How to Destroy the Universe Read online

  HOW TO DESTROY THE UNIVERSE

  And 34 Other Really Interesting Uses of PHYSICS

  PAUL PARSONS

  New York • London

  © 2011 by Paul Parsons

  All rights reserved. No part of this book may be reproduced in any form or by any electronic or mechanical means, including information storage and retrieval systems, without permission in writing from the publisher, except by reviewers, who may quote brief passages in a review. Scanning, uploading, and electronic distribution of this book or the facilitation of the same without the permission of the publisher is prohibited.

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  ISBN 978-1-62365-246-3

  Distributed in the United States and Canada by Random House Publisher Services

  c/o Random House, 1745 Broadway

  New York, NY 10019

  www.quercus.com

  Dr. Paul Parsons is a regular contributor to Nature, New Scientist and the Daily Telegraph. He was formerly editor of the BBC’s award-winning science and technology magazine Focus. The Science of Doctor Who (Icon Books) and was longlisted for the Royal Society Prize for Science Books. His last book was Science 1001, published by Quercus.

  CONTENTS

  Introduction

  1. How to build the ultimate rollercoaster

  2. How to predict the weather

  3. How to survive an earthquake

  4. How to stop a hurricane

  5. How to deflect a killer asteroid

  6. How to journey to the Earth’s core

  7. How to stop global warming

  8. How to launch yourself into space

  9. How to survive a lightning strike

  10. How to cause a blackout

  11. How to make an invisibility cloak

  12. How to be everywhere at once

  13. How to live forever

  14. How to teleport

  15. How to fit a power station in your pocket

  16. How to see an atom

  17. How to turn lead into gold

  18. How to build an atomic bomb

  19. How to harness starlight

  20. How to visit the tenth dimension

  21. How to survive falling into a black hole

  22. How to see the other side of the Universe

  23. How to recreate the Big Bang

  24. How to make the loudest sound on Earth

  25. How to destroy the Universe

  26. How to travel faster than light

  27. How to travel through time

  28. How to contact aliens

  29. How to make energy from nothing

  30. How to generate a force field

  31. How to predict the stock market

  32. How to crack unbreakable codes

  33. How to build an antigravity machine

  34. How to create life

  35. How to read someone’s mind

  Glossary

  INTRODUCTION

  Why is it that when you read about physics in popular books, it’s always about accelerating subatomic particles to near the speed of light in an attempt to unlock the ultimate secrets of the Universe, and yet when you study it at school all you end up doing is measuring the temperature of some ice in a bucket?

  Perhaps that’s an exaggeration but it’s not really a surprise that for all too many people, physics lessons were boring. Tediously, mind-achingly, duller than defrosting the fridge on a rainy Sunday, boring.

  When I was at school I had two physics teachers. One, Mr. H, spoke with a lisp and walked like the soles of his shoes were made of Zectron—that super-springy stuff they used to make balls that, if you lobbed them at the ground hard enough, could bounce right over your house. Despite his comical comportment he was, sadly, a droning bore. Albert Einstein once remarked how odd it is that an hour spent in the company of a pretty girl seems like a minute, while a minute with your hand on a hot stove seems like an hour. “That’s relativity,” he said. If only the great man could have come along to one of Mr. H’s classes, he could have witnessed time actually appear to run backward. I developed a deep loathing for the sections of the syllabus that Mr. H inflicted upon us—which, included thermodynamics (the science of temperature, ice and, yes, buckets).

  My other physics teacher—Miss M—was four foot ten and, so the story goes, had the power to make the school bully blubber without even raising her voice. Neither I nor any of my friends sympathized with school bullies but, nevertheless, we all regarded Miss M as quite terrifying and definitely not one to be aggravated. Homework was delivered promptly. That said, she was also perhaps the best physics teacher in the world. The vagaries of radioactivity, wave theory, gravity, optics, and all that other stuff, suddenly became clearer than centrifuged Evian. Not only that, but I don’t ever recall being bored. Scared, yes. Bored, definitely not.

  Thanks to Miss M, a very mediocre secondary school physics student was able to go away to university and ended up completing a doctorate in cosmology. Yes, that was me. I say “able to” but perhaps “wanted to” was her biggest achievement. I started off with next to no interest in physics, education or having a career of any sort, and came out of school inspired, largely as a result of her efforts.

  But why should it take such a good teacher to make physics interesting? Physics, I think it’s safe to say, is the best of all the sciences. That’s not just because it covers nuclear explosions, which are the biggest explosions we’re able to make. Or because it deals with space, which is inherently cool. It’s more because physics is the most fundamental of all the sciences. As the great Ernest Rutherford—the man who first split the atom—once declared, “Physics is the only real science. The rest are just stamp collecting.”

  I think what Rutherford meant is that physics underpins the fundamental behavior of the Universe—from that, everything else follows. The interplay between the subatomic particles—in particular, electrons orbiting around atoms—is what determines the laws of chemistry. And biology is just the chemistry governing the strange set of chemical reactions we call life. Life is classified into families and species—but giving things names and maintaining lists is no more innovative than keeping stamps in an album … But I digress.

  This book is your very own Miss M. I hope it won’t scare you quite as much as she scared me and my friends, but the aim in writing it was much the same as her goal in teaching us: to provide an interesting and accessible guide to the big ideas in physics. I don’t mean just the usual interesting fare of relativity and subatomic particle physics, but also mechanics (the science of moving objects), electromagnetism (the science of electric and magnetic fields) and even thermodynamics (temperature, ice and buckets). Along the way, I’ve tried to include some history of the subject and to put it all in a real-world context so that it doesn’t all seem like blue-sky science.

  Of course, there’s plenty of blue-sky science in here too—relativity and subatomic particle physics, along with antigravity, parallel universes, teleportation, time travel, immortality, invisibility and higher dimensions of space and time. You’ll find out how to save the planet from energy shortages by mining the vacuum of empty space, engineer the Earth’s climate to reverse the effects of global warming, and fend off killer asteroids like Bruce Willis and his vest. You’ll learn essential survival skills such as how to live
through a lightning strike, tough it out during an earthquake and fall into a black hole without being squashed into spaghetti. And you’ll discover some plain old cool stuff like how to turn lead into gold, travel to the center of the Earth, crack supposedly unbreakable codes and use physics to predict the stock market.

  Look at it this way: I got a physics education; you’re getting the keys to world domination. Is that a good deal? This one’s for you, Miss M—we salute you!

  CHAPTER 1

  How to build the ultimate rollercoaster

  • Gravitational energy

  • Launch catapult

  • G-forces

  • Centripetal force

  • Mind the gap

  Being accelerated from zero to 100 km/h (60 mph) in a little over a second, turned upside-down, spun round at over five times Earth’s gravity and then dropped 100 m (330 ft) might not be everyone’s cup of tea. But for rollercoaster thrill junkies it’s their idea of heaven. The ultimate rollercoaster ride is a delicate balancing act between safety and being scared witless.

  Gravitational energy

  After an age spent queuing you finally climb aboard, buckle in and wait anxiously for the off. You’ve never done this before and aren’t quite sure what to expect, although the green-faced individuals you’ve just watched stumble from the ride give you a fairly good idea. Amid fleeting concerns for your wellbeing, the controller’s voice crackles over the tannoy: “Go, go, go!” The car lurches forward and starts to accelerate. Most rollercoaster cars do not have their own internal power source. In fact, they are not propelled at all for most of the duration of their journey. Instead, they are hauled to the top of a high peak and then released. It is the speed the cars gain during this initial drop that provides the energy needed to carry them around the rest of the track. The rollercoaster really does “coast” the majority of the way. That this is possible at all comes down to a central principle of physics known as the “conservation of energy.” It says that when you add up the amount of all the different forms of energy locked away in a physical system you get a number—the total energy of the system—that must remain constant with time. Energy in the system is allowed to change from one type into another, but the sum total must always be the same.

  In a rollercoaster, the principal kinds of energy are kinetic energy, which is the energy associated with the motion of the rollercoaster cars, and “gravitational potential energy”—the energy the cars possess because of their height in Earth’s gravitational field, which can be thought of as rather like the energy stored in a stretched spring. At the peak marking the start of the ride, the rollercoaster’s speed and kinetic energy are both zero. All of its energy is in the form of gravitational potential energy. When it is released and begins to fall, it steadily gains speed, converting gravitational energy into kinetic energy as it descends—and back again as it climbs. In reality, this conversion is not perfect, as some energy will be lost due to friction between the wheels and the track and between the wheels and other moving parts of the rollercoaster. Friction is caused when the microscopic lumps and bumps on two surfaces chafe against one another as the surfaces rub together. There is also friction between the rollercoaster and the air. The lost energy is not destroyed but is carried away in the form of heat and sound. The loss of energy to friction means that all the peaks on a rollercoaster course must become progressively lower than the starting point. If any of the peaks were the same height (or higher), the rollercoaster would not have enough energy to clear them. Instead, it would roll back down into the last valley, oscillating back and forth in the dip as friction gradually carried the rest of its energy away, ultimately bringing it to a stop. While putting the dampers on most of the ride, friction is essential if you ever intend to stop and get off. It’s how the brakes work on most rollercoasters—by applying friction pads to the rotating axles to deliberately turn the rollercoaster’s kinetic energy into heat as quickly as possible.

  Conservation of energy is a concept that applies right across the whole of physics. It is an important principle in wave theory, thermodynamics, quantum mechanics and relativity. In 1918, German physicist Emmy Noether proved that the conservation of energy is a direct consequence of the laws of physics being “time invariant”: meaning that if I drop a stone out of my bedroom window today, then it will fall to the ground in exactly the same way if I repeat the experiment tomorrow.

  Launch catapult

  Of course, not every rollercoaster relies on gravity. Some of the newer designs incorporate launchers to provide the initial boost to gets things moving. These employ mechanical catapults, electromagnets or hydraulic systems that make use of compressed liquid to give the cars a kick down the track. For example, the hydraulic launcher used on the Stealth rollercoaster at Thorpe Park, England, accelerates the cars from 0 to 130 km/h (80 mph) in just two seconds. That’s an average acceleration of 18 m/s (60 ft/s) every second, roughly twice the rate you would accelerate by if falling freely under gravity. Physicists call this an acceleration of 2G. It creates a force pushing you back into your seat that is twice as powerful as the gravitational force on your buttocks as you sit reading this. G-forces such as this are an essential part of any rollercoaster experience. You feel them when the rollercoaster is accelerating forward (in the case of launched rollercoasters), accelerating backward (i.e. during braking—this normally only happens at the end of the ride) or changing direction.

  G-forces

  Changes in direction can take place in the vertical plane (passing over a crest or through a dip) or in the horizontal plane (turning a corner). The G-forces you experience in each case will vary according to what it’s safe for the human body to experience. The highest permissible forces are those pushing you into your seat at the bottom of a dip. These can briefly reach up to 6G. By comparison, astronauts on the Space Shuttle rarely experience more than 3G. (Although, admittedly, astronauts must endure high G-forces for many minutes during the trip into orbit, whereas on a rollercoaster they last just a split second.) The opposite forces, which lift you out of your seat as you pass over a peak, are typically much lower, at around 2G. The weakest forces are those experienced on rounding a horizontal bend. These should not exceed 1.8G, owing to the weakness of the muscles in the side of the human neck. Most rollercoasters try to ease these lateral forces by banking the track on bends so that some of the cornering force is transmitted down through the body and into your seat rather than pulling sideways on the neck.

  The forces you feel when you go round corners are all down to Newton’s laws of motion. These are three laws of physics that English physicist and mathematician Isaac Newton first published in his book Mathematical Principles of Natural Philosophy in 1687. The first law of motion says that an object will either remain stationary or carry on moving in a straight line at constant speed unless a force acts on it. This is sometimes also known as the law of “inertia.” It means that a rollercoaster on a straight and level track will carry on moving forever (assuming there’s no friction). If the track turns, however, the rollercoaster turns with it. The passengers—which Newton’s laws apply equally well to—have their own inertia and their own natural tendency to want to keep moving in a straight line. But instead they feel a force exerted on them by the side of the rollercoaster car as it turns.

  At the bottom of a loop (left) centrifugal force and gravity both push you into your seat. At the top they work in opposite directions, so if the centrifugal force is strong enough it can overcome gravity and hold you in your seat.

  If the centrifugal force exceeds gravity at a crest in the track (right) it can produce negative G-forces, lifting passengers up out of their seats.

  Newton’s second law of motion explains how the force makes the passengers turn the corner. It draws a distinction between forces and accelerations, and asserts that a force acting on an object causes the object to accelerate in the same direction as the force. If I push a toy car on a tabletop then I exert a force on the car, which makes
it accelerate. Similarly, the passengers on a rollercoaster feel the force exerted on them by the car as it turns and as a result of it they are accelerated in a sideways direction.

  Centripetal force

  Sideways acceleration is also what enables a rollercoaster to loop-the-loop without you falling out of your seat. (All rollercoasters have restraints to hold you in, but in all but the slowest loop-the-loops these are unnecessary.) Here, the acceleration acts at right angles to the track, toward the center of the loop, making the rollercoaster and the passengers move in a circle. At the top of the loop, where you are in the most danger of falling out of your seat, the acceleration pushes the seat into your bottom faster than gravity can pull your bottom out of the seat. As a result you stick to the seat. It’s a similar effect that makes your washing stick to the sides of the spin dryer. Physicists refer to the force that causes this acceleration as “centripetal force.” The strength of the centripetal force is determined by the radius of the loop and the speed at which the rollercoaster whizzes round it. The speed is lowest right at the top of the loop, but this is where the force needs to be strongest to stop you falling out. That’s why the loops on some rollercoasters aren’t circular but teardrop shaped, with a section of tight curvature at the very top to give maximum centripetal force where it is most needed.

  Although physicists prefer to talk in terms of centripetal force, most people are more familiar with “centrifugal force”—a force acting in the opposite direction that seems to be pushing them down into the floor of the rollercoaster as it loops. Centrifugal force is a consequence of Newton’s third and final law of motion, which states that for every action (that is, every force) there is an equal and opposite reaction (a force pushing in the opposite direction). So, for example, when I sit on a chair, the chair pushes back to support my weight and stop me crashing into the floor. You can also think of centrifugal force in terms of inertia—each passenger’s inertia makes them want to keep moving forward in a straight line at a tangent to the loop, in keeping with Newton’s first law. As the rollercoaster car turns inwards, following the path of the loop, this inertia pushes the passengers down into the floor. Considering the centrifugal force also makes it slightly easier to visualize the physics of looping the loop. At the bottom of the loop, both gravity and centrifugal force act in the same direction, making passengers feel extremely heavy in their seats. But at the top, the two forces practically cancel one another out, making the passengers feel almost weightless. It’s up to the engineers designing the ride to make sure the centrifugal force at this point is just bigger than the force of gravity to keep people in their seats. Going over a crest in the track, passengers experience the opposite effect to looping the loop. It’s rather like being on the outside of the spin dryer—the rollercoaster car drops away from under you faster than gravity can carry you after it, and you rise up out of your seat. Many rollercoaster junkies argue that these “negative G-force” moments are some of the best parts of the entire ride.