...we will not really be happy until we can escape from gravity. We are exiles here on dry land, in transit between the ocean of water in which we were born and the ocean of space where most of history will run its course.

--Arthur Clarke

As a kayaker, I love to spy on the California sea lions who hang out on the floating docks at Woodley Island and Eureka Public Marina every year at this time. They're much larger, of course, than our year-round harbor seals, and definitely noisier -- I've heard their lusty barks from as far away as Fifth Street.

Seals and sea lions are our mammalian cousins, enjoying their watery three-dimensional lives while we poor terrestrial creatures are confined to essentially two dimensions here on land. It's not just that we lack the everyday ability to effortlessly move in a vertical plane, as sea creatures do -- it's that they live their lives free from the constraints of gravity. They rise and fall through the dimension of "up and down" while we just sit here, our butts on chairs or our feet on the ground.

A physicist (or smart high-schooler) reading "free from the constraints of gravity" would argue that gravity is alive and well in the ocean, and that you don't magically enter a gravity-free environment as soon as you jump into the water. The sea is no more gravity-free than your bed is. When you're asleep at night, your weight is countered by the resistance of the mattress. Same in the water: gravity pulls you down, water buoys you up, everything balances out nicely. The difference between the sea and your bed is that you can't dive freely down into your mattress. You can in the water, so you experience the illusion of weightlessness.

Astronauts exploit this delicious feature of water when practicing for a mission. The latest Hubble refurbishing team (Mission 4) spent countless hours practicing on a mock-up of the space telescope in the 6,000,000-gallon super-clean water tank at the Johnson Space Center in Houston. As a result, Hubble should be good for another 10 years of service. (Yeah!)

Taking the long view, you can think of this period as our two-dimensional hiatus. Four hundred million years ago, our amphibious ancestors emerged from the oceans to begin a new chapter of life on land. If our species survives its present self-destructive phase, I think it's a safe bet that our heirs won't be content to hang out here on the Earth's surface. Humankind will colonize space, where, in Arthur Clarke's words, "most of history will run its course." I can't wait.

When he's asleep in Old Town Eureka, Barry Evans dreams of flying and diving in 3D.

CAPTION: Mission 4 astronauts practicing underwater on a Hubble model at the Neutral Buoyancy Lab in Houston. (NASA photo)