A User's Guide to the Universe , livre ebook

Table of Contents
 
Title Page
Copyright Page
Acknowledgments
Introduction
 
Chapter 1 - Special Relativity
 
Why can’t you tell how fast a ship is moving through fog?
How fast does a light beam go if you’re running beside it?
If you head off in a spaceship traveling at nearly the speed of light, what ...
Can you reach the speed of light (and look at yourself in a mirror)?
Isn’t relativity supposed to be about turning atoms into limitless power?
 
Chapter 2 - Quantum Weirdness
 
Is light made of tiny particles, or a big wave?
Can you change reality just by looking at it?
If you look at them closely enough, what are electrons, really?
Is there some way I can blame quantum mechanics for all those times I lose things?
Can I build a transporter, like on Star Trek?
If a tree falls in the forest and no one hears it, does it make a sound?
 
Chapter 3 - Randomness
 
If the physical world is so unpredictable, why doesn’t it always seem that way?
How does carbon dating work?
Does God play dice with the universe?
 
Chapter 4 - The Standard Model
 
What do we need a multibillion-dollar accelerator for, anyway?
How do we discover subatomic particles?
Why are there so many different rules for different particles?
Where do the forces really come from?
Why can’t I lose weight (or mass)—all of it?
How could little ol’ LHC possibly destroy the great big world?
If we discover the Higgs, can physicists just call it a day?
 
Chapter 5 - Time Travel
 
Can I build a perpetual motion machine?
Are black holes real, or are they just made up by bored physicists?
What happens if you fall into a black hole?
Can you go back in time and buy stock in Microsoft?
Who does time travel right?
How can I build a practical time machine?
What are my prospects for changing the past?
 
Chapter 6 - The Expanding Universe
 
Where is the center of the universe?
What’s at the edge of the universe?
What is empty space made of?
How empty is space?
Where’s all of the stuff?
Why is the universe accelerating?
What is the shape of the universe?
What’s the universe expanding into?
 
Chapter 7 - The Big Bang
 
Why can’t we see all the way back to the Big Bang?
Shouldn’t the universe be (half) filled with antimatter?
Where do atoms come from?
How did particles gain all that weight?
Is there an exact duplicate of you somewhere else in time and space?
Why is there matter?
What happened at the very beginning of time?
What was before the beginning?
 
Chapter 8 - Extraterrestrials
 
Where is everybody?
How many habitable planets are there?
How long do intelligent civilizations last?
What are the odds against our own existence?
 
Chapter 9 - The Future
 
What is dark matter?
How long do protons last?
How massive are neutrinos?
What won’t we know anytime soon?
 
Further Reading
Technical Reading
Index

This book is printed on acid-free paper.
Copyright © 2010 by Dave Goldberg and Jeff Blomquist. All rights reserved
Published by John Wiley & Sons, Inc., Hoboken, New Jersey Published simultaneously in Canada
Photo credits: page 48, © Akira Tonomura; page 187, Andrew Fruchter (STScI) et al., WFPC2, HST, NASA; page 204, NASA/WMAP Science Team; page 231, J. R. Gott & L.-X. Li
 
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Library of Congress Cataloging-in-Publication Data:
Goldberg, Dave, date.
A user’s guide to the universe: surviving the perils of black holes, time paradoxes, and quantum uncertainty / Dave Goldberg and Jeff Blomquist. p. cm.
Includes index.
ISBN 978-0-470-49G51-0 (cloth)
1. Physics—Popular works. I. Blomquist, Jeff II. Title. QC24.5.G65 2010 530—dc22
2009028773
 

 
Acknowledgments
This book has been a labor of love. We’ve tried to translate our love of teaching and our love of physics into something that could be understood and enjoyed by people at every level. We are so grateful for the feedback from our friends, family, and colleagues. First and foremost, Dave wants to thank his wife, Emily Joy, who was so supportive throughout, and who gave her honest opinions at every turn. Jeff wishes to thank his family (especially his brother), who remained politely neutral during the majority of his winded tirades and pointless doodling; he is also grateful to Frank McCulley, Harry Augensen, and Dave Goldberg, the three physicists who inspired him to give physics a fair shake. We are also indebted to feedback from Erica Caden, Amy Fenton, Floyd Glenn, Rich Gott, Dick Haracz, Doug Jones, Josh Kamensky, Janet Kim, Amy Lackpour, Patty Lazos, Sue Machler (aka Dave’s mom), Jelena Maricic, Liz Patton, Gordon Richards, David Spergel, Dan Tahaney, Brian Theurer, Michel Vallieres, Enrico Vesperini, Alf Whitehead, Alyssa Wilson, and Steve Yenchik. We also would like to acknowledge Geoff Marcy and Evelyn Thomson, with whom we had several enlightening discussions. We appreciate Rich Gott and Akira Tonomura allowing us to reproduce their figures. Thanks also to our very hardworking agent, Andrew Stuart, and our excellent editors, Eric Nelson and Constance Santisteban
Introduction
“So, what do you do?”

The life of a physicist can be a lonely one.
Imagine this: You sit down in an airplane, and the person next to you asks you what you do for a living. You reply that you’re a physicist. From here, the conversation can go one of two ways. Nine times out of ten, the first thing out of his or her mouth is something along these lines: “Physics? I hated that class!” 1
You’ll then spend the rest of the trip (or party, or elevator ride, or date) apologizing for the emotional trauma that physics has apparently inflicted on your erstwhile friend. These random encounters often reveal an almost joyful contempt, reserved specifically for the fields of physical science and mathematics. “Oh, I’m terrible at algebra!” for example, is said in an almost boastful tone, in a way that “I barely even know how to read!” never would. But why?
Physics has a somewhat unfair reputation for being hard, impractical, and boring. Hard? Perhaps. Impractical? Definitely not. Indeed, when people try to “sell” physics to the public, it is almost always in terms of how it can be used to build bridges or launch rockets—that is, how physics is ultimately the foundation for engineering or chemistry.
But boring? That’s where we really take issue. The problem, as we see it, is that the practical side of physics is almost always put forward at the expense of the interesting side. Even folks with technical focuses such as engineering and computer science typically don’t get past mechanics and electromagnetism to the really fun stuff. And that’s a shame, because quite frankly there has been very little cutting-edge research done on pulleys in the past few years.
This hostility to physics seems to be ingrained, and makes it difficult to have discussions without jading an audience. In starting a scientific conversation with a “civilian,” we purveyors of physics often feel like we’re trying to force people to eat their vegetables, and rationalize it in the same way. We never begin physics discussions with “It’s fun!” but almost always with “It’s necessary,” which naturally drains all of the fun out of it.
In an era when new technologies are constantly emerging, scientific literacy should be fundamental. On the other hand, it isn’t necessary that you have four extra years of college sciences to understand them. You don’t need to have a detailed knowledge of exactly how the physics works to appreciate the revolutions in quantum computing or cosmology. It is important, rather, to understand why these developments are significant, and how they are poised to change technology and our lives.
And it’s not simply that people need to understand a particular theory. Physics is the archetypal inductive science, and by understanding how science proceeds, people are better able to make informed decisions about issues from