There’s a ritual every young theoretical high-energy physicist goes through. It’s a silent ritual. No one tells you about it, or what to expect. No one talks about it afterward. You don’t know that everyone else goes through it except through sidelong comments and hints buried in subtext. It’s a simple ritual, usually done at night, while alone—always alone. The young theoretical physicist will be at his desk, working on a calculation, and he'll suddenly have a thought. An unexpected, but not surprising thought, and the ritual will be begin.

That ritual is what brought me, on a chilly March night in 2007, to the edge of a crowd in a parking lot of a 7-Eleven near Wrigley Field, on the north side of Chicago.

We look at protons and neutrons—the things atomic nuclei are made of, a hundred thousand times smaller than an atom—and we think, “Those are big. I bet they’re made of something smaller.”

High-energy physics is a bit of a weird name. Most fields are named by what they study: neuroscience (brains), geology (rocks), bio-chemistry (scary stuff). What we do should be called elementary particle physics. We look at protons and neutrons—the things atomic nuclei are made of, a hundred thousand times smaller than an atom—and we think, “Those are big. I bet they’re made of something smaller.” And so we go looking for that. Protons and neutrons, it turns out, are made of quarks and gluons. And those? Maybe made of something else. That’s the question. (Well, one of them.) The “high-energy” is the tool, not the subject. If you want to study tiny things, you need to take other, less-tiny things, and smash them together as hard as you can. You take a beam of protons, spin them around a particle accelerator, and run them into another beam of protons going the other way. If you want to do a good job of it, you need a machine twenty-seven kilometers around to make them smash into each other hard enough. High-energy.

I’d come to Chicago about a year earlier. I’d graduated with my PhD and had a postdoc at the University of Chicago. My job was to ask the question, “If there are new particles out there we haven’t discovered, how would we use the new accelerators to find them?” Pretty easy to state, if a bit like something out a science fiction novel.

I had also broken up with my girlfriend of three years to take that job. She had a great career in San Francisco, where we’d lived, and when I got the job in Chicago, neither of us wanted to give up our careers. And, as she very rightly put it, for it to really work, both of us would have to be willing to give ours up. But it was okay, because I was part of this grand adventure of science, discovering what the smallest things were made of. Except I wasn’t actually doing much science either.

Instead, I was reading the internets and playing games and wandering the streets late at night to get a bit of air, and otherwise avoiding work. And then, late one night, alone, “working” on a calculation, I had The Thought, and the ritual began. Now, as complicated and weird as it sounds, with the not telling and not talking about it, the name of the ritual is actually very straightforward. Its name is the thought the young physicist has, and it’s this:

“Can my research be used to make a bomb?”

Now, different scientists will have different versions of this question. Biologists might ask, “Will my research be used to make a deadly virus?” Chemists ask, “Can my research be used to make pepper spray?” and computer scientists of course ask, “Can my research be used to enable a new way for viral cat videos to assault us?”

But, it’s a particular problem for particle physicists. Our direct intellectual ancestors are the people who created and ran the Manhattan Project. And so the bomb looms large in our minds.

***

In fifth grade everyone in my class had to make an insect collection. We had to find fifty bugs and pin them to a board. Because that’s science. I couldn’t do it. For weeks it was normal procrastination, but as the due date got closer, I found I simply couldn’t do it. It made my stomach churn just to think about killing a fly. Eventually, I took a film canister and found an ant, and trapped it in the canister. Then I took it and put it in the freezer. The instant the door closed, I broke down and began to sob.

This wasn’t like the science I liked. I thought about space and astronomy, and the Viking lander on Mars, which I’d read about in Calvin and Hobbes. My dad, a geologist and therefore also someone who worked in a field where he didn’t have to kill things, suggested that I go find dead ones instead. I spent a couple of days looking in the windows of the school bus for dead bugs and I still couldn't handle that.  Plus, all I got was two flies. Eventually I talked the teacher into letting me use cutouts from a magazine instead of actually collecting them.

Later on in high school we were supposed to dissections in biology class—the standard fetal pig dissection that everyone does—and I knew at that point I couldn't handle it. I tried explaining to the teacher that I didn’t want to, that I get queasy. He wasn’t buying it, “Everyone has to do it.” But then he pulled one of the most brilliant bits of teacher jujitsu I’ve ever seen. As he was walking away, he turned a bit and said, “But you know, if you tell me it’s against your religion, I’m not allowed to ask any follow-up questions.” I immediately said, “Yes, it’s against my religion.” Which it wasn’t. At the time I was Unitarian Universalist, and they specialize in not caring what you do. But I was allowed to do the assignment by clicking through pictures of the dissection on a laser disc. (Remember laser discs? I’ve now dated myself very precisely.) The best part was that the pictures on the laser disc were incredibly clear, and everyone else was dealing with messy reality, so I aced the test and ruined the curve.

But, if I couldn’t handle dissecting a pig, how was I supposed to do research that might produce a bomb?

***

The first thing I did when I had The Thought was to go outside and take a walk. And that’s how I happened on the 7-Eleven parking lot. Some people had set up a stage, and a PA system. And one by one people were getting up on the stage and giving speeches. A small crowd had formed to listen, and I joined at the edge to give myself a break from thinking about bombs.

The thing was, I knew the answer to the bomb question. I knew it almost as soon as I had thought of the question.

The thing was, I knew the answer to the bomb question. I knew it almost as soon as I had thought of the question. It goes like this: To make a bomb you need two things. First you need the bit where it explodes; that’s sort of the definition of a bomb. And these new exotic particles that we study actually explode on their own. You make them, and they almost instantly decay, and when they do, they release a tremendous amount of energy. Nearly 100 percent of their mass gets converted into energy when that happens. Nuclear bombs, by comparison, convert about 2 percent of their mass when they detonate.

The problem is that the second thing that you need to make a bomb is the bit that makes sure it doesn’t explode until you want it to. That is also very important. And these particles that we study decay very, very quickly. A lifetime of ten to the minus twelve seconds, one pico second, is a very long lifetime for an elementary particle, so there's no way that what we do can be used to make any sort of weapon.

It’s a really simple and straightforward answer, but I still found myself turning it over and over as I walked the streets, and came to the crowd in the 7-Eleven parking lot.

It was an LGBT rights rally, and all the speakers were talking about the bigotry and violence in the city, the things that happened every day, even in as relatively liberal a place as Chicago. They were telling stories and making pleas for action.

As speakers, they were pretty bad. It was all stuff that everyone had heard before, said in ways that weren’t terribly impressive or inspiring. They certainly weren’t “I have a dream.” Honestly, they weren’t even “Mission Accomplished.”

But it was amazing.

I stood there at the edge of the crowd, transfixed. These people were making a difference. The work they were doing wasn’t brilliant, on technical grounds, but it was important, and all together, with everyone else doing it, it was working.

And that, I realized, was the problem with the answer to the bomb question. The reason my research wasn’t useful to make a bomb was because it was absolutely useless. If the particles didn’t stick around long enough to make a bomb, they didn’t stick around long enough to do anything else. They weren’t going to cure cancer, or give us new sources of energy, or stop a virus.

And if my work wasn’t just not harmful, but actually useless, then I had made a terrible mistake in moving to Chicago

I don’t know what most people do when they get depressed, but I read Carl Sagan essays.

I don’t know what most people do when they get depressed, but I read Carl Sagan essays. I went back home, and turned to one I’d read many times before—“When Scientists Know Sin.” It’s about the development of the hydrogen bomb. And there’s a little bit in there that I had of course read before, but it hadn’t really stuck. This time it did, and I went on the Internet and read more about it.

In the fall of 1971 Mariner 9 achieved orbit around Mars, and was the first spacecraft to successfully orbit another planet. Now, if you’re looking for something useless for life on Earth, sending an orbiter to another planet would seem to be textbook.

Mariner 9 had instruments to measure the Martian climate. It arrived in the middle of a dust storm. Mars is periodically enveloped in global storms that can last weeks. As the storm abated the researchers were fascinated to watch the global temperature rise and rise. What they realized was that the high temperature was normal, but during the storm the sun's energy was being blocked by the dust, and so Mars was effectively cooled. It was a tremendous effect. If there had been agriculture on Mars, if there had been people there depending on food, all of those crops would've failed and there would've been widespread famine and death because of it.

Fortunately storms like that just don't happen on Earth. Except . . . if there was a nuclear war, if somebody sent a few thousand megatons worth of nuclear bombs to the cities and the forests, and the cities and the forests started to burn, then the dust and the ash would be lofted up into the atmosphere. And, we don't know for sure, but that could be enough to trigger a nuclear winter and crop failures and that could kill more people than the bombs themselves. And we didn't know. In all the planning for nuclear wars and for Mutually Assured Destruction scenarios, no one had thought to ask what the effects on the climate would be. We had to go to Mars to find that out.

We go out and explore because we have to, and when we go out there we find things we don't expect, and you can’t control what they’ll be. Sometimes those things are beautiful, sometimes they're useful, sometimes they're evil, and sometimes when we find them we just look at that and say, “Huh. We needed to know that, and now we do.” So, I did make a mistake. But it wasn’t moving to Chicago, or picking a highly abstract field of study. The mistake was thinking I’d know where I would end up, and what the consequences would be ahead of time, and I was so worried about whether I’d made the right choice, that I wasn’t moving forward at all.

And it wasn’t that I chose correctly, either. I chose something. And it was time to figure out what happened next. Ben Lillie is a writer for TED.com and the producer, founder, and host of The Story Collider.

Illustrations by Zachary Garrett, appearing courtesy of Drawn Out Storytelling.