Andrew Zimmerman Jones / Эндрю Циммерман Джонс - String Theory for Dummies / Теория струн для «чайников»

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Andrew Zimmerman Jones / Эндрю Циммерман Джонс - String Theory for Dummies / Теория струн для «чайников»
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String Theory for Dummies / Теория струн для «чайников»
Год: 2010
Автор: Andrew Zimmerman Jones / Эндрю Циммерман Джонс
Жанр: Научно-популярный; учебное пособие
Издательство: Wiley Publishing, Inc.
ISBN: 978-0-470-46724-4
Язык: Английский
Формат: PDF
Качество: Изначально компьютерное (eBook)
Количество страниц: 387
Описание:
Фундаментальные понятия этой спорной теории
Как теория струн основывается на понятиях физики
Различные точки зрения в области
Физические значения теории струн

Почему ученые столь взволнованы теорией струн? Потому что теория струн - наиболее вероятный кандидат для успешности теории квантовой гравитации, - теории, которая, как надеются ученые, объединит два главных закона физики вселенной в один. Прямо сейчас, эти законы (законы квантовой физики и законы общей теории относительности), описывают два полностью различных типа поведения полностью различными способами; и в такой реальности, где никакая теория не работает полностью, мы действительно не знаем что, что происходит на самом деле! Понимание смысла теории струн означает понимание глубоких аспектов нашей действительности на самых фундаментальных уровнях. Есть ли параллельные вселенные? Существует ли только один
закон природы или их бесконечно много? Почему наша Вселенная следует за законами именно так, как она это и делает? Действительно ли возможно путешествие во времени? Сколько измерений в нашей вселенной? Физики страстно ищут ответы на эти вопросы. Конечно, теория струн - захватывающая тема, научная революция, которая обещает изменить наше понимание вселенной. Как вы увидите, такие революционные изменения были и раньше, и эта книга поможет вам понять, как физика развивалась в прошлом так же хорошо, как и то, как она может развиваться в будущем.
В этой книге есть идеи, которые, вероятно, в ближайшие годы, окажутся полностью неправильными. Но в ней содержатся и другие идеи, которые могут в конечном счете оказаться фундаментальными законами нашей вселенной, и, возможно, сформируют новые основания для полностью новых форм науки и техники. Никто не знает, какое будущее ожидает теорию струн.
Откройте книгу и найдите:
На какие вопросы пытается ответить теория струн
Понятные примеры
Объяснение теории относительности Эйнштейна, квантовой теории, и физики элементарных частиц
Успехи и провалы теории струн
Захватывающие области теории струн, включая струны и браны
Способы, которыми может быть проверена теория струн
Как теория может прикоснуться к космическим тайнам, от происхождения материи к черным дырам
The basic concepts of this controversial theory
How string theory builds on physics concepts
The different viewpoints in the field
String theory's physical implications

Why are scientists so excited about string theory? Because string theory is the most likely candidate for a successful theory of quantum gravity — a theory that scientists hope will unite two major physical laws of the universe into one. Right now, these laws (quantum physics and general relativity) describe two totally different types of behavior in totally different ways, and in the realm where neither theory works completely, we really don’t know what’s going on! Understanding the implications of string theory means understanding profound aspects of our reality at the most fundamental levels. Are there parallel universes? Is there only one law of nature or infinitely many? Why does our universe follow the laws it does? Is time travel possible? How many
dimensions does our universe possess? Physicists are passionately seeking answers to these questions. Indeed, string theory is a fascinating topic, a scientific revolution that promises to transform our understanding of the universe. As you’ll see, these sorts of revolutions have happened before, and this book helps you understand how physics has developed in the past, as well as how it may develop in the future. This book contains some ideas that will probably, in the coming years, turn out to be completely false. It contains other ideas that may ultimately prove to be fundamental laws of our universe, perhaps forming the foundation for whole new forms of science and technology. No one knows what the future holds for string theory.
Open the book and find:
The questions string theory attempts to answer
Easy-to-follow examples
Explanations of Einstein's theory of relativity, quantum theory, and particle physics
The successes and failures of string theory
Fascinating bits of string theory including strings and branes
Ways that string theory can be tested
How the theory may relate to cosmic mysteries, from the origin of matter to black holes
Скриншоты - Примеры страниц
Оглавление
Table of Contents
Introduction.................................................................. 1
About This Book...............................................................................................1
Conventions Used in This Book......................................................................2
What You’re Not to Read.................................................................................3
Foolish Assumptions........................................................................................3
How This Book Is Organized...........................................................................4
Part I: Introducing String Theory..........................................................4
Part II: The Physics Upon Which String Theory Is Built....................4
Part III: Building String Theory: A Theory of Everything...................5
Part IV: The Unseen Cosmos: String Theory
on the Boundaries of Knowledge......................................................5
Part V: What the Other Guys Say: Criticism and Alternatives..........5
Part VI: The Part of Tens........................................................................5
Icons Used in this Book...................................................................................6
Where to Go from Here....................................................................................6
Part I: Introducing String Theory.................................... 7
Chapter 1: So What Is String Theory Anyway? 9
String Theory: Seeing What Vibrating Strings Can Tell Us about the
Universe.........................................................................................................9
Using tiny and huge concepts to create a theory of everything.....10
A quick look at where string theory has been..................................11
Introducing the Key Elements of String Theory.........................................12
Strings and branes................................................................................12
Quantum gravity...................................................................................14
Unification of forces.............................................................................14
Supersymmetry.....................................................................................15
Extra dimensions..................................................................................15
Understanding the Aim of String Theory.....................................................16
Explaining matter and mass................................................................16
Defining space and time.......................................................................17
Quantizing gravity................................................................................18
Unifying forces......................................................................................18
x String Theory For Dummies
Appreciating the Theory’s Amazing (and Controversial)
Implications.................................................................................................19
Landscape of possible theories..........................................................19
Parallel universes..................................................................................20
Wormholes............................................................................................20
The universe as a hologram................................................................21
Time travel.............................................................................................21
The big bang..........................................................................................21
The end of the universe.......................................................................22
Why Is String Theory So Important?............................................................22
Chapter 2: The Physics Road Dead Ends at Quantum Gravity . 25
Understanding Two Schools of Thought on Gravity..................................26
Newton’s law of gravity: Gravity as force..........................................26
Einstein’s law of gravity: Gravity as geometry..................................28
Describing Matter: Physical and Energy-Filled...........................................28
Viewing matter classically: Chunks of stuff.......................................29
Viewing matter at a quantum scale: Chunks of energy....................29
Grasping for the Fundamental Forces of Physics.......................................30
Electromagnetism: Super-speedy energy waves..............................30
Nuclear forces: What the strong force joins,
the weak force tears apart...............................................................31
Infinities: Why Einstein and the Quanta Don’t Get Along..........................32
Singularities: Bending gravity to the breaking point........................33
Quantum jitters: Space-time under a quantum microscope...........33
Unifying the Forces.........................................................................................35
Einstein’s failed quest to explain everything....................................35
A particle of gravity: The graviton......................................................36
Supersymmetry’s role in quantum gravity........................................37
Chapter 3: Accomplishments and Failures of String Theory . 39
Celebrating String Theory’s Successes........................................................39
Predicting gravity out of strings.........................................................40
Explaining what happens to a black hole (sort of)...........................40
Explaining quantum field theory using string theory......................41
Like John Travolta, string theory keeps making a comeback.........41
Being the most popular theory in town.............................................42
Considering String Theory’s Setbacks.........................................................43
The universe doesn’t have enough particles....................................43
Dark energy: The discovery string theory
should have predicted......................................................................44
Where did all of these “fundamental” theories come from?...........45
Looking into String Theory’s Future............................................................45
Theoretical complications: Can we figure out string theory?.........46
Experimental complications: Can we prove string theory?............46
Table of Contents xi
Part II: The Physics Upon Which String Theory Is Built.... 49
Chapter 4: Putting String Theory in Context: Understanding
the Method of Science . 51
Exploring the Practice of Science.................................................................52
The myth of the scientific method.....................................................52
The need for experimental falsifiability.............................................53
The foundation of theory is mathematics.........................................55
The rule of simplicity...........................................................................56
The role of objectivity in science.......................................................57
Understanding How Scientific Change Is Viewed.......................................57
Old becomes new again: Science as revolution................................58
Combining forces: Science as unification..........................................59
What happens when you break it? Science as symmetry................60
Chapter 5: What You Must Know about Classical Physics . 63
This Crazy Little Thing Called Physics........................................................63
No laughing matter: What we’re made of..........................................64
Add a little energy: Why stuff happens..............................................66
Symmetry: Why some laws were made to be broken......................67
All Shook Up: Waves and Vibrations............................................................68
Catching the wave................................................................................69
Getting some good vibrations.............................................................70
Newton’s Revolution: How Physics Was Born............................................72
Force, mass, and acceleration: Putting objects into motion...........73
Gravity: A great discovery...................................................................74
Optics: Shedding light on light’s properties......................................75
Calculus and mathematics: Enhancing scientific understanding.....75
The Forces of Light: Electricity and Magnetism.........................................75
Light as a wave: The ether theory......................................................76
Invisible lines of force: Electric and magnetic fields........................76
Maxwell’s equations bring it all together:
Electromagnetic waves.....................................................................79
Two dark clouds and the birth of modern physics..........................80
Chapter 6: Revolutionizing Space and Time: Einstein’s Relativity 81
What Waves Light Waves? Searching for the Ether...................................82
No Ether? No Problem: Introducing Special Relativity..............................84
Unifying space and time.......................................................................85
Unifying mass and energy....................................................................87
Changing Course: Introducing General Relativity......................................89
Gravity as acceleration........................................................................89
Gravity as geometry.............................................................................91
Testing general relativity.....................................................................92
Applying Einstein’s Work to the Mysteries of the Universe.....................95
Kaluza-Klein Theory — String Theory’s Predecessor................................96
xii String Theory For Dummies
Chapter 7: Brushing Up on Quantum Theory Basics . 99
Unlocking the First Quanta: The Birth of Quantum Physics...................100
Fun with Photons: Einstein’s Nobel Idea of Light.....................................102
Waves and Particles Living Together........................................................105
Light as a wave: The double slit experiment...................................105
Particles as a wave: The de Broglie hypothesis..............................106
Quantum physics to the rescue: The quantum wavefunction......108
Why We Can’t Measure It All: The Uncertainty Principle........................109
Dead Cats, Live Cats, and Probability in Quantum Physics....................111
Does Anyone Know What Quantum Theory Means?...............................112
Interactions transform quantum systems:
The Copenhagen interpretation....................................................113
If no one’s there to see it, does the universe exist?
The participatory anthropic principle.........................................113
All possibilities take place: The many worlds interpretation.......114
What are the odds? Consistent histories.........................................115
Searching for more fundamental data:
The hidden variables interpretation............................................115
Quantum Units of Nature — Planck Units.................................................116
Chapter 8: The Standard Model of Particle Physics . 119
Atoms, Atoms, Everywhere Atoms: Introducing Atomic Theory...........120
Popping Open the Atomic Hood and Seeing What’s Inside....................121
Discovering the electron....................................................................122
The nucleus is the thing in the middle.............................................123
Watching the dance inside an atom.................................................123
The Quantum Picture of the Photon: Quantum Electrodynamics.........125
Dr. Feynman’s doodles explain how particles
exchange information.....................................................................125
Discovering that other kind of matter: Antimatter.........................127
Sometimes a particle is only virtual.................................................128
Digging into the Nucleus: Quantum Chromodynamics...........................129
The pieces that make up the nucleus: Nucleons............................129
The pieces that make up the nucleon’s pieces: Quarks................130
Looking into the Types of Particles...........................................................131
Particles of force: Bosons..................................................................131
Particles of matter: Fermions............................................................132
Gauge Bosons: Particles Holding Other Particles Together...................133
Exploring the Theory of Where Mass Comes From.................................134
From Big to Small: The Hierarchy Problem in Physics............................135
Chapter 9: Physics in Space: Considering
Cosmology and Astrophysics 137
Creating an Incorrect Model of the Universe............................................138
Aristotle assigns realms to the universe.........................................138
Ptolemy puts Earth at the center of the
universe (and the Catholic Church agrees).................................139
Table of Contents xiii
The Enlightened Universe: Some Changes Allowed.................................141
Copernicus corrects what’s where in the universe........................141
Beholding the movements of heavenly bodies...............................142
Introducing the Idea of an Expanding Universe.......................................143
Discovering that energy and pressure have gravity......................143
Hubble drives it home........................................................................145
Finding a Beginning: The Big Bang Theory...............................................146
Bucking the big bang: The steady state theory..............................147
Going to bat for the big bang: Cosmic microwave
background radiation.....................................................................148
Understanding where the chemical elements came from.............150
Using Inflation to Solve the Universe’s Problems of
Flatness and Horizon................................................................................150
The universe’s issues: Too far and too flat.....................................151
Rapid expansion early on holds the solutions................................152
Dark Matter: The Source of Extra Gravity.................................................153
Dark Energy: Pushing the Universe Apart.................................................153
Stretching the Fabric of Space-Time into a Black Hole............................156
What goes on inside a black hole?....................................................156
What goes on at the edge of a black hole?......................................157
Part III: Building String Theory:
A Theory of Everything............................................... 159
Chapter 10: Early Strings and Superstrings:
Unearthing the Theory’s Beginnings . 161
Bosonic String Theory: The First String Theory.......................................161
Explaining the scattering of particles with
early dual resonance models.........................................................162
Exploring the first physical model: Particles as strings................164
Bosonic string theory loses out to the Standard Model................165
Why Bosonic String Theory Doesn’t Describe Our Universe.................166
Massless particles...............................................................................166
Tachyons.............................................................................................167
No electrons allowed..........................................................................168
25 space dimensions, plus 1 of time.................................................168
Supersymmetry Saves the Day: Superstring Theory...............................170
Fermions and bosons coexist . . . sort of.........................................171
Double your particle fun: Supersymmetry
hypothesizes superpartners..........................................................172
Some problems get fixed, but the dimension problem remains.....173
Supersymmetry and Quantum Gravity in the Disco Era.........................174
The graviton is found hiding in string theory.................................174
The other supersymmetric gravity theory: Supergravity.............176
String theorists don’t get no respect...............................................176
A Theory of Everything: The First Superstring Revolution.....................177
xiv String Theory For Dummies
But We’ve Got Five Theories!......................................................................178
Type I string theory............................................................................179
Type IIA string theory........................................................................179
Type IIB string theory........................................................................179
Two strings in one: Heterotic strings...............................................179
How to Fold Space: Introducing Calabi-Yau Manifolds............................180
String Theory Loses Steam..........................................................................182
Chapter 11: M-Theory and Beyond:
Bringing String Theory Together 183
Introducing the Unifying Theory: M-Theory.............................................183
Translating one string theory into another: Duality......................184
Using two dualities to unite five superstring theories...................188
The second superstring revolution begins:
Connecting to the 11-dimensional theory....................................188
Branes: Stretching Out a String..................................................................190
The discovery of D-branes: Giving open strings
something to hold on to.................................................................190
Creating particles from p-branes......................................................192
Deducing that branes are required by M-theory............................192
Uniting D-branes and p-branes into one type of brane..................193
Using branes to explain black holes.................................................194
Getting stuck on a brane: Brane worlds...........................................195
Matrix Theory as a Potential M-Theory.....................................................196
Gaining Insight from the Holographic Principle.......................................197
Capturing multidimensional information on a flat surface...........197
Connecting the holographic principle to our reality.....................198
Considering AdS/CFT correspondence............................................199
String Theory Gets Surprised by Dark Energy..........................................200
Considering Proposals for Why Dimensions Sometimes Uncurl............201
Measurable dimensions.....................................................................202
Infinite dimensions: Randall-Sundrum models...............................202
Understanding the Current Landscape: A Multitude of Theories..........204
The anthropic principle requires observers...................................204
Disagreeing about the principle’s value..........................................207
Chapter 12: Putting String Theory to the Test . 209
Understanding the Obstacles......................................................................210
Testing an incomplete theory with indistinct predictions............210
Test versus proof................................................................................211
Testing Supersymmetry...............................................................................211
Finding the missing sparticles..........................................................212
Testing implications of supersymmetry..........................................212
Testing Gravity from Extra Dimensions.....................................................213
Testing the inverse square law.........................................................214
Searching for gravity waves in the CMBR........................................214
Table of Contents xv
Disproving String Theory Sounds Easier Than It Is.................................215
Violating relativity..............................................................................215
Mathematical inconsistencies...........................................................216
Could Proton Decay Spell Disaster?...........................................................217
Looking for Evidence in the Cosmic Laboratory:
Exploring the Universe.............................................................................218
Using outer space rays to amplify small events.............................218
Analyzing dark matter and dark energy...........................................222
Detecting cosmic superstrings.........................................................222
Looking for Evidence Closer to Home: Using Particle Accelerators......223
Relativistic Heavy Ion Collider (RHIC).............................................224
Large Hadron Collider (LHC).............................................................224
Colliders of the future........................................................................226
Part IV: The Unseen Cosmos: String Theory On the
Boundaries of Knowledge........................................... 227
Chapter 13: Making Space for Extra Dimensions 229
What Are Dimensions?.................................................................................229
2-Dimensional Space: Exploring the Geometry of Flatland.....................230
Euclidean geometry: Think back to high school geometry...........231
Cartesian geometry: Merging algebra and Euclidean geometry.....231
Three Dimensions of Space.........................................................................233
A straight line in space: Vectors.......................................................233
Twisting 2-dimensional space in three dimensions:
The Mobius strip.............................................................................234
More twists in three dimensions: Non-Euclidean geometry.........236
Four Dimensions of Space-Time.................................................................237
Adding More Dimensions to Make a Theory Work..................................238
Sending Space and Time on a Bender........................................................239
Are Extra Dimensions Really Necessary?..................................................240
Offering an alternative to multiple dimensions..............................241
Weighing fewer dimensions against simpler equations................242
Chapter 14: Our Universe — String Theory, Cosmology, and
Astrophysics . 245
The Start of the Universe with String Theory...........................................245
What was before the bang?...............................................................246
What banged?......................................................................................247
Explaining Black Holes with String Theory...............................................250
String theory and the thermodynamics of a black hole................250
String theory and the black hole information paradox.................252
The Evolution of the Universe....................................................................253
The swelling continues: Eternal inflation........................................253
The hidden matter and energy.........................................................255
xvi String Theory For Dummies
The Undiscovered Country: The Future of the Cosmos..........................257
A universe of ice: The big freeze.......................................................257
From point to point: The big crunch................................................257
A new beginning: The big bounce.....................................................258
Exploring a Finely Tuned Universe............................................................258
Chapter 15: Parallel Universes: Maybe You Can
Be Two Places at Once 261
Exploring the Multiverse: A Theory of Parallel Universes......................261
Level 1: If you go far enough, you’ll get back home.......................264
Level 2: If you go far enough, you’ll fall into wonderland..............265
Level 3: If you stay where you are, you’ll run into yourself..........267
Level 4: Somewhere over the rainbow, there’s a magical land.....269
Accessing Other Universes.........................................................................270
A history of hyperspace.....................................................................270
How quantum mechanics can get us from here to there..............272
Chapter 16: Have Time, Will Travel 275
Temporal Mechanics 101: How Time Flies................................................276
The arrow of time: A one-way ticket................................................276
Relativity, worldlines, and worldsheets:
Moving through space-time...........................................................278
Hawking’s chronology protection conjecture:
You’re not going anywhere............................................................279
Slowing Time to a Standstill with Relativity..............................................280
Time dilation: Sometimes even the best watches run slow..........281
Black hole event horizons: An extra-slow
version of slow motion...................................................................282
General Relativity and Wormholes: Doorways in Space and Time........282
Taking a shortcut through space and time with a wormhole.......284
Overcoming a wormhole’s instability
with negative energy.......................................................................286
Crossing Cosmic Strings to Allow Time Travel........................................286
A Two-Timing Science: String Theory Makes
More Time Dimensions Possible.............................................................287
Adding a new time dimension...........................................................287
Reflecting two-time onto a one-time universe.................................288
Does two-time physics have any real applications?.......................289
Sending Messages through Time................................................................290
Time Travel Paradoxes................................................................................290
The twin paradox................................................................................291
The grandfather paradox...................................................................292
Where are the time travelers?...........................................................292
Table of Contents xvii
Part V: What the Other Guys Say:
Criticisms and Alternatives........................................ 295
Chapter 17: Taking a Closer Look at the
String Theory Controversy . 297
The String Wars: Outlining the Arguments...............................................298
Thirty years and counting: Framing the debate
from the skeptic’s point of view....................................................299
A rise of criticisms..............................................................................300
Is String Theory Scientific?..........................................................................301
Argument No. 1: String theory explains nothing............................301
Argument No. 2: String theory explains too much.........................302
Turning a Critical Eye to String Theorists.................................................305
Hundreds of physicists just can’t be wrong....................................305
Holding the keys to the academic kingdom....................................306
Does String Theory Describe Our Universe?............................................308
Making sense of extra dimensions....................................................309
Space-time should be fluid................................................................309
How finite is string theory?................................................................310
A String Theory Rebuttal.............................................................................311
Chapter 18: Loop Quantum Gravity:
String Theory’s Biggest Competitor . 313
Taking the Loop: Introducing Another Road to Quantum Gravity.........313
The great background debate...........................................................314
What is looping anyway?...................................................................314
Making Predictions with Loop Quantum Gravity.....................................317
Gravity exists (Duh!)...........................................................................317
Black holes contain only so much space.........................................317
Gamma ray burst radiation travels at different speeds.................318
Finding Favor and Flaw with Loop Quantum Gravity..............................318
The benefit of a finite theorem..........................................................318
Spending some time focusing on the flaws.....................................319
So Are These Two Theories the Same with Different Names?................320
Chapter 19: Considering Other Ways to Explain the Universe 323
Taking Other Roads to Quantum Gravity..................................................324
Causal dynamical triangulations (CDT):
If you’ve got the time, I’ve got the space.....................................324
Quantum Einstein gravity: Too small to tug....................................325
Quantum graphity: Disconnecting nodes........................................326
Internal relativity: Spinning the universe into existence...............327
xviii String Theory For Dummies
Newton and Einstein Don’t Make All the Rules:
Modifying the Law of Gravity..................................................................328
Doubly special relativity (DSR): Twice
as many limits as ordinary relativity............................................328
Modified Newtonian dynamics (MOND):
Disregarding dark matter...............................................................328
Variable speed of light (VSL): Light used to travel even faster....329
Modified gravity (MOG): The bigger the distance,
the greater the gravity....................................................................331
Rewriting the Math Books and Physics Books at the Same Time..........332
Compute this: Quantum information theory...................................333
Looking at relationships: Twistor theory........................................334
Uniting mathematical systems: Noncommutative geometry........334
Part VI: The Part of Tens............................................ 337
Chapter 20: Ten Questions a Theory of Everything
Should (Ideally) Answer 339
The Big Bang: What Banged (and Inflated)?..............................................340
Baryon Asymmetry: Why Does Matter Exist?...........................................340
Hierarchy Issues: Why Are There Gaps in Forces,
Particles, and Energy Levels?..................................................................341
Fine-Tuning: Why Do Fundamental Constants
Have the Values They Do?.......................................................................341
Black Hole Information Paradox: What Happens to
Missing Black Hole Matter?.....................................................................341
Quantum Interpretation: What Does Quantum Mechanics Mean?........342
Dark Mystery No. 1: What Is Dark Matter
(and Why Is There So Much)?.................................................................343
Dark Mystery No. 2: What Is Dark Energy (and Why Is It So Weak)?.....343
Time Symmetry: Why Does Time Seem to Move Forward?....................344
The End of the Universe: What Comes Next?...........................................344
Chapter 21: Ten Notable String Theorists . 345
Edward Witten..............................................................................................345
John Henry Schwarz.....................................................................................346
Yoichiro Nambu............................................................................................347
Leonard Susskind.........................................................................................347
David Gross...................................................................................................348
Joe Polchinski...............................................................................................348
Juan Maldacena............................................................................................348
Lisa Randall...................................................................................................349
Michio Kaku...................................................................................................349
Brian Greene..................................................................................................350
Index........................................................................ 351