The Future of Bridges: Self-Replicating and Weird-Looking

Last week's collapse of the I-35W bridge in Minneapolis prompted (justifiably) an orgy of recriminations over what pretty much everyone calls "America's crumbling infrastructure." Too many links to muster, but for a good, concise summary of the problem you can check out infrastructure expert Stephen Flynn's editorial from Popular Mechanics. The gist:

In the end, investigators may find that there are unique and extraordinary reasons why the I-35W bridge failed. But the graphic images of buckled pavement, stranded vehicles, twisted girders and heroic rescuers are a reminder that infrastructure cannot be taken for granted. The blind eye that taxpayers and our elected officials have been turning to the imperative of maintaining and upgrading the critical foundations that underpin our lives is irrational and reckless.

So, yes. The bridge collapse was an heartbreaking tragedy made all the more awful by the fact that we could have avoided it.

But how? Can we, in fact, build bridges that don't fall down?

An answer—"yes"—from an unexpected source: Stephen Wolfram, creator of the software Mathematica and advocate of the idea that tiny, reiterating bits of software can generate hugely complicated patterns.

The little programs are called cellular automata, and they can even make cell phone ringtones. He blogged on Friday:

I strongly suspect that there are much better truss structures for bridges than the classic ones from the
1800s--but they won't look so simple.

I suspect one can do quite well by using simple rules to generate
the structure. But as we know from NKS [New Kind of Science, Wolfram's book], just because the rules to generate something are simple, it doesn't mean the thing itself will look simple at all.

Two students at our NKS Summer School (Rafal Kicinger and Tom Speller) have investigated creating practical truss structures this way—and the results seem very promising.

So what should the bridges of the future look like? Probably a lot less regular than today. Because I suspect the most robust structures will end up being ones with quite a lot of apparent randomness.

Those new kinds of bridges being built may be a bit shocking at first. After all, classic regular bridge structures—and things like the Eiffel Tower—are icons of our modern engineering-based civilization.

And in fact, even biology—with its iterative process of natural selection—probably can't find structures as good—and irregular—as the ones I expect are out there.

So we're going to end up being exposed to something really quite new. Something that exists in the abstract computational universe, but that we're "mining" for the very first time to create structures we want.

I've illustrated this post with some of the possible universe of weird bridge structures that Wolfram's students generated. It's a striking idea—that irregular-looking, self-replicating bridges might be more robust than the nearly magical pieces of civil engineering that human beings come up with. Wired ran a sort of ode to some of the more amazing ones a couple years ago. One of the more amazing things about the built environment—about cities, really—is that within the chaotic, fractal-seeming urban landscape, every individual part is generally highly regular.

Ari Handel once told me a story, before he started writing movies and was just a brilliant neuroscientist and sometime-journalist, about working with a high school (maybe it was junior high) science class in New York on engineering concepts. He told them they were going to build a bridge out of, like, tongue depressors or something, but that they had to learn all the principles and come up with some hypotheses about what bridges had to be like before they started trying designs. Because, he said, without hypotheses, you're not doing science—you're doing arts and crafts.

Anyway, Ari got the kids up to speed on the engineering and physics involved, and then had them start building. And when they were finished, they looked up from their work, stood back, and were astonished. Why? "It looked exactly like the Brooklyn Bridge," Ari said. His class had found a sort of urban Platonic form, the perfect span.

But Minneapolis proves that without attention, even the perfect span can fall. So of course we need to spend more money on infrastructure.
Of course we need to maintain and rebuild our bridges, roads, ports, railways, airports, etc. But we need to listen to the spirit of what
Wolfram said if not the exact notes of the ringtone: We have to build all this stuff different, better. Right.

A New Kind of Science, Stephen Wolfram

Minnesota Bridge Collapse Reveals Brittle America: Expert Op-Ed, Stephen Flynn, Popular Science

Via Kathryn via Noah