搜档网
当前位置:搜档网 › Lecuture12 special theory of relativity

Lecuture12 special theory of relativity

Lesson 12 Special Theory of

Relativity

Objectives

●Concept: Length Contraction, Time

Dilation, Electron Cloud, Energy Level ●Theory of Special :Relativity, Wave-

Particle Duality of Matter Wave

Something about Eintein

1.Born on March 14,1879, in ULM, Germany;

2. In 1900, received diploma, and found work in the Swiss Patent Office in Berne;

3. In 1905, published three papers of immense importance;

4. In 1915, published his paper on the general theory of relativity;

5. In 1933, immigrated to the United States and joined the Institute for Advanced Study in Princeton, New Jersey;

What is relativity all about?

Relativity deals with:

Measurements of events;

Transforming of such measurements between reference frames that move relative to each other.

Where and when they happen?

How much they are separated in space and in time?

How was the special theory found?

1. Contradictions between classical mechanics and electromagnetism.

A hypothetical medium Motion is relative,

Laws of mechanics are the same in any inertial reference frames .

——Ether

Einstein considered that all physics laws should be the same in any inertial reference frames.

Some conclusions we’ve gotten in classical mechanics m/s

1038

?=c One conclusion of electromagnetism is 2. Solving methods:

Two Postulates

1.The relativity postulate

2. The speed of light postulate

The laws of physics are the same for

observers in all inertial reference frames. No frame is preferable.The speed of light in vacuum has the same value c in all directions and in all inertial reference frames.

The Relativity of Simultaneity

If two observers are in relative motion, they will not, in general, agree as to whether two events are simultaneous. If one observer finds them to be simultaneous, the other generally will not, and conversely.

Simultaneity is not an absolute concept but a relative one, depending on the motion of the observer.

v

'

x '

y 'o 1

2

12

36

9

12

3

6

9'

x '

y 'o 1

2

x

y o v

12

36

9

12

36

912

3

6

9

Time Dilation

When two events occur at the same location in an inertial reference frame, the time interval between them, measured in that frame, is called the proper time

interval or the proper time .

x

y

o

s

d

12

3

6

9

12

3

6

91

x 2

x 12

36

9'y x

'

x y v

o '

o s'

s d

B

12

3

69Measurements of the same time interval from any other inertial reference frame are always greater.

Length Contraction

The length of an object

measured in the rest frame of the object is its proper length or rest length .

x

y

o

z

s

1

x '

y 'x v

'

o '

z '

s B

A

γ

β0

2

01l l l =

-=Measurements of the length from any other inertial reference frame that is in relative motion parallel to that length are always less than the proper length.

Relativistic Mass

2

01β

-=

m m ——rest mass

0m 2

0)

(1c

v t t -=

2

)

(1c

v l l -=20

)

(1c

v m m -=

Classical mechanics results are approximations of special theory of relativity at low speed.

相关主题