没有合适的资源？快使用搜索试试~ 我知道了~

首页Principles of Quantum Mechanics(Dirac).pdf

# Principles of Quantum Mechanics(Dirac).pdf

需积分: 50 51 下载量 48 浏览量
更新于2023-03-03
评论 2
收藏 1.59MB PDF 举报

非常经典的量子力学教程，值得参考学习，内容包括最基础的数学部分，欢迎下载阅读。pdf版本！适合各个阶段的读者

资源详情

资源评论

资源推荐

THE

PRINCIPLES

OF

QUANTUM MECHANICS

by

P. A. M. DIRAC

Typewritten by D. B. Ling

Department of Physics, Anhui University, Hefei

lingdb@ahu.edu.cn

21 November, 2006

PREFACE TO THE FOURTH EDITION

The main change from the third edition is that the chapter on quantum

electrodynamics has been rewritten. The quantum electrodynamics given

in the third edition describes the motion of individual charged particles

moving through the electromagnetic ﬁeld, in close analogy with classical

electrodynamics. It is a form of theory in which the number of charged

particles is conserved and it cannot be generalized to allow of variation of

the number of charged particles.

In present-day high-energy physics the creation and annihilation of

charged particles is a frequent occurrence. A quantum electrodynamics

which demands conservation of the number of charged particles is there-

fore out of touch with physical reality. So I have replaced it by a quan-

tum electrodynamics which includes creation and annihilation of electro-

positron pairs. This involves abandoning any close analogy with classical

electron theory, but provides a closer description of nature. It seems that

the classical concept of an electron is no longer a useful model in physics,

except possibly for elementary theories that are restricted to low-energy

phenomena.

P. A. M. D.

st. john’s college, cambridge

11 May 1957

ii

FROM THE PREFACE TO THE FIRST EDITION

The methods of progress in theoretical physics have undergone a vast

change during the present century. The classical tradition has been to con-

sider the world to be association of observable objects (particles, ﬂuids,

ﬁelds, etc.) moving about according to deﬁnite laws of force, so that one

could form a mental picture in space and time of the whole scheme. This

led to a physics whose aim was to make assumptions about the mecha-

nism and forces connecting these observable objects, to account for their

behavior in the simplest possible way. It has become increasingly evident

in recent times, however, that nature works on a different plan. Her fun-

damental laws do not govern the world as it appears in our mental picture

in any very direct way, but instead they control a substratum of which we

cannot form a mental picture without introducing irrelevancies. The for-

mulation of these laws requires the use of the mathematics of transforma-

tions. The important things in the world appear as the invariants (or more

generally the nearly invariants, or quantities with simple transformation

properties) of these transformations. The things we are immediately aware

of are the relations of these nearly invariant to be a certain frame of ref-

erence, usually one chosen so as to introduce special simplifying features

which are unimportant from the point of view of general theory.

The growth of the use of transformation theory, as applied ﬁrst to rel-

ativity and later to the quantum theory, is the essence of the new method

in theoretical physics. Further progress lies in the direction of making

our equations invariant under wider and still wider transformations. This

state of affairs is very satisfactory from a philosophical point of view, as

implying an increasing recognition of the part played by the observer in

himself introducing the regularities that appear in his observations, and a

lack of arbitrariness in the ways of nature, but in makes things less easy

for the learner of physics. The new theories, if one looks apart from their

mathematical setting, are built up from physical concepts which cannot

be explained in terms of things previously known to the student, which

cannot even be explained adequately in words at all. Like the fundamen-

tal concepts (e.g. proximity, identity) which every one must learn on his

arrival into the world, the newer concepts of physics can be mastered only

by long familiarity with their properties and uses.

From the mathematical side the approach to the new theories presents

no difﬁculties, as the mathematics required(at any rate that which is re-

quired for the development of physics up to the present) is not essentially

different from what has been current for a considerable time. Mathemat-

ics is the tool specially suited for dealing with abstract concepts of any

kind and there is no limit to its power in this ﬁeld. For this reason a book

on the new physics, if not purely descriptive of experimental work, must

be essentially mathematical. All the same the mathematics is only a tool

and one should learn to hold the physical ideas in one’s mind without

reference to the mathematical form. In this book I have tried to keep the

iii

iv FROM THE PREFACE TO THE FIRST EDITION

physics to the forefront, by beginning with an entirely physical chapter

and in the later work examining the physical meaning underlying the for-

malism wherever possible. The amount of theoretical ground one has to

cover before being able to solve problems of real practical value is rather

large, but this circumstance is an inevitable consequence of the funda-

mental part played by transformation theory and is likely to become more

pronounced in the theoretical physics of the future.

With regard to the mathematical form in which the theory can be pre-

sented, an author must decide at the outset between two methods. There

is the symbolic method, which deal directly in an abstract way with the

quantities of fundamental importance (the invariants, etc., of the transfor-

mations) and there is the method of coordinates or representations, which

deals with sets of numbers corresponding to these quantities. The second

of these has usually been used for the presentation of quantum mechan-

ics (in fact it has been used practically exclusively with the exception of

Weyl’s book Gruppentheotie und Quantenmechanik). It is known under one

or other of the two names ‘Wave Mechanics’ and ‘Matrix Mechanics’ ac-

cording to which physical things receive emphasis in the treatment, the

states of a system or its dynamical variables. It has the advantage that the

kind of mathematics required is more familiar to the average student, and

also it is the historical method.

The symbolic method, however, seems to go more deeply into the na-

ture of things. It enables one to express the physical laws in a neat and

concise way, and will probably be increasingly used in the future as it

becomes better understood and its own special mathematics gets devel-

oped. For this reason I have chosen the symbolic method, introducing the

representatives later merely as an aid to practical calculation. This has

necessitated a complete break from the historical line of development, but

this break is an advantage through enabling the approach to the new ideas

to be made as direct as possible.

P. A. M. D.

st. john’s college, cambridge

29 May 1930

v

Eö{

Ú?ÔnÆ[).£P. A. M. Dirac¤ù5þfåÆn6

´éØþfåÆ¡²;Ö§±îêÆÚg¤NXª¶u

"3·þÆÿ§Òk¤ª§´ýsmÖùÜÍ

m´2006c¢G"ÖÜ©Ù!BkùÀÄ§F"U

3SÆÔnÆ§±ùÖ¡)áùÇþfåÆ"

´ùùÇªÚy1þfåÆÆ¿ØoN"ù·B

CÏ{§^ùÖá§?1þfåÆ§VÆ

}Á"

¢Ã´3¥IºÃ{ïùÖ½K<"ÆÑQ

u1979cÑL¥È§´y3vk{ïù"ù¹

e§·U{Ò´^L

A

T

E

XEùÜ¬§u´Ò)y3ù

E"TE¥)Öc 11 ÙSN§ù ´ ·ù V §

CXSN"3L§¥§·ë¥È§?UO<MØ"Ó

ÎÜy3S.§UÜ©ÎÒµÎ\þˆ§r f¯K

¥ÎÒU¤y3ÊHæ^)«Î/ª"~HÑ

<Ø½ö6w{§e/3µ¡þ"

TE´S ÆÀ? ù§ÓÆO§==^SÜ6

ÆS^§¦^öØ¿DÂ"áý?Û/ªû1"XJ

á±,«/ªÑy3½|§@oùEòÊDÂ"

3"duæ^L

A

T

E

Xü§ÄkaT

E

XMEö Donald E.

Knuth§vk¦ù{u²§üÑùJ´J± "a

³5k)Ú¨¬å¬§éõ±"Ñ3¦[Éî´ê§ùv

±y·küU¿°åéX>Mèúª"aSÆ,°P§

¦õg/·200§¦·^|±=ÝF"a®ÆÔnÆ+

Æ¬§¦Rx·éõ²;Ö§)y3Ãþù).¥©

"aSÆÔnÆ04?@ÏÚ·?ØþfåÆ¯f§

¦J¯!?ØÚ)4·ÉÃf"a·I1§´Ï¦

¢D·BèxNÚU=ÉÕ%§·â±3c

õmpj±¤ù¡Øvó"

¶8c¤c8ÙSN§¡SN¬ºYÖà"·¿

vkæ^ùÖVÆ^Ö§´kþÇSNáuùÍ

§¤±ùÀ?ù§ÄÀëÖ"ïÆµ).Ö¥ú

ª@ýí§©iÜ©EÖ"

(²µduEmk§¿Øyùp¡SN("

2007c12§'ÀÅuSÆÇ«Ø

剩余174页未读，继续阅读

qq810902374

- 粉丝: 1
- 资源: 19

上传资源 快速赚钱

- 我的内容管理 收起
- 我的资源 快来上传第一个资源
- 我的收益 登录查看自己的收益
- 我的积分 登录查看自己的积分
- 我的C币 登录后查看C币余额
- 我的收藏
- 我的下载
- 下载帮助

#### 会员权益专享

### 最新资源

- zigbee-cluster-library-specification
- JSBSim Reference Manual
- c++校园超市商品信息管理系统课程设计说明书(含源代码) (2).pdf
- 建筑供配电系统相关课件.pptx
- 企业管理规章制度及管理模式.doc
- vb打开摄像头.doc
- 云计算-可信计算中认证协议改进方案.pdf
- [详细完整版]单片机编程4.ppt
- c语言常用算法.pdf
- c++经典程序代码大全.pdf
- 单片机数字时钟资料.doc
- 11项目管理前沿1.0.pptx
- 基于ssm的“魅力”繁峙宣传网站的设计与实现论文.doc
- 智慧交通综合解决方案.pptx
- 建筑防潮设计-PowerPointPresentati.pptx
- SPC统计过程控制程序.pptx

资源上传下载、课程学习等过程中有任何疑问或建议，欢迎提出宝贵意见哦~我们会及时处理！
点击此处反馈

安全验证

文档复制为VIP权益，开通VIP直接复制

信息提交成功

## 评论0