Steven Weinberg P% l W2 G1 A+ E8 K) a6 c9 { ) j* {' K, a- t: E& d9 CSteven Weinberg is in the Department of Physics, ) z6 x8 d( w4 t x4 q* hthe University of Texas at Austin, Texas 78712, $ a+ V6 ]/ o+ e/ fUSA. This essay is based on a commencement talk & q6 o+ V0 N# j% Mgiven by the author at the Science Convocation at / v! Q* U- g' _8 s, p! h" W$ o P* XMcGill University in June 2003.+ _* @2 t- y. R5 K0 h1 p
6 }9 ~# r; O$ L# H. D; z, w
When I received my undergraduate degree — about a hundred years \( z: {) a! o+ Q0 g) A/ g: bago — the physics literature seemed to me a vast, unexplored ocean, : h; @: o0 b% z: G5 j8 uevery part of which I had to chart before beginning any research of my own. How* D- [4 M& d: Z
could I do anything without knowing everything that had already been done?. U. e% j0 `, N' b' n
Fortunately, in my first year of graduate school, I had the good luck to fall into the9 Q( I0 C. Z$ j* `( b4 T: O
hands of senior physicists who insisted, over my anxious objections, that I must start ; Q0 f$ x# `* r* i$ |6 ^doing research, and pick up what I needed to know as I went along. It was sink or( O! ?. A/ k0 j% s0 q8 `( P
swim. To my surprise, I found that thisworks. I managed to get a quick PhD —0 E: K3 f x, c1 I- n0 D/ ]7 g; C
though when I got it I knew almost nothing about physics. But I did learn one big7 K% V8 C+ E& k% L0 ]) @; B: ?" o
thing: that no one knows everything, and you don’t have to . ~' @ p/ y9 N0 L! q+ @7 p
6 l/ _& t% h( z. M/ e! g6 f' N7 aAnother lesson to be learned, to continue7 H0 k4 Z6 E9 y% V
using my oceanographic metaphor, is that " J8 ?/ a; S( w' \' Y2 A: {while you are swimming and not sinking you1 {- }8 ], d! _/ T% ]; C
should aim for rough water. When I was. o" J( b4 H& z; E; B0 O( R
teaching at the Massachusetts Institute of+ @! z5 n' T6 J! S. o8 m- u
Technology in the late 1960s, a student told' S# W3 s' Z% }8 `# _# t
me that he wanted to go into general) f0 t( ^+ @; E1 p
relativity rather than the area I was working; x9 x3 b, \8 v. ~3 w* F( e
on, elementary particle physics, because2 }9 p" X1 S7 X
the principles of the former were well5 M/ z: U/ \! a( |4 N, {/ m4 a
known, while the latter seemed like a mess % r4 n- ^* T& Z) `1 yto him. It struck me that he had just given 3 h+ _: e+ q4 I7 I$ ?& }: d, E" Ba perfectly good reason for doing the opposite. 0 K Q4 n( Y# r R/ }+ X5 \* AParticle physics was an area where $ C4 L L& q1 _! h+ ncreative work could still be done. It really was + [& a* q- T6 R/ Da mess in the 1960s, but since that time the $ {6 Q$ V0 A5 o3 f& e1 mwork of many theoretical and experimental - @# j/ ^- B( O- Dphysicists has been able to sort it out, and 1 q/ m. V+ |8 j" ?# n% R Aput everything (well, almost everything)/ R6 x, J0 r" v, x7 U- B- q
together in a beautiful theory known as; k4 L* t2 v: p6 l$ B6 o, @. D
the standard model.My advice is to go for the 4 T) i! L& w& b1 B# {messes — that’s where the action is. 8 m5 ~: Y v4 Z) _6 C 9 m7 q2 k1 g2 J' d" A, h% uMy third piece of advice is probably the " \# |/ o- a& A6 g4 ?6 p/ ahardest to take. It is to forgive yourself for ' x* d* T, y" d# M6 ]& o) {: Wwasting time. Students are only asked to - k5 r% |9 Z! [4 V" Wsolve problems that their professors (unless' G6 V# X8 y$ J
unusually cruel) know to be solvable. In d! [/ T8 z1 g" S4 l* B aaddition,it doesn’t matter if the problems are + v3 B8 V @. q C; m" k. nscientifically important — they have to be ! I: z3 k* N" `. }+ X, A- w1 fsolved to pass the course. But in the real9 L9 d" L# q" d- f& n. D. \; I
world, it’s very hard to know which problems/ I/ V4 g2 C: e2 A! k& M
are important, and you never know whether 2 D; J/ ~9 X5 I4 J& D0 Gat a given moment in history a problem is 6 O% r# I& m8 w ^) ?/ hsolvable. At the beginning of the twentieth, \( Z% K2 ^3 g+ X4 n& o) x
century, several leading physicists, including1 N( `2 }2 S3 ?1 Q. k! w
Lorentz and Abraham, were trying to work " I" Z% ?8 N. @( V6 d, {7 Iout a theory of the electron. This was partly: Z, l! F7 v4 n; M' C- a, _+ g2 v; `
in order to understand why all attempts to 2 r; _0 x! w) G7 f7 [( A2 mdetect effects of Earth’s motion through the% M6 x3 @3 `# X* P0 f
ether had failed. We now know that 4 y, ^; P% V1 R/ c7 z! W1 w: Cthey were working on the wrong problem.3 ], W8 K* X- Z+ L4 x- H! Y
At that time, no one could have developed a& t; {6 Y3 \; m4 L# e& z
successful theory of the electron, because ! u) z1 j' p( O; W! m Jquantum mechanics had not yet been1 e3 v/ |1 Y' j
discovered. It took the genius of Albert5 _/ a6 L+ O l3 y5 G0 [
Einstein in 1905 to realize that the right / K0 \' ]) G) ]4 Q0 f5 `problem on which to work was the effect ! Z: k& n$ B+ d1 k) x: ^+ uof motion on measurements of space and & I" W0 d+ m* B# g+ r1 S- Rtime. This led him to the special theory of) t% t0 t) P. I4 s# R3 n9 b7 w
relativity. As you will never be sure which 3 i. |3 P- d# m* M: qare the right problems to work on, most ' \- [* h! d7 t8 Y& Cof the time that you spend in the laboratory : u0 d: p, g! O7 F9 y. ?7 Eor at your desk will be wasted. If you want; m$ p* H( v/ P1 f& l
to be creative, then you will have to get used 5 t. ?( Q1 v* A2 [% J4 _to spending most of your time not being& m: U* l6 ~% m- y/ x1 M' Y( o$ o! T
creative, to being becalmed on the ocean of $ I" l' H9 Y$ n+ b: f) Nscientific knowledge. , c3 K# u- I r: L% ]3 u; g% f! y5 K c) }. ]3 o, K/ F
Finally, learn something about the history9 ~/ g1 L! c3 @$ H$ k
of science,or at a minimum the history of your & U7 }, _2 p$ X$ A0 C: Zown branch of science. The least important o5 ^+ o1 s" areason for this is that the history may actually% F" p& t; Q& L3 [* b' g. f
be of some use to you in your own scientific# f1 x4 V( K- `, Y- f; L
work. For instance, now and then scientists; d9 @# T0 |$ p4 M
are hampered by believing one of the oversimplified( g1 q+ k4 ^ _! U$ d/ k
models of science that have, ~9 E9 u5 |% T/ \6 E$ |
been proposed by philosophers from Francis ( X0 |4 F5 R D4 rBacon to Thomas Kuhn and Karl Popper. 0 g! M' k1 p& f' E6 l# IThe best antidote to the philosophy of science0 K9 M5 w- w" L/ }6 e' r8 s& y
is a knowledge of the history of science.' G c. x i3 I
More importantly, the history of science 4 X3 S% v4 S" C$ {3 a. z! ?can make your work seem more worthwhile 1 @0 \3 U3 f. h) B: j8 C& jto you. As a scientist, you’re probably not 6 ^8 o" u- q, J/ e6 fgoing to get rich. Your friends and relatives * x1 ^/ B+ `5 a/ rprobably won’t understand what you’re4 n$ ?) D% u8 M- `7 O
doing.And if you work in a field like elementary ' ~1 ^" W8 i i3 V* @particle physics, you won’t even have the & |- |$ H/ J4 o: v( K1 ?3 l0 {! tsatisfaction of doing something that is 1 H ?0 [8 r; v' rimmediately useful. But you can get great & V- |& m! h6 Q; S7 ^( Jsatisfaction by recognizing that your work in! Y0 s2 P" o6 F9 ~ z
science is a part of history.3 B3 f/ K9 d3 P; q \
5 e: H# ~" r/ a) d5 x
Look back 100 years, to 1903. How( f: a( D. O/ u( R
important is it now who was Prime Minister# a: R& c- W2 J- ?) d o2 ^1 }1 ^
of Great Britain in 1903, or President of the 1 \) Y! b+ z$ A% Y+ G1 ~United States? What stands out as really9 s; v% ` G5 g
important is that at McGill University,# T, p- c% l8 r; Z" [& L$ P0 Z$ d7 Z) F
Ernest Rutherford and Frederick Soddy were1 ~+ z4 ]9 c8 W6 Z% L! W
working out the nature of radioactivity.! ^0 {" `4 @- I5 _
This work (of course!) had practical applications,. C$ N' m ?, Z
but much more important were its 3 ~2 T1 ^! D5 {) {- U+ ^ h7 }2 zcultural implications. The understanding of 5 O: O) e( V8 ~, M* n" J6 l0 R/ v/ Z+ }2 Xradioactivity allowed physicists to explain" C3 q; u. U8 v/ a" X
how the Sun and Earth’s cores could still be * L6 v# D; j, G# ghot after millions of years. In this way, it / g3 u- r) P4 J/ m8 C: l" mremoved the last scientific objection to what $ O$ T0 v+ Q/ S+ H7 g& q Hmany geologists and paleontologists8 s3 j/ j) o$ t6 P8 c
thought was the great age of the Earth and% U; o+ l' V7 Q- D( u3 L7 O, h
the Sun.After this,Christians and Jews either ) _ Y3 R5 O0 f8 q9 p# k. nhad to give up belief in the literal truth of 9 Q5 D' G: z& O& H) I6 T( K7 E# jthe Bible or resign themselves to intellectual 5 ~; m7 ^' S, v7 h% N8 Qirrelevance. This was just one step in a" d5 `0 `3 t1 j
sequence of steps from Galileo through - @" |. M7 l3 _2 ~( ANewton and Darwin to the present that,time 9 K5 R# D: q5 B r$ `after time,has weakened the hold of religious9 _- R. `- j# p/ [% T2 X7 e/ q8 d
dogmatism. Reading any newspaper nowadays1 D) x0 U. L3 ~2 D7 A& K8 x
is enough to show you that this work' @" ?( `2 J' W7 N. r+ y- c# q/ T& g- ~
is not yet complete. But it is civilizing work, \- S# r) B/ S' n$ ~of which scientists are able to feel proud.