The Universe Within (4 page)

Leavitt became fascinated by one type of star that changed regularly from bright to dim over the course of days or months. Mapping seventeen hundred stars, she charted every property she could measure: how bright they were, where they sat in the sky, and how rapidly these
variable stars went from bright to dim. With all of these data, Leavitt uncovered an important regularity: there is a constant relationship between how fast some stars cycle from bright to dim and their
real
brightness
.

Leavitt’s idea seems awfully esoteric, but it is profound. Starting with the principle that light travels at a constant
speed, and knowing how bright the star actually was and how bright it appeared, meant that the
distance of the star from Earth could
be estimated. With this insight, Henrietta Leavitt gave us a ruler with which to measure distances in deep space.

We have to imagine astronomy in that era to appreciate the transformative power of Leavitt’s discovery. From the time of Galileo to Pickering, people observed the sky and saw the
planets,
nebulae, and fuzzy patches of light with ever-increasing clarity. But the central questions remained. How big is the universe? Is our own galaxy, the
Milky Way, all there is?

No sooner had Leavitt proposed her idea in 1912 than other astronomers began to calibrate and apply it to the heavens. One Dutch scientist used Leavitt’s ruler to measure the distances between individual stars. It gave him a big number. The galaxy is vast almost beyond imagination. Then
Edwin Hubble, armed with Leavitt’s idea, used the biggest
telescope of the time to change our view of the universe almost overnight.

In 1918, Hubble, a Rhodes scholar and law student turned astronomer, deployed his enormous new
Mount Wilson telescope to find one of the stars made famous by Leavitt. This star was special. It wasn’t alone in the sky; it sat inside a
cloud of gas, known as the Andromeda Nebula. When Hubble applied Leavitt’s ruler to the star, he encountered a stunning fact: the star, in fact the whole nebula that contained it, was farther away from us than anything yet measured. The game changer came from the realization that this object was much more distant than any star in our own galaxy. This nebula was no cloud of gas; it was an entirely separate galaxy light-years from our own. With that observation, the Andromeda Nebula became the
Andromeda Galaxy, and the world above our heads became vast and ancient almost beyond description.

Hubble, using the largest telescope of the day, mapped everything he could see with Leavitt’s variable stars inside. The Andromeda and Milky Way
Galaxies were only the tip of the iceberg. The heavens were filled with other galaxies composed of billions of stars. Many of the fuzzy patches of gas seen by
observers for a century or more were really star clusters that lie far beyond our own galaxy. In a scientific
age when people were grappling with the age of Earth, then thought to be on the order of 10 million to 100 million years old, the age and size of the universe revealed our planet to be just a minuscule speck in a vast universe composed of innumerable galaxies. These insights emerged as people learned to look at the sky in a new way.

Hubble applied another technique to measure objects in the sky. This one relied on an essential property of light. Light radiating from a source that is traveling toward us looks more blue than light traveling away, which looks more red. This color shift happens because light shares some
features with waves. Individual waves emanating from a source moving closer to you will look more compressed than ones moving away. In the world of color, more closely spaced waves are on the blue end of the spectrum, more separated ones on the red. If Leavitt’s technique was a ruler to measure distance in deep space, then the search for color shifts in light was a radar gun to measure speed.

With this tool, Hubble found a regularity: stars emit
red-shifted light. This could mean only one thing. The objects in the heavens are moving away from us, and the universe itself is expanding. This
expansion is not a pell-mell scatter; the heavens are scattering from a common center. Wind things back in time, and all the matter in the sky was at some distant time occupying a central point.

Not everybody liked this new idea; in fact, some experts hated it. Rival theories for the origin of the universe abounded. A proponent for one of them poked fun at Hubble’s by giving it the moniker “
big bang.” Lacking in Hubble’s theory, or in any other for that matter, was direct evidence in the form of a smoking gun.

The major breakthrough was an incidental by-product of people’s need to
communicate with one another. With technological innovations in wireless technology and expanding international commerce and collaboration in the late 1950s came a demand for
transmission of
radio, TV, and other signals across the oceans.
NASA devised a special
satellite, code-named Echo 1, for this purpose. Looking like a large shiny metal balloon, it was meant to bounce signals transmitted from one part of Earth to another. The problem with this system was that the signals returning to Earth were often far too weak to interpret.

Working for AT&T’s
Bell Laboratories, at the time a utopia for scientists doing creative science,
Arno Penzias and
Robert Wilson were designing a radar dish to detect the extremely weak microwave signals reflected from NASA’s
Echo 1 satellite. They spent a considerable amount of time, money, and expertise to develop a specialized radar dish for the task. Then, in 1962, NASA launched
Telstar, a satellite that doesn’t passively bounce signals but relays them with a boost of its own. The bad news for Penzias and Wilson was that their dish was now useless for NASA.

The good news was that, now free of anyone else’s priorities, Penzias and Wilson were able to turn the dish to their real goal—observing the
radio waves that hit Earth from space. But their wonderful contraption was not up to the new job. The sensitivity, so essential for their gig with NASA, made the dish a nightmare to work with. It picked up all kinds of faint signals and noise, almost like persistent static on a TV.

Their efforts to remove the noise read today like an attempt to find and remove a fine needle from a shag rug. First they tried to filter out the signals produced by radios. No luck; interference remained. Then they cooled the detector to -270 degrees centigrade, a temperature at which
molecules come close to stopping their movement. Still interference. They climbed inside the detector and found that birds had sullied the interior via their digestive processes. Wiping away the evidence of those encounters helped a bit, but the interference remained. This
background noise was constant through day and night and was about one hundred times more than they would have expected.

Unknown to Penzias and Wilson, a set of
Princeton scientists used computer models to make a conjecture. If there was a big bang, some of the energy should be remaining in the heavens, drifting like smoke from an explosion. With 13.7 billion years of
cooling and expansion since the event, this radiation should be found everywhere and be of a particular wavelength. This was quite a specific quantitative prediction, and it offered no room for waffling. A friend showed Penzias and Wilson these papers, and
immediately they saw the real meaning of their static interference. The background interference was not noise; it was a signal. And it was of the exact type predicted by theory. Penzias and Wilson had discovered the remnants of the big bang, a discovery that won them the
Nobel Prize in 1978.

Being a fossil hunter, I dig in the ground to uncover relics. But every astronomer is a paleontologist of sorts. As
Carl Sagan famously said, the light of the stars we see was formed in chemical reactions from a long time ago. The vastness of space means that starlight hitting our eyes is no artifact; it is the real deal—a visitor from a time before the birth of our
species, even in some cases our
planet itself. With such time travelers coming down to us each night, the trick to reconstructing our past comes from learning to see the light and radiation of stars in new
ways.

For thousands of years, mankind considered itself the pinnacle of
life’s creation on a planet sitting in the center of the universe. Science changed that perception.
Leavitt,
Hubble, and others helped us see that we live near the margin of a vast galaxy, in a universe of
galaxies, with our planet one of many worlds.
Darwin and the biologists had their say too. Our entire species is but one little twig on an enormous tree of life filled with all life on Earth. But each discovery that moves us from the center of creation to some obscure corner brings an entirely new relation between us, other species, and the entire universe.
All the galaxies in the cosmos, like every creature on the planet, and every atom, molecule, and body on Earth are deeply connected. That connection begins at a single point 13.7 billion years ago.

As a species whose history has been in oceans, streams, and savanna plains, we humans have had our senses tuned to the chemical and physical world of land and water—to predators, prey, and mates we can see or hear. Nowhere in our history has there been a premium on the ability to perceive extra dimensions, times on the order of billions of years, or
distances in a virtual infinity of light-years. To achieve these insights, we repurpose tools that served us so well in our terrestrial existence to new ends. Logic, creativity, and invention project our senses and ideas to the far reaches of time and space.

The physics of the point that existed 13.7 billion years ago is mostly beyond our imaginations, not to mention our conceptual tools.
Gravity,
electromagnetism—all the forces at work around us did not have an independent existence.
Matter as we know it didn’t exist either. With everything that would become the universe packed so tightly in one spot, there was an enormous amount of
energy. In such a universe, the physics of small
particles,
quantum mechanics, and that of large bodies,
general relativity, were somehow part of a single, overarching, and still unknown theory. Just what that theory is awaits the next
Einstein.

By about .0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​0​1 second the universe was roughly 1,000,​000,​000,​000,​000,​000,​000,​000,​000,​000,​000,​000,​000,​000,​000,​000 degrees Fahrenheit, and the state of things starts to come more clearly into focus. This
time begins the period of very rapid expansion of the universe. The big bang is not like an explosion where objects are projected from each other; space itself expands. With this expansion comes
cooling over time. As the universe cooled and expanded, the forces and
particles that make our world today emerged.

Einstein’s relation
E =
mc
²
holds a key to the early events of the universe. The equation reveals the relationship between energy (E) and
mass (
m
). Since the
speed of light (
c
) is a huge number, it takes an enormous amount of energy to make an ounce of mass. The converse is also true: an infinitesimal amount of mass can be converted into a vast amount of energy.

One-trillionth of a second after the big bang, the universe was the size of a baseball. The energy contained in the universe at these early moments was the raw material for the production of a gargantuan amount of mass. As space expanded, energy, following Einstein’s equation, converted into mass, in this case ephemeral particles. In such a hot and small universe, everything was unstable: particles formed, collided, and disintegrated only to repeat the process trillions upon trillions of times.

The particles at this moment of history were of two opposing kinds, matter and
antimatter. Matter and antimatter are opposites and annihilate each other on contact. As energy converted to mass, no sooner were matter and antimatter particles produced than they collided. Most of these collisions led to the particles being completely extinguished. If this were the complete state of affairs, we—people, Earth, even the Milky Way—would never be. Particles would have been destroyed almost as soon as they formed. A slight—and by that we mean about one-billionth of 1 percent—excess of matter over antimatter was enough for matter to take hold in the universe. Because of that tiny imbalance, we are, as the physicist
Lawrence Krauss once described, every bit the direct descendants of that one-billionth of 1 percent surplus of matter over antimatter as we are of our own grandparents.

At one second, our universe started to form entities we would
recognize, if only very briefly. These are the collection of subatomic particles that make momentary appearances in some of the largest
atom smashers today—leptons, bosons, quarks, and their kin.

A little over three minutes after the birth of the universe began the stirrings of one of the deepest patterns in the world, captured by the chart that is the source of either awe or angst for young science students—the
periodic table. The periodic table catalogs all known
elements by the weight of their nuclei. The chart drawn for this moment of time would be a huge relief to our students. There would be only three boxes on it: hydrogen, helium, and
lithium.