The Physics of Wall Street: a brief History of Predicting the Unpredictable

A New Manhattan Project 
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away to Bern, where the only job he could find was as a patent clerk. 
occasionally, he was permitted to teach at the local university.
Gradually, however, as more physicists came to understand the im-
portance of the 1905 papers, einstein’s reputation grew. In 1911, he was 
offered a professorship at the German university in Prague; the next 
year, his alma mater offered him a job. By the time einstein returned 
to Zürich, he was already a shining star of the physics community. His 
reputation had exploded in just a few years. He didn’t stay at Zürich for 
long — in 1914, he was appointed director of the Kaiser Wilhelm In-
stitute in Berlin — but the year that einstein and Weyl spent together 
was enough to change the course of Weyl’s research. though initially 
a mathematician in the purest sense, Weyl found einstein’s relativity 
theory captivating, particularly because when they met, einstein was 
just beginning to realize the importance of high-powered modern ge-
ometry to the theory.
the basic idea underlying general relativity is that matter — or-
dinary stuff like cars and people and stars — affects the geometrical 
properties of space and time. this geometry, meanwhile, determines 
how bodies move. It is this movement of massive objects through de-
formed space and time that we ordinarily think of as gravitation, the 
physical phenomenon that keeps us firmly planted on the surface of 
the earth, and that keeps the earth in its elliptical orbit around the 
sun. the general relativistic picture is as different as can be from the 
older, newtonian theory of gravity. In newtonian gravitation, space 
and time are static. their properties are unrelated to the matter that’s 
distributed through space. Bodies gravitate toward one another via an 
unexplained force that acts instantaneously at a distance.
Matter affects space and time in einstein’s theory by inducing 
curvature. When physicists and mathematicians say something is 
“curved,” they mean just what we would ordinarily mean. A tabletop 
or an unfolded piece of paper is flat; a basketball or a paper towel roll 
is curved. But from a mathematical point of view, the thing that dis-
tinguishes a tabletop from a basketball isn’t that a basketball rolls and a 
table doesn’t, or that it’s easier to stand on a table than on a basketball. 
Instead, the feature that characterizes curvature for a mathematician is 

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how hard it is to keep an arrow pointing in the same direction as you 
move it around the surface. If an object is flat, it turns out to be very 
easy. not so if the object is curved.
I admit that this is a weird thing to say. But it isn’t hard to see how 
it works in practice. first, imagine you’re standing on a city sidewalk, 
somewhere in midtown Manhattan, say, where the streets are laid out 
like a grid. try to picture what would happen if you did a clockwise 
lap around the block, all the while trying to keep yourself pointed in 
one direction — north, say, toward the Bronx. (the direction you’re 
facing, here, is taking the place of an arrow.) You might begin by walk-
ing forward for a while as you head uptown. When you get to the next 
corner, you would head right, east on the crosstown street. But you 
aren’t allowed to turn your body at the corner, since you’re trying to 
stay pointed in the same direction all the time. this means you have 
to walk sideways down the cross street. And when you get to the next 
corner, where you should start heading south again, you have to walk 
backward. If you follow these instructions, never once turning your 
body as you do the lap, you should find yourself back at the original 
corner looking in just the same direction as before.
this might not come as a surprise. After all, you never turned your 
body — why in the world wouldn’t you be facing in the same direc-
tion? But now let’s imagine a longer journey. Instead of doing a lap 
around the block, imagine trying to keep yourself pointed in the same 
direction — it might as well be north — as you circumnavigate the 
globe. for the first leg of your trip, you’re going to start in new York 
and just head east, toward europe. When you arrive in france, you’re 
going to start crab-walking your way toward Asia, all the while keep-
ing your face firmly pointed toward the north Pole. After a very long 
(and probably uncomfortable) walk, you will finally reach the Pacific 
ocean, and then you’ll head for california. When you finally arrive in 
new York, if you never turned your body, you should still be facing 
north.
Here’s a different itinerary that begins and ends in the same place. 
You start by heading east, just as before. When you get to Kazakhstan, 
though, you take a detour. Instead of continuing on toward china, 
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t h e p h y s i c s o f wa l l s t r e e t

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