Falling for Inertia : 13.7: Cosmos And Culture Inertia. You can't leave home without it. Even if it does, sometimes, make it hard to get up off the couch.

# Falling for Inertia

By now, it's probably become pretty clear that you're not going to keep most of those New Year's resolutions. Lack of willpower is certainly part of the equation, but so is inertia. Inertia is my favorite force, even though some people like to call it a pseudo-force, because it's really just the tendency for things to keep doing what they're doing, a resistance to being pushed around. Nobody who's ever been thrown forward by a sudden stop would call inertia "pseudo" however; if it walks like a force, well, you decide. (Gravity, among other familiar "forces," are also "pseudo" in the sense that whether you feel them or not depends on your frame of reference. But that's another story.)

We tend to blame inertia for keeping us stuck in ruts, and it does, but it's also often the only thing that keeps us going. Inertia keeps planets in their orbits, roller coaster riders in their seats,clouds attached to the sky. It certainly saves gas; imagine how much your gas bills would be if you had to use energy merely to coast!

People tend to forget the power of inertia. Everyone knows it takes energy to get a car moving at 60 mph--but forget that it will take just as much energy to slow it down. In fact, it's relatively easy to blast your way to a distant planet compared to what it takes to slow down when you get there.

The same is true of anything, whether it's moving journalism from print to on-line or resisting the temptation to pay bankers huge bonuses. It was even inertia, some argue, that resulting in the bombing of Hiroshima. With everything necessary for the bombing already set it motion, it would have been unbelievably difficult to stop. In terms of energy required, there's not much difference getting up to speed, and stopping.

That's why fighting inertia is so hard, and so frequently generates heat.

At the same time, there's something to be said for a force that keeps change from happening too quickly. That might seem like a bad thing when your side is in power and you want change to happen fast. But it's a good thing when the other side is in power, and inertia stops them from pushing through policies you find odious. Democracies tend to be stable in part because inertia works so well.

I first fell in love with inertia when I heard about the late Ernst Mach's idea that inertia was due to the fact that everything in the universe was gravitationally connected to everything else. Every heavy sofa is connected to every flower, every star. So you can't push one without tugging on the whole tangled web. Should you walk into a wall and come face to face (so to speak) with the wall's unwillingness to move out of the way, well, you can comfort yourself by remembering you're running up against all the matter in the universe.

Mach didn't get it entirely right, but he was a big influence on Einstein, who followed the surprising equivalence between gravity and inertia to the discovery that gravity was actually the curvature of space-time caused by the presence of massive objects. (And if you don't think that equivalence is surprising, do drop a crumpled piece of paper and your keys at the same time, and do be amazed--I always am--that they hit the ground at the same time. Yes, gravity pulls harder on the keys, but the keys also have more inertia--exactly the right amount to make the two objects fall at the same rate.)

Today, physicists are looking for the source of inertia at the Large Hadron Collider in Europe; well-tested theory suggests that particles acquire sluggishness (and therefore mass) as they move through the vacuum because they have to slog their way through something called the Higgs field, which pervades empty space. If the LHC can collide particles with enough oomph, perhaps the energy produced will briefly create a Higgs particle--a "chip off the old vacuum," as physicist Frank Wilczek described it to me years ago.

Now that would be almost as exciting as pulling on stars.