Steven Weinberg & X. C) a- Y5 {# V3 G- c6 B$ K: u4 P9 W; S
Steven Weinberg is in the Department of Physics, - D+ T( i, R0 C. ?7 g/ Jthe University of Texas at Austin, Texas 78712, g2 y+ {: T/ u) J5 P
USA. This essay is based on a commencement talk " e$ T3 W1 G& ^3 [1 Tgiven by the author at the Science Convocation at 3 f! L+ p1 d( ?: T D: bMcGill University in June 2003.9 [. x; @: {( \7 R+ N
! a+ Z M6 g; Z- X! C
When I received my undergraduate degree — about a hundred years; u; t6 X4 p0 E2 V. @8 t
ago — the physics literature seemed to me a vast, unexplored ocean,6 o9 E f. h$ v) f J T
every part of which I had to chart before beginning any research of my own. How 9 `, I/ Q2 H. k$ G/ d0 Kcould I do anything without knowing everything that had already been done?+ K u7 y& I8 @" @% ]2 d( i
Fortunately, in my first year of graduate school, I had the good luck to fall into the4 i N; U& h- a0 D& N$ K' K
hands of senior physicists who insisted, over my anxious objections, that I must start# j! E& R. }% ]' c
doing research, and pick up what I needed to know as I went along. It was sink or) B0 `. U; M/ i
swim. To my surprise, I found that thisworks. I managed to get a quick PhD — / z5 |: y: `0 t) |1 {2 b" @, Jthough when I got it I knew almost nothing about physics. But I did learn one big5 j' V' y- n( b) C$ ]& g
thing: that no one knows everything, and you don’t have to .% k0 r5 C: k9 ?9 X/ H* v- \* Y7 y
2 T1 X: Q" _. s; t; P1 S, o0 \Another lesson to be learned, to continue & M5 E2 }$ G5 F9 cusing my oceanographic metaphor, is that ! Z- d: p* }1 ]+ `while you are swimming and not sinking you ' h$ q1 T% F6 z# W+ \: u; Bshould aim for rough water. When I was2 M/ ?8 i/ j& ~; N0 e, R) c0 a
teaching at the Massachusetts Institute of ; e. U9 X9 j& {4 \) ]0 y$ @: oTechnology in the late 1960s, a student told + K" U5 a; y4 v a0 qme that he wanted to go into general ) ?3 W5 _$ `& V3 d3 \! ~* lrelativity rather than the area I was working ; A. G2 F" T9 M3 M* {on, elementary particle physics, because + |( Y9 b( f8 V: h& U- othe principles of the former were well; a& e, d8 l' @4 J, b! B [/ n. a
known, while the latter seemed like a mess ' c4 r! @( P7 q( Q- r5 Zto him. It struck me that he had just given2 ^9 `& ~; _/ b6 R. H3 b, t
a perfectly good reason for doing the opposite.. U) _. ]+ u, J
Particle physics was an area where9 d9 y2 O+ \, z; k
creative work could still be done. It really was 4 J7 K R, I" p+ u3 p& l, [a mess in the 1960s, but since that time the2 |* S% ^; a, B; A, l1 ^
work of many theoretical and experimental + J4 }; ~/ ^$ _; p: m) G6 l- Sphysicists has been able to sort it out, and ' B4 A. k6 q1 L; u4 rput everything (well, almost everything) ; i0 S: `% O ?together in a beautiful theory known as 7 \" e! j# @' i0 ^9 Nthe standard model.My advice is to go for the8 r1 S# R; l: t
messes — that’s where the action is. + O4 T$ |+ f5 _( {% k$ j% `, Q+ m8 U) ^
My third piece of advice is probably the- w/ v& t7 x! X( A# D6 \
hardest to take. It is to forgive yourself for" I. u1 y+ F q
wasting time. Students are only asked to 3 N' m j9 q1 e g+ U3 Esolve problems that their professors (unless0 p) o I2 O: R: m5 }* o/ s9 b: w
unusually cruel) know to be solvable. In' E- m+ o$ N: \1 l7 t
addition,it doesn’t matter if the problems are 5 a! [( o9 D' G+ q% |- `6 Tscientifically important — they have to be' W- o! S# p7 v# J. X! [3 x
solved to pass the course. But in the real+ @4 ` L8 I' U5 l+ L" S" y
world, it’s very hard to know which problems! _( Y* `0 Z( A
are important, and you never know whether& s2 C- V7 b. d2 \- Z% w
at a given moment in history a problem is& V7 w' n" [& _* B, u( t
solvable. At the beginning of the twentieth# B9 x) a2 _4 w& ?
century, several leading physicists, including' b2 ?' `- d9 k" k" F
Lorentz and Abraham, were trying to work % W- K/ [" Y% G e, bout a theory of the electron. This was partly* W j, G. f& @) i7 R; j
in order to understand why all attempts to 2 q7 {9 J6 |+ i& Kdetect effects of Earth’s motion through the( e) s* b2 x, \5 k3 ]: l; {
ether had failed. We now know that. q$ i4 i2 P8 ^5 E4 z9 M5 m6 h
they were working on the wrong problem.% ?8 Y9 O+ K- ?2 ^( c0 D9 b
At that time, no one could have developed a " u0 M( E7 U+ Y% n- w Ssuccessful theory of the electron, because7 P' @+ j9 f3 x$ h0 [8 m$ f6 P
quantum mechanics had not yet been# c0 x: X \3 e' _" e
discovered. It took the genius of Albert % T6 H' t7 n3 O9 T3 [Einstein in 1905 to realize that the right @3 v% {6 w3 W! p" o
problem on which to work was the effect2 Y9 D- D. M X; w4 b
of motion on measurements of space and! Q/ e5 [: K/ _
time. This led him to the special theory of % t6 v! I4 b& k/ S. rrelativity. As you will never be sure which 4 }; w! n! |3 |5 ~8 V4 }2 _are the right problems to work on, most: i9 F% b& u2 z0 F
of the time that you spend in the laboratory 6 \7 Y1 E: h- O1 Sor at your desk will be wasted. If you want % z/ Y; T/ x/ {- J; rto be creative, then you will have to get used ; _4 C9 ~! v. O+ T6 R1 Mto spending most of your time not being, ?" Z! c6 _1 [
creative, to being becalmed on the ocean of & R$ x$ b8 W. |4 R* P3 ?; k+ H8 R. F7 kscientific knowledge. ; w8 j$ @# S2 h6 a; |9 h5 V * d; M4 V7 o4 X9 ~Finally, learn something about the history 4 k$ W! ?( L4 x4 G, F* }* G% bof science,or at a minimum the history of your- l& U' x0 t7 x2 d0 R) F
own branch of science. The least important. H: E7 z H$ b+ u
reason for this is that the history may actually6 f* [- w' z n* {
be of some use to you in your own scientific/ C/ Z5 b0 i+ e7 ^' j. \4 r! n7 @
work. For instance, now and then scientists- G0 V& H1 m# V! ~$ \! ?
are hampered by believing one of the oversimplified 7 [6 V9 z0 m* f* r1 E. pmodels of science that have 6 x; A3 |+ c& n' A# qbeen proposed by philosophers from Francis / `2 y% ]- d @! \Bacon to Thomas Kuhn and Karl Popper.- E& {# _ Y& W6 D0 F
The best antidote to the philosophy of science 2 @, L' X) Z7 R' B( Mis a knowledge of the history of science.5 N- U4 b8 Z- Y" q& K
More importantly, the history of science; z9 i% c h! g; Y+ J
can make your work seem more worthwhile $ P! X3 L$ Y I& ?- a. w5 eto you. As a scientist, you’re probably not9 z; p+ _; Q0 o" l
going to get rich. Your friends and relatives- {- k9 o1 Z' f' \
probably won’t understand what you’re; n4 C3 f7 I- z0 m
doing.And if you work in a field like elementary/ Q. o% B( h9 e3 u1 d! D
particle physics, you won’t even have the # j+ t% q6 m) g/ g( Ksatisfaction of doing something that is2 m# E2 |+ f+ V9 S8 r: F3 o
immediately useful. But you can get great2 N( R# D+ }4 {; [. S8 a# m
satisfaction by recognizing that your work in. m q1 R& g: g* h v% j
science is a part of history.! D( \9 T4 B' A
% h7 c' I) q- ^7 I$ s# e
Look back 100 years, to 1903. How/ w, L0 ~/ @! n6 S& ^! O- F
important is it now who was Prime Minister6 n9 U6 O- {1 f$ I* \! ^
of Great Britain in 1903, or President of the5 v4 F' S7 @0 s/ |% f7 `4 X& Q7 I
United States? What stands out as really 0 s8 w2 A$ m" L& j2 u, c7 cimportant is that at McGill University,7 t: ~0 H1 I z v) E- p) k0 m
Ernest Rutherford and Frederick Soddy were ; Q4 o; _% B* Z4 g- a [5 H! J( uworking out the nature of radioactivity. - t: a) m5 g3 _ ^8 z1 D( n5 ^This work (of course!) had practical applications, - k1 r N; m. v. \but much more important were its- D# o) }; n. n6 P. U5 J; w; H' F: q/ E
cultural implications. The understanding of 2 v+ m) H) f9 xradioactivity allowed physicists to explain; R! ?( ~( O+ z* X: b7 H
how the Sun and Earth’s cores could still be * j4 T* f0 L7 |% Q3 W, vhot after millions of years. In this way, it& q, i! ~% B8 F
removed the last scientific objection to what9 p+ _) W+ Q8 o0 Z$ h9 }- F0 A
many geologists and paleontologists ' }9 O; E3 d. V% A% } {thought was the great age of the Earth and0 ~* ?& r& z2 g! Y3 C( `
the Sun.After this,Christians and Jews either / }0 V7 I. Q! s9 Chad to give up belief in the literal truth of: M* d5 `1 Q3 k% L' s# F+ Y8 n
the Bible or resign themselves to intellectual. t3 \* C- k; R, o, D/ K
irrelevance. This was just one step in a; E+ ]: k0 K8 G
sequence of steps from Galileo through" f( M9 e7 p1 [
Newton and Darwin to the present that,time ' `( ]/ Z% g# g3 j5 K% b& _after time,has weakened the hold of religious ) l \; Z" b, U( Idogmatism. Reading any newspaper nowadays% n b* L8 E; t3 G- n
is enough to show you that this work G! L0 G0 D! T; ~
is not yet complete. But it is civilizing work, $ Q5 K5 ?. R8 wof which scientists are able to feel proud.