! Z8 O( ^$ Q3 Y* JSteven Weinberg is in the Department of Physics, # S7 w9 X; B q: K0 C% qthe University of Texas at Austin, Texas 78712, 0 W! }9 m* N3 e7 }: gUSA. This essay is based on a commencement talk: {7 R3 V( s. M$ M( t
given by the author at the Science Convocation at ' G6 J3 l5 B" x' n4 h$ TMcGill University in June 2003.+ v) h! k( w' n% y6 `- g S5 {0 {( Z
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When I received my undergraduate degree — about a hundred years & x. y) _8 m( o. y5 Q" jago — the physics literature seemed to me a vast, unexplored ocean, - O6 S, P' b5 @ N7 ?5 [every part of which I had to chart before beginning any research of my own. How1 b( H/ D, {5 C0 E: Q$ |/ P. ~
could I do anything without knowing everything that had already been done?3 |* G o( Q* L( e+ _7 a9 P4 |
Fortunately, in my first year of graduate school, I had the good luck to fall into the+ b9 E" {) L; N9 [8 p) L& [4 e
hands of senior physicists who insisted, over my anxious objections, that I must start( j# |/ t" G5 ?/ _
doing research, and pick up what I needed to know as I went along. It was sink or& b1 D# }; }7 j5 M+ D( E
swim. To my surprise, I found that thisworks. I managed to get a quick PhD — ( I: I* L" Y% W9 ~though when I got it I knew almost nothing about physics. But I did learn one big 9 h% p/ ^- [: }& A% A9 d0 _thing: that no one knows everything, and you don’t have to . . m: C' m* t9 L' y) W9 h b! `2 J# d7 s G
Another lesson to be learned, to continue+ {& }7 b1 E* @( W
using my oceanographic metaphor, is that# s' w. {1 Z% s* [) W
while you are swimming and not sinking you 5 N2 l, z F4 T2 W* pshould aim for rough water. When I was . `9 [& L6 |1 m3 Gteaching at the Massachusetts Institute of6 s/ L8 X j- m+ t2 b0 ?9 t& {
Technology in the late 1960s, a student told! f( v' b( [. P: T- ?
me that he wanted to go into general 2 j" [0 T) ?7 Q, D8 Yrelativity rather than the area I was working. W. N/ Z& \! K
on, elementary particle physics, because5 ?, ]/ \5 I/ L8 c4 i
the principles of the former were well * z5 P' N8 r! |! Bknown, while the latter seemed like a mess G7 T. R1 r0 N- B/ t7 I
to him. It struck me that he had just given , @# H) ]9 b6 _. xa perfectly good reason for doing the opposite. / B3 R. h+ b; Z( MParticle physics was an area where! g- h; n& m6 ?; b
creative work could still be done. It really was ' p/ w6 E7 _) |2 s1 [& c) u+ |a mess in the 1960s, but since that time the 8 i# @" Y% h. \: Mwork of many theoretical and experimental; d2 s8 |5 ?4 u* C I% A
physicists has been able to sort it out, and ! x+ A+ _, N% x3 W0 q8 t' Vput everything (well, almost everything) ; J+ b; S% S1 ~0 Rtogether in a beautiful theory known as' r9 X! t* h s
the standard model.My advice is to go for the( ?/ j5 i; z9 F1 E6 k, j
messes — that’s where the action is.$ m7 v# i& P$ [( l! T$ m
, s+ @. A2 T8 j2 S3 }" k) [; `& }My third piece of advice is probably the ; s& H( A9 O1 d/ \- O+ R; ghardest to take. It is to forgive yourself for- C- y' ?8 w) h5 Y* ^/ g
wasting time. Students are only asked to % s# z9 ]) g5 S! p$ r1 z+ Dsolve problems that their professors (unless( I9 ^" Q3 V; x, }
unusually cruel) know to be solvable. In& N& b) Z9 q# V$ m+ ~: w, |# L
addition,it doesn’t matter if the problems are% v& c3 @0 {& r- N" F4 ?- S$ y
scientifically important — they have to be 2 Z3 z3 V% J' l3 |' i. Ysolved to pass the course. But in the real 8 j! o# g+ a3 a: c) xworld, it’s very hard to know which problems 1 k3 j2 ?, V1 b* V) w1 E' J4 Rare important, and you never know whether 9 \# z4 O# {% W9 q& wat a given moment in history a problem is7 x- d8 ? x& _3 P1 l/ ?. P/ a! @; V
solvable. At the beginning of the twentieth 4 x/ x- B0 A8 A% r2 v4 Y4 }. A9 W( Acentury, several leading physicists, including5 Q6 f" o5 |9 X7 @1 f- H5 w( ]; E" y
Lorentz and Abraham, were trying to work. }9 j! E+ Q, Y: p+ w G
out a theory of the electron. This was partly* d6 s% r. n8 r: u, E% o) h( X
in order to understand why all attempts to# ^: k+ e/ i2 F! b3 ?+ f4 E
detect effects of Earth’s motion through the 0 t% R1 A! U* K* h, kether had failed. We now know that ; r. z2 i" r) z, cthey were working on the wrong problem.+ }: W1 S1 {5 g1 w1 O/ s
At that time, no one could have developed a5 g2 H" P- \) \8 ]% V$ {
successful theory of the electron, because; k) S+ \! j* u
quantum mechanics had not yet been$ f: [$ y ?/ w& t' z
discovered. It took the genius of Albert$ |& ]2 \$ F0 P& X; `
Einstein in 1905 to realize that the right, s0 x. |- o: |( H$ ?; H( l
problem on which to work was the effect' R' I% D; r) x! a8 f
of motion on measurements of space and 8 a8 H+ F. h7 f2 D0 x& A% J; Itime. This led him to the special theory of / t5 G( k: y' `# u! ~* frelativity. As you will never be sure which " b$ W4 x# B$ c0 iare the right problems to work on, most! f. F# R3 c. f; X
of the time that you spend in the laboratory ) _" ^: @8 H2 M- }, t4 o+ j$ ror at your desk will be wasted. If you want . G3 q2 V1 Z2 q9 `/ C/ E: `1 e4 tto be creative, then you will have to get used 0 r. Y" m9 h2 K5 Q5 g0 @6 ^9 Cto spending most of your time not being # ~1 P- z& \) c8 }creative, to being becalmed on the ocean of, l, ~: v3 I* N: o
scientific knowledge., y( }2 e* ]3 c+ R5 Y3 O
; C- j0 A1 @: D( CFinally, learn something about the history 5 |$ h. }2 r- j& a5 L5 F0 [( Wof science,or at a minimum the history of your+ ~0 U+ t/ [! J# @& D( }
own branch of science. The least important( {3 B) U2 [" d( S- V @
reason for this is that the history may actually 7 b# R4 v( [# ?be of some use to you in your own scientific . ~3 l- \- u* e" O+ t8 Awork. For instance, now and then scientists3 {' s, p- |, W+ Q/ |
are hampered by believing one of the oversimplified( ]. u3 p1 B7 j- `5 f5 y$ J
models of science that have % R# O5 p9 c! _7 e8 M1 b/ Z" Ubeen proposed by philosophers from Francis ) h+ l, m# C- P8 Q" G$ D# RBacon to Thomas Kuhn and Karl Popper. 4 _% k8 ]$ J4 _The best antidote to the philosophy of science* t6 G. M: C2 z5 x' T2 S1 m' }
is a knowledge of the history of science.8 W1 D( n4 s' [9 q
More importantly, the history of science 5 @1 P2 ?; N$ a7 z3 P% dcan make your work seem more worthwhile # U9 A1 E9 C; L8 [to you. As a scientist, you’re probably not4 m- X8 R5 H, s& h( `& `5 E
going to get rich. Your friends and relatives8 N7 G2 O$ x. R% m6 Y$ e3 ]: p
probably won’t understand what you’re$ O7 e3 T8 x8 V
doing.And if you work in a field like elementary( x8 B$ s1 {* F& E0 D' _9 f
particle physics, you won’t even have the4 V o+ B B" @. U
satisfaction of doing something that is # T2 ~. v* F2 ~! Simmediately useful. But you can get great % h8 B6 |1 J6 M( N+ H. t4 n8 `0 hsatisfaction by recognizing that your work in 3 `- {7 d! D6 S. zscience is a part of history. ' F8 b- q4 n8 D ) B( J0 V( y0 g5 j* bLook back 100 years, to 1903. How ; ~, `' U4 g% M$ ? w6 P) f8 Yimportant is it now who was Prime Minister4 w2 s/ {7 M+ n9 k. C. V- H$ J
of Great Britain in 1903, or President of the / e' d/ N a8 C9 ?7 u- ]United States? What stands out as really/ d0 ?+ f ~% g/ n9 }8 M; i
important is that at McGill University,! @/ I0 ^9 b- _8 `, n m
Ernest Rutherford and Frederick Soddy were2 f; X5 w" Z+ v9 f8 `
working out the nature of radioactivity.) [, h' y. ~" A3 p4 {
This work (of course!) had practical applications,4 ?6 {( E& X2 o" U, `$ R$ z
but much more important were its; l | ^$ v! H. }
cultural implications. The understanding of% G2 c4 y" k! O; f6 X8 i# j2 [
radioactivity allowed physicists to explain2 A0 R: h( R0 O! x" @
how the Sun and Earth’s cores could still be U- b5 \6 V0 v2 o& i( v& R5 u. `hot after millions of years. In this way, it& q1 l: s; Y5 y; o
removed the last scientific objection to what' v) N9 r. G$ f# ^% O3 m& E/ X
many geologists and paleontologists 3 h. z: o$ b! }) K2 I1 p1 u+ D4 wthought was the great age of the Earth and+ I! k5 B6 {% P& E8 R( v
the Sun.After this,Christians and Jews either7 ?/ P1 H7 ~* y# y
had to give up belief in the literal truth of 0 J8 u$ y& A# ^$ u8 ~# i% ?the Bible or resign themselves to intellectual. q: F+ s. D5 x! b
irrelevance. This was just one step in a * ~3 [% q% _3 Bsequence of steps from Galileo through 1 c" \' C; L, M4 LNewton and Darwin to the present that,time / V! K" M! n$ [: Jafter time,has weakened the hold of religious* i0 E4 I6 `& H3 \/ U+ c
dogmatism. Reading any newspaper nowadays , C* U- ]* x8 C# m7 a" a# f! dis enough to show you that this work 8 ?; x5 y: G7 D) D5 i. b3 ?is not yet complete. But it is civilizing work,) O8 ?: h" |/ H x0 J1 T
of which scientists are able to feel proud.