Steven Weinberg L. _5 w6 H* [6 L4 m : a2 C& S# ?4 P; n! ]: x* g0 JSteven Weinberg is in the Department of Physics, |' J! C( m) Z2 gthe University of Texas at Austin, Texas 78712,4 B4 o& B% t) a4 O6 S
USA. This essay is based on a commencement talk ; r z8 i& b& z# B& ygiven by the author at the Science Convocation at4 U. |7 H7 L) P# P4 P0 [
McGill University in June 2003. / R$ d7 z! K$ Z& z( n& d' I6 P/ Q! t- M K Z: x; U9 F: u( ]; r
When I received my undergraduate degree — about a hundred years & r4 b: E% ~0 W( d3 }) `- h& tago — the physics literature seemed to me a vast, unexplored ocean,( O6 G9 ]2 p# [% F# K4 \! X
every part of which I had to chart before beginning any research of my own. How : S: I. [( J3 c+ B" f% ccould I do anything without knowing everything that had already been done?7 w; G3 y3 r: K& c0 |3 R4 j
Fortunately, in my first year of graduate school, I had the good luck to fall into the; G8 w |( r" x6 O
hands of senior physicists who insisted, over my anxious objections, that I must start " h& l, I# J3 {" m- \doing research, and pick up what I needed to know as I went along. It was sink or+ M6 h& r# h2 M% U& G6 a H# `- C
swim. To my surprise, I found that thisworks. I managed to get a quick PhD —( S" S" b6 U) l* y m
though when I got it I knew almost nothing about physics. But I did learn one big& z# h' E4 ~/ V
thing: that no one knows everything, and you don’t have to . % a3 P0 _, Q" { $ U9 ?" H; o- O: t+ I+ dAnother lesson to be learned, to continue ) Z1 r) J' a$ o4 Busing my oceanographic metaphor, is that 8 F; B: q- q& h% O3 J- Swhile you are swimming and not sinking you 8 x4 \) `! g! x8 o5 ishould aim for rough water. When I was1 S3 Y/ E$ c3 s& B8 b& l
teaching at the Massachusetts Institute of* W+ A! N1 U9 N y# s# K0 `" ~
Technology in the late 1960s, a student told) q5 @7 b4 d4 }
me that he wanted to go into general6 J$ l" {7 e% o& |# l
relativity rather than the area I was working0 l: \, }5 z$ E, W) h; B: Z+ @- |
on, elementary particle physics, because ( J6 w3 c9 e* K# tthe principles of the former were well& I+ d! Z3 r) c6 V
known, while the latter seemed like a mess ( O, l' h, c# U4 u- qto him. It struck me that he had just given$ G" [+ W% `: Q
a perfectly good reason for doing the opposite.9 V- ], u, v8 Z {; q
Particle physics was an area where ! V6 l9 w# ?: e1 c% {creative work could still be done. It really was3 l! {9 }4 y& a0 a! E% U- ^% \
a mess in the 1960s, but since that time the4 z5 p' v4 a( ?% G* o# _' `: L. @
work of many theoretical and experimental; h! J% |( N3 T( b. [
physicists has been able to sort it out, and ) w4 V& a& |9 j4 r/ b: v8 zput everything (well, almost everything) / j2 X, ~9 H* K5 ?together in a beautiful theory known as8 L- y% M5 c( ~* p
the standard model.My advice is to go for the p1 e4 L9 P5 v! @' w4 ]! Kmesses — that’s where the action is.% H" s# ]9 a9 P! a
7 ]* m6 K; L% [My third piece of advice is probably the6 D) v/ T+ ?. \; ~0 c0 O1 ?
hardest to take. It is to forgive yourself for' c* }$ Z# A4 n- P/ I' {- G
wasting time. Students are only asked to & x# t2 c9 {! c* d$ N% csolve problems that their professors (unless " ?7 A: v! D4 {) z1 dunusually cruel) know to be solvable. In/ M7 C. V% K( L0 ]$ i
addition,it doesn’t matter if the problems are 6 R0 ^) }$ E) F* V! c; Sscientifically important — they have to be & X# x; G3 D8 F3 Vsolved to pass the course. But in the real ' x0 a! s$ {3 D; r! M: Tworld, it’s very hard to know which problems5 W# _/ Z, n8 ]8 i9 e( K$ N
are important, and you never know whether8 k; r H* m k8 g* i- P
at a given moment in history a problem is . z; M0 D a. V! @solvable. At the beginning of the twentieth 6 J/ y2 Z- Y- B* F8 Y) y7 B" lcentury, several leading physicists, including+ ~6 O4 C$ G$ v1 q3 r
Lorentz and Abraham, were trying to work " g5 ^8 a0 G" O% _1 Kout a theory of the electron. This was partly: Z4 D# X& a7 w1 k0 D2 C4 L5 c
in order to understand why all attempts to( Y9 A6 Z: K/ q
detect effects of Earth’s motion through the: [# O8 A( F }. ^) k+ A8 n
ether had failed. We now know that 4 [7 t" Y$ k6 k9 Xthey were working on the wrong problem. + H- V6 a/ l# PAt that time, no one could have developed a , y" U! {# B% a1 ?- d) V& asuccessful theory of the electron, because t6 Z# g! q' {- X! I6 N
quantum mechanics had not yet been # D) J. _- j4 w( f4 idiscovered. It took the genius of Albert 1 e }# @7 Z! ?. d UEinstein in 1905 to realize that the right: s: v2 [7 m+ q: d
problem on which to work was the effect " f4 A+ M' d3 Q; @, Q& Gof motion on measurements of space and# R4 V" t/ N4 M) J7 u7 H
time. This led him to the special theory of ' _6 C' e( @7 @6 ]2 {relativity. As you will never be sure which! I7 N2 u4 v/ C) }7 ?
are the right problems to work on, most# X% J E! T" Z' p2 _+ b2 A4 A
of the time that you spend in the laboratory1 s3 x4 \8 T O1 x( t6 R
or at your desk will be wasted. If you want7 P% w1 D6 n% ?8 K
to be creative, then you will have to get used 2 m$ I" j; V9 S3 h- |. ?4 u+ h' M. qto spending most of your time not being; R" q; U# \; p2 N
creative, to being becalmed on the ocean of 9 y" v- u0 I( ]) t- yscientific knowledge. 0 U9 D4 Z0 `. j; A, L$ G9 n* t- H0 q9 E1 G, B9 t2 {/ ^* g2 L/ K
Finally, learn something about the history & [8 F: d7 z9 y+ \of science,or at a minimum the history of your6 Y: a! T3 |, c; ~. G7 R5 v/ B4 }
own branch of science. The least important! T$ l: w' L" E) s: H7 f
reason for this is that the history may actually+ @# t O1 [/ S1 [
be of some use to you in your own scientific . h+ K: h# P. ]( mwork. For instance, now and then scientists1 l& J4 x# }/ F; |
are hampered by believing one of the oversimplified# z3 M& }; r$ r) d6 h. B7 F% O9 g
models of science that have + j! w! j+ F1 Q6 c4 D. obeen proposed by philosophers from Francis. a" f J3 v/ w6 n1 G6 n
Bacon to Thomas Kuhn and Karl Popper.+ S; y$ @3 i( v- D
The best antidote to the philosophy of science 0 V* u0 Y# q9 V$ q+ J g/ k; Mis a knowledge of the history of science. $ V( [- F6 p/ p& Q8 w5 UMore importantly, the history of science; ?- T7 Z4 y/ z* ~1 h
can make your work seem more worthwhile& A* U* ?% M8 h& x2 r
to you. As a scientist, you’re probably not & i2 s9 C) e/ t+ _. Y8 G" `! dgoing to get rich. Your friends and relatives ( P: c1 I2 K- c4 Bprobably won’t understand what you’re5 S! ~4 Q- n& Y; ~+ @
doing.And if you work in a field like elementary# B' |$ T, A9 n1 h- G% W
particle physics, you won’t even have the 5 q3 h; X U! @satisfaction of doing something that is3 S" O* [4 l A8 C0 t$ Q) V
immediately useful. But you can get great * Z5 y, X% {3 K2 A- J- T2 dsatisfaction by recognizing that your work in 1 `8 @) K" b2 C1 U9 U9 Fscience is a part of history.: y4 l- J2 d( K
: i- c7 `( _6 r8 y) @Look back 100 years, to 1903. How# \' J( t+ \& t* I! b' _9 N
important is it now who was Prime Minister8 f ?# M- S M. [0 K( ~, {' o" b& u
of Great Britain in 1903, or President of the 1 g( k3 J* }0 UUnited States? What stands out as really0 s9 T5 E4 ?3 n( {/ h6 g- V
important is that at McGill University, / G, N' v4 G+ d6 P; ?$ S" `, }2 \Ernest Rutherford and Frederick Soddy were% E% ]6 X, |; {! {9 x% l
working out the nature of radioactivity. : n. s$ H6 i/ k4 Z% O0 k dThis work (of course!) had practical applications,4 {& n4 z) V* J" M1 {# k3 w
but much more important were its$ T: J+ ^. p$ ^
cultural implications. The understanding of 1 ^1 r% X7 X# Xradioactivity allowed physicists to explain2 `# T' u3 L6 T m( J
how the Sun and Earth’s cores could still be6 X9 ~( c% J+ c# y7 X
hot after millions of years. In this way, it) j6 O e) N C- O1 }
removed the last scientific objection to what - d# i% J+ F7 y5 Kmany geologists and paleontologists: o0 J3 w! H# S7 ?; }
thought was the great age of the Earth and1 y; j: \. @8 G4 e& ` h
the Sun.After this,Christians and Jews either : ]# Q+ {4 C( v3 a1 R- y$ i7 _/ {' G* ghad to give up belief in the literal truth of . W. ^1 m# W7 Ithe Bible or resign themselves to intellectual3 w" w) R/ p, Y- d, `" ^
irrelevance. This was just one step in a6 A' z8 V: e6 L0 H) G+ g
sequence of steps from Galileo through) _7 c+ i6 c: G8 A5 B |3 E7 E# z. ]
Newton and Darwin to the present that,time / r+ _5 D0 u: j4 P a. m( X* [( bafter time,has weakened the hold of religious8 u. P7 k8 k1 Z8 ~" G- n
dogmatism. Reading any newspaper nowadays( a& F2 t! ]4 \# b
is enough to show you that this work: N+ D# D# a2 w+ w0 v- L4 n
is not yet complete. But it is civilizing work, . H# ?* ~! t2 Q) Y! L7 kof which scientists are able to feel proud.