查看了一下1957年诺贝尔物理奖颁奖仪式上诺贝尔物理奖委员会成员O.B. Klein教授的讲话，李政道排在杨振宁前面。这应该代表了诺贝尔物理奖委员的意见。全文如下：

Award Ceremony Speech

Presentation Speech by Professor O.B. Klein, member of the Nobel Committee for Physics

Your Majesties, Your Royal Highnesses, Ladies and Gentlemen.

The Nobel Prize in Physics to Professor Tsung Dao Lee and Professor Chen NingYang for this year is concerned with some of the fundamental physicalprinciples, the so-called parity laws - in the first place the symmetry of Naturewith respect to right and left - in their application to elementary particlesand their reactions.

When during this century the old dream about atoms came true, it soon becameclear not only that reality is by far richer than was the dream but also considerablydifferent from it. The atoms that were found and which one learnt to count andto measure did by no means correspond to the ideal of indivisibility andunchangeability of the old atomists. But instead, there appeared a hithertounknown, strangely unvisualizable feature of indivisibility in all atomicprocesses and therefore also behind all usual physical events, without whicheverything in the world would be in flux. The new edifice of laws, which wasthe consequence of these discoveries - it is called quantum theory - containsthe laws of earlier physics as a correct but greatly simplified limiting case.They have a similar relationship to the laws of atomic physics as an airphototo a near-picture of the same landscape.

The lesson learnt from quantum theory made that the literally unchangeableatoms of the old philosophers were hardly seriously sought in thoseparticles-electrons, protons, and neutrons - from which atoms are made. As thename elementary particles under which they are summarized would seem toindicate, there was nevertheless a certain inclination towards this direction.But already the ordinary elementary particles are by no means unchangeable,which is still more strongly the case with the lot of new, similar particlesdiscovered during later years, the transformations of which now stand at thecentre of interest of atomic physicists. In our attempts to find a theory whichcomprehends all the new facts concerning old and new elementary particles,certain wittingly unreal, symbolic particles appear in our equations, whichwith a little good will could be regarded as the eternally immutable atoms ofphilosophers. Of the real elementary particles we could then, followingLao-tse, the old Chinese thinker, say: "The elementary particles, whichcould be defined, are not the eternal elementary particles". Lao-tse didnot talk of elementary particles, of course, but of Tao, the deepest principleof life. And physics is certainly considerably simpler than human life. Andthere we have powerful auxiliaries in the art of experimentation andmathematics.

As to mathematics and elementary particles it has, in the first place, led totwo theories, each of which has been developed by a Nobel Prize winner inPhysics, Dirac and Fermi. Hereby the former theory is the outermostwing of the edifice of quantum mechanics, while the latter may be regarded asthe first, still unfinished room in the new edifice of elementary particlelaws. But they are both concerned with electrons and thus border on oneanother.

But what has the question of right and left to do with elementary particlephysics? Well, in the first place only in a negative way, in that it wasassumed almost tacitly, that elementary particle reactions are symmetric withrespect to right and left. This assumption was to play an important part in theelaboration of Fermi's theory. That this assumption was made was very natural,not least in view of the mentioned theory of Dirac, according to which itlooked as if the electrons, the best known elementary particles, possessed nofeature which would permit a distinction between right and left. In fact, mostof us were inclined to regard the symmetry of elementary particles with respectto right and left as a necessary consequence of the general principle ofright-left symmetry of Nature. Thanks to Lee and Yang and the experimentaldiscoveries inspired by them we now know that this was a mistake.

The starting-point of Lee and Yang in their revision of the whole question ofright-left symmetry in elementary particle reactions were certain strangeobservations concerning a kind of new particles called K mesons, which lookedas if they were in contrast with the assumption mentioned. Even if theseobservations puzzled greatly many physicists, it was only Lee and Yang whoseriously took the consequences of them, in that they asked themselves whatkind of experimental support there was for the assumption that all elementaryparticle processes are symmetric with respect to right and left. The result oftheir investigation was unexpected, namely that the validity of the symmetryassumption even in the best known processes had no experimental supportwhatsoever, the reason being that all experiments had been so arranged as togive the same result whether the assumption was valid or not. As if one hadthought that Olav Tryggveson had his heart in the middle of the body because hewas equally skilled with the left as with the right hand. Lee and Yang did notconfine themselves to this negative statement but devised a number ofexperiments which would make it possible to test the right-left symmetry indifferent elementary particle transformations, and proposed them to theirexperimental colleagues. The first of these experiments was carried out by theChinese physicist, Mrs. C.S. Wu and her collaborators. Very schematically itconsisted in the following. Atomic nuclei of a radioactive isotope of the metalcobalt were exposed at very low temperature to a magnetic field - they arethemselves small magnets - whereby they became directed just like compassneedles. The distribution as to direction of the electrons due to radioactivitywas then investigated.

Let us assume that the magnetic field is created by means of a coil placed likea spool of thread on a table, and that the electric current is flowingcounterclockwise in the wire. Then the north poles of the cobalt nuclei will bedirected upwards. The experiment, now, gave the result that the electrons fromthe radioactive process with this arrangement were preferentially throwndownwards towards the floor. From this it follows unambiguously that theprocess lacks that right-left symmetry, which one had earlier assumed. Thus, bymeans of this experiment it could be explained to a person, who did not know it- let us say an inhabitant of a distant stellar system - what we mean by rightand left. In fact, it would be sufficient to ask him to arrange the experimentso as to make the preferential direction of the electrons point downwards. Thecurrent will then have the same direction as that in which he has to turn atthe command "left face".

However - and this is a thing of the utmost importance for the incorporation ofthe new discoveries into our edifice of physical laws - the person on thedistant planet will be able to follow our prescriptions only if he knows whatwe mean by the direction of an electric current. And to know this he must knowthat our atoms and his are made up of the same elementary particles. We know,however, that not only are there double sets of electrons - positive andnegative - but that the same holds for protons and neutrons, the buildingstones of atomic nuclei. It is therefore possible that his atoms contrary toours would consist of positive electrons and negative nuclei. If they did, hewould judge the direction of the current opposite to what we would do, with theresult that he would call right left and left right. In stating this we havetacitly made an assumption which is not quite confirmed as yet but which, asfar as the experiments go, seems probable, namely that the results of allexperiments performed with the opposite kind of elementary particles would bejust such as to reestablish the right-left symmetry. With other words, oneshould be able to regard the antiparticles not only as the electric oppositesof the particles but also as their mirror images.

Professor Lee and Professor Yang. In the very incomplete sketch of yournew work I have just made in Swedish, time has not allowed me to mention themany other beautiful contributions to theoretical physics made by each one ofyou, nor could I at all do justice to the enthusiasm your new achievement hasaroused among physicists. Through your consistent and unprejudiced thinking youhave been able to break a most puzzling deadlock in the field of elementaryparticle physics where now experimental and theoretical work is pouring forthas the result of your brilliant achievement.

It is with great satisfaction, therefore, that The Royal Swedish Academy ofSciences has decided to award you this year's Nobel Prize for Physics for yourfundamental contributions to this branch of science.

On behalf of the Academy I wish to extend to you our heartiest congratulationsand now ask you to receive from the hands of His Majesty the King the NobelPrize for Physics for the year 1957.

From Nobel Lectures, Physics 1942-1962, ElsevierPublishing Company, Amsterdam, 1964