱德华·特勒
获奖 诺贝尔物理学奖(1932年)

维尔纳·海森贝格(Werner Heisenberg,1901年12月5日-1976年2月1日),德国著名物理学家,雅利安人,量子力学的奠基人之一,“哥本哈根学派”代表性人物,因创立量子力学而获1932年诺贝尔物理学奖。

他对物理学的主要贡献是给出了量子力学的矩阵形式(矩阵力学),提出了“测不准原理”(又称“不确定性原理”)和S矩阵理论等。他的《量子论的物理学基础》是量子力学领域的一部经典著作。
目录
[隐藏]

* 1 生平
* 2 研究
* 3 荣誉
* 4 参考资料

[编辑] 生平

维尔纳·海森贝格1901年12月5日出生于德国维尔茨堡,1920年从慕尼黑的一所中学毕业后,在慕尼黑大学学习物理学,师从阿诺尔德·佐默费尔德(Arnold Sommerfeld)等,1922年冬天转去格丁根大学,师从马克斯·玻恩(1954年诺贝尔物理学奖)、詹姆斯·夫兰克(1925年诺贝尔物理学奖)和大卫·希尔伯特。1923年他在慕尼黑大学获得博士学位,并去格丁根大学担任玻恩的助手,1924年获得大学任教资格。

1924年至1925年,他在哥本哈根大学工作,与尼尔斯·玻尔(1922年诺贝尔物理学奖)共事,1925年夏天回到格丁根。1926年又前往哥本哈根大学教授理论物理学,1927年,年仅26岁的海森贝格被任命为莱比锡大学的教授。1929年,他又前往美国、日本和印度巡回讲学。1941年成为柏林大学的物理学教授和物理研究所主任。

第二次世界大战结束后,他和其他德国物理学家作为囚犯,被美国军队送往英国。1946年重返德国后,他和他的同事们重建了格丁根物理研究所,该研究所在1948年改名为马克斯-普朗克物理学研究所。1948年他在英国剑桥讲学数月,1950年和1954年又应邀前往美国讲学,1955年冬天他在苏格兰的圣安德鲁斯大学教书,这些课程后来出版成书。1955年作为马克斯-普朗克物理学研究所的主任,与研究所一起迁往慕尼黑,1958年成为慕尼黑大学的物理学教授,他的研究所被改名为“马克斯-普朗克物理学和天体物理学研究所”(现为马克斯-普朗克天体物理学研究所)。

海森贝格爱好古典音乐,是个出色的钢琴手,1937年与伊丽莎白·舒马赫(Elisabeth Schumacher)结婚,生有7个孩子,居住在慕尼黑。海森贝格逝世于1976年2月1日。

[编辑] 研究

海森贝格的名字一直都和他的量子力学理论联系在一起,这一理论发表时他年仅23岁,他也因为提出这一理论及其应用(尤其是氢同位素的发现),获得了1932年的诺贝尔物理学奖。

海森贝格提出的新理论,是完全基于对原子辐射的观察,他认为,在某一个给定的时间点,一个电子所处的位置是无法确定的,也无法跟踪它的轨迹,所以玻尔假定的电子轨道并不存在;诸如位置、速度等力学量,无法用通常的数字来描述,但可以用抽象的数学结构即矩阵来表达,海森贝格用矩阵形式给出了他的新理论(矩阵力学)。

*** 此后,海森贝格又提出了著名的“不确定性原理”(又称“海森贝格测不准原理”),在一个量子力学系统中,一个运动粒子的位置和它的动量不可被同时确定,位置的不确定性Δx和动量的不确定性Δp是不可避免的,它们的乘积不小于h / 4π(h为普朗克常数),这些误差对于人类来说虽然是微小的,但是在原子研究中并不能被忽略。***

在莱比锡期间,海森贝格为原子核物理学做出了重要贡献,为基本粒子理论引入了内部对称量子数(1932年,1933年),发展了一种铁磁性理论(1928年),和沃尔夫冈·泡利对量子场论进行了开创性研究工作。海森贝格和John Archibald Wheeler同为S矩阵(1942年,1944年)之父,他很早就研究了量子场论的基本长度模型(1938年)。1940年代,他还研究了宇宙射线及其产生的离子碎片,导致不久后在英国发现了第一个介子。

1957年起,海森贝格的研究兴趣转向了等离子体物理和高热原子核反应问题,并与日内瓦国际原子物理研究所紧密合作,他担任该研究所的科学政策委员会主席,并一直是该委员会的成员。在他于1953年成为洪堡基金会主席后,为基金会做了很多促进工作,他邀请各国科学家来德国,并协助他们在德国开展研究工作。

1953年起,他的理论工作偏向基本粒子的统一场理论,这对于他来说,是理解基本粒子物理学的关键。

[编辑] 荣誉

除了获得马克斯·普朗克奖章、德国联邦十字勋章等奖章,诺贝尔物理学奖等奖项外,海森贝格还被布鲁塞尔大学、卡尔斯鲁厄大学和布达佩斯大学授予荣誉博士头衔。他是伦敦皇家学会的会员,英国功绩勋章骑士勋章,他还是格丁根、巴伐利亚、萨克森、普鲁士、瑞典、罗马尼亚、挪威、西班牙、荷兰、罗马、美国等众多科学学会的成员,德国科学院和意大利科学院的院士。1953年成为洪堡基金会的主席。

[编辑] 参考资料

* Nobel Lectures, Physics 1922-1941, Elsevier Publishing Company, Amsterdam, 1965.
* Werner Heisenberg - Biography. The Nobel Foundation. (诺贝尔官方网站关于维尔纳·海森贝格简介)
* Ivan Todorov: Werner Heisenberg. Institut für Theoretische Physik, Universität Göttingen. Göttingen, Germany.
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