Gravity's Engines

Gravity's Engines

A computer sits among the coffee-stained papers scattered across my desk. Its screen has been blank all morning. Suddenly it lights up and displays a pixelated image. A message is coming in from space.

A few days earlier, high above Earth’s surface, a great orbiting observatory has stared for forty hours over the bows of the Milky Way galaxy. With chilled eyes it has patiently tracked a tiny patch of the cosmos, a speck of sky close to the constellation Auriga—the Charioteer. In this direction is a glorious view for a spotter peering into the abyss in the hope of finding treasure.

This remarkable instrument is called Chandra. Decades of work went into its construction, with hundreds of people toiling in multiple countries. The blood, sweat, love, and tears of a highly technological civilization produced the smooth surfaces and exquisitely precise devices inside it. Careers started and ended while it grew from a dream into a reality. Finally it was lofted into space and released with tender delicacy from the belly of NASA’s space shuttle Columbia, becoming a tangible example of humanity’s endless curiosity.

Now it has captured a whiff of something from the deep. Photons, particles of light, have found their way down through its mirrors and filters, forming an image on the silicon sensor of a digital camera. That image, encoded as a stream of data, has passed to Earth, first beamed as microwaves to a ground station and then relayed around the globe. Processed and sent on across a continent, another journey through hundreds of miles of wires and fiber optics, it finally re-forms as a monochrome picture on a screen in my small and untidy office ten floors above the streets of twenty-first-century Manhattan.

On any given day, we don’t expect to see much that is particularly remarkable in the vast flood of incoming data that is a part of modern science. Patience is a hard-won lesson. Yet there, amid the rough noise of the image, is a structure. It’s small and faint, but unmistakable. I can see a pinpoint of light surrounded by something else—a fuzzy streak jutting out to the left and right. It looks like a small dragonfly pinned to a piece of cardboard. Something is very curious about this image. It has the flavor of a new species.

Traffic out on the street echoes noisily up the canyon of buildings, but for an instant it rings hollow. My mind is not in this world anymore, but away in a very, very distant corner of the universe.

Twelve billion years ago, the photons that made this image began their journey. They are X-rays, invisible to human eyes, but able to penetrate through our soft bodies. For 12 billion years they have passed unimpeded through the cosmos. But as they have traveled, the universe has changed; space itself has expanded, stretching the photon waveforms and cooling them to a lower energy.

When they set out there is no star called the Sun, no planet called Earth. It isn’t until they are two-thirds of the way through their journey that part of a collapsing nebula, a cloud of interstellar gas and dust in a still impossibly remote galaxy, produces a new star and a set of new planets that will eventually become our home.

Excerpted from GRAVITY’S ENGINES: How Bubble-Blowing Black Holes Rule Galaxies, Stars, and Life in the Cosmos by Caleb Scharf. Published in August by Scientific American, an imprint of Farrar, Straus and Giroux, LLC. Copyright © 2012 by Caleb Scharf. All rights reserved.