Bulletin Special Supplement Nov 1970

E n g l i s h V e r s io n o f D r . T s u n g - D a o L E E ' s A d d r e s s I t is a deep honour and a g rea t pleasure fo r a ll o f us to be here to receive our hono ra ry deg rees . Fo r me, th is is an especially g ra tify ing experience. The Chinese U n ive rs ity o f Hong Kong, though established no t too long ago, is a lready an in te rna tio na lly renowned in s titu tio n th a t represents the un ifica tion o f two cu ltu re s : East and West. In th is respect, the s p irit o f th is Un ive rsity also m irro rs my own academic experiences. W h ile my research has been done almost e n tire ly in the Un ited States, most o f my education was received in China. These ea rly periods in China have been p a rtic u la rly in fluen tia l in shaping my la te r th in k in g towards science. As you a ll know , h is to rica lly there, are some basic differences in the a ttitude towa rds natu re between these two cultures. In the West, a t least in the past ， one adopts more the mechanistic viewpo in t, and the emphasis has been more on how to analyse and to conquer nature, w h ile in the East, one takes more the ph ilosophical a ttitude , and concerns more on how to understand and to be in harmony w ith nature . These two a ttitudes, though d iffe ren t, are ac tua lly comple ments o f each o th e r ； they can be jo ined toge the r to fo rm a single unified view , wh ich , as we shall see, is ra th e r s im ila r to the view po in t adopted in modern physics. The present fo rm o f physics has its o rig in in the Renaissance period o f the West. We ca ll the physics developed du ring the period from Renaissance to the ea rly tw en tie th century, "classical physics” . Classical physics has its founda tion in New tonian mechanics; it comp lete ly adopts a mechanistic po in t o f view. I t regards the fu tu re as to ta lly determ ined from the present. To illu s tra te th is view, we may consider the th row ing o f a ba ll. Acco rd ing to New tonian mechanics, in o rde r to p red ic t the pa th o f the ba ll, a ll we need is to determ ine the position and the ve loc ity o f the ba ll a t the beginning. The more accurate is the in itia l determ ina tion, the more accurate w ill be the fin a l p red iction , and there is no theo re tica l lim ita tio n to such an accuracy. Therefore , in classical physics, i f we can f u lly contro l the in itia l cond ition o f any object, then we can f u lly determ ine its fu tu re . This is, then, a p u re ly mechanistic po in t o f view . One can, o f course, app ly classical physics to the whole Universe. We ourselves co llec tive ly fo rm on ly a ra th e r small ob ject in the Universe. Acco rd ing to the same v iew , o u r fu tu re is then also a lready comp lete ly determ ined by our present configu ra tion , wh ich in tu rn is completely determ ined from our past. Th is mechanistic view , the re fo re , leads to the so-called “ determ inism ” . However, since the beginning o f th is centu ry there have been enormous strides made in physics. F rom our studies th a t range from molecules, atoms ， nuclei, fundam en ta l particles to astrophysics, we rea lize th a t the classical physics is only an app roxima tion. The mechanistic view is no t accordance w ith nature, and New tonian mechanics must be replaced by quantum mechanics. In th is connec tion , I w ish to b rie fly discuss one o f the fundam en ta l p rincip les in quantum mechanics. I t is ca lled the unce rta in ty p rinc ip le . — 1 0 —