Education Next - Winter 2006

Tom Carter

Description

• cours - matière potentielle : life
• cours - matière potentielle : students
• cours - matière potentielle : year
• cours - matière potentielle : with a greater percentage of cross
• cours - matière potentielle : desegregation
• expression écrite
• cours - matière potentielle : activities
• cours - matière potentielle : students with the highest grades
• cours - matière potentielle : into two groups of equal size
• cours - matière potentielle : for white students
• cours - matière potentielle : research
• cours - matière potentielle : edge
• cours - matière potentielle : for students to self
• cours - matière potentielle : advantage

IL LU ST R AT IO N BY K EV IN G H IG LI O N E

• most studies of academic achievement
• social sanctions
• successful members
• ethnic friendships
• ference among ethnic groups
• white students
• achievement
• school
• group
• students

Sujets

• Student
• Déségrégation
• Research
• Advantage

Informations

• Publié par: orzi
• Nombre de lectures: 12
• Langue: English

Extrait

WHAT IS LIFE? numerous sections were originally intended to be
ERWIN SCHRODINGER marginal summaries, and the text of every
First published 1944 chapter should be read in continuo. E.S.
Dublin September 1944
What is life? The Physical Aspect of the Living
Cell. Homo liber nulla de re minus quam de morte
Based on lectures delivered under the auspices of cogitat; et ejus sapientia non mortis sed vitae
the Dublin Institute for Advanced Studies at meditatio est. SPINOZA'S Ethics, Pt IV, Prop.
Trinity College, Dublin, in February 1943. 67
To the memory of My Parents
(There is nothing over which a free man ponders
Preface less than death; his wisdom is, to meditate not on
A scientist is supposed to have a complete and death but on life.)
thorough I of knowledge, at first hand, of some
subjects and, therefore, is usually expected not to CHAPTER 1
write on any topic of which he is not a life, The Classical Physicist's Approach to the Subject
master. This is regarded as a matter of noblesse
oblige. For the present purpose I beg to renounce This little book arose from a course of public
the noblesse, if any, and to be the freed of the lectures, delivered by a theoretical physicist to an
ensuing obligation. My excuse is as follows: We audience of about four hundred which did not
have inherited from our forefathers the keen substantially dwindle, though warned at the
longing for unified, all-embracing knowledge. outset that the subject-matter was a difficult one
The very name given to the highest institutions and that the lectures could not be termed popular,
of learning reminds us, that from antiquity to and even though the physicist’s most dreaded
throughout many centuries the universal aspect weapon, mathematical deduction, would hardly
has been the only one to be given full credit. But be utilized. The reason for this was not that the
the spread, both in and width and depth, of the subject was simple enough to be explained
multifarious branches of knowledge by during without mathematics, but rather that it was much
the last hundred odd years has confronted us too involved to be fully accessible to
with a queer dilemma. We feel clearly that we mathematics. Another feature which at least
are only now beginning to acquire reliable induced a semblance of popularity was the
material for welding together the sum total of all lecturer's intention to make clear the fundamental
that is known into a whole; but, on the other idea, which hovers between biology and physics,
hand, it has become next to impossible for a to both the physicist and the biologist. For
single mind fully to command more than a small actually, in spite of the variety of topics
specialized portion of it. I can see no other involved, the whole enterprise is intended to
escape from this dilemma (lest our true who aim convey one idea only -one small comment on a
be lost for ever) than that some of us should large and important question. In order not to lose
venture to embark on a synthesis of facts and our way, it may be useful to outline the plan very
theories, albeit with second-hand and incomplete briefly in advance. The large and important and
knowledge of some of them -and at the risk of very much discussed question is: How can the
making fools of ourselves. So much for my events in space and time which take place
apology. The difficulties of language are not within the spatial boundary of a living organism
negligible. One's native speech is a closely fitting be accounted for by physics and chemistry? The
garment, and one never feels quite at ease when preliminary answer which this little book will
it is not immediately available and has to be endeavor to expound and establish can be
replaced by another. My thanks are due to Dr summarized as follows: The obvious inability of
Inkster (Trinity College, Dublin), to Dr Padraig present-day physics and chemistry to account for
Browne (St Patrick's College, Maynooth) and, such events is no reason at all for doubting that
last but not least, to Mr S. C. Roberts. They were they can be accounted for by those sciences.
put to great trouble to fit the new garment on me
and to even greater trouble by my occasional STATISTICAL PHYSICS. THE
reluctance to give up some 'original' fashion of FUNDAMENTAL W DIFFERENCE IN
my own. Should some of it have survived the STRUCTURE
mitigating tendency of my friends, it is to be put That would be a very trivial remark if it were
at my door, not at theirs. The head-lines of the meant only to stimulate the hope of achieving in the future what has not been achieved in the past. calling the periodic crystal one of the most
But the meaning is very much more positive, viz. complex objects of his research, I had in mind
that the inability, up to the present moment, is the physicist proper. Organic chemistry, indeed,
amply accounted for. Today, thanks to the in investigating more and more complicated
ingenious work of biologists, mainly of molecules, has come very much nearer to that
geneticists, during the last thirty or forty years, 'aperiodic crystal' which, in my opinion, is the
enough is known about the actual material material carrier of life. And therefore it is small
structure of organisms and about their wonder that the organic chemist has already
functioning to state that, and to tell precisely made large and important contributions to the
why present-day physics and chemistry could not problem of life, whereas the physicist has made
possibly account for what happens in space and next to none.
time within a living organism. The arrangements
of the atoms in the most vital parts of an THE NAIVE PHYSICIST'S APPROACH TO
organism and the interplay of these arrangements THE SUBJECT
differ in a fundamental way from all those After having thus indicated very briefly the
arrangements of atoms which physicists and general idea -or rather the ultimate scope -of our
chemists have hitherto made the object of their investigation, let me describe the line of attack. I
experimental and theoretical research. Yet the propose to develop first what you might call 'a
difference which I have just termed fundamental naive physicist's ideas about organisms', that is,
is of such a kind that it might easily appear slight the ideas which might arise in the mind of a
to anyone except a physicist who is thoroughly physicist who, after having learnt his physics
imbued with the knowledge that the laws of and, more especially, the statistical foundation of
physics and chemistry are statistical throughout. his science, begins to think about organisms and
For it is in relation to the statistical point of view about the way they behave and function and who
that the structure of the vital parts of living comes to ask himself conscientiously whether
organisms differs so entirely from that of any he, from what he has learnt, from the point of
piece of matter that we physicists and chemists view of his comparatively simple and clear and
have ever handled physically in our laboratories humble science, can make any relevant
or mentally at our writing desks. It is well-nigh contributions to the question. It will turn out that
unthinkable that the laws and regularities thus he can. The next step must be to f compare his
discovered should happen to apply immediately theoretical anticipations with the biological facts.
to the behaviour of systems which do not exhibit It will then turn out that -though on the whole his
the structure on which those laws and regularities ideas seem quite sensible -they need to be
are based. The non-physicist cannot be expected appreciably amended. In this way we shall
even to grasp let alone to appreciate the gradually approach the correct view -or, to put it
relevance of the difference in ‘statistical more modestly, the one that I propose as the
structure’ stated in terms so abstract as I have correct one. Even if I should be right in this, I do
just used. To give the statement life and colour, not know whether my way of approach is really
let me anticipate what will be explained in much the best and simplest. But, in short, it was mine.
more detail later, namely, that the most essential The 'naive physicist' was myself. And I could not
part of a living cell-the chromosome fibre may find any better or clearer way towards the goal
suitably be called an aperiodic crystal. In physics than my own crooked one.
we have dealt hitherto only with periodic
crystals. To a humble physicist's mind, these are WHY ARE THE ATOMS SO SMALL?
very interesting and complicated objects; they A good method of developing 'the naive
constitute one of the most fascinating physicist's ideas' is to start from the odd, almost
and complex material structures by which ludicrous, question: Why are atoms so small? To
inanimate nature puzzles his wits. Yet, compared begin with, they are very small indeed. Every
with the aperiodic crystal, they are rather plain little piece of matter handled in everyday life
and dull. The difference in structure is of the contains an enormous number of them. Many
same kind as that between an ordinary wallpaper examples have been devised to bring this fact
in which the same pattern is repeated again and home to an audience, none of them more
again in regular periodic