測不準原理

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Erwin Schrödinger
1887-1961
薛丁格
認知 心靈 自由意志
生命
DNA, Evolution(演化)
非生命物質
Democritus (460B.C.-370B.C.)
Atomism 原子論 Henri Bergson The Philosophy of Poetry
“In short, bodies and souls as well as objects and
worlds are composed of atoms; natural phenomena
and thinking are movements of atoms; there has
never been and will never be anything other than
atoms, void, and movement.”
Materialism 物質主義 唯物主義 唯物論
Democritus
Epicurus (341B.C.-270 B.C.)
“He was no scholar. He scorned the sciences in general,
equated mathematics and falsehood, and showed
contempt for rhetoric and letters.The important thing was
how to live happily”
“happiness consists of inner peace”
“two concurrent forces constantly threaten our peace of
mind”
 Gods – interfere at every turn
 Death – gateway to hell
Bust of Epicurus
“How can the soul recover the tranquility which it
has lost? It must be shown that the gods take no
part in the daily lives of men, and that death is the
end of everything. “
“Epicurus saw that atomism, better than any other
system, could furnish the proof required by the soul.”
atoms obey mechanical laws ─gods cannot interfere,
no mysterious and supernatural forces!
 soul is simply a combination of atoms, therefore it
decays after death just as the body and all other things
decay─ Death is no evil, for we are completely
destroyed!
物質的組成
物質
原子
10 – 8公分
原子核 電子 質子 中子
夸克
R. P. Feynman
1918-1988
費曼
測不準原理
Uncertainty Principle
海森堡 1927
不確定原理
哥本哈根詮釋與客觀實在
Copenhagen interpretation and objective reality
哥本哈根詮釋與客觀實在
Copenhagen interpretation and objective reality
測量
measurement
奇異的量子
粒子
波
Particle
Wave
兩者是截然不同的概念。粒子不
可能是波,波不可能是粒子。
運動方程式
軌跡
馬克斯威爾(J. C. Maxwell, 1831-1879)
在1860年代以四個數學方程式來描述一切電與
磁的現象。
他並且將光解釋為電磁波,也就是電場與磁場
的振盪。
馬克斯威爾還算出光速 (在以太座標)大約為
每秒30萬公里
光速= c
平面波
電磁波的能量密度和電場強度平
方與磁場強度平方之和成正比,
但和電磁波的頻率沒有關係。
我們可以用干涉現象來證明光不是一種物質。
利用光學方法將來自單一光源的一束光分成
兩束光,讓它們走不同的路徑,然後再把這
兩束光結合起來,並落在屏幕上。如果我們
將兩束光之一檔掉,則另一半會落在屏幕上,
因而出現亮點。但是如果我們讓兩束光都通
過,屏幕上有些地方會變暗,這就證明了光
的兩部份相互消滅了對方。
J. C. Maxwell
馬克斯威爾
但是我們不能假設兩個物體一但放在一起,可以
相互消滅,所以光不可能是一種物質。我們所證
明的是光的一部份可以正好是另一部份的相反,
就如 a正好是  a的相反─無論a是什麼。在
物理量之中,我們發現有些量的正負號可以顛倒
過來,但是有些則不行。例如,在某個方向上的
位移正好是在反方向上同樣位移的相反。這樣的
量不能代表物質,只能代表一種物質中的過程。
所以我們的結論是光不會是一種物質而是一種發
生於某種物質中的過程,(前面所述)第一束光中
發生的過程正好永遠是同一時刻在另一束光中發
生過程的相反,所以當這兩束光合併在一起後,
就不會出現任何過程。
以太的振動
黑體輻射
普朗克
1900
能量是不連續的
愛因斯坦 1905
光子
光打上金屬表
面會將電子打
出來
光電效應
由於紅光(子)照
射而出現的電子
所帶的動能較低
紅光頻率較低
由於藍光(子)照
射而出現的電子
所帶的動能較高
藍光頻率較高
我思索光量子的時間遠多
過我思索相對論的時間
A. Einstein
什麼是目前描述量子世界的最
佳方式(理論架構)?
量子力學、量子場論
量子電動力學(Quantum Electrodynamics,簡稱QED)
是一個很好的例子
Niels Bohr
1885 - 1962
波爾
Quantum
Electrodynamics
R. P Feynman
理查‧費曼
量子電動力學
1918-1988
Grand Principle: The probability(機率) of
an event is equal to the square(平方) of
the length(長度) of an arrow called the
“probability amplitude (機率幅).”
General Rule for drawing arrows if an event
can happen in alternative ways: Draw an
arrow for each way, and then combine the
arrows(“add”them) by hooking the head of
one to the tail of the next. The final arrow is
the one whose square gives the probability of
the entire event.
Only A open ,1%
Only B open, 1%
Both A & B open, from 0 % to 4%
How does the photon know?
“either one way or the other” is false.
對於光子來說,在進入偵測器之前的
狀態是不能用古典觀念去看待的。愛
因斯坦曾問說:「如果妳不去看月亮,
月亮還會在那裡嗎?」
光子沒有軌跡可言!
但沒有軌跡的粒子又是什麼東西?
光子和電子既不是(古典概念中
的)粒子也不是(古典概念中的)
波。
沒有軌跡的粒子?
古典的狀況:粒
子沿著某條路徑
從A到B。
量子的狀況:我
們只能計算如果
粒子某時刻位於A,
它稍後出現於B的
機率有多大。
測不準原理
在量子力學這一套理論中,粒子並不具
有單一軌跡。但是我們是否能夠從實驗
中測量出粒子的軌跡?如果可以,量子
力學就會「出大麻煩」!
測不準原理:
實驗永遠無法告訴我們粒子的軌跡為何。
(如果我們希望保留粒子的量子特性)
海森堡
Heisenberg: The Physical Principle of Quantum Theory, p.20
“This formulation makes it clear that the uncertainty
relation does not refer to the past; if the velocity of the
electron is at first known and the position then exactly
measured, the position for times previous to the
measurement may be calculated. Then for these past
times ∆p∆q is smaller than the usual limiting value, but
this knowledge of the past is of a purely speculative
character, since it can never (because of the
measurement) be used as an initial condition in any
calculation of the future progress of the electron and
thus cannot be subjected to experimental verication. It
is a matter of personal belief whether such a
calculation concerning the past history of the electron
can be ascribed any physical reality or not.”
Feynman: The Feynman Lectures on Physics Vol. 3,
p2-3
“Sometimes people say quantum mechanics is all wrong.
When the particle arrived from the left, its vertical momentum
was zero. And now that it has gone through the slit, its
position is known. Both position and momentum seem to be
known with arbitrary accuracy. It is quite true that we can
receive a particle, on reception determine what its position is
and what its momentum would have had to have been to
have gotten there. That is true, but that is not what the
uncertainty relation refers to. The uncertainty relation refers
to the predictability of a situation, not remarks about the
past.‧‧‧The fact that it went through the slit no longer
permits us to predict the vertical momentum.”
Copenhagen interpretation: (Bohr,
Heisenberg)
Prior to the measurement of an object, the
object has no definite physical existence.
Prior to a measurement, an object’s existence
and properties cab be described only by
various probabilities.
愛因斯坦的床!
測不準原理 (Uncertainty Principle):
我們不可能設計出一種裝置既可
以決定電子從那個孔通過,又可
以不過於干擾電子地讓干涉圖樣
保留下來。
我思索光量子的時間遠多
過我思索相對論的時間
A. Einstein
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