Edge of the Universe , livre ebook

Contents
Cover
Title Page
Copyright
Dedication
Prologue: Cosmology’s Extraordinary New Frontiers
Chapter 1: How Far Out Can We See?
Seeing Back in Time
Journey from the Center of the Universe
Light’s Extraordinary Tale
Hubble and the Expanding Universe
Hatching the Cosmic Egg
Chapter 2: How Was the Universe Born?
Blast from the Past
Postcards from the Dawn of Time
Happy 13.75 Billionth Birthday to Space!
Chapter 3: How Far Away Will the Edge Get?
Gauging Cosmic Destiny
Roll Over, Copernicus
The Theory Formerly Known as Einstein’s Blunder
Chapter 4: Why Does the Universe Seem So Smooth?
A Burst of Creative Energy
Building the Astronomical Beehive
Eternity’s Challenge
Chapter 5: What Is Dark Energy?
The Mr. Universe Competition
Cosmic Chameleons
The Phantom Menace
Chapter 6: Do We Live in a Hologram?
Into the Maelstrom
Holographic Sky
Reality’s Mosaic
The Primal Quantum Sea
Chapter 7: Are There Alternatives to Inflation?
The View from Flatland
Supertheories to the Rescue!
Stringy and the Brane
Cosmic Wheels
Fire and Ice
Chapter 8: What Builds Structure in the Universe?
Fickle-Flavored Neutrinos
Will-o’-the-WIMPs
A Detergent for Dark Matter
Gravity on Steroids
Chapter 9: What Is Tugging on Galaxies?
Beyond the Zone of Avoidance
The Great Void in Eridanus
Dark Flow to Reaches Beyond
Intruder Alert
Chapter 10: What Is the “Axis of Evil”?
Hawking’s Monogram in the Sky
The Axis of Evil
The Multiverse Shows Its Spots
Chapter 11: What Are the Immense Blasts of Energy from the Farthest Reaches of Space?
Tales of the Dark Ages
Generations of Stars
Voracious Supermassive Black Holes
Frenzied Flashes: The Mystery of Gamma-Ray Bursts
Dragon Quest
Into the Vortex
Chapter 12: Can We Journey to Parallel Universes?
Making Contact
The Trouble with Time Travel
Life in Other Universes
Chapter 13: Is the Universe Constantly Splitting into Multiple Realities?
Zombie Cats
House of Mirrors
Occam’s Barber Shop
The Multiverse Family Reunion
Chapter 14: How Will the Universe End?
Rewinding the Big Bang
Life in Deep Freeze
The Heart of a Lonely Universe
The Thaw after the Frost
Nurseries for Baby Universes
Reality’s Last Stretch
Chapter 15: What Are the Ultimate Limits of Our Knowledge about the Cosmos?
Changing of the Guard
A Tangled Webb
Where Is the Antimatter?
Into the Unknown
Acknowledgments
Further Reading
Index

Copyright © 2012 by Paul Halpern. All rights reserved
Cover Image: © iStockphoto Cover Design: Jose Alamaguer
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Dedicated, with love, to Felicia, Eli, and Aden
Prologue
Cosmology’s Extraordinary New Frontiers
Everything that we once believed about the universe is wrong! We thought that most of the material in space was made up of atoms, or at least of visible substances. Wrong! We thought that the expansion of the universe was slowing down—that its growth from the Big Bang was losing steam. Wrong again! We thought that galaxies were fairly evenly spread out and that there were no large regions of space without them. That was before the discovery of giant voids rendered that notion null and … wrong once more! We thought that there was a single universe—after all, “uni” means one. While the jury is still out on that one, some scientists are already claiming evidence of a multiverse—a collection of parallel realities. So ultimately even the name “universe” could turn out to be wrong!
Welcome to twenty-first-century cosmology, a highly precise field that is unafraid to admit that the vast majority of the universe is made of things beyond our current understanding. Dark matter, dark energy, and vast voids in space are the much-discussed cosmological topics of today that, like the 1990s television series Seinfeld , are all “about nothing.” Nothingness is literally on cosmologists’ radar screens, as they are learning about the enormous gaps through comprehensive sky surveys by space-based and ground telescopes as well as by detailed probes of the radio signals left over from the dawn of time, among other sources.
Clearly these things aren’t really “nothing”—we just don’t know enough to say what they are. Traditionally, astronomers have focused on what can be directly observed—the stuff of stars and planets. They estimate that about 4 to 5 percent of the universe is composed of conventional matter. But for those following the latest trends, ordinary matter is so twentieth-century. We’ve been there, done that, and now wish to tackle the exquisite enigma of fathoming the unseen majority of the cosmos.
As the science of the entire physical universe, cosmology shifts its goals and scope in tandem with the ebb and flow of knowledge about space. Through modern techniques, many great mysteries that once baffled philosophers and scientists have been resolved. All manner of cosmological data point to a primordial era of the cosmos that was incredibly hot and unbelievably dense, called the Big Bang. Astronomers have homed in on the approximate age of the universe, 13.75 billion years (give or take 100 million years or so), and have developed a detailed picture of some of its early stages. Recent models estimate the size of the observable universe (the part potentially detectable by instruments that measure signals from space) to be approximately 93 billion light-years in diameter. Yet, ironically, it seems that as we learn more and more about the cosmos, we realize how much of it lies beyond our grasp.
Five centuries ago intrepid European explorers set sail beyond the sea’s visible horizon and mapped out lands hitherto unknown to them. Today, astronomers have embarked upon an even more extraordinary quest: to gauge the shape, horizons, and extent of the universe itself, including the enormous invisible regions. For this cosmic voyage, compasses, sextants, and parchment scrolls have been replaced by powerful telescopes, delicate microwave receivers, sophisticated computer algorithms, and a host of other tools for capturing light waves from across the spectrum. The emerging cartography of the universe is being pieced together from its immensely intricate record of luminous signals—even as we attempt to penetrate the secrets of the darkness. In this sunrise of the new cosmology, it is the multifarious hues of collected, scientifically analyzed light that will illuminate the endless night.
Darkness surrounds our world, broken only by scattered points of light. We are used to the void, and undaunted by the task of gleaning information from far-flung objects that only dimly announce their arrival each night. Our adeptness with fashioning light-gathering mirrors and lenses has served us well, enabling us to map out parts of space from which signals literally take billions of years to reach us. Astronomy is now comfortable with such challenges.
Yet we have grown increasingly cognizant of a far more perplexing darkness that so far has defied all attempts at understanding. While sheer nothingness without effect is easy to dismiss, invisible material that exerts unseen influence cannot be taken lightly. More and more, we realize that the things we observe are guided by substances we cannot see. The Milky Way and other galaxies have at their cores supermassive black holes, are steered by dark matter, and are driven apart by dark energy. These are three different types of cloaked entities. The latter two provide, when added up, the lion’s share of all the matter and energy in the universe.
At least we know what conventional black holes are made of—highly compressed material states formed when the cores of massive stars catastrophically collapse. Th