1. The Big Bang

Big history begins with the Big Bang, today's best explanation for how the Universe came to be. This view has been shaped by ever sharper theories built through new technologies and observations over thousands of years.

How has our view of the Universe changed?

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The hissing was driving them crazy.

Two scientists with the best equipment available were getting nothing but interference. Maybe the pigeons were to blame.

A flock of pigeons had taken to perching atop the big metal “horn” of their radio antenna near Holmdel, New Jersey, in 1964. Shaped like a giant ear canal 20 feet wide and 50 feet deep, the horn's smooth interior was designed to receive extremely faint radio signals from far off. The two scientists figured the droppings had to be what was interfering with their readings. They asked workers to clean out the pigeon droppings. Someone – no one admits just who – ordered the pigeons killed.

Again they pointed the giant ear toward outer space and listened. Even without the pigeon droppings, they heard the same steady, low hiss.

By now they'd done everything they could think of to eliminate it. They had adjusted their sensitive amplification equipment. They had tried receiving in warm weather, and in cold. They had swiveled the big ear opening on its turntable and aimed it directly at New York City, only 50 or so miles away, thinking that the hiss might be originating from all the radio stations or other electronic activity there. They had eradicated the pigeon droppings – and the pigeons.

Nothing changed. No matter what they tried, Arno Penzias and Robert Wilson heard it wherever they aimed the antenna. That steady hum would prove to be a critical piece in understanding the origins of the Universe.

The notion that the Universe might actually be expanding had been proposed at least since the 1920s but it was greeted by a great deal of skepticism from the very start. Albert Einstein himself believed quite fervently in a “steady-state” model of the Universe.

In the late 1920s, Einstein dubiously reviewed the calculations of a young Belgian priest who held a doctorate in math as well as physics, Georges Lemaître. Brilliant and with a cosmological bent, Lemaître had just started his career as a young lecturer at Catholic University of Leuven. Using Einstein's own theory of relativity to justify his assertions, Lemaître had proposed that the Universe was actually expanding.

Einstein didn't agree.

“Vos calculs sont corrects, mais votre physique est abominable,” he remarked in French to Lemaître.

At about the same time, on a mountaintop overlooking Los Angeles, another astronomer was making observations of the distant reaches of the Universe. This was the remarkably multitalented, Midwestern-raised Edwin Hubble. A young Illinois basketball and track star, Hubble had gone on to Oxford as a Rhodes scholar, where, as promised to his dying father, he studied law. After his father's death, however, he started a new career in the field of his passion, astronomy.

Hubble took a job as an astronomer at Mount Wilson Observatory soon after World War I. He and his wife, Grace, would make San Marino home for much of their lives, and they would become friends with Gary Cooper and other luminaries in the film world. The same cloudless skies and still air that lured the fledgling movie industry to Hollywood had brought the world's most powerful telescope to this cavernous dome atop Mount Wilson. Pipe-smoking, practical, and meticulous in his observations, Hubble spent his evenings in the quiet observatory studying the heavens with the Hooker telescope's 100-inch-wide polished mirror, which, on July 1, 1917, had been painstakingly hauled up the steep, rocky road on a flatbed truck going 1 mph. While the 1920s roared in the glittering nighttime city far below him, Hubble peered deeper into the Universe than humans had ever seen before.

He made a series of astonishing discoveries.

First, he discovered that there were many, many other galaxies out there besides our own. What some had thought to be objects spinning within our own galaxy, the Milky Way, were actually entirely separate galaxies far beyond it. Suddenly, the Universe grew vastly larger and more complex.

I am an observer, not a theoretical man, Hubble noted modestly about himself.

And observe he did. Building on the work that Harvard College Observatory's Henrietta Leavitt, one of the first woman astronomers, had done with Cepheid variable stars and that Vesto Slipher of the Lowell Observatory in Arizona had done with redshift, Hubble determined the approximate distances to the galaxies he had identified outside the Milky Way. He found that these galaxies were speeding away from each other. But there was something very strange about this: The farther away they were, the faster they were moving apart.

The observer and the theoretician now suddenly converged. This was exactly what Lemaître had claimed: The Universe was expanding. It was as if entire galaxies like the Milky Way were little ballpoint-pen marks on a deflated balloon; as the balloon inflated, the marks separated from each other ever faster. It was a bizarre notion, and it was emphatically resisted by scientists who believed in the steady-state model of the Universe. Despite Hubble's calculations, debate about whether the Universe was expanding or fixed continued off and on for the next several decades.

One reason for resistance to the notion of the Big Bang was the great leap required to wrap one's mind around the infinite and profound – and perhaps unanswerable – questions it posed. “If the world has begun with a single quantum,” wrote Lemaître in a widely cited 1931 letter to the journal Nature, “the notions of space and time would altogether fail to have any meaning at the beginning; they would only begin to have a sensible meaning when the original quantum had been divided into a sufficient number of quanta. If this suggestion is correct, the beginning of the world happened a little before the beginning of space and time.”

When Penzias and Wilson were battling the static in the Holmdel Horn radio telescope in the early 1960s, no one had yet definitively settled the debate about the Big Bang and steady-state concepts of the Universe.

Then Penzias happened to mention the inexplicable hiss to a physicist friend at MIT. The friend in turn mentioned that he had recently read about research by a Princeton University physicist who had predicted, hypothetically, that if the Universe had been expanding for eons, its earliest stages must have been incredibly hot and dense, and radiation from that early hot, dense state would still exist today in the form of a “background” of microwave radiation filling all of space. The remarkable thing to Penzias when he heard the story was that the predicted radiation or energy fell in just the same wavelength as the static he and Wilson heard in their horn.

Princeton University sits about 20 miles away from the horn at Bell Laboratories. Penzias called Robert Dicke, one of the Princeton professors involved in the microwave radiation research, and invited him to drive over and listen to the hiss in the Holmdel Horn. Several other scientists elsewhere in the world had detected this same curious energy in their radio antennas, but no one had ever figured out what it was. The coincidence of this physicist's being so close by helped solve one of the most profound and distant mysteries of the Universe. When he heard it for himself, Dicke understood the strange noise immediately.

The hiss coming from all over was, as it's since been described, the microwave embers of the Big Bang.

One of the best places to study space lies high in the desert and mountain terrain of western New Mexico. Driving east from Los Angeles and the Mount Wilson Observatory, you follow the interstate past Palm Springs, skirting the Mojave Desert into Arizona and crossing to New Mexico, where you veer north on a long, empty, two-lane highway around the dark mountain ramparts of the Gila Wilderness, climbing higher through rolling forest until you finally emerge more than 7,000 feet above sea level upon the Plains of San Agustin.

It's an expanse of sagebrush and flatness 60 miles long by 20 wide about midway between Albuquerque and the small town of Truth or Consequences. First you might notice just one – a giant half-eggshell, glowing a creamy white, tilted up toward the deepening sky. Then you might notice, a mile or so beyond the first, another half-eggshell, tilted alertly toward the heavens at exactly the same angle. A mile or so farther along, appearing smaller in the distance, is another. By then you realize you're looking at a perfect row of these great tilted eggshells spaced at one-mile intervals all the way to the mountainous horizon, intersecting with two other rows to form a giant “Y” measuring 22 miles in length. Sheltered on this high remote plain from radio station interference, its scale is surreal, its perfection disconcerting – as if you had happened onto a giant Zen garden sculpture or strayed onto the set of a sci-fi movie.

The aptly named Very Large Array (or VLA), with its 22-mile-wide “aperture” is one of a new generation of radio telescopes that are up to a million times more powerful than those from the Holmdel Horn era. Some, such as Europe's Planck Satellite and NASA's Hubble Space Telescope, orbit high above the Earth, free from the atmosphere's distortion, looking outward into space instead of downward at the surface on which we live. Probing distant galaxies and more than 13.7 billion years of history and transmitting data back to computers on Earth, they are guided by scientists seeking answers to enormous questions: How big is the Universe?
How are stars formed?
What else is out there?

You can drive right to the front door of the VLA. Its offices comprise a modest collection of buildings, landscaped with young trees, an oasis of green on the high-desert plain. A self-guided tour leads through the exhibition rooms. You can then walk out on a graveled path to the nearest dish.

If your timing is right, you might hear a whirring sound as you stand beneath it. The 82-foot dish looming a hundred feet above your head will turn slowly, changing its position as it probes different sectors of the Universe. All the other dishes strung to the horizon will swivel and tilt in precise unison, a slow-motion ballet across the landscape, as the experiment of another astrophysicist at a distant research university directs them, via computer commands to the VLA control room, where an operator sits at a bank of screens and wide windows, watching out onto the plain, monitoring.

You might feel closer to space and time here, to the big questions, to infinity, standing at this empty place, the only signs of life a few low buildings and the string of dishes across the arid mountain plain.

You're here on a journey. You're standing in the center of an eye that's watching and an ear that's listening to the deepest and oldest reaches of the Universe. There's an intelligence behind that eye and that ear – our human intelligence. It's an intelligence that has begun to understand that the Universe itself is on a journey – a journey toward ever greater complexity – while at the same time we, as humans, move toward ever greater interconnectedness, both among ourselves and with the vastness that lies out there.

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