People will help each other because there is a sense of camaraderie that springs up, which is a survival tactic. You help them because you know you might need their help later. And that is incredibly reassuring.

The one thread that was most surprising and most consistent was the lack of fear that people felt at the worst moment. They felt a lot of fear in early stages, when they're just realizing what's happening. But then things really seemed to be at their peak of terror, the fear went away. You can imagine why that's useful. At that moment your brain needs to focus all its attention on surviving, so people will feel a sense of calm as their brain tries to sort out a plan.

A lot of the time you see a warning, in the subway, or in a movie theater, the main thrust of the warning will be to not panic if there is an emergency. To listen to directions. Now that's a waste. They could have given you information, but you can see their expectation that you're going to screw up.

Most serious plane crashes are survivable. There's a sense that, 'Oh, if we go down, that's it, it's out of my hands.' And that's just statistically not true. I have more optimism and more faith that my own actions can make a difference.

The health of your family or your office or your city directly affects the health of it after. The better you are at handling high-stress situations with little information, those skills lead to resilience and the ability to recover afterward.

I can't tell you how many times I've been with very smart, knowledgeable Homeland Security experts who are essentially tasked with saving your life who do not trust you with information. They just don't. They kind of dismiss the media and the public in one fell swoop.

By sort of combining the research of a lot of smart people, I came up with an equation for dread [dread=uncontrollability+unfamiliarity+imaginability+suffering+scale of destruction+unfairness]. The dread equation is a simplification, but it's a way to explain why we fear something so much when it is so unlikely. Part of it is the lack of control. That's why we're more scared of plane crashes than car crashes even though we know rationally which is more dangerous.