Sometimes the Beauty Really Is Skin Deep

People are always telling us that surfaces don’t matter. It’s what’s on the inside that counts, they say. Skimming the surface is superficial.

If you ask me, however, the inside is vastly overrated. Outsides are where the action is. Think walls, borders, ceilings, membranes, crusts, skins, doors. Surfaces are where the rubber meets the road--both literally and figuratively. Edges are a lot more than frills.

This is hardly news to the people of L.A., living, as they do, on the uneasy border of several rather large continental plates. The land masses on either side of the San Andreas fault are, of course, traveling at cross purposes--one creeping toward Canada while the other makes tracks for Mexico.

But it’s what happens where the two slip past each other that makes life shaky for those who live upstairs, sending shock waves through the Earth to rattle our glassware, our freeways, our nerves.

Earthquakes are only the most obvious example of action at the edges. The walls of cells, like the walls of castles, are where you’ll find armies of molecular sentries standing guard, ready for action, deciding what comes in and goes out. The surfaces of water and earth are places where life likes to bloom.

Surfaces, after all, are where things make contact, including land, sea and sky. So it comes as no surprise that nearly all the life that populates our planet makes its home on or near the thin margins of its crust.

Surfaces also tell stories.

The geological history of the planet is written in the wrinkles on its face--the great slashes where rivers run through it, the giant pockmarks where asteroids have come to call, the ashy mounds where hot rock has blasted right through, depositing mountains. Overactive hot spots, like the overactive glands of adolescents, break out on the surface of the skin, occasionally squirting out--among other things--diamonds cooked deep inside the Earth.

Everyone knows that people wear their emotions on their skins: We turn red with embarrassment, white with fear. But stars, too, show their colors to broadcast their ages, their temperature, even their compositions. The spots on their surfaces tell of fierce magnetic storms roiling underneath.

There are all kinds of surfaces. Horizons, for example, are the surfaces of what we can see. The Earth’s horizon told early sailors that our planet couldn’t possibly be flat. Ships approaching it sank slowly into invisibility, trailing their masts behind them, rather than disappearing precipitously over some abrupt edge.

In the same way, it is the horizons of black holes that should broadcast the existence of these great voids in space-time. Matter, as it falls in, should skid around the edges, stirring things up, sending out a last gasp of gamma rays before retiring into permanent oblivion.

Does the universe have a horizon? Is there a surface that enfolds everything? An edge to space and time? The answer, curiously, is yes and no.

Space does not come to an abrupt end, although it may well curve around on itself like the surface of the Earth, finite but unbounded.

Time, however, is a different story. Since light travels at a finite speed, we cannot see light signals that have taken longer to reach us than the age of the universe. So for all intents and purposes, there is a wall in time--the edge of the observable universe.

Another interesting cosmic wall marks the moment--when the universe was about 300,000 years old--that light first separated from matter, making the universe transparent.

Remarkably, that light still lingers, imprinted with information about the universe at these earliest moments. Astronomers call it the “surface of last scattering” because it marks the “surface” in time when this light last interacted with matter. This surface, called the cosmic microwave background, promises to tell scientists much about the shape and composition of the universe at age 300,000.

Of course, it’s true that some surfaces are simply nice to look at. Soap bubbles get their colors from thin films that reflect light off closely separated surfaces.

Sometimes, thank goodness, beauty really is skin deep.

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Cole can be reached at kc.cole@latimes.com.