19,99 €
Mehr erfahren.
- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
Discover the undiscovered with this jargon-free introduction to astrophysics
Astronomy is the study of what you see in the sky. Physics is the study of how things work. Astrophysics is the study of how things in the sky work, from large objects to tiny particles. Astrophysics For Dummies breaks it all down for you, making this difficult but fascinating topic accessible to anyone. Tracking the topics covered in a typical undergraduate astrophysics class, this book will teach you the essential pieces to understanding our universe. Get ready to launch into outer space with this ever-changing branch of science.
- Discover the latest advances in the world of astrophysics
- Understand how and why galaxies form and evolve
- Find out the origins of cosmic rays
- Get a standalone primer on the science or supplement your astrophysics course
Students in introductory astrophysics courses and would-be astronomy buffs who want to better understand the mechanics of the universe will love Astrophysics For Dummies.
Sie lesen das E-Book in den Legimi-Apps auf:
Seitenzahl: 647
Veröffentlichungsjahr: 2024
Ähnliche
Astrophysics For Dummies®
To view this book's Cheat Sheet, simply go to www.dummies.com and search for “Astrophysics For Dummies Cheat Sheet” in the Search box.
Table of Contents
Cover
Title Page
Copyright
Introduction
About This Book
Foolish Assumptions
Icons Used in This Book
Beyond the Book
Where to Go from Here
Part 1: Getting Started with Astrophysics
Chapter 1: Welcome to the Universe
The Science of Astrophysics
Tools of the Trade
Stars, Galaxies, and Their Cosmological Friends
Chapter 2: The A to Z of Physics
Building Blocks of the Universe: Particles
What Matters About Matter?
Let the Force(s) Be With You
Store It or Use It, But Don’t Waste Energy
It’s the Law! (of Physics)
Heat and Energy Unite with Thermodynamics and Statistical Mechanics
Chapter 3: Astronomy in a Nutshell
Where to Begin … Or, How It All Began
Mapping our Solar System, Galaxy, and the Universe
Observational Astronomy: What are Those Dots in the Sky?
Chapter 4: Bridging the Gap Between Astronomy and Physics
More Than the Sum of Its Parts: The Unique Study of Astrophysics
Diving into the Details of Astrophysics
The Nitty-Gritty of Telescopes and Astronomical Instruments
The Sun, the Star of Our Solar System
Eclipses, or Throwing Shade in a Scientific Way
Part 2: When You Wish Upon a …
Chapter 5: Star Power: Hydrogen, Helium with a Twist of Nuclear Fusion
Happy Birthday! A Star Is Born
Getting to Know Your Stars: Properties, Types, and Characteristics
All Good Things Must Come to an End
Chapter 6: Friends for Life: Star Systems and Dust Clouds
The More the Merrier: Binary and Multiple Star Systems
Huddle Up There, Star Clusters
Pedal to the Metal with Interstellar Gas and Dust
Adding Structure to That Gas and Dust: Nebulae
Chapter 7: Exoplanets: The Search for Earth 2.0
Beyond beyond Earth
Exoplanets Come in Many Shapes and Sizes
Looking Under (or Around) Hidden Rocks: Exoplanet Detection
The Nitty-Gritty of Exoplanet Formation
What the Hail … Exoplanet Atmospheres
Can Life Be Found on Exoplanets?
Chapter 8: White Dwarfs, Black Holes, and Neutrinos, Oh My!
Snow White and the Seven …
There Is No Escape: Black Holes
Surf’s Up! Gravitational Waves
Neutron Stars, or Total Core Collapse
Quasars, Bursters, and Blazars
Part 3: Galaxies: Teamwork Makes the Dream Work
Chapter 9: From Fuzzy Blobs to Majestic Spirals: The Milky Way and Other Galaxies
Where in the World Are We?
Unraveling the Mystery
Galaxy Classification
Chapter 10: Quantifying the Unknown, or How Galaxies Work
Galaxy Formation Helps Unravel the Cosmos
Mechanics of a Star System
Galactic Structure
Black Holes and Their Role in Galaxies
The Hubble Deep Field
Chapter 11: Bigger Than Huge: Galaxy Clusters
Making Friends: The Basics of Galaxy Clusters
A Galaxy Cluster of Our Very Own: The Local Group
Galaxy Cluster Structure and Formation
Physics of Galaxy Clusters
Galaxy and cluster mergers
What Galaxy Clusters Tell You About the Universe
Chapter 12: Weird and Wacky Galactic Phenomena
Not Quite Dinosaurs: Galactic Archaeology
High Energy Astrophysics
Gravitational Lensing
Heading Down the Wormhole
Part 4: Cosmology: The Beginning and the End of Everything
Chapter 13: The Big Bang: How It All Began
What’s the Point? A Primer on Cosmology
Scientific Evidence: Why Do We Think There Was a Big Bang?
Making Sense of the Unimaginable with the Theory of Inflation
Radiation Dominance in the Radiation Era
Nothing Matters More Than Matter in the Matter Era
Metric Expansion of Space: The Cosmological Principle
Chapter 14: First Light in the Universe, or How a Star is Born
The Cosmic Dark Age
Early Star Formation
Star Classification: Population III
Star Classification: Population II and I
The Epoch of Reionization
Formation of the First Galaxies
Chapter 15: And Then It Gets Weirder: Dark Matter, Dark Energy, and Relativity
General Facts about General Relativity
Advancing Theories Require Advancing Models
Galactic Glue: Dark Matter
Dark Energy in Review
Where Did Dark Energy Come From?
Chapter 16: The End of It All
No Refunds: What Happens When the Sun Explodes
Omega Value of the Universe
The Big Freeze: An End of the Universe Theory
The Big Rip: Another End of the Universe Theory
The Big Crunch: Yet Another End of the Universe Theory
Something Before Nothing: Did Anything Come before the Big Bang?
Now That We’re at the End — How Will It End?
Part 5: The Part of Tens
Chapter 17: Ten Scientists Who Paved the Way for Astrophysics
Albert Einstein: 1879–1955
Edwin Hubble: 1889–1953
Cecelia Payne-Gaposchkin: 1900–1979
Karl Jansky: 1905–1950
Subrahmanyan Chandrasekhar: 1910–1995
Vera Rubin: 1928–2016
Kip Thorne: 1940–
Stephen Hawking: 1942–2018
Jocelyn Bell Burnell: 1943–
Alan Guth: 1947–
Chapter 18: Ten Important Space Missions for Astrophysics
Hubble Space Telescope (1990–present)
James Webb Space Telescope (2021–present)
Kepler and TESS (2009–2018 and 2018–present)
SOFIA (2010–2022)
Chandra X-Ray Observatory (1999–present)
Spitzer Space Telescope (2003–2020)
Compton Gamma-Ray Observatory (1991–2000)
Fermi Gamma-Ray Space Telescope (2008–present)
Herschel Space Observatory (2009–2013)
Nancy Grace Roman Space Telescope (planned 2027 launch)
Glossary
Index
About the Authors
Supplemental Images
Advertisement Page
Connect with Dummies
End User License Agreement
List of Tables
Chapter 2
TABLE 2-1 Basic Subatomic Particles
TABLE 2-2 Forces of Nature
TABLE 2-4 Newton’s Laws of Motion
TABLE 2-5 Laws of Thermodynamics
Chapter 3
TABLE 3-1 Solar System Details
TABLE 3-2 Kepler’s Laws of Planetary Motion
Chapter 5
TABLE 5-1 Properties of Stars and the Sun
Chapter 6
TABLE 6-1 Quick Differences between Types of Star Clusters
Chapter 9
TABLE 9-1 Galaxy Types Defined by Hubble
Chapter 10
TABLE 10-1 Parts of a Galaxy
TABLE 10-2 The Contents of a Few Better-Known Galaxies
Chapter 13
TABLE 13-1 An overview of the Radiation Era, Matter Era, and Dark Energy Era
Chapter 14
TABLE 14-1: Characteristics of Population III, II, and I Stars in the Local Grou...
Chapter 16
TABLE 16-1 Expansion Parameters for the Universe
List of Illustrations
Chapter 1
FIGURE 1-1: The electromagnetic spectrum.
FIGURE 1-2: The Crab Nebula emitting radiation at different wavelengths.
FIGURE 1-3: The Large Binocular Telescope Observatory in Arizona.
Chapter 2
FIGURE 2-1: The atom and its most basic components.
FIGURE 2-2: The periodic table of elements.
FIGURE 2-3: The structure of a water molecule.
FIGURE 2-4: Kinetic versus potential energy.
FIGURE 2-5: Blackbody radiation curve.
Chapter 3
FIGURE 3-1: The Hubble Space Telescope, deployed into space in 1990.
FIGURE 3-2: The solar system, galaxy, and universe.
FIGURE 3-3: Diagram illustrating relative planetary size (with bonus Pluto).
FIGURE 3-4: Kepler’s laws of motion.
FIGURE 3-5: Halley’s Comet, last viewed from Earth in 1986.
FIGURE 3-6: Diagram of the ecliptic.
Chapter 4
FIGURE 4-1: Redshift versus blueshift.
FIGURE 4-2: Cosmic distances, in light-years.
FIGURE 4-3: Schematic diagram of the Earth’s orbit.
FIGURE 4-4: Diagram of a reflecting and refracting telescope.
FIGURE 4-5: The Very Large Array, a radio telescope array in New Mexico.
FIGURE 4-6: An example of a mid-level solar flare as captured by NASA’s Solar D...
FIGURE 4-7: Diagram of a lunar eclipse.
FIGURE 4-8: Diagram of a solar eclipse.
FIGURE 4-9: Using your hand or an index card as a pinhole viewer during a parti...
FIGURE 4-10: Annular and total solar eclipses.
Chapter 5
FIGURE 5-1: Solar nuclear fusion diagram — from hydrogen to helium.
FIGURE 5-2: Star formation region in the Carina Nebula, as viewed by the James ...
FIGURE 5-3: A protostar forms within the dark molecular cloud L1527, as seen by...
FIGURE 5-4: An H-R diagram shows how a star’s luminosity relates to its tempera...
FIGURE 5-5: The interior structure of a pre-supernova high-mass star.
FIGURE 5-6: The possible life cycle phases of a star.
Chapter 6
FIGURE 6-1: Diagram showing orbits in a binary star system.
FIGURE 6-2: Types of binary star systems.
FIGURE 6-3: Light curve of an eclipsing binary star system.
FIGURE 6-4: Binary star system spectrum and radial velocity.
FIGURE 6-5: The orbital paths of the six stars in the TYC 7037-89-1 system.
FIGURE 6-6: The Pleiades open star cluster.
FIGURE 6-7: Image of globular cluster M15, as seen by the Hubble Space Telescop...
FIGURE 6-8: The Horsehead Nebula, as seen by the Hubble Space Telescope.
Chapter 7
FIGURE 7-1: The major bodies in our solar system.
FIGURE 7-2: Types of exoplanets.
FIGURE 7-3: Radial velocity.
FIGURE 7-4: Transit diagram showing a dip in brightness.
FIGURE 7-5: Two giant exoplanets orbiting the star TYC 8998-760-1.
FIGURE 7-6: Protoplanetary disk surrounding the young star HL Tauri.
FIGURE 7-7: How JWST observes exoplanet atmospheres during eclipses and transit...
FIGURE 7-8: The size of a star’s habitable zone depends on the star’s brightnes...
FIGURE 7-9: Comparison of Kepler-452b to our solar system.
Chapter 8
FIGURE 8-1: Supermassive black hole in the center of Galaxy M87.
FIGURE 8-2: Artist’s conception of gravitational waves from neutron star merger...
FIGURE 8-3: Pulsar diagram.
FIGURE 8-4: Artist’s conception of a gamma-ray blazar as detected by the Fermi ...
Chapter 9
FIGURE 9-1: The Milky Way Galaxy.
FIGURE 9-2: Artist’s conception of the Milky Way Galaxy.
FIGURE 9-3: Cepheid variable star V1 in the Andromeda Galaxy M31.
FIGURE 9-4: The Hubble tuning fork diagram.
FIGURE 9-5: Spiral galaxy M100, as imaged by the Hubble Space Telescope.
FIGURE 9-6: Barred spiral galaxy NGC 1300, as imaged by the Hubble Space Telesc...
FIGURE 9-7: Elliptical galaxy NGC 2865, as seen by the Hubble Space Telescope.
FIGURE 9-8: Lenticular galaxy NGC 6861, as seen by the Hubble Space Telescope.
Chapter 10
FIGURE 10-1: Torque and gravitational torque.
FIGURE 10-2: Merging galaxies, as seen in a combination of data from the Spitze...
FIGURE 10-3: Combined image of radio galaxy Hercules A, showing the central gal...
FIGURE 10-4: Seyfert galaxy NGC 1566, as seen by the Spitzer Space Telescope.
FIGURE 10-5: The Hubble Ultra Deep Field.
Chapter 11
FIGURE 11-1: Stephan’s quintet, a galaxy group, as seen in the infrared by the ...
FIGURE 11-2: Perseus Galaxy Cluster, as imaged by the Euclid Space Telescope
FIGURE 11-3: Map of the Local Group with distances.
FIGURE 11-4: Interaction of a supermassive black hole at the center of a galaxy...
FIGURE 11-5: Merging galaxies as seen from the Hubble Space Telescope.
FIGURE 11-6: Galaxy cluster collision Abell 2146, as seen in a combination of x...
FIGURE 11-7: Abell 1689, a densely-packed galaxy cluster, as seen by Hubble.
FIGURE 11-8: Ancient galaxy cluster SPT2215, as seen in a combination of images...
Chapter 12
FIGURE 12-1: Artist’s conception of cosmic rays in the heliosphere.
FIGURE 12-2: Active Galactic Nucleus (AGN) Centaurus A, in optical (left) and r...
FIGURE 12-3: Gravity can bend the fabric of space.
FIGURE 12-4: Light as it bends through a lens.
FIGURE 12-5: Gravitational lensing and space-time curvature.
FIGURE 12-6: Einstein Cross G2237 + 0305, as seen by the Hubble Space Telescope...
FIGURE 12-7: Diagram showing how gravitational lensing bends the light from a d...
FIGURE 12-8: Einstein Ring SDSS J0146-0929, as seen by the Hubble Space Telesco...
FIGURE 12-9: The inner workings of a wormhole.
Chapter 13
FIGURE 13-1: Artist’s conception of the universe beginning at a single point in...
FIGURE 13-2: Timeline of the Big Bang.
FIGURE 13-3: The cosmic microwave background radiation, as seen by the WMAP spa...
FIGURE 13-4: Universal expansion following the Big Bang.
Chapter 14
FIGURE 14-1: A neutral hydrogen atom.
FIGURE 14-2: First stars and the Reionization Era.
Chapter 15
FIGURE 15-1: Three tests for general relativity.
FIGURE 15-2: Types of energy in the universe.
FIGURE 15-3: Hubble image of galaxy cluster CI 0024+17 (left), and locations of...
FIGURE 15-4: Ancient Supernova 1997ff, as seen by the Hubble Space Telescope.
FIGURE 15-5: Diagram showing changes in expansion of the universe due to dark e...
FIGURE 15-6: Observations of the changing expansion of the universe over time, ...
Chapter 16
FIGURE 16-1: End-of-life phases of our Sun.
FIGURE 16-2: Critical density and the geometry of the universe.
FIGURE 16-3: Union plot of multiple methods of estimating the critical density ...
FIGURE 16-4: Three possible fates for the future of the universe, and the role ...
Chapter 18
FIGURE 18-1: Artist’s conception of the JWST telescope with the sunshield deplo...
FIGURE 18-2: SOFIA in flight with its telescope hatch door open.
FIGURE 18-3: The Compton Gamma Ray Observatory floating away from the Space Shu...
Guide
Cover
Table of Contents
Title Page
Copyright
Begin Reading
Glossary
Index
About the Authors
Pages
i
ii
1
2
3
4
5
7
8
9
10
11
12
13
14
15
16
17
18
19
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
379
380
381
382
Astrophysics For Dummies®
Published by: John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030-5774, www.wiley.com
Copyright © 2024 by John Wiley & Sons, Inc., Hoboken, New Jersey
Published simultaneously in Canada
No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without the prior written permission of the Publisher. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008, or online at www.wiley.com/go/permissions.
Trademarks: Wiley, For Dummies, the Dummies Man logo, Dummies.com, Making Everything Easier, and related trade dress are trademarks or registered trademarks of John Wiley & Sons, Inc. and may not be used without written permission. All other trademarks are the property of their respective owners. John Wiley & Sons, Inc. is not associated with any product or vendor mentioned in this book.
LIMIT OF LIABILITY/DISCLAIMER OF WARRANTY: WHILE THE PUBLISHER AND AUTHORS HAVE USED THEIR BEST EFFORTS IN PREPARING THIS WORK, THEY MAKE NO REPRESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY OR COMPLETENESS OF THE CONTENTS OF THIS WORK AND SPECIFICALLY DISCLAIM ALL WARRANTIES, INCLUDING WITHOUT LIMITATION ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. NO WARRANTY MAY BE CREATED OR EXTENDED BY SALES REPRESENTATIVES, WRITTEN SALES MATERIALS OR PROMOTIONAL STATEMENTS FOR THIS WORK. THE FACT THAT AN ORGANIZATION, WEBSITE, OR PRODUCT IS REFERRED TO IN THIS WORK AS A CITATION AND/OR POTENTIAL SOURCE OF FURTHER INFORMATION DOES NOT MEAN THAT THE PUBLISHER AND AUTHORS ENDORSE THE INFORMATION OR SERVICES THE ORGANIZATION, WEBSITE, OR PRODUCT MAY PROVIDE OR RECOMMENDATIONS IT MAY MAKE. THIS WORK IS SOLD WITH THE UNDERSTANDING THAT THE PUBLISHER IS NOT ENGAGED IN RENDERING PROFESSIONAL SERVICES. THE ADVICE AND STRATEGIES CONTAINED HEREIN MAY NOT BE SUITABLE FOR YOUR SITUATION. YOU SHOULD CONSULT WITH A SPECIALIST WHERE APPROPRIATE. FURTHER, READERS SHOULD BE AWARE THAT WEBSITES LISTED IN THIS WORK MAY HAVE CHANGED OR DISAPPEARED BETWEEN WHEN THIS WORK WAS WRITTEN AND WHEN IT IS READ. NEITHER THE PUBLISHER NOR AUTHORS SHALL BE LIABLE FOR ANY LOSS OF PROFIT OR ANY OTHER COMMERCIAL DAMAGES, INCLUDING BUT NOT LIMITED TO SPECIAL, INCIDENTAL, CONSEQUENTIAL, OR OTHER DAMAGES.
For general information on our other products and services, please contact our Customer Care Department within the U.S. at 877-762-2974, outside the U.S. at 317-572-3993, or fax 317-572-4002. For technical support, please visit https://hub.wiley.com/community/support/dummies.
Wiley publishes in a variety of print and electronic formats and by print-on-demand. Some material included with standard print versions of this book may not be included in e-books or in print-on-demand. If this book refers to media such as a CD or DVD that is not included in the version you purchased, you may download this material at http://booksupport.wiley.com. For more information about Wiley products, visit www.wiley.com.
Library of Congress Control Number: 2024931757
ISBN 978-1-394-23504-9 (pbk); ISBN 978-1-394-23505-6 (ebk); ISBN 978-1-394-23506-3 (ebk)
Introduction
If you spend your evenings pondering the constellations and spotting shooting stars, you’re already hooked on astronomy.
If you’re one of those people who “gets” how things work, and if you’ve ever mentioned Newton or Einstein in casual conversation, apologize to your friends because you’ve got a keen interest in physics and are willing to share it.
Put the two together, and welcome to astrophysics! This field combines the excitement of recognizing planets and stars with the satisfaction of applying mathematics and physics to those same objects. Astrophysics goes beyond cataloging and observing the night sky into performing calculations, making measurements and creating predictions about future behaviors.
As a field, astrophysics covers everything you can see in the sky and then some. From the smallest molecule (no, you can’t see these without specialized equipment) to stars and planets, individual celestial bodies have a creation story that mimics that of the universe’s evolution. And the cosmos certainly isn’t limited to planets and stars!
For example, nebulae are massive dust and gas clouds that often result from the explosive death of a star but, coincidentally (actually not a coincidence, as you’ll read in Chapter 5), they’re also regions where new stars are born. Galaxies are vast groupings of stars, often containing nebulae and other high-energy astronomical features such as black holes and neutron stars, and they group together to form clusters of galaxies. Nothing in the universe exists in isolation, not even quarks (these are the smallest particles in the universe. Curious? Check out Chapter 15).
And speaking of things that are infinitely tiny, the Big Bang is the both the ending and the starting point of our exploration into astrophysics. The universe began as a single point in space and time, growing explosively over subsequent seconds as it expanded. The forces at play in our current universe (think gravity, electromagnetism, and the nuclear forces) emerged, atoms began to form, matter separated from radiation, and every element in today’s world was created. From the cloud of cosmic dust emerged stars, galaxies, dark matter, and all the other pieces of the cosmic puzzle.
But eventually, all good things must come to an end, and unfortunately that includes our universe. Theories abound as to how we’ll all meet our demise, but those theories only open the door to more questions. Is this universe the only one to have ever existed? Will another one be created when this one’s gone? Or, as some theories suggest, is our universe only one in a series? There are no definitive answers at this point to many of these questions, but studying astrophysics gives you the knowledge you need to start asking those questions, and perhaps even answering those questions for yourself.
About This Book
Welcome to the cosmos! Whether you’re curious about how the universe began, want to know more about the science behind eclipses, or are considering becoming an astrophysicist (and if that’s the case, we expect to see you at conferences and lectures down the road), this book will get you started.
Astrophysics is a notoriously difficult idea to wrap your head around because it’s incredibly vast, yet also extremely detail-oriented. We’ve broken down the information into digestible chapters so that you can read this book all at once, or can flip through to only the sections that interest you. We’ve written each chapter as a stand-alone piece with references to other parts of the book as needed. If you have the time and interest, try reading the book cover to cover for a more complete sense of the story: Decipher what you observe in the night sky, understand the science behind it, and get a holistic overview of this universe we call home, from start to finish.
Got questions on unfamiliar terms? Check the glossary at the back of this book for a quick guide. Need a quick refresher on which formula goes with which concept?
Finally, please consider us as resources for any additional questions you may have. Wiley can put you in contact with us directly for follow-up questions, and you can always request additional books and content directly from the publisher. We want to share our love of space science with you! Let us know how we can help.
Foolish Assumptions
We assume you have picked up this book because you think astrophysics sounds interesting — dare we say cool? Maybe you are concerned about the end of the universe. Maybe you want to know what you’re looking for at a star party, or perhaps you’re looking for a bit of light bedtime reading (hint: maybe save the end-of-the-world chapters for the morning). Any reason to learn about astrophysics is a good one, and we hope this book has fun and thought-provoking information for you.
We don’t assume that you are a scientist or have even taken any science classes since high school — or maybe you’re a high school student now! Whatever your starting point, this book is for you.
A few key tips before we get started. Scientists, no matter their location, typically use the metric system when running physics or astronomy calculations. The metric system is also known as the International System of units, or SI units. Although you may be more accustomed to the standard American system of feet and pounds (amusingly, this system is actually called the Imperial system!), in this book we provide key quantities in both systems of measurement. Don’t worry, though, we won’t make you convert the speed of light into furlongs per fortnight! (If a conversion like that is needed, we provide it for you.)
Many of the key words used in this book derive from languages more ancient than modern-day English. Nebula for example, comes from Latin and its plural in Latin is nebulae. We use the language-appropriate plural for these words throughout the book rather than improper Englishizations (you’ll not see reference to nebulas). Similarly, scientists prefer standard units of time, and so we refer to CE (common era, starting at the year zero) and BCE (before common era, starting before the year zero).
Icons Used in This Book
Throughout this book, helpful icons can guide you to particularly useful nuggets of wisdom, and also help you see what’s fine to skip if your eyes are glazing over. Here’s what each symbol means:
The string-tied-on-a-finger icon points out information that will be useful to remember for the future.
This icon indicates technical info; the content next to these icons will typically be information related to the topic you’re reading about but with a more in-depth technical explanation. Feel free to skip over these if you’re looking for the bigger picture, but use these callouts when you’re searching for more detailed information on a subject.
The light bulb graphic highlights particularly useful or interesting tidbits. Scan the page quickly and let your eye be drawn to the Tips for nuggets of information — such as, for example, how stars created light in the first place!
From black holes to solar eclipses to getting tangled up in the math of general relativity, astrophysics can head into complex and dangerous territory. The warning icon calls out areas that may be dangerous (either intellectually or physically!) and require a careful approach.
Beyond the Book
In addition to the book you’re reading right now, be sure to check out the free Cheat Sheet. It offers a timeline of astrophysics discoveries, a list of misconceptions, and a list of world record holders, among other things. To get this Cheat Sheet, simply go to www.dummies.com and enter Astrophysics For Dummies in the Search box.
There are also some other books in this series that you might enjoy. Astronomy For Dummies, by Stephen Maran and Richard Fienberg, could be a great starting point if you want to learn more about the observational side of astronomy. You can also brush up on your physics knowledge in Physics I For Dummies or Physics II For Dummies by Steven Holzner.
Where to Go from Here
We’re overjoyed to greet you on your journey into astrophysics. If this book were a welcome into our home, you’d be greeted with the aroma of chocolate chip cookies fresh from the oven. We suppose the information contained inside may be a poor substitute, but we’ve done our best to provide an overview of astrophysics using the written word instead of chocolate.
Feel free to consume this book all at once or sample as you go. Looking for a basic overview of astronomy and physics before you get in too deep? Try out Chapter 2 and Chapter 3 for a quick refresher on everything you wanted to know about astronomy and physics but might have forgotten or been afraid to ask.
How did those stars form? Chapter 5 has you covered. Got a yearning for black holes? Don’t worry, Chapter 8 is ready to suck you in (literally? You be the judge). How did it all begin, and how will it end? The Big Bang starts in Chapter 13, then concludes in Chapter 16 with the end of it all.
The universe seems to have had a beginning, a middle (we’re in it now), and an end. As you’ll learn between these pages, there’s a lot going on in between. We hope that by the time you reach the end of your exploration, you’ll be able to look up at those stars with a sense of both awe and understanding. Welcome to astrophysics!
Part 1
Getting Started with Astrophysics
IN THIS PART …
Refresh your understanding of matter, forces, and energy — the fundamental laws of physics.
Discover the world of astronomy, from our solar system to our galaxy, and see how the constellations fit in.
Gain a big-picture understanding of how astrophysics bridges the gap between astronomy and physics. Learn how telescopes are used, and study the Sun as a star to find out more about space weather and eclipses.
Chapter 1
Welcome to the Universe
IN THIS CHAPTER
Discovering the universe
Uncovering the mystery of planets, stars, and galaxies
Revealing the electromagnetic spectrum
Learning about where we came from and where we’re going
Have you ever looked up at the night sky and wondered what you’re seeing? How did all those dots in the sky appear? Why are some brighter than others? Have you felt that sense of awe and wonder deep in your soul, and realized that you’re only a small part of something much greater? If any of these apply to you, welcome to Astrophysics For Dummies!
You’re in good company with your pondering of the universe. Since our earliest surviving records, humans have shared this fascination with the cosmos. And, fortunately, information and knowledge about the universe are exponentially greater today than they were during the time of our ancestors.
Although simply gazing up at the heavens can be inspiring, understanding what you are looking at can make the experience mind-blowing. Gazing at the sky reveals not only other worlds in our solar system but also other stars, many of which may have planets of their own. For example, if the sky is dark enough you can see the Milky Way, the bright band of stars stretching across the sky that’s actually the disk of the Milky Way Galaxy. Your knowledge of astrophysics turns a beautiful spectacle into something known but no less amazing.
With good eyesight or some binoculars and/or a telescope, you can start to see nebulae, and understand that many are clouds of gas and dust that are stellar nurseries, where new stars are being born. You can even see galaxies beyond the Milky Way, and realize that they contain billions of their own stars. Due to a fundamental property of astrophysics (the speed of light being a constant), the vast cosmic distances to these objects also means that when you see them, you are actually looking back in time. Astrophysics can then be seen as a study of time as well as of space, and it can take you all the way back to the dawn of time itself — the Big Bang, the event that created our universe.
The word astrophysics may seem daunting, but it’s nothing more than a scientific term combining a descriptive view of the universe (that’s the astronomy part) with a mathematical understanding of the theoretical basis for what you are seeing (that’s the physics part). Don’t worry; we bring you up to speed on the fundamentals before diving into the details of the universe. Before you know it, you’ll be able to explain and understand your place in the cosmos, and know a bit more about how the world works.
Welcome to astrophysics!
The Science of Astrophysics
It’s only been within the last 150 years that the field of astrophysics has really taken off as separate from either astronomy or physics. Astronomy is essentially a science of observation, whereas astrophysics is more concerned with understanding those observations. Gear up and let’s dive in!
The start of astronomy
The first few thousand years of astronomy can be seen as largely descriptive. Humans around the world documented the sky, observed changes, and made up stories to explain what they saw. These stories were recorded into the names of the constellations, and they were created by cultures all around the world. People observed that although most stars had fixed patterns in the sky, there were also repeating patterns. The Sun rose and set predictably, for example. Early observers noted a few interlopers: Stars that changed position over the course of the year were later shown to be planets, and flashy visitors such as the occasional comet and meteor made their own appearances.
As time went on, astronomical observations became more rigorous as telescopes were invented and used to observe the sky in more detail. Astronomers soon discovered that there was more to the sky than sparking points of light. Although most of these objects were stars, 19th-century telescopes and the discovery of photography revealed the larger, fainter, and fuzzier objects as nebulae and galaxies. With this expanded cast, the stage was set, and interest in the cosmos was sufficiently piqued to incite an entirely new field of study, one that stretched both imaginations and creativity to the maximum.
A beautiful connection: Physics, astronomy, and astrophysics
Physics, as you might recall from high school, is the study of how the natural world works. If you drop a can of beans on your toe, that’s gravity at work. Astronomy, on the other hand, is the study of everything in the sky, from planets to stars to galaxies. Astrophysics joins the party as a more quantitative study that combines the observations of astronomy (“what”) with the underlying theories of physics (“how”). Put simply, astrophysics is the study of how the cosmos works from beginning to end.
Astrophysics is, in many ways, a field that focuses on studying the intangible. Astrophysicists need to come up with specific ways of gathering information about phenomena that are, quite literally, out of this world. There are several ways in which scientists can tackle this problem:
Observations:
Using Earth- and space-based telescopes and instrumentation, astrophysicists observe the universe at different wavelengths.
Laboratory work:
Specially-designed equipment allows astrophysicists to simulate certain aspects of the cosmos right here at home. Assuming your home is an advanced-science lab, of course.
Theory:
More than chalk on a blackboard, state-of-the-art supercomputers are used to run simulations on everything from the birth of a star to the end of the universe.
Check out Chapter 4 for more information on each of these concepts.
Let there be light! The electromagnetic spectrum
The observational part of astrophysics requires — surprise! — observations.
Astrophysicists observe the universe using a variety of methods. Because we can’t (yet!) travel to other stars and galaxies, these observations are all based on detectable information that distant objects send out into space. Most of this information comes in the form of electromagnetic radiation.
Electromagnetic radiation (commonly known as light) is a way that energy travels through space, and it’s a critical concept for anyone conducting astrophysical observations. The world visible to humans comprises only a small portion of what scientists call the electromagnetic spectrum, a way of describing all types of electromagnetic radiation in the universe.
The electromagnetic spectrum consists of seven classes of electromagnetic waves (all defined in terms of meters):
Gamma rays:
Shorter than 1 × 10
−11
meters
X-rays:
1 × 10
−11
meters to 1 × 10
−8
meters
Ultraviolet (UV) light:
1 × 10
−8
meters to 4 × 10
−7
meters
Visible light (optical):
4 × 10
−7
meters to 7 × 10
−7
meters
Infrared:
7 × 10
−7
meters to 1 × 10
−3
meters
Microwaves:
1 × 10
−3
meters to 1 × 10
−1
meters
Radio waves:
Longer than 1 × 10
−1
meters
These types of radiation are sorted by wavelength. The shorter the wavelength, the higher the energy. Gamma rays are the highest-energy type of radiation but they also have the shortest wavelength. This sorting of electromagnetic radiation in order by wavelength, is what’s called the electromagnetic (EM) spectrum; see Figure 1-1.
FIGURE 1-1: The electromagnetic spectrum.
Electromagnetic radiation is carried by a particle called a photon, and the energy and wavelength of a photon are related by this simple equation:
In this equation, E is energy, h is a constant called Planck’s constant, c is the speed of light, and λ (the Greek letter lambda) is the wavelength. You can see from this equation that energy is inversely proportional to wavelength, because wavelength is on the bottom of the fraction. As wavelength shrinks, energy grows.
And what is electromagnetic radiation? It’s a way that photons, in the form of electromagnetic waves, travel through space. These waves carry both energy and momentum, and they can travel through the vacuum of space and through some materials. Visible light is a kind of electromagnetic radiation, as you can see in Figure 1-1, but so are radio waves, x-rays, and other kinds of familiar radiation.
Making waves
Wavelengths are what let us see colors. If you’ve ever looked up at the sky after a rainstorm to see a beautiful rainbow, that beautiful arch is caused by tiny droplets of water splitting visible light apart into all its different colors — the colors of the rainbow! The violet light you see has the shortest visible wavelength, green is in the middle, and red has the longest wavelength. As you’ll learn in this book, the idea of colors can be extended broadly across the electromagnetic spectrum. The wavelengths of light given off or reflected by an object are related to its composition and can also be used to find its velocity and distance from us.
This simple wavelength story might be starting to make sense but like many ideas in astrophysics, it’s a bit more complicated than it seems. Light in particular, and electromagnetic radiation in general, have aspects of both a wave and a particle. Light can also travel through a vacuum at the speed of light (shocking, isn’t it, to hear that the speed at which light travels is the speed of light?). As it turns out, the speed of light is a fundamental, fixed constant — nothing can go faster than light, and light (which is electromagnetic radiation after all!) always travels at this speed through a vacuum.
We refer to various parts of the electromagnetic spectrum throughout this book because different celestial bodies in space make their presence known in various ways. Stars, for example, emit mostly visible light that we can easily detect, but other objects such as neutron stars emit gamma rays.
Celestial bodies emit more than one type of radiation. Figure 1-2 shows a famous cloud of gas and dust called the Crab Nebula as viewed through telescopes at five different wavelengths, from the radio to the visible to the x-ray. See the color photo section for a beautiful multi-wavelength composite version.
Courtesy of G. Dubner (IAFE, CONICET-University of Buenos Aires) et al.; NRAO/AUI/NSF; A. Loll et al.; T. Temim et al.; F. Seward et al.; Chandra/CXC; Spitzer/JPL-Caltech; XMM-Newton/ESA; and Hubble/STScI
FIGURE 1-2: The Crab Nebula emitting radiation at different wavelengths.
Astrophysicists use different kinds of telescopes, both on Earth and in space, to observe at wavelengths across the electromagnetic spectrum. It’s often the combination of datasets taken at different wavelengths, such as in Figure 1-2, that yields new insights into how the cosmos operates.
When you get to shorter wavelengths, astronomers sometimes use frequency instead to define them. Frequency is just defined as the number of wave cycles per second, so it is inversely related to wavelength. As the wavelength increases, the frequency decreases. In fact, for light and other kinds of electromagnetic radiation that travel at the fixed speed of light, the relationship can be expressed as
where c is the speed of light, λ is the wavelength, and ν (the Greek letter nu) is the frequency. Wavelength is expressed in units of length (usually meters or nanometers), whereas frequency is expressed in units of Hertz (one Hertz means one cycle per second).
LIGHT VERSUS SOUND
It’s not just light that comes in waves! Another highly familiar type of wave is the sound wave. Sound is a completely different process (and a completely different kind of wave) than electromagnetic radiation. The biggest difference is that sound requires a medium to move through in order to travel. Sound can be transmitted through air but also through the vibration of a musical instrument or even through the floor from your downstairs neighbor’s speakers. Unlike light, however, sound can’t travel through a vacuum. All those science fiction movies with ships whooshing through space are just that — fiction.
Tools of the Trade
No matter how good your eyesight may be, you’ll never be able to see anything in deep space unaided. Unless you’ve got superpowers, you’ll also have trouble seeing gamma rays, x-rays, or radio waves with the naked eye. Celestial objects such as pulsars and black hole accretion disks emit x-rays, for example, and x-rays are invisible to the human eye at the short end of the electromagnetic spectrum. There would be no realistic way to learn about these types of objects without specialized equipment. The following sections describe the most common types of observing tools astrophysicists require, and the differences between them.
The nitty-gritty of telescopes and astronomical instruments
If you’ve ever compared your view of the night sky from a major city to the countryside or desert, you know that the darker the sky, the more stars you can see. Astronomers take the “dark sky is better” concept to the next level when they are locating observations. Although your unaided eyes, binoculars, or a small telescope are great for a preliminary tour of the sky, performing the observational science that’s key to astrophysics requires using a bigger telescope.
Is bigger better when it comes to telescopes? Absolutely, because most professional telescopes gather starlight using a mirror; larger-diameter mirrors gather more starlight that in turn allows you to see objects that are fainter or farther away.
Most professional optical astronomical observatories are located on the tops of mountains, as far away from civilizations as possible, for two reasons:
Mountains are usually some distance away from big cities. The skies are darker because there’s less light pollution from city lights.
Mountaintops are typically at higher elevations than cities (unless you’re someplace like Denver, Colorado, the “Mile High City.”) The atmosphere is thinner the higher you go, creating less air and stuff like water vapor between you and the stars. Because the atmosphere is constantly in motion, more atmosphere can mean blurry images, and water vapor blocks some colors of light. The less atmosphere, the better.
Some types of observatories don’t actually require a long winding mountain road for access. Radio telescopes can be located at sea level. They also need to be away from civilization, though, because they’re extremely sensitive to interference in the radio portion of the EM spectrum. If a scientist is observing with an optical telescope, they have to be careful to keep flashlights away from the telescopes because that light would interfere with viewing.
At a radio telescope observatory, though, cell phones are banned because the radiation they give off interferes with those radio telescopes. Solar telescopes, on the other hand, operate during daytime and don’t need a dark sky location; these telescopes often use special filters to dim our Sun’s intense light enough to take observations without catching our instruments on fire.
Pro tip: Don’t try to stare at the Sun without special observing glasses! The Sun’s ultraviolet rays can easily burn your retinas and cause permanent damage.
Also, not all observatories contain the same types of telescopes. Optical observatories use telescopes that see light in the infrared and visible portions of the EM spectrum, but millimeter-wave and radio observatories observe at longer wavelengths.
Telescopes that operate at different wavelengths look nothing like each other. For example
Optical reflecting telescopes have reflecting mirrors to capture light.
Optical refracting telescopes (used only in amateur astronomy today) are longer with two or more lenses connected via a tube.
Radio telescopes use the same technology as enormous satellite dishes.
Some radio telescope observatories are even larger by virtue of having dozens (or more) of radio telescope antennae. Their signals combine using a process called interferometry, a technique that increases the effective baseline of the telescope array to increase its sensitivity and detect smaller objects farther out in space. You can also do interferometry at visible wavelengths — the Large Binocular Telescope Observatory (see Figure 1-3) in Arizona has twin 28-foot (8.4-meter) mirrors and can combine the two beams of light to take observations of exoplanets and distant galaxies that would otherwise require a much larger single telescope.
Try holding your cell phone up to the eyepiece of a telescope. You’re using the same principle that professional astronomers use with their enormous optical telescopes. Taking astronomical observations requires that the light from an optical telescope’s mirror is directed into a scientific instrument. The two main types of instruments used at professional optical observatories are
Courtesy of Large Binocular Telescope Observatory
FIGURE 1-3: The Large Binocular Telescope Observatory in Arizona.
An instrument that focuses light from an astronomical object into an image. This can be done with a specialized digital camera that’s sensitive to minute variations in brightness, and sometimes combined with filters at multiple wavelengths. Observations through different filters can be combined to make color images, or ratioed to look for compositional differences and trends.
An instrument that splits astronomical light into its separate wavelengths. This can be done with an instrument called a spectrograph. When attached to the telescope, the spectrograph has a diffraction grating that spreads out the light into its individual wavelengths. Like a prism, this technique allows the spectrum of a star or galaxy to be recorded, providing information about its chemical composition.
Radio telescopes and other types of telescopes operate throughout the electromagnetic spectrum — check out Chapter 4 for more details.
Viewing from above: Space-based telescopes
Sometimes the top of a mountain just isn’t tall enough to allow the observations astronomers need. Earth’s atmosphere absorbs light from stars and galaxies at specific wavelengths of light, particularly at infrared and UV (and higher) portions of the EM spectrum. If the atmosphere is absorbing this light, it can’t make it through to our telescopes. To avoid the Earth’s atmosphere (who needs the atmosphere? only everything on the planet that breathes air!), astronomy must head upward into space and beyond the reach of Earth’s atmosphere.
Placing a telescope into space requires launching it from a rocket on Earth. Think of a space-based telescope as a satellite that is also a telescope. A satellite in this context is any celestial body or piece of equipment that orbits the Earth. Space-based telescopes use specialized equipment to point toward a desired portion of the sky and record data. This data is then transmitted back to Earth using radio waves. Scientists analyze the data and may use it to create those famous images you’ve seen, for example, from the Hubble Space Telescope. Chapter 4 has more on space telescopes, and Chapter 18 contains a summary of 10 important space missions for astrophysics.
Stars, Galaxies, and Their Cosmological Friends
You’re up to speed with how astrophysicists observe the sky, and have a baseline for the tools they use to make those observations. Next up: a brief tour of what’s out there.
The objects visible from Earth in the night sky are at a huge range of distances, from close to very far away, but many of those objects are separated from you in time as well as in distance. For example, shooting stars — or meteors — are tiny flecks of cosmic dust that burn and glow in Earth's atmosphere as much as 100 km up. These are some of the closest objects to Earth. A larger space rock may make it down to the ground and land in your backyard as a meteorite, but that happens only rarely.
You may also see a satellite in the sky, perhaps the International Space Station or a communications satellite several hundred or thousand miles up. These human-made objects are orbiting the Earth and are farther away than shooting stars, because they’re outside of the Earth’s atmosphere. Also orbiting the Earth but even farther away is our Moon. It’s about 239,000 miles (384,000 km) away from us but looks bigger and brighter than any star in the sky. Why? It’s farther out past our atmosphere than a satellite but it's much larger; although the Moon is smaller than a planet or star, it’s still significantly closer to us.
Beyond the Moon lie the planets of our solar system. Venus, Mars, Jupiter, and Saturn are the easiest to see due to their combinations of size and distance (Jupiter and Saturn are far but huge, and Mars and Venus are both near neighbors). Tiny Mercury is hard to see but can be seen with your eyes. Uranus and Neptune, however, are so far away that they require telescopes to catch. The Sun is the closest star to the Earth. We’re 93 million miles (150 km), or 1 astronomical unit (AU), away from it, but the Sun is so big and bright that it dominates our daytime sky.
What about the rest of the stars that are so pervasive in the night sky? They’re stars, just like our Sun, but farther away and appear dimmer. The closest star to us, besides our Sun, is Proxima Centauri at 25 trillion miles (40 trillion km) away. All of the individual stars in the sky are part of our Milky Way Galaxy. Our solar system is located in one arm of its spiral structure. With a telescope, you can see other faint and somewhat fuzzy objects in the sky. Some are nebulae within our own galaxy, but others are different galaxies, each of which can contain billions of stars.
Because light has a maximum speed (the speed of light, c, is 186,000 miles per second or 300,000 km/sec), light from these distant stars and galaxies can take thousands or even billions of Earth years to reach us. Cosmic distances like this are often measured in light-years — a light-year is the distance light can travel in one year through a vacuum, or about 5.9 trillion miles (9.5 trillion km). The distance to Proxima Centauri, for example, is about 4.3 light-years. It takes light 4.3 years to reach the Earth from Proxima Centauri, meaning that the light you see was actually given off 4.3 years ago. 4.3 years may not seem like much, but Proxima Centauri is relatively close. When you see distant galaxies, you’re seeing light that was given off millions to even billions of years ago.
Every time you see pictures of a distant galaxy or star, you’re looking back in time. Astrophysicists use these types of observations to peer through the cosmos all the way to the beginning of time itself, to the events surrounding the Big Bang. Between viewing ancient galaxies and detecting high-energy astronomical phenomena such as black holes and quasars, astrophysics works to solve a bit of a detective story of the universe.
Ready to dive into astrophysics? This book will take you on a ride through the universe, piecing together the elements (literally!) that make up stars, galaxies, and the universe — and, coincidentally, humans like yourself. Learn what you are seeing, how to see it, and what it all means, and then you’ll be ready to learn about how the universe got here in the first place, and where it all might end.
Chapter 2
The A to Z of Physics
IN THIS CHAPTER
Constructing the universe with fundamental particles
Weighing the odds with matter and gravity
Storing, using, and sharing energy
Moving, grooving, and gravitating your way into understanding Newtonian motion
Heating, cooling, and everything in between
Where would you be without physics? Nowhere on this planet, that’s for sure. Physics is a scientific description of how the world works on a fundamental level. Everything in the universe relates to four primary forces — gravity, the strong and weak nuclear forces, and electromagnetism. These forces not only unite tiny particles into atoms, but they also allow those atoms to stick together and form matter, stars, galaxies, cheese pizzas, and everything in between. Without these primary forces, we (and the universe) would cease to exist.
The earliest humans used physics in their daily lives. Constructing a cave dwelling, fashioning an arrowhead, and digging out a canoe all made heavy use of the basic principles of physics. The only difference today is that we’ve given these forces names and associated equations, and we are able to use what we know to model that which we cannot see or experience directly.
There’s no astrophysics without physics. Before we get into the whole “astro” side of things, you need an understanding of the foundational physics. That said, compressing all of physics into one chapter of this book would be a meaningless undertaking. There’s too much information to cover, and we wouldn’t be able to do justice to any topic before moving on to the next. Also, although physics is grand and important and exciting (really!), not all of it is directly relevant to astrophysics. For these reasons, the scope of this chapter will be condensed to material that
Relates directly to topics covered in this book
Builds up the language and knowledge you’ll need
Is fundamental to your understanding of astrophysics
From atoms to galaxy clusters, physics affects every detail of your journey into astrophysics. Let’s begin!
Building Blocks of the Universe: Particles
We begin at the beginning. Or, put another way, let’s start with the universe’s tiny fundamental units: particles. Everything in the universe that we observe through a telescope or touch with our hands is made of matter. Whether it’s a liquid, gas, star, or planet, matter is at the core, and matter is made of particles. Astrophysics, in a lot of ways, is the study of things that are huge and far away. It may seem strange to start out with something so small we can’t see it with a microscope, but the fundamental particles that make up everything in the universe are generally the same particles that comprise the familiar stuff of our everyday lives here on Earth. Understand them here, and you are one step closer to understanding the cosmos.
That “generally” in the previous paragraph is hiding the fact that the universe is really a mysterious place. There are many aspects, like dark matter and dark energy, that seem to be important components but may require new physics to understand. Or not … we don’t know yet. For the meantime, we focus on the more familiar types of particles and cover the stranger elements in later chapters.
The big three: Protons, neutrons, and electrons
You’re likely already familiar with the basic building blocks of matter as we know it. Protons, neutrons, and electrons are the backbone particles that comprise most of the ordinary matter in the universe. But, of course, particles by themselves won’t get the job done. Combining particles into groupings called atoms allows these building blocks to start stacking into larger and larger objects and even molecules. Chemistry is the scientific field of study that focuses on this molecular level.
Atoms are made up of subatomic particles, the fundamental units that make up atoms. There are several main types of subatomic particles. We break this down a little: Table 2-1 has some basic properties of these fundamental particles, and Figure 2-1 shows the basic components of an atom.
TABLE 2-1 Basic Subatomic Particles
Type
Charge
Size
Proton
Positive
2000x mass of electron
Neutron
Neutral
2000x mass of electron
Electron
Negative
Almost no mass (2x10−30 pounds, or 9x10−31 kg)
FIGURE 2-1: The atom and its most basic components.
Atoms are the smallest building blocks of regular matter. Different kinds of atoms are made with different combinations of protons, neutrons, and electrons. In the right circumstances, atoms combine according to their charge and a set of rules that governs their structure. The simplest atom is hydrogen. In its standard form, hydrogen atoms consist of a single proton and neutron in the nucleus, with one orbiting electron.
In hydrogen, the positive charge of the single proton is balanced out by the negative charge of the single electron. The neutron itself has no charge, meaning that the net charge of a hydrogen atom is zero.
Atoms become more complicated when you start adding more protons and neutrons in the nucleus, balanced out by the same number of electrons orbiting the nucleus. Helium, for example, has two neutrons and two protons in the nucleus, and has two electrons in orbit. Carbon: six protons in its nucleus (and usually six neutrons), surrounded by six electrons. And so on.
„Ich bin wirklich begeistert. Auch die Möglichkeit des zusätzlichen eReaders im Abo finde ich persönlich toll.”
Happy Booktime
„Die Auswahl von Legimi ist großartig.”
Bücherleser
„Der Leser findet seine E-Books/Hörbücher sehr schnell und sie lassen sich, ob mit oder ohne Internetverbindung problemlos öffnen.”
Wurm sucht Buch
„Ich finde das Angebot von Legimi richtig toll.”
TheSarahStory
„Besonders schön finde ich die große Auswahl an möglichen Abo-Modellen und besonders die Abos mit eReader.”
Miss Foxy Reads
„Ich muss sagen, dass ich von dem E-Reader mehr als positiv überrascht bin.”
Wortmalerei
„Das ist wirklich eine großartige Idee und mal was ganz Anderes.”
Mikka liest das Leben...
Tausende von E-Books und Hörbücher
Ihre Zahl wächst ständig und Sie haben eine Fixpreisgarantie.
Sie haben über uns geschrieben:
Dabei gewährt der E-Book-Anbieter größtmögliche Freiheiten
Größter Vorteil die Möglichkeit, in der aktuellen App komfortabel zwischen E-Book und Hörbuchversion eines Titels
Spotify for E-Books
