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The essays in the first part of this book deal mainly with matters of fact. Those which follow are more speculative. Haldane advanced genetics, population biology and evolutionary theory. This volume emphasizes important developments in natural sciences in the early-20th century. It describes Haldane's views on society, art, religion and economy as seen through the eyes of a politically alert major scientist.

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Publié par	Rare Treasure Editions
Date de parution	05 novembre 2021
Nombre de lectures	1
EAN13	9781774642733
Langue	English

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Possible Worlds and Other Essays
by J. B. S. Haldane

First published in 1927
This edition published by Rare Treasures
Victoria, BC Canada with branch offices in the Czech Republic and Germany
Trava2909@gmail.com
All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval system, except in the case of excerpts by a reviewer, who may quote brief passages in a review.
Possible Worlds

AND OTHER ESSAYS

by J. B. S. HALDANE

PREFACE
T HE essays collected in this book have mostly,but not all, appeared in print. In Europe theyhave appeared in the Rationalist Annual , the Bermondsey Book , the Nation , the Daily Mail , the WorldTo-Day , the Manchester Guardian , the Graphic , the Weekly Dispatch , Discovery , Modern Science , and the Haagsche Maandblad . In America they have beenpublished by Harper’s Magazine , the Forum , the Century Magazine , the Atlantic Monthly , and the NewRepublic . They have been written in the intervals ofresearch work and teaching, to a large extent in railwaytrains. Many scientific workers believe that theyshould confine their publications to learned journals.I think, however, that the public has a right to knowwhat is going on inside the laboratories, for some ofwhich it pays. And it seems to me vitally importantthat the scientific point of view should be applied, so faras is possible, to politics and religion. In such spheresthe scientific man cannot, of course, speak with thesame authority as when he is describing the results ofresearch; and in so far as he is scientific he must tryto suppress such of his own views as have no morescientific backing than those of the man in the street.
Some of these essays are on medical topics. As I donot hold a medical degree I can speak more freely thana qualified physician. But if a doctor cannot answerquestions with regard to individual cases which he hasnot examined, an unqualified person is still less able todo so. I have rarely written on a medical subjectwithout receiving letters from would-be patients. It isobvious that I cannot answer such communications.
The essays in the first part of this book deal mainlywith matters of fact. Those which follow are morespeculative. In scientific work the imagination mustwork in harness. But there is no reason why it shouldnot play with the fruits of such work, and it is perhapsonly by so doing that one can realize the possibilitieswhich research work is opening up. In the past theseresults have always taken the public and the politicianscompletely by surprise. The present disturbed conditionof humanity is largely the result of this unpreparedness.If the experience is not to be repeatedon a still greater scale it is urgent that the average manshould attempt to realize what is happening to-day inthe laboratories.

ON SCALES
‘L E silence éternel de ces espaces infinies m’effraie,’said Pascal, as he looked at the stars andbetween them, and his somewhat irrationalterror has echoed down the centuries.
It is fashionable to find the distance of even thenearest fixed stars inconceivable, and to make noattempt to grapple with the number of atoms in one’sthumbnail. And this habit of mind makes it quiteunnecessarily hard for the plain man to understandthe main results of modern science, many of which arequite straightforward, but happen to involve ratherlarge numbers. For Pascal’s attitude is neitherscientific nor religious. ‘I shall soon be above thatfellow,’ said Sir Thomas More, as he took his last lookat the sun before his execution, and the modernastronomer views the sun as a rather small but quitefairly typical star in a particular cluster.
There is no reason to suppose that interstellar spaceis infinite. Very probably the whole of space is finite,and certainly the distances of all the visible heavenlybodies are within the range of the human mind. Infinityis the prerogative of mind rather than matter.We can reason about it, but we certainly cannot anddo not observe it. As for the silence of interstellarspace, one could not live in it, and hence could notdiscover whether it is silent or not. But if one wereshut up in a steel box in it, like Jules Verne’s travellersto the moon, one would probably hear fairly frequently(at least in the neighbourhood of a star) the soundmade by a minute dust particle moving at enormousspeed hitting one’s abode.
The average man complains that he cannot imaginethe eighteen billion miles which is the unit in modernastronomy when once we leave the solar system, andis called a parsec because the apparent parallax of astar at this distance is a second; in other words theearth’s orbit from a parsec away would subtend anangle of a second, or look as large as a halfpenny atsix thousand yards’ distance. Of course one cannotimagine a parsec. But one can think of it, and thinkof it clearly.
For every educated person learns a process which isreally of extraordinary difficulty, and involves a stupendouschange of scale. That process is map-reading.In ordinary life our practical unit is about a centimetre,or two-fifths of an inch. Rather few of the measurementsof everyday life exceed this in accuracy. Nowsuppose we look at a map of the world on a globemeasuring sixteen inches round the equator, we areusing a model on a scale of one in a hundred million(10 -8 ) and the average man learns to understand itsmeaning and draw practical information from it. AnEnglishman hears that his son is going to New Zealand,and has only to look at the globe to see that his letterswill take longer to arrive than those from his other sonin Newfoundland. But although we are at home onthis particular scale, of 1000 kilometres or about sixhundred miles to a centimetre, as regards the earth,the average person has not yet grasped the fact thaton the same scale the sun is a mile off and as largeas a church.
Our grandchildren will have learnt to do the oppositemental trick, namely, to be familiar with models on ascale of a hundred million to one. On this scale theatoms of the common elements are represented as lessthan an inch across, and molecules of fairly complexorganic substances are a foot or so long. The electronsin these atoms and the nuclei round which they arebelieved to circulate would still be too small to bevisible, but we could mark out their orbits, just as ina map we can represent railway lines, though only byexaggerating their width. It is doubtful whether amuch greater magnification would serve any realpurpose. When we come to deal with the eventsinside the atom the attempt to represent them in spaceand time breaks down, or at any rate the properties ofspace and time in very small quantities are so unlikethose of common sense space and time, that modelsare of rather slight value. On the other hand modelsof chemical molecules deduced from X-ray analysisof crystals are most reliable guides, and are openingup a new era in chemistry.
Let us now take a second step in the opposite directionand try to construct a model such that in it theglobe will be as much reduced as the earth had been inrepresenting it as the globe. That is to say our modelis to be on a scale of one in ten thousand million million(10 -16 ). This would really show us very little, for notonly the earth, but its orbit round the sun would beinvisibly small, and even the orbit of Neptune wouldbe comfortably contained on a pin’s head, which wouldalso represent the size of the largest known star.Unfortunately however even on this scale the nearestfixed star would be four yards away, and only abouta hundred would be within thirty yards. The MilkyWay would be a good day’s walk across. Light wouldcreep much more slowly than a snail, but quicker thanthe growth of most plants!
A third step in the same direction would probablybe legitimate. If we reduced our scale once more by ahundred million times, the Milky Way would be almostinvisibly small, and the nearer spiral nebulae would berepresented only a fraction of an inch away from it,while probably all the spiral nebulae visible with thebest telescope could be represented within a radius ofhalf a mile. It is not clear that we could repeat theoperation a fourth time. For the extended theory ofrelativity seems to lead inevitably to the view that theuniverse is finite, and that progress in any directionwould ultimately lead back to the starting-point. Infact an attempt to make a model on this scale wouldperhaps produce results as misleading as those obtainedwhen, by Mercator’s projection, we try to represent thesurface of the earth on a single plane. On the fourthorder model the volume of the whole of space mightbe as small as one hundred thousandth of a cubicmillimetre, though this is a lower limit.
We have seen then that we can usefully think ofmodels up to a hundred million times life-size, anddown to a scale of about a million million millionmillionth. Beyond those limits space does not havethe properties ascribed to it by common sense, andvisual imagination does not help us. We are compelledto plunge into the mathematics of the quantumtheory at the small end, of relativity at the big end.But long before that is necessary, people are frightenedoff the attempt to think, apparently by the word‘million.’ This is because it is generally applied tolarge aggregates like a million pounds or a millionyears, which we cannot easily imagine, though as amatter of fact a quite ordinary room would hold ahundred million gold sovereigns, provided its floor didnot give way. But we ought to get the million habit byremembering that we wash ourselves daily in a bat