E-Book Content
REINVENTING
GRAVITY A PHYSICIST GOES BEYOND EINSTEIN
John W. Moffat
To Patricia whose dedication and help made this book possible
Contents
Introduction: A N E W G R A V I T Y T H E O R Y
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Prologue: T H E E L U S I V E P L A N E T V U L C A N , A P A R A B L E
1
P A R T 1: D I S C O V E R I N G A N D R E I N V E N T I N G G R A V I T Y 1: T H E G R E E K S T O N E W T O N 2: E I N S T E I N
PA R T 2: T H E S TA N D A R D M O D E L O F G R AV I T Y
7 9 25
49
3: T H E B E G I N N I N G S O F M O D E R N C O S M O L O G Y
51
4: D A R K M A T T E R
69
5: C O N V E N T I O N A L B L A C K H O L E S
78
PA R T 3: U P D AT I N G T H E S TA N D A R D M O D E L 6: I N F L A T I O N A N D V A R I A B L E S P E E D O F L I G H T ( V S L ) 7: N E W C O S M O L O G I C A L D A T A
PA R T 4: S E A R C H I N G F O R A N E W G R AV I T Y T H E O R Y
89 91 110
125
8: S T R I N G S A N D Q U A N T U M G R A V I T Y
127
9: O T H E R A L T E R N A T I V E G R A V I T Y T H E O R I E S
14 3
10: M O D I F I E D G R A V I T Y ( M O G )
15 3
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CONTENTS
PA R T 5: EN V ISIONING A ND T ES T ING THE MOG UNIVERSE
171
11: T H E P I O N E E R A N O M A LY
173
12: M O G A S A P R E D I C T I V E T H E O R Y
181
13: C O S M O L O G Y W I T H O U T D A R K M A T T E R
19 3
14: D O B L A C K H O L E S E X I S T I N N A T U R E ?
200
15: D A R K E N E R G Y A N D T H E A C C E L E R A T I N G U N I V E R S E
205
16: T H E E T E R N A L U N I V E R S E
212
Epilogue
221
Notes
225
Glossary
24 6
Bibliography
257
Acknowledgments
26 0
Index
261
About the Author Credits Cover Copyright About the Publisher
Introduction A N E W G R AV I T Y T H E O R Y
n 1916, Einstein published his new theory of gravity called general relativity. In 1919, the theory was validated by the observation of the bending of light during a solar eclipse, as the sun’s gravitational pull warped spacetime. Since then, there has been much speculation as to whether Einstein’s theory of gravity is perfect and unchangeable, much like Michelangelo’s David. Why would we want to modify Einstein’s outstanding intellectual achievement? Until recently, most physicists have considered Einstein’s general relativity theory to be in perfect agreement with observational data. However, this is not necessarily true. Neither have the attempts succeeded to unify Einstein’s gravitational theory with quantum mechanics, despite much effort: Many physicists consider the search for a successful quantum gravity theory the holy grail of modern physics. Moreover, there are some fundamentally unsatisfactory features of Einstein’s theory, such as those related to the beginning of the universe and the collapse of stars under their own gravitational forces. Finally, since the early 1980s, a growing amount of observational data has been accumulating that shows that Newtonian and Einstein gravity cannot describe the motion of the outermost stars and gas in galaxies correctly if only their visible mass is accounted for in the gravitational field equations.* There are much stronger gravitational forces being observed—causing the peripheral orbiting stars and gas to move faster—than are predicted by Newton’s and Einstein’s theories. There is now overwhelming evidence for stron-
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* Einstein’s gravity theory reduces to Newton’s theory for weak gravitational fields and slowly moving bodies.
vi I N T R O D U C T I O