“Wasn’t that a miracle? she remarked. Her guardian angels were with her that day.” Those were the words of my sister-in-law a couple of years ago after Will’s older sister walked away unscathed from a rollover collision.
Stopping an object’s momentum requires force acting over a period of time. When a car crashes, the force required to stop an object is very great because the car’s momentum has changed instantly while the passengers’ has not – there is not much time to work with. The goal of any supplemental restraint system is to help stop the passenger while doing as little damage to him or her as possible.
What an airbag wants to do is to slow the passenger’s speed to zero with little or no damage. The constraints that it has to work within are huge. The airbag has the space between the passenger and the steering wheel or dashboard and a fraction of a second to work with. Even that tiny amount of space and time is valuable, however, if the system can slow the passenger evenly rather than forcing an abrupt halt to his or her motion. – How Airbags Work
Yesterday, my daughter was in a collision, rear-ending the car in front of her while traveling 60 mph heading south on I-5. She walked away with only a fractured collarbone. Fourteen-month old Bria, in the center backseat in a state-of-the-art child car seat, was not injured at all. Nobody in the other two cars was injured.
[Engineers] needed a way to set off a chemical reaction that would produce the nitrogen that would inflate the bag. Small solid-propellant inflators came to the rescue in the 1970s.
The inflation system is not unlike a solid rocket booster (see How Rocket Engines Work for details). The airbag system ignites a solid propellant, which burns extremely rapidly to create a large volume of gas to inflate the bag. The bag then literally bursts from its storage site at up to 200 mph (322 kph) — faster than the blink of an eye! A second later, the gas quickly dissipates through tiny holes in the bag, thus deflating the bag so you can move.
Even though the whole process happens in only one-twenty-fifth of a second, the additional time is enough to help prevent serious injury. The powdery substance released from the airbag, by the way, is regular cornstarch or talcum powder, which is used by the airbag manufacturers to keep the bags pliable and lubricated while they’re in storage. – How Airbags Work
Michaela and Bria were taken via ambulance to Swedish Hospital in Edmonds as a precautionary measure, labeled a potential “trauma case” due to the force of the impact and the damage to the front of our car. When I got to the ER to meet them (knowing in advance that they were okay as I’d been in communication with Michaela the whole time), I thought about guardian angels. Not about how they’re sent from a fictitious god to randomly protect some people and not others. Not about how only those who profess faith in Christianity have one. Not about how praying or performing any other sort of meditative activity can influence one to act on your behalf. I did not think about wings, or trumpets, or flowing robes and golden hair or names like Michael and Gabriel.
I thought instead how there is no such thing as a guardian angel. There are only people. Really smart people. People who devote their lives to design, engineering, and science to master the rules of physics, biometrics, electrical and mechanical engineering, and chemistry and then exploit these rules to save lives and prevent harm. People who stand on the shoulders of giants like Archimedes, DaVinci, Newton, Einstein, Pasteur, Curie, Edison, Tesla, Ford, and the Wright Brothers everyday, advancing human evolution by building on what has come before.
So maybe I take that back. Maybe there are guardian angels. But they’re not celestial beings hovering eagerly in some ethereal sky to save you or rescue me. They are teams of designers, engineers, doctors, and scientists. Our family, friends, neighbors, coworkers, and fellow citizens. People, just like you and me. Think about that the next time a “miraculous” event occurs. Then think critically about it for a moment and thank a designer, engineer, or scientist for that miracle instead.