Einstein for Beginners

FOR BEGINNERS

Text by Joe Schwartz

Illustrations by ~~~1===~ Michael McGuinness r1~MI

P;:mthpnn

'-"

Rn~k>\:::1

~

.;;, ,,',

Text Copyright © 1979 by Joe Schwartz Illustrations Copyright © 1979 by Michael McGuinness All rights reserved under International and PanAmerican Copyright Conventions. Published in the United States by Pantheon Books, a division of Random House, Inc., New York, and simultaneously in Canadaby Random House of Canada Limited, Toronto. Originally published in England by Writers and Readers Publishing Cooperative. Library of Congress Cataloging in Publication Data Schwartz, Joe, 1938Einstein for beginners. Bibliography: p. 1. Einstein, Albert, 1879-1955. \. McGuinness, Michael, 1935joint author. I\. Title. QC16.E5S32 530.1'1 79-1889 ISBN 0-394-50588-3 ISBN 0-394-73801-2 pbk. Manufactured in the United States of America

02468B97531

About the Author and Illustrator Joe Schwartz, who is Associate Professor of Physics at the City University of New York, received his Ph.D. in higher energy physics from the University of California in 1964. He is the author of many scientific articles that have appeared in Nature, New Scientist, and other magazines. Michael McGuinness studied fine arts at the Royal Academy in London. He is a former art director at Reader's Digest and designer for the Observer.

'If relativity is proved right the Germans will call me a German, the Swiss will call me a Swiss citizen, and the French will call me a great scientist. If relativity is proved wrong the French will call me a Swiss, the Swiss will call me a German, and the Germans will call me a Jew.'

A\be,rt Einstein was born in ulm, Germany on March 11.1875 'Into a war Id not of his

own making .

.-{ Just like the rest ofus.

]

hat was going on 'In the world? ~~

The 1880'5 marked the beqinning of

the ag5 of

imperialism and mon0p,0ly capitdlisr'n.~~

LENIN 11

6

1870

Franco-Pru..ian War - Prussia annexes Alsace-Lorraine, declares a German Empire, receives 5,000,000,000 francs indemnity and blows it all in financial speculation.

1871

The Parla Commune - Workers and soldiers take over the

1873

The Great World-Wide Financial Crash. The next 17 years

government of Paris for 3 months. The Commune suppressed with the help of the Prussian Army. 30,000 Communards executed by the French authorities.

meant hardship for ordinary people; great profits and consolidation for a few. Small businessmen, like Einstein's father, were badly hit. This was a time of labor struggles, immigration, the rise of militant socialism.

1878

Bismarck passes anti-socialist laws to suppress working-class political agitation.

~! The great questions of

the day w'llI not be settled by resolutions and majority votes but

by blood and iron.~!1

%Ittpis~

CItt
83

181J-I 8 Chcmcellor of GermGlry' 1811 -1890

Wilhelm Marr coins the word anti-Semitism and founds the

League of Anti-semites.

Jews qet

the bldrne for the Finoncicl cnsis.

The Jewish tribe has indeed a different blood from the Christian peoples of Europe, a different body, a different constitution, other affects and passions. If we add to these peculiarities the thick fat skin and the volatile, mostly disease inclined blood, we see before us the Jew as white Negro, but the robust nature and capacity for physical work of the Negro are missing and are replaced by a brain which by size and activity bring the Jews close to the Caucasian peoples.

Bi5ll1orcK's

friend ~nd

contidant . •

Mamma rnic, /' w'lth us, they blarnethe . Sicilians!

8

t'5 a period of tremendous overall industrial expansion. People throughout Europe are forced off the land and into the cities.

The rural Jewish population of southern Germany falls by 70% between 1870and 1900. Many emigrate to the Americas.

n 1880 Albert's father's business -fOils because of the

depression and the fOl1lily moves from lJlm, p'opulat!on 1.500, to Munlc~, population 2.3°,000. Aloert 15 one year old.

Pauline,

Ithink things are 5e.tter ' in

Munich.

Fine!

You congo into business with your brother there.

5fe,.l11atJfltffl6fa1v ep~d 181T-1.902

AI bert's father.

Freeman of Buchau. Jews were not completely ermncipqred until 1867,59 being a freeman was special.

18.5 8 -1.9 20 A/bert's mother.

Daughter ot a court pvrveyc;:>r, JulIus Koch-

Bernheimer;

9

entral to Germany's industrialization is ihe growth of

the chemical am' electrical industries.

10

........ Slgn81Ing by Electricity 1837: telegraphs, cables, batteries, terminals, insulated wire coils, switches, measuring instruments.

Electroplating 1840: for fancy tableware and household objects for the prosperous middle classes.

Electric lighting 1880-80: arc lighting for streets, docks, railways and finally homes.

Electric Power Production 1.: electrification of railways, furnaces, machinery, construction of power plants and distribution systems.

1881. In the suburbs of Munich, Albert's father opens a small factory with his brother Jacob, a tmined enqineer. They manufacture dynamos, electric instruments and electric arc lights.

Hermann and Jacob are part of the German electrical industry 0000000

"i~::', II .,

whioh is

~~~~U9h peric58 of

II1 I!II a

intense monopol-

ization.

12

.

Darmstadter Bank 1853 Diskontogesellschaft Bank 1856 Deutsche Bank 1870 Dresden Bank 1872

13

y 19135 half the worlds Ircde in electro-chemical products was in German hands.

& . ' '. • had ''f- other Who the

half?

Glad you asked.

.........."",...... The U5ofA.

General Electric Co.• a combine of Ihomson- Houston & Edison Co.

ermann and Jacob Einstein are in for trouble. Tneir small company, cannot compete against giants like Siemens and flalske.

W~

ii

~c:f~ t816-1892

t808·1(J86

Scientific

From o

prominent

instru-

Hanover

ment maker at the University of

family.

Educated inthe Prueson

Be~lin.

Army.

Joined forces with Siemens

Artillery and .

Enqineerlng

in 184"1

Scnool.

Inventor of modern Since electricity Figures so strongly, in

dynamo in ISGr.

our story "It is worth looking at the firm of Siemens and Halske in

more detail.

15

iemens' firsTplating. invention was an Improved ' and si Iver process fur gold

With the his brother Cha~ Ies actiIn~ <;15 agent, he sold ' in 18+3. rights to Elkington of""BIrmingham, U.K.,

'J'BB WONDBK of the AGB

r!

INS'rANTA.'lEOUS CO)B!UNICAnON.

------

Under the speci3.1 P<1tr(,)Dag~

V~S

5iemerys J9i~s the circle of .Be~lm UnIversity SCI~ntlst5. He develops an Improved telegraph system. This is a m~thoq ofcoveri ng the '!'lIre vxrth seamless

Insula~lon mode of cheap morenoI Cgutta-perche]' a rubberlike plant .

SUbstance.)

In 1811 he found~ Telegra.phen

B9uensTadt von SIemens und Halske to '!1anufacture and

Instal telegraph

systems. 16

of Her ltIo.jesty &. H.R.U. Prince Albert.

_.-.~_. .

QA,I!,VlAll'teO AllfO

&C.illC;'lT~O·lI"I"Q;NE"~C

TBLBClBAPBS, GT. \VESTERN' RAIL\V AY. )hy be

~een in

CIlu,stantoperati\)R, daily,

(Sunda)'~ ellcepted) from

9 tin R. It ,111'

TELECRAPH OFFICE, LONDON TERMINUS, PADCINCTON AND TELECRAPH COTTACe, SLOUCH STATION.

Au Es.hibiLion admitted by its nercerccs Visitor~ to be the most iotern.un1;\: and ATTRACTIVE of an,. in tbi~ great 'Metropoli~. In the list of vi~itor~ arc the iUWltrious Il.llmel of several ut' the Crowned Headi of Eurol,e, and nearly the wDo\e-oCtbe lIiobility of Engteed"Thill f:~"llbiti,,". w'airh IVJJ _l'J mlle't ur.it~rl PllUk atttntil't"t ,,/ lalt, i, M:ll worthy 4 tli,.t fr"OTII all tt'/w {Ol" to ,wi tiu wr)"d.no! u.,;tnC~"_~IOIt!'mi'l:: POST. The Electric Telegnaph is unlimited in tbe D_tur. eed utent of iu ecremunicatioll&; by its tltraordinary agency a penon in l'/lndon could COD\'eUe ",jIlt allothu at Ne ....Yor1c.or 310lnyother place however tli'ltant, lUI euilyand nurly u rapidly as iTboth parti.es ",ne in the seine room. Cotue'tion"proposed by Vhitot~ ...n1 be asked by means of this Apparatu~. and eeswers thereto will instaLf&neoull,. be murnett hy a person 20 1\\~11.'~ otr, who will alto. at their requel't, ring a bll{ or ,fin a can non, in an increu.:bly ,Lo~t I?ac!! uf time ••nu the signal for his dOing so ha~ been given

The Electric Fluid travels at the rate of Z80,OOO Miles per Second.

By irs i \'I'f'rflll "'geney Mu:-Jercr~ have teen appl'l:'hcnll"tt l"'l ill rhe late ('lit." 1C of T."cJl,)-Tbi("vc~ detected; and :."t17. wbid\ i. oi no little impvrh"Y'ce. the timely lIS~i..tl\l;,:,.,.f :'IledicallU-d hu been procured. in ca..es which otl1...r.,.,i~e would

or thi~ w.)nderful in"('ntion ill 1IO well knewn to hOimerits ""ould be supf'rf!.uo'J-S. with the most cOllfiding secrecy. raph" 'Menenr"'\,,' in condA\1t attendance. '0 tbat comrllunitatioDS recei v.:J. "eleg woehl be forwlU:d..d, if l'eiJ.uir~, to "ny part of Lendou, Wirold~,r. Eice, &e.

have crcved T!;.. grutf.~I.L llaliof.llt thAt allY fur'in,-f

N.D.

irnportlln('~

'1.\.1u~i"fc here

DC"l',~::h .." jell! t'" .lId fro

b~'

ADMISSION ONE SHILLING. T. HOIllI:, Licf1It«.

n 18t8 he gets the Prussian government contract to build q network in NorThern Germany.

1;~1he Frankfurt Revolutionarv ossemolv h05

JUS! electeq the KIng to be I emperor.

Siemens loses ihe Pruesiori conTract in 1850. But 'In Ruesio he succeeds in seIling fhe Tsar on an extensive sysre-m.

11

1854-56

Thanks to Siemens we can find out how that. Crimean war i'5 doin ~

~~~~ Siemens

uses his profits from Russia for the next Big Dealunderwater coble

-

telegraphy!

18

~---.

he first transatlantic cable is laid between 1857-1868.

Siemens orqonizee the Indo- European telegraph in 18ro. It connects London- Berlin-Odesso-Teheran and Calcutta. He becomes consultant to the British government. His ship, the faraday, loys 5 transatlantic cables between 1875-1885.

-

~e better

(pullout of that

\ 'gold deal.

I

~n.

---....

'\ vJhats the I price of cotton \ in London this ",-week?

----

19

lectric power becomes a cornmod ity .

The first market 15 lightIng for docks, rai Iways and streets.

Schuckert,

who combines

withSiemens, worked with Edison in NewJersey.

Edison organizes the construction of the first centra I generating station in 1882.

Th'l,) should turn d nice

profit,hey?

Pearl

st. Station

of

Edison Electric Illuminatinq Company 20

feet· . is II r/clty Everyo .0 the on t~ ne tnes 1- rage. fie oct. 10 get in

21

n 18B7 the German government opens the

Physikolische - Technische - Reichsanstalt for research in the exact sciences and precision technology. Siemens donates 500,000 marks to the project. His old friend, Hermann von Helmholtz of the University of Berlin circle.is appointed head.

21

So Albert was born when electricity had become big business and the most popular of the sciences. His future would be greatly influenced by the commitment of the German state to technical education and state-supported research.

In 1881 Alberts sister MojC\ is born.

OUf

fumily

was very close-knit and very ho.spitable.

Albert proves to be a slow,dream'ichi ld. Even at oge 9 he spoke hesitantly.

Al bert's

friend in

closest

childhood.

Ach,

donT worry.

Perhap5

he'll De a

profseeor

onedoy!

Alberts Germany is a very military ploceoooooooo

There,there. W'el/ worry about it later.

24

Arms expenditure nearly triples between 1870 and

1890.

The officer corps increases from 3000 to 22,500. Three year military service is compulsory. Socialist Iiteratu re is forbidden. Youths are subjected to fear and humiliation.

Veterans organizations are state supported. Membership increases from 27,000 in 1873 to 400,000 in 1890and 1,000,000 in 1900.

Heads of state all appear in military uniform.

Even the taxi drivers wear uniforms.

Albert

doesn't

like it.

\

25

Albert

goes to

schoolooo

000

which

is. very

military. _ - - - - I Christ was

ro

nailed

the cross with

nails liRe

thiS.

Albert goes to a Catholic school. He is the only Jew in his closs.. ••

(Albert's father was a non-religious Jew who regarded the kosher dietary laws as ancient superstition.)

2.0

AI bert, what do yo u

think' of this?Ifs called q

compass.

· lbert had a much better time

at home

with his

playing

sister M~a.

---==:---'

~gneti~m.

Hush now and go to sleep.

21

, lbert's uncle Jacob introduces him to math I

\i~e

my

uncle

Jake. He always shows me things.

/

00000000

Algebra is a merry science. : / When the animal we are hunting cannot be caught, we call it x . temporarily and conunoe to hunt it until it IS caught.

And his mother introduces him to music and literature.

Oh.no, not violin lessons! ~ Its Just '\·11 liRe school.

2.8

e e e e o o e e-e

Go on.you

you \ik?e to ploy ~ L when you.r cousins ~

.J-: ",

~now

come.

t was a Jewish custom in southern Germany to invite a p'0or Jew to dinner on lhursday's. 'Max Ta\mey, a medical student in Munich! visited the Einstein

home when Albert was 12.

Great public interest in science in Germdn'y.' produced poputor science best-sellers ana vice versa,

Talmey brought some of these with him.

29

With Talmey'~ assistance,

Albert worked through Spieker's Plane ~--""~--­ GeomeT~y and later went ontoteoch himself "the elements of colculus.

Hermann~

do you think Albert

reads too

mucn?

Better- he should read

than do nothin9.'

lbert's reading undermines hi5 faith in authority.

Through the reading of popular scientific books I soon reached the conviction that much of the stories in the Bible could not be true. The consequence was a positive fanatic orgy of free thinking coupled with the impression that youth is intentionally being deceived by the State through lies. It was a crushing impression. Suspicion against every kind of authority grew out of this experience, a skeptical attitude towards the convictions which were alive in any specific social environment - an attitude which never left me, even though later on, because of a better insight into causal connections, it lost some of its original poignancy.

31

· presence Einstein, YOL!5r disruptive inthef~a~ithe other and 0 re etudents.

'(odll stay

for t. deten Ion.

Emperor Charles

N 1346-1378

o

Emperor

Charles

s:

1519-1556 EllI~ror

chorles

~

1711-1140

~p The

teochers in

elementary school appeared to me .lil<e

) /'" sergeants, and In /'" the Gymnasium, the teochers were lik?e \ieutenant5.'~

33

n 1894 Hermann's business fails. The family moves south to Milan, Italy.

Albert, you'll stay here to sc.hool and qet your diploma, y,0ulr ,~----. neea i t . ' Finish

After two months

on his own, I\\bert

obtains a doctors certificate saying "that he is suffering

a nervous breakdown.The school

authorities dismiss

hi'l~--

Just whot I wClnted! o

4

Papa,lm renouncing my Oerman citizens hip.

1m off to the

rnountnins. I

thinK I'll visit our cousins in Genoo.

Albert spends a free harRY year in Italy. But his father's business fails again. lhe family moves to Pavia where ogain it fails!

Albert, I can no longer

support you. You must become an

enqineer anc1 go into f

Business.

35

Evenwhen I was a fairly precocious young man, the nothingness of the hopes and stirrings which chases most men restlessly through life came to my consciousness with considerable vitality. Moreover I soon discovered the cruelty of that chase, which in those years was much more carefully covered up by hypocrisy and glittering words than is the case today. By the mere existence of the stomach everyone was condemned to participate in that chase.

ithout a diploma, Alberi can't enter University. But the

Eidgenossiche Technische Hochschule, the ETH, in

ZUrich, the most elite tech nical school outside of Germany, would admit him if he passed an entrance exam. Hefuiled miserably.

Einstein, you've roiled French, English. Zoology ana Botany. But you have a superior knowledge of mathemat iC5 .

37"

· Ibert has a good ti me in Aarau.

Ooh,that Albert Einstein is Cute. =

He stays with the headmaster of the school, Professor Winteler, who has 0 son,Paul,and a daughter Albert's age. Alberts sister Moja later marries Paul Winteler. He studies physics with •••

Auqust Tuschmid, considered a fTrstclass te'acher of physics. 0000

The centml problem In p'hysics Today is the resolution

of Newton's

mechanical world view With the new equotions of electromagnetism.

38

0

· t the end of the year Albert graduates

and passes his ETH exam .

. Jat1 ~/~~~f!.J)

;Aatat' J896

• n 2.8January 1896 Albert's official opplicotion for the termination of his German nationality is approved. He becomes a statelessperson! Albert convinces his father that he should be a teacher instead of an engineer. In October 1896 he is ready for The.... 1h .... "big time" e bigtimewhat's he mean? Dunne, let's see.

39

he ETH was 0 Big League outfit. The Physics Institute was planned by Heinrich Weber and his friend Siemens.

It attmeted 00"

worldwide

attention

Description by Henry Crew, PhD, U.S. physics professor in 1893:

"H. F. Weber and Dr Pernetare at the head of the physics department in the Polytechnic. They not only have the most complete instrumental outfit I have ever seen, but also the largest building I have ever seen used for a physical laboratory. Tier on tier of storage cells, dozens and dozens of the most expensive tangent and high resistence galvanometers, reading telescopes of the largest and most expensive form by the dozen, 2 or 3 in each room. The apparatus cost 400,000 francs, the building alone 1 million francs."

40

But the

,A engineers

-:/

/ottneETH complqmed

" ;;'/' motfheir teachers

rff; %'

were too

abstract.

The students , orqonized . J;jj demonstmnons ~ agoinstthe . I "mathematics . \\·.lectu res.

\

\\

---~ +1

· Ibert qUickly decided t~at mathematics was far too specialized to be interesting

.

Those engineers ore right on.' '. : ~

~--=-~/("--)~,!", U

qnd spent his time In the .superb physical

laboratory doing

experiments. He had a cavalier attitude toward formal instruction

42.

.

........ and

naturally he quickly antagonized some of his instructors.

You're clever, Einstein, extremely, clever. But you have one great fuuIt:

you never let yourself be told anything!

yes, Herr Weber....

Some old stuff!

Here's the notee.

43

I

lbert gets icofinncs a month from his relatives. He saves 20 francs of iteach month toward his Swiss citizenship. Ex~nsive . . . .

ond

restricted to a few

appliconts.

e forms friendships with Michelangelo Besso. "jhe finest sounding-boord in all Eur0p.€:' Marcel Grossmann,who later helps Albert get his first .secure Job in the Swiss Patent Office,onCl Mileva Maric, a mathematician from Serbia whom he marries in 1903. They have a good time in the lively political atmosphere of Zurich.

xiled revolutionaries from Germany and "Russia 01\ come to Zurich. Alexandra Kollontoi, Trotsky, Rosa Luxemburg,and later Lenin, are there.

Albert learns

(f!~

about f(f~ revolutionary ~ socialism from ~ his rrierd ~--Friedrich Adler, ({(~ ajunior -./ lecturer in physics.

Friedrich is the son of Victor Adler. the leader of the Austrian Social Democrats, sent by his father to study physics "and forget politics" But Adler remains involved in the socialist movement. In 1918 he assassinates the Austrian Prime Minister. Albert submits testimony on his behalf. Friedrich gets amnesty and doesn't serve any time.

15

n physic5.Newton's

of mechanics had previous 200

years.

consolidation of the laws

dominated for ihe

Attended Trinity College, Cambridge. Whig MP for Cambridge 1689-1690. Longterm interest in metallurgy led to his becoming Master ofthe Mint from 1696 to his death in 1727. Founder of the theoretical basis of mechanics. Using Kepler's summary of the measurements of the motions of the planets he formulated laws of motion of material objects.

Cl o ck work . v

Op t ick.s .

Newton's mechanical world view is part of 18th & 19th century European philosophy and vice versa.

Albert was skeprical bui nevertheless impressed by the achievements of the mechanical world view.

Dogmatic rigidity prevailed in all matters of principles. In the beginning God created Newton's law of motion together with the necessary masses and forces.

But what the 19th century

achieved on this basis was

bound to arouse the admiration of every receptive person.

,,

II

I \

Albert, like most beginning physics students, particularly admired the ability of mechanics to explain the behavior of gases. The relationship between the pressure, volume and temperature of a gas could be derived by treating the particles of a gas as projectiles constantly bombarding the walls of the container. From this treatment came a number of impressive results: the way the energy of a gas depended on temperature, how viscous a gas is, how well it conducts heat and how fast it can diffuse. Comparison of this model to experiment also yielded the first estimates ofthe sizes of atoms.

I

-., ') \

~

l

41

ut it was the p.hysic5 of electricity and the electrodynamics of faradoy,MaxwalI and Hertz that most attracted his attention .... Faraday: the most accomplished experimental physicist of the 191tlC. 56n of a blockemith.

He worked Txears as a bookbinder betore .

coming to the attention of Sir Humphrey Davy.

liJ

3

(f) In 1832 Foraday

Sir HumphreyDavy was head of the

published the experirpental and iheore1ical work ihai p'avedthe way forfV1axwell'5 ih8or. y. ofeleciromagneiism.

I

Royallnstitutlon in London. Faraday

I

become Dovy's

ossistant and ha.d to endure the recline insults of the British class system _

His work was

hampered in laier years by a

throughout h'lS

early years. Davy'5

failure ofmemory

_caused by

Wi fe refused to

eat at 1he same table with him and demanded that

Davy do "the same.

-T.r

C~_~

mer~ry'

_. ..F:::" ~~olsonlng·1/ lUf~

--

~-

91 -186 48

-=

~~~~;;~~.-

,

Child of a prominent Edinburgh family. from 185110 1861' he worked aT puttIng farodaY,'s results into mathematical form.

Maxwell's equations showed

that elecTric and magnetic forces should move through empty space at exactly the speed cf light.

Hmrn.,.. Faradois picture of lines ot'

force :traversing all gooa one. I ihink I can use

S gaGe \s a

that.

-~i

~ ",,~.

. -.

~~

~

K~ ~/

:'\ Maxwell expressed himself in obscure and contradictory language so his results weren't accepted in Europe. In 1871,1 waded through his papers and realized that he was probably right. I put my best student on the problem of showing experimentally that the electric force propagated at the speed of light.

49

Son of a la\l\{yer and SenaTor of Homburg.Trained as on engineer

he became aifrocTed to Helmholtz's lob in Berlin. In 1886,ofter 8Jears work on fVlaxwell '5 ifJeory, fie

or

demonstrated eXQerimentally

thor the electric force propagates thro!Jqh space crt the spee4 of Ilgl1t

o/dlertz '\18Jl-

.9f

18

H~rtz's experiments were

widely popularized and insp.ired 100 20-year-old Guglielmo Marconi. Working with "Professor Auqusto Ri9.hl,o friend and n~ighp:6r -+he British in "Bologna, Marconi pUllt admlrolty a signaling devices. self-propelled

torpedo In 1896.

I

Ibert got VeAy exdted about ihi5 line of work.

The incorporation of optics into the theo electromagnetism with its relation to the speed of light to electrical and magnetic measurements ... was like a revelation!

EJectric1y ? science Magnetism? is rfwst eroptiCS? IOU5.

5cience is a force

Hey,

science

In

about curiosity?

is social relations.

production.

wnat

.51

ow fur would Alberts childhood curiosity. about the maqnet have gptten without a social basis?

Withoui'the organized work of rmny people like Faraday., Maxwell, Hertz and others? knowledge accumulaies ihroug h worK

'CuriosityJis ju?t a way of sayin9 thot human beings con change ' their environment,can improve' "

things, can discover wha1 is use- " fiji

or not...

If only we could use

-those

volcanoes to worm us

in winter.!

52.

atural

magnets. or

When youdiq for iron! YOlJ find lots ofthem.

lodestones! were reported by the Chinese circa 2600B.C.

odestones are magnetized by ihe E.ar1h's own magnetism. Also called magnetite. It is an oxide of iron (iron combined with oxygen).

lhe Chinese used them firsT for burial purposes and only later for novigation . 1here were occult

speciolisls in China called deomoncers.lheir lob wos t6 see that a per:-son's grave

was correctly lined up fOr pcoper entry to the -----.//

atlBr-lire.

Far

I

out.

.53

· round 900 B.C. magnetized needles began

used

05

direc1ion irldicotors.

LucretiU5 (ciRCA 55 B.c.) wrote

0

to be

poem about magnetism;

u!he sfee/ willf1WV(!;-foseel(lk~emb~ Or up or chW11 (J('f~ o1f!erfkwe- " FItOM DE RERUM NATURA

And that W(}.6 that ror 1600 YeQrs. Magnetism was C,Jood fOr dIrections and as a curiosity for the leisured .

"My brother told me that Bathanarius produced a magnet and held it under a silver plate on which he placed a bit of iron. The intervening silver was not affected at all, but, precisely as the magnet was moved backward and forward below it, no matter how quickly, sowas the iron attracted above."

from

me

utt! yod

lectriety has a similar history. ,...---'-"''-----

----_--/'_------..

The Greeks circa 400 B. C.

....

Etruscans hove a method for

contrail ing

And

that's where thar sTood

lightning.

fora very long time!

In 1726 a student of Newton '5, 5tephen Gray, showed! that frictional electr icity....

.... can be made to travel along 0h hempt reo

55

y the end of the 18thC. a number of people like Coulomb in fronce and Galvani and Volta in Italy, supported by wealthy .pp~rons, were exploring the phenomena of elecTricity.

Volta invented a battery which made steady currents available for the first time,

17

~~~t

'r-------

l , I,nterest dropped off in

frictiono I electricity and everyone rushed

they

56

to make batteries because were so much betrer.

oulornb made detailed

measurements of-the electric force. His experimente> showed that a formula could be written fur the electric force sim i 10r to Newton'5 formula for gravitation.

D

12

D

Ex peri menters tried to see if there wa s a connection between electric and magnetic forces.

In \820 Oersted took

·.0 piece

of

0/

~-..... and a •

~

ond showed that when current flowed in tne wire the cornposs would deflect from magnetic north.

It's L=:'.~-.I..-

easy. '(au

~ ~

~

1IO

Wit ~i for yourself.

~

:::;)

I-

~

5f

I

ndre Ampere made even more precise measurements of "this new force exerted by currents flowing ihrough wires.

Amperes

discovery. wa5

eleganT buT Oersted's was commercial. Electric tele9raph~ become pOSSible because 1he electric current could be used to deflect a magnetized needle somewhere elee and hence pass on messages! Havinq..,shown fuat electricity in "the torm of electric current could produce mag netic effects, it now remained to be shown that magnetism could produce electric effects.

This proved to be a touqh nut which was not cracked unti I 1831 by Faraday.

oraday was able it> show flnally -that you could get en electric current from magnetism. (The maqnetism had 10 change. Astatic magnetic force couldnT'do it.)

It had been a big gamble and a lot of hard work.

This discovery, showed that you could get an electric current from the mechanical motion ofmognets.

Most everyone dropped research into batteries and

storied building qenerotors.

Hippolyte Hxiis was the first.. · 69

· ... which was Q long way from Siemens' First dynamo in 186(":

And otthe same time

people sorted experi,menting with electric motors ....

. ... which didn't payoff

until wide-sea Ie

distribution of power become profitable

in the 1880'S.

60

'IS how faraday tried to understand ihe effect he observed. Faraday was one of the very.fuw working-class scientists. His bockqrourd of rich practical experience served him well in hie experimental work. And his overall Derspective was very down to earth. , Instead of trying 10 make up elegant force rl aws, Faraday tried to visualize what was happening when

.' ut the key thing for our story

a magnet and a current interacted. 50 he made pictures of what wos happening.

(

Iron filings placed near magnets D tend to rline up'. faraday proposed . that a magnet or a current- carrYing wire sends out lines afforce in a definite pattern ~ depending on -the shope and strength of the magnet or current.

61

Faraday's I?iciures showed that the vdtage generated in a circuit was ~uol totne rote or which ihe lines of force through the circuit were changing.

Forthe ftr5t time ph~5ical theory moved away from forces actinq at a distance as in glUvitallon,

Now lhe spoce between

the bodies was seen 05 the active carrier of -the force.

A5 soon 05 Faraday discovered ihis effect he s1aried asking how 'It was tnatthe lines afforce 90t1hrough space.

62

Certain of the results which are embodied in the two papers entitled Experimental Researches in Electricity lead me to believe that magnetic action is progressive and requires time.

When a magnet acts on a distant magnet or piece of iron, the influencing cause proceeds gradually from the magnetic bodies and requires time for its transmission.

Here's on exam ple.Check it out. ~ When the ~ is closed ihe ~ attracts the e 0 nd deflects it

from magn etic north.

The influencing cause proceeds here and requires time for its transmission.

63

25 years later Maxwell made very good use of this picture. He renamed the magnetic lines of force the magnetic field. He renamed the electric lines of force the electric field. He produced equations showing how the fields were related to each other. And, as an extra bonus, the equations predicted that under certain conditions the fields (lines of force, magnetic influence, it's all the same) should move like waves through space at the speed of light.

Measurements of the speed of light 1670 I. Newton

instantaneous

1676 O. Roemer

141,000 miles/sec

1727 J. Bradley

186,233 miles/sec

1849 H. Fizeau

194,000 mi/sec

1875 A. Cornu

186,400 mi/sec

1926A. Michelson

186,281 mi/sec

1941 C. D.'Anderson 186,269mi/sec modern value...

61

186,279 mi/sec

Yes. Maxwell's equations implied thai liqht wos on electromog nefi"c phenomenon,o hitherto unsuspected

form

of the electric furce.

lhe

study

oflightwo5 now

to become a pari of the study of electromognetism.

ut not everyone liked

Maxwell's equations. Even

Faraday was a bit piqued.

He wrote to Maxwell: There is one thing I would be glad to ask you. When a mathematician engaged in investigating physical actions and results has arrived at his conclusions may they not be expressed in common language as fully, clearly, and definitely as in mathematical formulae71f so, would it not be a great boon to such as I to express them so 7 - translating them out of their hieroglyphics, that we also might work upon them by experiment. I think it must be so, because I have always found that you could convey to me a perfectly clear idea of your conclusions, which, though they may give me no full understanding of the steps of your process, give me results neither above nor below the truth, and so clear in character that I can think and work from them. If this be possible, would it not be a good thing if mathematicians, working on these subjects, were to give us the results in this popular, useful, working state, as well as in that which is their own and proper to them.

It wasn't until Helmholtz in 1811 decided to put all itle

competing "theories in order flaT Maxwell's equaTions emerged as ihe p'rime candidate fur ihe correct 1i1eorv. Helmholtzslab become the center for research into eJectromagnetic waves and the propagation ot light Every,one agreed that liqht was __ a form of electric and d' magnetic"'" interaction. • • •

"'-

;,;i*1}

-,

• •••• but nobody

coul~ under-

stanu how it

qot from

I

p lace to place.

65

he mechanism of -the transmission of electric and magnetic forces was now a mqjor Rroblem. Everyone believed thot some sort of medium (or substance) was necessary to eupporf !he fjelds. rr

We have reason to believe, from the phenomenom ofli~hta29

heaf,thot mere

is an oethereal medium filling space

and permeofng

bodies.

This was-the

fomous,

luminiferous nether that was to occupy some physicisfs for the

next40 years.

UntiI AI bert did away with it all.

66

~,

lhe oeiher was supposed io fill all space ... . . . and had to have the contradictory properties: 1 completely permeable to material objects, while .:

But did 2at the same time, infinitely rigid in order to support the -t~~i~JJi light properly. ~

ihe aether really.

exist?

6,

n 1887two U.S. Americons, A.A. ty1ichelson and E.W.Morley, tried 10 detect ihe motion ofihe Earth

through 1he oether using

very sensitive apparatus.

Thb massive stone block,

floating mercu ry,in with

IMI'

onll-rnefer -inierterometer....

'=",10/1

~~~~~

.... srould settle this once and fOroll.

18jt.-19Ji

Traveled 10 Europe 1880 -rssz where he began aether experiments in Helmholtz's lab. 68

hE?Y found no effect. 1he motion of-the Earih throu.9h ihe

oefuer was undetectable.

. .alreodj? So, what did Albert do .••.. When Albert comes on the scene in 1895:

1 Hertz has experimentally verified Maxwell's equations 2 Marconi is busy trying to get money to build more wireless radios 3 The aether is assumed to exist but no one can find it.

¢'

Albert does

\ I

\ \

experiments to try to detect the aether ••••• '$

••••• and

neor~

injureS himself

eeriously....' trying

to

pusnthe opparatus

~.---J

beyond

its limits. 69

.l.

I

•••• he wanted to

understond what's qoing on when

fight propagates

(spreads out) tram placeto place.

like faraday,

AI bert r-referred

simple pictures.

Remember ,os q child Albert wondered how !he com ROSS need Ie

couICJ line up pointing to ltle Nann Pole

without anything

touching it.

7°

50 Albert tried to form a simple- picture of how light works.

~~~M.l wonder what would

~~f~ ~o~~6 i0qht olong with itcrt 11Ie

eoeed of light?

from 1his perspective,

and ofter Q lot of hard work with his friends,

Alb..ert come up with a differentogproochJoihe problem dt'the oen ,er: 11

, f course we

don't

know

exactJv how

aport

with just one

"It haP.f~eneer because aItho' Albert cou ld mke an Q~urnent punch he tHdn'r like to talk about it all fuat much. I

No. Albert never got used to being treated like a qenius. He aidn't like it. -So he avoided going into detail about 1he WOy he thought about things.

" An d be51'd6S, ...."In sCience.. ...the work ofthe ind ivld uaI is 50 bound up with that of his scientific contemporaries mot it appears almostos an in1P6rSonol product of his qenerotion."

he key puzzler in his discuesions with his friends WOo •.. , What exoctly would hoppen if he rode along' with a light wave ofihe speed or light? Waves throush the oether

Supp,0se I was holding Q mirror·· ... '.

.. .. and

moving at the

speed of nght

13

You remember. Mike Besso, one of

Albert's friends.

Listen Mike.

lve been

No listen. JhiS i,s difrerynt Imagtne youre movmq at the

Again? Didn't

tryinq to understand the aether ogain.

thot accident

I

it this time?

5~c:rof

inthe lob cure you? well? whatis

light....

Wait a minute. OK I've got it.

Now ifyou're moving at me

speed of light

')

and f11~

mirror 15 . moving at F '" I W,~,the sp'eed 01 IJliqhtJ lhe l[ght tani catch up to the /

Hrnmm, 50 ?

mirror.

15

5o,doesn't

Hmmm. You mean

thotmean

1hd~our 1m e six> Id

disappear

that if liqht is a

vrove in the

?!

stationary

oether....

• And if you sit on top of thewave.··

:..then fr:1e lighT Isn't"mOvlnQ

with respect to you ...

... and can't catch up to

the mirror

I

to get reflected.

Interesting! Listen. You should read Mach's

stufF. He rejects the

idea of absolute

SMce anCl motion

completelY. A\bert~lored "\his puzzle with his friends fOrlo.~ear5. fir5t at C{ ETH in Zurjf,h from 1895c19oo,and tnen atthe wse Patent Qttlce in Bern nom 1901to 1905·

hen Albert ~raduated his ETHgrofessor.s wouldn't 50 he did dd tecchinQ jobs fOr Q veer (he was a very qood teacher) unHI Marcel Grossmann was able to pull eorne 5frings to get him ajob atihe Swiss Patent office ... recornmerd''hirn,

• ' ... 0

common civil servicejob fOr

d

science graduaTes inlhose C!j5.

lr

In Bern he meets MouriceSolovine Qnd

Conrad Habicht.They formitleI!O~rnpiqAcodemy'~ .. and alonq with Mileva Maric, Marcel Grossmann and Mike Bes~, Albert conlmues to chew over •

•

0

that puzzIe. Moving with the speed of liqht, 'will mJ imQge disappear or11ot?

ach believed that Q physicol theory snou ld be tree of metaphysical constructions.

No one is competent to predicate things about absolute space and absolute motion; they are pure things of thought. pure mental constructs that cannot be produced in experience.

--~ ttn6tdfud 18)8-f.j16

ach also believed that a physical iheory mlJ.5r be bosed only on prim03 5en~~ r?en;ep'n:oQ.s (a b'el iE(t thar Lenin golrtlCClI mlsChlet later on). Albert benefit trornMach's willingness to challenge the accepted ideas ot mechanics .•. saw as crean

-

Moch's Science of Mechanics

6Xfi:rcised a profound e leer on me while 1 was a student

,. . . . . .,.-----'-_ _---'1 Iv----~-~___r

I ~ N:ach's 9r~tne5s in his IncorruptIble skepticism.

19

ach'5 ideas were useful because -they helped Albert to ~ect =the aether. Since DO one

could rind 'rt

anyway.

Here's what .Albert thouqht

.

000

No metter how it is that I/Sht

gets from place to Rloce (.aether, sHmaether') my image should not disappear.

But, fuel") on observer on ihe grourd would see the

light leaving Albert's face at twice Its normal veloci1}'.!

~

If I'm moving at

-~ ~~~~18ii6i,oioio miles per second•••

_

and the light leaves Ylj iDce crt 186,000 miles )er second. o

0

0 0

then relative to the Braund the light should be moving at 186.000 t 186,000 ~ 3rJ.,OOO miles per secoivx] "Right? 000

80

But that didn't.

make sense either •• 0

The speed of waves depended only on the medium and not on the source. For example, according to wave theory, sound from a passing train covers the distance to the observer in the same time no matter how fast the train is moving. And Maxwell's equations predicted the same thing for light. The observer on the ground should always see the light leaving Albert's face at the same speed no matter how fast Albert was moving. But if the observer on the ground were to see the same speed for the light leaving Albert's face no matter how fast Albert were moving, then Albert should be able to catch up to the light leaving his face and his image should disappear. But if his image shouldn't disappear, then light leaving his face should travel toward the mirror normally. But then the observer on the ground should see the light traveling toward the mirror at twice its normal speed. But if the observer on the ground ... Oy veh!

Albert began to try to see if there were any way for the speed of light to be the same for both the moving and the ground observers!

81

t nearly gave him a nervous breokdown ...

I must confess that at the very beginning when the Special Theory of Relativity began to germinate in me; I was visited by all sorts of nervous conflicts. When young I used to go away for weeks in a state of confusion, as one who at that time had yet to overcome the state of stupefaction in his first encounter with such questions.

me Theory of Relativity is Albert's solution 10 thi5 apparently impossible reguirement.

In order to make progress Albert first needed to convince himself that his image should be normal even if he were moving at the speed of light. Albert needed to find some gener8. principle that could give him the confidence to continue. He found it in an old principle of physics that had never been particularly useful before. And that was ...

62

THE PRINCIPLE OF RELATIVITY

The

principle of . relativity ?

Galileo got into a lot of. . trouble with the InqU/stlon. His ex\?eriment5 on motion

led to The Principle of ReIativi t.>:.:

All steady

motion is relative and cannot be

detected without

reference to an outside

point.

6;

Galileo was

Profes50r of

Mathematics and Military Engineering at Pisa, Itoly: 'Z.ZZ •••

8+

ollleo worked on a lot of thinqs. He built "the first telescope in Italy ond promptly eold it to the Doge of Venice for 1000 ducats ana a lile professorship.

"I have made a telescope, a thing for every maritime and terrestial affair and an undertaking of inestimable worth. One is able to discover enemy sails and fleets at a greater distance than customary, so that we can discover him two hours or more before he discovers us, and by distinguishing the number and quality of his vessels judge whether to chase him, fight or run away ... "

85

e 0150 used me tele.sc0p.e to observe -the moons of Jupiter. Being Q prQctical man who needed money hetried to oefl 1tlis first to the King of Spain and ihen tothe states General of Holland as a navigational aid.

And ~ in addition,-the di'5cove~y helped convince people -thoT planets

did revolve around tne sun.

ut Galileo's main concerns were with terrestrial motion ...

Because of cannon bolls-

Galileo took up from

Nicolo Tartaglia who hod guesood lhoTthe maximum range you

could get from a cannon point it at 15~

WQSID

alileo realized ihotihe motion cf projectiles ~ou\d be analyzed by treating the horizontal and vertical

motions

separately.

if horizontal and should mean thai.

50

vertical motion are combined this

0 0 0

the cannonball fired from

0 perfectly horizontal connon and another otthe same time which fOlie> verticallv from 1tle mouth of ire connon should hit the ground ot ihe sometime!

Thafs a strange result! 88

Doesn't the horiz.ontal marion affect the vertical motion at all? When I'm moving smoothly the cannonball's vertical motion isn't affected at all.

Galileo then extended his argument to say that you couldn't use vertical motion orany other kind of motion to detect horizontul motion.

liiillii '

Yes.lve

often wondered in my cobin whether the ship was. moving or standing

still.

still.

89

And ihat's "the principle of relativity. You can "t tell ~~r

it" you're moving smoothly

without looking outside.

lYle r.rinciple of

relativity sounds harmless encqqh. Negati ng the idea of

absolute rest wasn't a burninq issue. / But whel1 app lied l6 the problem of tMe

ae1'He.r it paved /The way tor the pow~rtul

arguments

that Decome-the

1heo~ ofReloTlvi!y

0000

which first.

appeared in

mogozme.

~~

~

90

rns

osed on the principle of t:ek;1iiv·~ Albert ~rgued he should be able iO eee his (moO e norma!!y even if he were moving ar the speed ot ight

o

Because if your image disappeared when you were moving at the speed of light, you could tell you were moving at the speed of light just by looking in a mirror, right? You wouldn't need to look outside, right? Which would violate the principle of relativity I

91

Damn!

there gOO? my

lrY10t oqoln.l kee ten in_q them ~o 18'6,000 miles- er-second

not

mm;;;;;;;;;;;;m;;;;;;;;;;;;;;;;;;;;;;;;m;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;m;;;,when tin shovi~. //

Speed is distance

That was half the problem solved. Albert's image should be normal. But could Albert see the light move away from his face at the speed of light relative to him . . . while, at the same time, observers on the ground would see the light leave Albert's face at the same speed of light relative to them? How could this be possible?

92

divided by time (as in miles/nour). So Albert realizeQ thai if the speed were to be 1rle some ihen me disTance and time wo~ld have to be difrerent. Which meant that there

must be .something suspect with time.

Perhaps "the moving ~b58rver and 1he stationary observer observed cliflerent times ...

If both

were to observe the same

velocitv fOr /igrTt.

Because Albert

took the principle

of relativity as a starting point,

ne was led tOk

rettun the

concepts

of space

and

time

in order

make it come out

all right 93

This is how Albert

finally' expressed it in his Annalen der

Physikarticle in 19°5: ON THE

ELECTRODYNAMICS OF MOVING BODIES ... the unsuccessful attempts to discover any motion of the earth relatively to the light medium

like the Michelson -Morley experiment suggest that the phenomena of electrodynamics

he mean~ ihe propagation oF'light which isthe same thing /// as well as of mechanics possess n~ properties corresponding to the idea of absolute rest.

He means Galileo's principle of relativity ohould be good for light as well as for ordinory motion. We will raise this conjecture (the purport of which will be hereafter be called the 'Principle of Relativity') to the status of a postulatej"

*postulate: a basic assumption and also introduce another postulate, which is only apparently. irreconcilable with the former

he means he's found a

way out of the contradiction

namely, that light is always propagated in empty space with a definite velocity c which is independent of the state of motion of the emitting body.

He means everY,~>ne should always observe the

same velocity iOr light.

These two postulates suffice for the attainment of a simple and consistent theory of the electrodynamics of moving bodies based on Maxwell's theory for stationary bodies.

The introduction of a 'luminiferous aether' will prove to be superfluous inasmuch as the view here to be developed will not require an 'absolutely stationary space' provided with special properties ...

He means he's doing awoy with the oemer once and for 011 . Space will no longer require . r.special properties' in order TO transmit light.

Bur, cerroin

conventional ideas

about time about lenqths, about moss ,

obout velocity

had to be chucked out and replaced.

95

· Ibert5 arquments ore veCY simple because "they are very logicar. If .yOU accept file two postulates Albert shows exac11y now to make it come out O. K. Albert was ver.v pleased with the result. He wrote to his friend Conrod'

Habicht··· ... '

.' 6reot! He's reallY done it!

96

ow. Do you see what is .

happening? Albert says:

Nice and 5u y I dnn to thin~.I'll qo r (j drive.

no matler how liqht propagates Wflen:you are

srandi"h9 still ....

. .. it pro 899 ates exactlY the eorne way when

movln.9'

This i5the Such a nice

principle of • relativitv, Alberrs first posfuIare.

doy.

9,

ut Albert also says rr

Liqht is alwa~5. propaQ~ted in empty space wd:h q detinrle velocity C which is Indej:?endent of

the stcfte of mo1ion at The emitting or receiving body"

An observer an /he ground hos ID see light moving ot the same velocity os the moving observer. lhis is Alberts 2na postulate.

96

Bur what does it mean?

P-B1mate.

I'm not sure.

what about, KtxP dis ch?

Remem ber the compass?

Albert wondered how the cornROss needIe interacted with fue Earth's magnetism. How do maqnetic(or electric) effects get transmitted from one pl ace to another?

Maxwell and Hertz fact they showed "that such In showed magnetjc that every interactions could electromagnetic only take place effeq takes ota certain maximum speed. time to get transmiITed. 99

Radio waves, microwaves. sun rays,etc., all take time to getfrom place to place.

100

o Albert mode an inference. Based on fhe experience with elecTricity as summariz.ed by Maxwell ana verified by Hertz, Albert proposed that ihere are no insTantaneous intemcilons at on in nature. Here is "the simple physical meaning of Alberfs 2nd postulaie:

Every interaction takes time it:' getfrom one place toihe

next.

{j

And if ihere are no insTantaneous interactions in nature then "there ,must be a maximum possible speed

ofi nterocllon.

I

.I

This is so im portant we will repeat it: Iffhere are no instantaneous interactions in Doture -then -there must be a maximum possible speed ot interaction. 101

he maximum possible speed of interaction in nature is the speed of the electromC?qnetic interaction - wliich is the speed cf light!

It's quite revolutionary really.

Now by the 8rinciple of

relotivity~ the

maximum

epeed or interaction must 1'~~I51' be the same for every J...l observer no ma1ter how they are moving.

e

~

The speed of Iighf(1he maximum speed of interaction) is a

universal constant.This is Albert5 2nd postulate.

102

Everyone sees ihe some speed 10r light no matler how th~ are movi n.9. 103

-This means ,of course;that nothing con go - foster than ,-.. speed of light . r; +L

..

me

Noihngluste~lrlon

the speed

~'~.

01

fi9ht?

Nonsense!

h

Un·American! ~ We crocked . ~~ tne 60und - berner

C~.

.

-

by qol~ the light: barrier.

and

we'll crdok

Nothinq

faster

~.---,.,.",,-

1tlanthe

.s-eed

~Iight!??

Now IVe heard ihing.

everj-

104-

The maximum poesible speed is a material

property of our world.

But how is it possible?

Well ... -L Alberl has lo show

that &omell1in.9

l:Jnexpected

IS gOIng on.

Albert has to show:

1 How everyone can ... the same speed for light (c). and

2 What happens when you try to get an object to move f88terthan c.

To do this Albert shows that:

The concept of time must be changed

The concept of length must be changed

The concept of ma.. must be changed

105

o ihis is A\beri~ position:

1

There ore no

instantaneous interactions

in nature.

2J Therefore fhere

must be a maximum Q05sible speed of interaction.

J The rnoxirnum poeeible speed

of interaction isibe speed .of

the electromagnetic inleroctlon.

4 lhe ~d ofihe electromagnetic Interaction is -the speed . of light

5 The speed of lioht;5 1tle maximum possible speed. The reoll" difficult part wos showinq how everyone couId see -the some speed fur light'.

Let·5 ioo

see how he

did it:

· Ibert nearly drove himself craz~until he real ized that TIME was 111e Joker In the ck! The time elapsed between events was no necessarilY the sorre fOrall observers!

Remem ber speed

is disTance ~one divided by me time

it takes. In symbols:

D

.5 = T

o the moving person could observe the Iiqht travel in,q a certain distance D in a certaif'l time T 10 give itie speed of light c ....

while a station.QIY person could observe the ligbT traveling a ditterent distance D in a arfferent time T in jusT such a way 1haT she would measure eJCQt.tly -the same spee~ 0 •••

..

~~ 10T

t is neat. Here's .how A\bert analyzed "the phenomenon of simultaneous events . 5imultaneous .. " ..

.... events?

Yes. Albert points out that any measurement of time uses "the idea of simultaneous events.

We have to understand that all our judgments in which time plays a part are always judgments of simultaneous events. If, for instance, I say "That train arrives here at 7 0' clock" I mean something like this: "The pointing of a small hand of my watch to 7 and the arrival of the train are simultaneous events."

A\bert arqued ihat simultaneous events in one frome of referer1te would nO(Iloces5cwily be simultaneous when viewed from 0 dittereni fmnie. Albert called this the RELATIVITY OF

SIMULTANEITY 8\bert suqqests. ihat we try to picture his argument In terms


• • • . as ihe moving nome of reference and the roilwoy embankment as the sTationary Frome of reference . 109

ow we co0 put them together. Let's hove

car too. MIke.

(I {

(f

0

passenger

/'/ '-( ,

i( {('

There. Now imogine that someone in the ce nter ofthe pgs5enger car Holds a device which can send out a beam of light in the forward direction and atihe same time a beam oflight in the backward direction. 1/

1/

---F

1/

110

((If(/'/-/(((If r

111,((7((1

II

((ff

j ; 1 / 0 il /'

(t/(; I ..-

· nd we furTher imagine ihat ihe rront door and back door can be opened automatically byrne \i9ht beams.

"t.~, e

~~ 1hen

to the person hold ing -the device the doors

of the passenqer car will eoen simultaneously. But to a person 6n the embanK.ment, ~berr Ol'"qU6S, tne bock door will open before the front dOdr/

111

~ee ? Becouse for fue

stationor'\'

~roons

the back door moves fOrward to rrieet the Iiqhi Prul 5 e, whiIe 1tle" froni door moves away from fhe light pulse.

o

Bu1 which is it? Do the doors open at the

5ame time or don'they?

112

hat's ihe point Since "the speed of lighi i~ to be the same for both frames, Albert argues fhot. 0 ••

--~:~~

r------------t()~_i':~~~-]·::~8!i·-")'·:·nS~ Events which are simultaneous with reference to the train are not simultaneous with respect to the embankment and vice versa.

You better give us

a chance to get used to ihis.

ake a more common sense example: distance traveled.

Imagine that our pereon middle ofihe carriage gets up and goes 10 thin1he e front door.

~.

Hang

00 .

. • :J) J~-.....,r------@l

J

OKay.

>

113

ow, how for h05 our imaginary person gone?

Relative to the train ihe person has gone J1. a car length. But relative to the embankment the person hos gone farther. ----~

Distance

gone IS

a

relative

measure.

So you see, Albert argues that elapsed time is a relative measure also. To the person in the passenger car the opening of the doors is simultaneous; the time elapsed between the opening of the front door and the opening of the back door is zero. But to the person on the embankment the time elapsed between the opening of the doors is not zero and depends on how fast the train is moving.

114

Next, Albert argues, isihe relativity ofthe measurement of length. Albert asks'fwhat is the length a ihe passenger car?

An observer in the train measures the interval by marking off his measuring rod in a straight line. (This is the length measured by the moving observer) But it is a different matter when the distance has to be judged from the embankment.

115

Riqh.t Albert argues ihatto measure the length ofthe cat as seen from the embankment, we have to

mark the positions on ihe embankment which are being passed b~ the front door and the bock door

at the same timeT-as judqed from the embankment. The distance between ffiese points is tnen tneasured with a measuring rod.

(This is the length of the car as measured by the stationary observer)

116

· Ibert says: It is by no means evident that this last measurement will supply us with the same result as the first. Thus, the length of the train as measured from the embankment may be different from that obtained by measuring in the train itself.

Albert i~'prep,aring the ground for a reconsider-

arion or Newton's analysis of space time t:t motion.

Classical mechanics assumes

"that:

1The time interval

between events if> independent oF-the motion of the observer.

Z

The spoce interval (length) of d bact' is . inde8endent offue motion of the observer.

Unjusiiflable!

11'1

ffewton 6aY{

Spoce and time Intervals ore. absolute ond the speed of light is relative.

Albert replaces Newton's metaphysical absolutes, the constructs of absolute space and time, with a material absolute: there are no instantaneous interactions in nature!

Albert's contribution was dramatic because it so fundamentally challenged the framework of classical physics that had been accepted for the previous 200 years.

dossicol

_

perfect

_ _ _\[_HtjJr------J 50?

How does

this aff€Ct us?

Quite rilrlht There's

no neecrto get

mat excited about relativity just

b~uee a bunch

at P0ysici5t~ got excited

118

by IT.

Relativity theory had nothing to do with the development of the A-bomb. The Anti-Nuclear Handbook tells the story. And we'll discuss this again later.

Mean whi Ie lets see what ihe -rest of Alberts argument consists or,

119

· Ibert didn't just argue that space and time intervals needed to Be reformulated. He showed exact~ how to do it. Albert's program: To find a place and time of an event relative to the railway embankment when we know the place and time of the event with respect to the train

such that

Every ray of light possesses the speed c relative to both the embankment and the train.

Since we ore iol~ing about ofdlstances

rneceurernenrs

and time, we are talk'ina about numbers. Alber"E needs to use the troditional lonqua~e of numbers to mo~e it

come our right

120

~

he nmtsfep of cwrse was counung.

lhere aro at least 1 more dinosaurs qround here. We'd better iell

me others.

Tallyinq has been dated t9 30,000 B.c.They used scmtcnee on bones to do It ((111

1 II}!I

I/J(I

VII;))!)}

JIII;}l;' 1ft) IJ II

And the next big step' was measurement, which got its real start wittllhe rise of the cities. 121

Hey tnan,howfur is "It to Gizeh?

he Eqyptian

ruler-priests needed measures of distance..Lorea, volume and weight 10 osse ss taxes

and run me state.

We'\1 need

o lot more groin and

beer to feed ihis lot.

122

o ~eep records of what "they were doinq they hod to write down -the accounts. 50 written l"Iumerals were 1he next step. And 1tlis if> where mathematics beqon 10 qet mystitled. Because 1he priests kepr wrlnng tor fnemselves. Hiero -glyph = priest's writing

Anyway, "\he Bobvloriion and Sumerian priests

gotrather

qood at <:lriihmetic

starting

about 3000 B.C.

. ' ..

'

.

,

.. ,. - ...... ",

,

.' ::.

.. . "

"

;

.. ...... ' ".

. . :':.: .:. :..:...::...=....::', :'.",: :: ..::::.:;:

123

· t fret fuey wrote their numbers like -this

y 50

~

1

and

<.

=

10

a number like.59 would be written

-<~« ~~~ , VVy

= 59

But later "the Baby-Ion ions developed the first place system fOr numbers.

They used a base of 60

If I I 1Y

2x60x60

+

LX 60

+-

2.

... 7322

or: r322 = T X (lOX lOX 10) +3 x (lox 10) + zx 10 +2 The Babylonians hod as good a computation system 05 ours. You owe me

yyyy

bushels of wheat

12.t

lhots Il2 bushels too mony.

mow a skill developed in.may .

isololion fbr centuries by a special qroup, otpeople become somewhotborinq. By 1900 -e.~. 1heBabylonians hod made up lars of litHe pfo15lems lor their own instruction and amusement.

This was -the

beginning of

ALGEBRA

lhev. wrote it 011 down on clay-

tablet 5

Babylonian inblet.1)ooBG.

wilh algebra equation on It

Of course it was not exactly what we now use. The Babylonians didn't hove. olqebroic ot at ion. (That hod to wait tor me rise of the

Pslam and Hindu merchant closs)

hat "the Babylonians did was to pose on obstroct problem 0

0

0

0

-=::;:::----U

(V

Find the of

5 ide

o o

if

a square the area less -than

the side is l4-x60 t 30

me solutionand ihen give-the 00 0

detailed 5teps to

r Take hair rf one .and

mUltlQly by half of one.

126

0

L

Now add half of one and the result ie 30, the side oFthe square.

hile what we do now is write x:- x .. 870 -+ X ~~ +VCiY"+ 870' : .30

lheres noT much difference really. In focT we solve equations on modern computers with exoc11yihe some st~p-by-~reQ method hrst used by me

bobyloruon pne5rs.

2

To run: enter 810 enter 1 hit start

DIV 5TO 1 ENTE.R MUL.T PLUS

f

-r: RC

L

divide 1bXl and sTore it,multir?ly ix~ and add 870,

1

PLUS

RTN

ml<e the squore

. . . . . . . root, recallt and add it.

Ans, '"'30'

., . rom here Its a blq

-=

~ Jump to the GreeKs who came up with the Idea of

. 121

PROOF

Some soy it was the Greek legol system ihat paved the way.

PYrhogora5 is soid

to hove token up . Egvptlqn, Babylonian and O'llnese results and tried (with h'15

followers) to prove-thern.

~S ~o1B·C. 'iB't;CJ I

......,"ru ..'u

mystic,mathematicJan.

showmen.

128

famou5 example is the Py1hogorean Theorem.

Rem ember th is from echoo I ?

The square on -the hypotenuse equals -the sum of the squares on th~ other two sides .

,.

. . . and we mean: Take the length of side C and multiply it by itself. This gives the area of square C. Do the same for squares Aand B.

keep this in mindAlbert will use it later. 129

· ny-how, Greek

mathematIcs fell into the hands of Plato. ~~~ii

Plato used

mathematIcs

as an l.Q.

test.....

. .. and he had

ihese weird rules about whQt was permitted In qeom~try

rnys1iti eo

"\hot

every-

one for Q longTIme.

reek mathematicians labored for centuries -trying to

rrisecl an onqle .with only a compass and a eiraighLedge

0

000

,

- - -

Why dont we just

meosure it?

000 0

end "thor was where

matters

stood untiII !he Hirdus invented our modern

algebra.

Ary.obhato{A.D.410) wrote down all the Hindu methods of multiplicotlon, long division and alQebra ihat we use today. They made up ex~rcises(lTke -the Bab>:lonlons)

to herp "them interest.

of fuxatlon, debt and

with colculotions

Amerchant

PO~ au

on

ceraln ~OodS at

different places.

At the first

he gives -s of his,qoods, at me second # of what he has left and atthe third

'3 ofihe

remainder.

The total

eguol? 24 cOins.

what

x=- what he hod

he ot frer ?

1

had

;l.

3 21" ::.

at first

gives up ~x gl:ves up ~ C. ~x) gives up ~ (~(~x.)) -!.ox. + J.. X. ojo.Lx.

" 6 X ::. 36 COinS

132

6

eanwhlle Medieval Europe wallowed in the throes cf the Age of Faith until .0 0

u

f

0

mWo The Renoi6sance.

:o\rth -tt> you

~

Mary' ie 24years old. Mary is mice 05 old as

I

ask /

Ann.

Ann was when Mary was as old 65 Ann ·'s now. How old is Ann?

Now improved mathemqtics was needed tor

for noviqotion , fOr gunnery, for ship'buildinq, fOr hyaraulic engineering. for

astronomy,

building technology. 50 there

come: Algebraic notation Vieta (1580) Decimals Logarithms Slide rule

stevinus (1585) Napier (161-+) Gunter (1620)

AnalyTic geometry Adding machine Calculus calculus

Descorres(te37) Pascal (1642) NewTon (1665) Lei bn iz. 06S~) 133

ihere has been 0 long histor:Y c! nom ber mystics who were very Impreosea with 1helr own

• f course

cleverness

Ann 15

18

yoors old

0000

Fytha9oras:~PBle55 us divine number, who generated Gods and men. f\lumber containest the root and source of eternally flowing creation."

Plato:

rr

Galileo:

lIThe book ofihe Universe

Hertz:

(Jad ever geometrizes

It

is wri1ten in molhemoticol language" without which one wanders.in vain throv9h a dork, labyrlnth.55 re One cannot escape the fuelinq that Theoo math em aticaI funnulas haye an independent eXIstence and intelliqence of their own, thatffleyore

wiser than we am. wiser even ihan

-theirdiscoverers.mot we get rnor:e out ef'them than was orisinally put ,Onto them."

.00

0

ond who forgot

the onqinol impulses "that led them to

mathematics

in the first place.

134

-( p5SST.. ,.. ever since 111e mattlematicians have started on relativity, I myself no longer understand it.'

But in reoli~ mo1hemarics is only a Iqnqu9Qe

51Z~ and and re atiol16hips between meosuroble

invented by human Ibelnqs to describe

Q~antitie5

ttl1n95. And ihat's.exactly how Albe.rt used moth

to express the relaTionshIp between the place and time cfon event in relotion to -the embankment when we know ire ploce and i1me of the event with respect to the train. 0 •• 0

And now let's have that passenger car O!jQin Mike.

135

Actually this pa5senger car is a bit complex" can we have oomelhing 0 Iitle simpler lookin.9?

Thafs better. You knowJwe could do awoy with ihe car altoqether and just "IndIcate a movi ng frame of reference. HoW"about trylf'1g that?

X' isthe distance along

me CQr.

y'is the distance up the car. v i5 the speed of the

moving frame.

136

>

y'?» x·

V

here,that's ~ifT}pler. Now we have a moving finme of reference y x .

And a stationary frame of reference

x

1r

rx isihe distance along the embonkment

zr

ism distance up the embankment

y'

m >V x: x

Which corresponds to ihe p056e!]qer car and the emboDkment. We marl< ,an eyent in lfIe movlrJQ fume by its coordinotes y'x'and tim~ t and we mark ffle same event In:fue J.sTationary trame by \ts coordinates ti- x

and

a

Its ttrf1e-t-,

Albert noworgues(u.5lng

olqebra) thafthe relationship

between the coordinates

ofevents in "the two systems is x' = x-vt VI-V/c2.'

y'''~ t , ,.

;..::L

1.- - C,.X

VI-V/~,.,

137

The sy5lem of

~uatlons on page 137 15

Known

'My name.

by

!f~Uztzphysic~tJ 19fj-(3fB Dutch iheoretlcol

discovered

the

.

senior 51otesmon of

phxsics end friend Of Einstein.

Right. Now we must show what's going on here

0 tJ 0 0 0

Imooine ihat both frome5 df reference ore at rest (rslofive to each other ofeourse). And we hove two idenhccl rather spec·IQI I~qht docks in them (designed byihe U.s. physicr5r R.P.feyrnman).

X'

x

138

1he liqht bulb gives out regular pulses ofliqm- which qo up tottle mi rrortjqet retlocted and . . bounce bark to ~ counter which goes dickfclick.

y'

S'

Now we imagine that the s' system

is q iven a verocity V50tnat it if> a movinq system W"lttl respect to ire SY6tem .e.

5'-+

v-+

y

The observer in

s' Bees her clock work exactly the eorre as when she was at reer,

x

otherwise ihe principle of relativity would be wrong. If her clock chonqed when she was moving she could then tell she 'NQS moving by notiCln9

ihe change.

-eut -the stationary observer, /C). \ooking at fue

moving 5'clock

sees someihin9 completely

different.

14-0

I

",,=--=,

l

fEV}

j

,--- n • "" n D1 ~.:!j }zl':!---r~ ~

&1

PULSE

PULSE

EMITTED

AP>50RBED

Mov'lng frame of reference 5 as seen by the coservenn-c'

Albert points out

that the veloeity

of Iiqht isthe some fur c:r1\ observers. Thus ihe stationary observer hears more time elapse between clicks on

the moving dock thon onthe statlona ry

dod<. because ofthe longer m.th leqqth

Oh

qround. AIber-tsoys

finish at

a5 seen tram me

movinq cocks run slower-than stationary decks.

I

let

him

leo6t

AND we am

derive a

formula from the difference.

141

Dorit have a nervous breakdown. 8

go.lowly

b

use pencil8nd peper

c

get 8 friend to come 810ngl

The Key Terms:

v = the speed of the moving frame t' = the time between clicks in the moving frame = the time between clicks in the stationary frame c = the speed of light

n

The time, t', between clicks in the moving frame is the time the light takes to reach the mirror Lie plus the time it takes to return, again LIe. I

2L

sot=C

DO

EJ

But the time, t, between clicks as heard in the stationary frame is the time it takes light to travel the triangular path, h.

,...-------, L... J

1ft

,...-------T L i

D

Now in the time t. the moving frame moves a distance d. And d = vt,

r------....., -J

l-

DO

!DO I

I

And now we can use the 1500-year-old Pythagorean Theorem (on page 129). Remember? "The square on the hypotenuse equals the sums of the squares on the other two sides."

o

h

But we just saw that

h

is related to t:

t· 2c or h= c2t

d

is related to t:

d= vt or J.2. d= .l.vt 2

L is related to t':

t' = 2LC

or L =

m

So what we got before (h2 = (Y2 d)2 + L2) can now be substituted for:

(~r=(l vtY

+(1)2

c t'

2

· nd if we want to solve for what t eguoIs we get

An astronaut goes off in a rocket at 8/10 the speed of light relative to the Earth. After 30 years has elapsed on the rocket how much time has elapsed on Earth?

t

I,

the time elapsed on the rocket = 30 yrs.

v, the speed of the rocket

=

.8c

So with Albert's formula

30yrs

or

t=

V'36

=

=

50JYS.

·6

elapsed onEorth.

Now stop and decide if you feel like reading it through once more.

Albert '. conclusion i•. . .

14t

trA~..Judqed.from 5 WITn

velocitv v;

but

1

itlec1oe;:,k is moving the time whi~h

50

elapses between two elrokes 01 "the dock is nor one second

y 1-V 2.1c2

seconds.

'

i.e. a somewhat longer time. As a consequence cf tHe motion, the

dock qoes more slowly than when 6T rest. 55

Well~'d ~~~t

fo

:::::=,===-

L -_ _

_

find out about relativity, didn't you?

What Albert achieved was a glimpse into how the world looks when things move at close to the speed of light. This is so far removed from everyday experience that it takes a certain amount of work to visualize it.

But remember, Albert was led to this picture by a desire to understand how electric and magnetic forces propagate. He realized that the new area of experience represented by Maxwell's equations required deep modifications of the ideas based on the old area of experience represented by Newton's laws.

115

ow all we have to show is how "the velocities come our right.

Yes, you remember

ever,y observer must

see me some velcx:;:lty of Iiqht no matter. how1hey are moving O'n a sTeady' way of course).

Mike, lets have our passenger car agoin.

Good, Now we imagl'l1e that our person in the midd Ie d fhe car get5 up and wall<s to "the front door at a rate of w = 3 mHesper hour. We

further imagine that the trom is

°

moving at velocity of v per hour.

c

2D miles

50?

146

ell, how fast is . our person moving U. WIth

respect to the embankment?

2'V+W'20+~ :Ph? 1hat's riqht (almost).

But AI berr tells us ihat the distances and times measured on thetrain ore not the same as the distances and times rneosu red on the embankment

~@ I

~~ ~

:i ..

50 what

do

we

do?

Well ,10 toke relativity inro account we. just have to be very precise. In reality when we say mot a

person walks or 3 miles per hour with respect to -the train we mean that thej cover "the distance 10 the front door X in atime t where xandt are measured on thetrain, right ?

147

· nd

we know that distances and times as measured on are not the some as when measured from the

-the train

embankment, right?

50 what we need todoisto convertx'ondt.os measured

on the train into x, and t as measured on the embankment

Doina this AI bert shows }hat the velocity U of the person as seenrrom the ground 15 gIven by

V+W u=--1+Y.J!J! C2

50 you see the velocity of the person with reepecr to

the ground ischanged Just a little from zo-ymp.h.

= 20miles!hr+ 3miles!hr

U 1 +20X 3

(Velocity of light) 2

Nqw the velocity of liqht is very great, 186,000 miles per second .so fhot the Correction is very small ordinarily.

149

ut lets try me formula when ihetrain goes atthe speed of light

C Now imagine "that our person sends out 0 light flash to the front of -the train. What, according to Alberts formula, isthe velocity of the light flash wi1il respect to the ground?

~~rve

U=

V+W W 1+ VC2

In -this case V· velocity ofihe train-C and W· velocity of the liqht flash

with respect 10 ltle ira in = C

.

so U the velocity of the Iight Flash 'yVith respect to the ground 15 c+c 2C CI• - 1 C·C = 2 =

u-

~

+ C2

150

It's a neat formula. Albert has shown that his proposed modifications of space and time intervals lead to a new formula for the addition of velocities. The new formula expresses the new fact: there are no instantaneous interactions in nature, nothing can go faster than the speed of light.

Don't get worried. Among physicists there's a saying: "You never really understand a new theory. You just get used to it,"

Understanding is based on experience and it is difficult to accumulate experience about things moving near the speed of lightl (Unless you're a worker on high-speed particles.) <• •

151

, Ibert now has to enow what happens when you try

get an object to exceed thespeed of light.

to

lhls is how Albertargue5: To get on oblect moving you've got to apply a force.

_______ Force sTrength, power 13C. bodyof'

armed men

14c.

strong,2roducing

a powertuIeffect 16c. From Latin

AD.200 orearlier fortis 5trong

or a kick

152.

.-.JfIY-~ .J:n physics force IS an6ther word for 0 0 0 0

~~ooo interaction! ~~~~~ ('

To get ono~ect.movl'n9 really fast you ye got to give it lots oPrllts'

or a constant steady push, say, by an engine.. There are lots of prccncol difftculties in applying a large steady force to an object. Air resistance. Mechanical breakdown. Running out of Fuel.

153

ut Albert is concerned with Q peeper difficultv. Iffthere ore no instantaneou5 interactions in nature arid i -the speed of liqht is the fastest you can go, what exactly

does hOPR~11 ~hetn on object storts to appoach the speea at I'gh ? , Wow.

Does it explode ?!?

No. Waitand see.

We imagine w~ apply a steady force to Q pqr1icle (which we coil an electron).

NOoNo.

Electrons ore much

smaller. Oh well. Never mind.

15t

hen on oQjeet picks up epeed we soy 'It accelerates.

It was Newton

who postulated a connection between force and acceleration.

Oh,

stop

Hey,what aboutMach~ anti Hertz's critlcism?

I

6howing off.

Newton eoid F=mo. Or a=F/m. The occelerorion,«, i~ proportional to the applied force, F, and is inversel,y' p,rovoriionaJ to the mass, m (0150 coiled me inerTia) or the object

lhe biqqer the force the faster it picks up speed . "The bigg.errhe mass or inertia itle harder it is to getit moving fast. Some call it the

"power to , weight ratio."

155

t is easier to get a light car rolling than a loaded true\<..

But we'I\ return to the concept of mass or in a moment

j nertia 000'

1

156

leading to E=mc2 ?

If the electron is at rest then its subsequent motion is given by F = rna.

2

But suppose the electron already has a speed v? Then the electron is at rest with respect to a frame of reference S' moving with velocity v with respect to S.

s'

) Fl=t I---+-----------....j} S' is moving

u )

15

•

stationary

Relative to S', the electron has an acceleration a = F/m (because the electron is at rest relative to S').

hOI

Ah Albert uses -the Lorentz rronsformction (see page 131 )

Right. Albert knows how to find the place and time of an event with respect to the embankment S, when he knows the place and time of the event with respect to the train S'.

151

he event in fuis case is -the acceleration ofthe electron. Here'. what happen.: 1 The electron goes faster because of the force

but 2 In the frame where the electron is at rest the time over which the force acts gets smaller and smaller compared to the stationary frame (moving clocks run slow, remember?) 80

3 In the frame where the electron is at rest the force acts for a shorter and shorter time, the closer the electron gets to the speed of light. As seen from the ground the electron hardly has time to get pushed at all!

Wow. You qive relativity your little fi'nge'r and itiokes your whole arm!

AI bert expresses the process by a concrete

new forrnula.

EINSTEIN'S FORMULA

1905

Y~~K~~W

one (19°5)

Compared

mx /

to old one.

NEWTON'S FORMULA

1686

F a=M ~---r\"--~

Once again, the new formula re-expresses the new fact: There are no instantaneous interactions in nature. Nothing can go faster than the speed of light.

Albert's fonnula shows that when V-C, a-zerol So even if you keep on pushing, the electron doesn't pick up any more speed.

What does it

mean?

The meaning is 'relatively' straightforward.

If you push on an object with a force and"it hardly picks up any speed at all, you say it has a lot of inertia!

Thus as the electron approaches the speed of light it appears to get heavier and heavier because it becomes harder and harder to increase its speed.

159

Ah, / energy.

The definition of energy goes back again to Newton's Laws. 1 When a force, F, acts on a body of mass, m,

for a distance, d. it is useful to say that work, W, has been done on the body.

2 The work, W, is assigned a value W= Fd.

3 By using F= ma you can show that the work as defined by W = Fd is exactly equal to Y, mv 2.

4 The expression Y, mv 2 is also given a name. It is called the kinetic &nergy of the body.

6 The more work (Fd) you put into pushing a body, the more kinetic energy (y, mv 2) it gets.

160

, Its all a

AIbert now says a minute."

er Wait

naminq qpme

We can Rut in -the work ( W= Fd) but ihe body

c.onneCteti up by f=ma!

doesn't pick up sf?eed in tne some way. Why? Because now

F-

.;....m,;..:..o.-,,-,-_

- (1- ~~) ~

50 Alberfs modification leads to formula. The work now equals;

Me 2.

Ilk

Alberts formu10

new

Jr-----J.. 2 mv

W= (1_ -t~)1-MC ~. W = 1

Q

2.-----'

Newton's formula

161

· lbert i5 5Cltisned. He concludes

0 000

When v=c, W becomes infinite. Velocities greater than that of light have - as in our previous results - no possibility of existence.

REMEMBER:

V -velocity

C ... speed of light W-work

00 0.,

instead of going fOster andfaster

itgets heavier and heavier!

50 even iFyou gave a rocket 1,OOO,ooo~ooo,0

3,000,000,000,000 ,000 ,000 ,00 0 .00

I

o, 000,000, 000.000.000,000. 000, 0 p:P.ooopoo,ooo .000,000,000,000,000,000 po

b

.

00. 000 foot Rounds ofthrust, it would still be

going less tilan lhe speed of light! 162.

[JutIf work that's not all. goes into

giving me . Dody more inertIa. 00.

o'

then inertia

must contain energy!

Yes. Albert says we need a new definition of energy. The old Newtonian one (k.e. = Y, mv 2) is only good for speeds much less than the speed of light.

50000

1 2 3

m~

Albert has shown (page 161) that the work W equals (1- V 2/ c 2) Y, -

mc 2

mc 2 So Albert says let's call the quantity (1_ V2/ y, the energy Eof the electron. c2)

Then, with this definition of energy, Albert's formula reads

E= W

+ MC2

What Alberrsays i5ooo6ven if W=zero, If you -

If

don'tput in any workata ., men the electron sri" has an energy equo] to

Not quite li~e this··

.

Albert wosnt afraid to

reach for

a simple qeneral I conclusion!

And to show how it could work: he wro~te q litile 3 PJgB poper in 1905 called .... :

"

() I!!I"

164

DOES THE IN.ERTIA OF A BODY DEPEND ON ITS ENERGY CONTENn

Albert's argument in this paper isn't a proof.

You can't prove a definition. All you can do is show that is makes sense. So without driving ourselves crazy with more formulas, here's what Big AI is driving at:

the old definition of work (W = Fd). combined with

the new fact, nothing can go faster than the speed of light expressed by

mq

:!J

F::. (l-V}(}) 12

h

meanst at

the woe' go", into makinq the body heavier. Theretore

work adds to the inertia of a body and by implication inertia has energy and to make it CONCRETE ...

o

the relationship between enerqv and inertia is E-me2

But remember ... nobody really knows what inertia is or why objects have it in the first place!

165

Albert iust argued thotenergy has ineriiaand inertia has errergy. Hedjdn!t sqy anything

out In 111efirst place.

about how togetlhe energy

E = MC2 is not (as some folks think) the formula for the A-bomb. Remember, Albert proposed relativity in 1905. The A-bomb project began in 1939. Nuclear physics was developed by other scientists, like Joliot Curie, Enrico Fermi and Leo Szilard. Szilard in 1934 came up with the idea ofthe "chain reaction" release of atomic energy. Szilard wrote a famous letter, 2 August 1939, to President Roosevelt, which Einstein signed. Roughly, this letter said: Nuclear energy is here. Scientists in Nazi Germany are also working on it. Plainly, it is a decisive strategic weapon. The President must decide what to do about it. Later, after the A-bomb was dropped on Hiroshima, Albert said: "If I knew thevwere going to do this, I would have become a shoemaker!"

166

Einstein won the Nobel Prize in' 1921 and became a popular world figure.

AI, here's

your Nobel Prize

money.

Hmmm, gravity and electricity must be related

somehow .....

Albert made other fundamental contributions to physics. His general theory of relativity (1916) was a new relativistic theory of gravitation which replaced Newton's old theory. And Albert was.a central figure in the debates raging round the quantum theory a new theory of the electron. Albert's materialist questioning attitude had encouraged a younger generation of research-workers to overthrow even more of classical Newtonian physics.

16'T

These researchers went so far as to throw out the rules of cause-and-effect. (Essentially, they said you couldn't know for sure where an electron would go when you hit it. All you could say was where it "probably" would go!) Albert didn't approve of this at all.

Albert,

quantum theory seems such a good way to vnde rsto nd the

electron. Why won't you accept

?

Iit .

Danish phY5icist and rounder of the "Cppenhoqen School n ofquontum theory. Up to his death in 1955 Einstein was active, opposing McCarthyism, working with Bertrand Russell on disarmament, and still worrying about how to unify electricity and gravity. It may still be done!

166

Albert wasa radical and a Jew. He never lost his political perspective and his consciousness of being a member of an oppressed ethnic minority. This statement on socialism, part of a longer analysis, appeared in the U.S. magazine Monthly Review in 1949 ...

The

-

situation prevailing in an economy based on the private ownership of capital is characterized by two main principles: first, means of production (capital) are privately owned and the owners dispose of them as they see fit; second, the labor contract is free. Of course, there is no such thing as a pure capitalist society in this sense. In particular it should be noted that the workers, through long and bitter political struggles, have succeeded in securing a somewhat improved form of the of the 'free labor contract' for certain categories of workers. But taken as a whole, the present day economy does not differ much from 'pure' capitalism. Production is carried on for profit, not for use. There is no provision that all those able and willing to work will always be in a position to find employment; an 'army of unemployed' always exists. The worker is always in fear of losing his job. Technological progress frequently results in more unemployment rather than easing the burden of work for all. The profit motive, in conjunction with competition among capitalists, is responsible for an instability in the accumulation and utilization of capital which leads to increasingly severe depressions. Unlimited competition leads to a huge waste of labor and to a crippling of the social consciousness of individuals. This crippling of individuals I consider the worst evil of capitalism. Our whole educational system suffers from this evil. An exaggerated competitive attitude is inculcated into the student who is trained to worship acquisitive success as a preparation for his future career. I am convinced that there is only one way to elimi nate these grave evils, namely through the establishment of a socialist economy, accompanied by an educational system which would be oriented toward social goals.

P. A. Schlipp, ed., ALBERT EINSTEIN, PHILOSOPHER - SCIENTIST, Library of Living Philosophers, Evanston, III. 1949. The closest thing to an autobiography. . Carl Seelig, ALBERT EINSTEIN: A DOCUMENTARY BIOGRAPHY, Staples Press Ltd., London 1956.

MORE RECENT WORKS ARE: R. W. Clark, EINSTEIN, THE L1FEAND TIMES, Hodderand Stoughton, London/ Avon, New York 1971. Lots of facts ruined by the author's thinly veiled hostility to Einstein's politics. Lewis S. Feuer, EINSTEIN AND THE GENERATIONS OF SCIENCE, Basic Books, New York 1974. The first book to confront the politics of the times in any depth. But Feuer's bitter opposition to the student rebellions of the 1960shas produced an odd and unworkable theory of generational conflict as the moving force in science. C. P. Snow, VARIETY OF MEN, Scribners, New York 1971. A nice portrait from an elitist vantage point.

A. Einsteinefal., THEPRINCIPLEOF RELATIVITY, Dover, New York 1952. A collection of papers on special and general relativity. A. Einstein, RELATIVITY, Methuen, London 1916/Crown, New York 1961, J. Bernstein, EINSTEIN, Fontana, Collins Glasgow/New York 1973. An overview of all of Einstein'S work. L. Landau and Y. Rumer, WHAT IS THE THEORY OF RELATIVITY?, MIR Publishers, Moscow 1970/Basic Books, New York 1971. A popular Soviet account. If you're not put off by the math, textbooks can be quite helpful because the accounts are nice and brief. Here are another two somewhat advanced but useful books: THE FEYNMAN LECTURES ON PHYSICS, volume 1, Addison Wesley, London/Reading, Mass. 1963. Chapters 15-16contain Feynman'scomments about relativity. L. Landau and E. Lifschitz, THE CLASSICAL THEORY OF FIELDS, Addison Wesley, London/Reading, Mass. 1951. A graduate level text, but pages 1-4 are an exceptionally clear outline of the theory.

BOOKS ABOUT RELATIVITY There are thousands. The trick is to find ones that seem to make sense and stick with them. Working from three or four at once can be helpful. But there's no substitute for talking the ideas over with friends. I have based my own presentation on Einstein's 1905 paper and on his popular book which closely follows the outline of the 1905 paper.

ADDITIONAL BACKG ROUND READING (0) advanced texts

W. Abendroth, A SHORT HISTORY OF THE EUROPEAN WORKING CLASS, New Left Books, London 1965/Monthly Review, New York 1972. E.Anderson, HAMMER OR ANVIL: The Story of the German Working Class Movement, Victor Gollancz, London 1945/0riole Editions, New York 1973.

E. T. Bell, THE DEVELOPMENT OF MATHEMATICS, McGraw-Hili, London/New York, 1940. J. D. Bernal, THE SOCIAL FUNCTION OF SCIENCE, MIT Press, 1967. G. Barraclough, ORIGINS OF MODERN GERMANY, Blackwell, Oxford 1947/Putnam, New York 1973. C. B. Boyer, A HISTORY OF MATHEMATICS, Wiley, London/New York,l968. R. Courant and H. Robbins, WHAT IS MATHEMATICS?, Oxford Univ. Press, London/NewYork,1941. H. Cuny, ALBERT EINSTEIN, Souvenir Press, Paris 1961. P. Dunsheath, A HISTORY OF ELECTRICAL ENGINEERING, Faber and Faber, London 1962/MIT, 1969. A. Einstein, LETTRES A MAURICE SOLOVINE, GauthierVillars, Paris 1956. ENCYCLOPEDIA JUDAICA, Macmillan, Jerusa lem 1971. * J. D. Jackson, CLASSICAL ELECTRODYNAMICS, Wiley, London/ New York 1972. H. G. Garbedian, ALBERT EINSTEIN MAKER OF UNIVERSES, Funk and Wagnalls, New York 1939. C. C. Gillespie, ed., DICTIONARY OF SCIENTIFIC BIOGRAPHY, Scribners, New York 1972. B. Hoffman, ALBERT EINSTEIN, CREATOR AND REBEL, Hart Davis, LondonlViking Press, New York 1972. * M. Jammer, CONCEPTS OF MASS, Harper Torchbooks, New York 1964. *F. A. Jenkinsand H. E.White, FUNDAMENTALS OF OPTICS, McGraw-Hili, London/New York 1965. D. K. C. MacDonald, FARADAY, MAXWELL AND KELVIN, Anchor Books, New York 1964.

P. W. Massing, REHEARSAL FOR DESTRUCTION: AStudy of Political Anti-Semitism, Harpers, New York 1949. oW. D. Niven ed., THE SCIENTIFIC PAPERS OF JAMES CLERK MAXWELL, Dover, New York 1965. V.1. Lenin, IMPERIALISM, THE HIGHEST STAGE OF CAPITALISM, Foreign Languages Press, Peking. 1965. * A. O'Rahilly, ELECTROMAGNETICS, Longmans Green and Co., London 1938. * W. K. H. Panofsky and M. Phillips, CLASSICAL ELECTRICITY AND MAGNETISM, Addison Wesley, London/Reading. Mass. 1955. E. J. Passant, A SHORT HISTORY OF GERMANY 1815-1945, Cambridge Univ. Press, Cambridge/New York, 1959. oW. Pauli, THETHEORYOF RELATIVITY, Pergamon, New York 1921. P. G. J. Pulzer, THE RISE OF POLITICAL ANTI-SEMITISM IN GERMANY AND AUSTRIA, Wiley, London/NewYork 1964. E. Sagarra, A SOCIAL HISTORY OF GERMANY 1648-1914, Methuen, London 1977. H. Schwab,JEWISH RURAL COMMUNITIES IN GERMANY, Cooper Book Co., London 1956. * A. Sommerfeld, ELECTRODYNAMICS, Academic Press, London/NewYork 1952. F. Stern, GOLD AND IRON, Georg,e Allen and Unwin, London/Knopf, New York 1977. D. Struik, A CONCISE HISTORY OF MATHEMATICS,3rded., Dover, NY 1967. * E. F. Taylor and J. A. Wheeler, SPACETIME PHYSICS, W. H. Freeman, London/San Francisco 1963. * S. Weinberg, GRAVITATION AND COSMOLOGY, Wiley, London/New York 1972.

1;3