The Invisible Universe (eBook)

Author of seven books, co-author or editor of 3 text books in radio astronomy and astronomy in general, has written over 80 scientific research articles, and  90 + popular astronomy articles.  He lectures widely on astronomical topics, pioneered the study of the interstellar magnetic field and active in radio astronomical studies of interstellar matter for over 40 years.  Published the first ever, full-length, technical paper on the radio search for extraterrestrial intelligence in 1973.  Has taught in the physics departments of some half-a-dozen universities, world-wide.  He is the holder of a dozen patents. 

Acknowledgments 6
Contents 8
Introduction: Adventure, Imagination, and Curiosity 13
The Exploration of the Radio Astronomical Unknown 13
Seeking New Knowledge 14
Radio Astronomy and Imagination 14
What is Radio Astronomy? 16
1.1. A Little History 16
1.2. The Birth of Radio Astronomy 17
1.3. So What Is Radio Astronomy? 20
1.3.1. How Radio Waves from Space are Generated 20
1.3.2. Radio Telescopes 20
1.3.3. What is a Radio Source? 22
1.4. Radio Interferometers 23
1.4.1. Very Large Array 23
1.4.2. Very Long Baseline Array 23
A Science is Born 26
2.1. Caught between Two Disciplines 26
2.2. Postwar YearsÛRadar Everywhere 28
2.3. The Southern Skies 30
2.4. Who Could Have Guessed? 31
2.5. Identity Crisis 32
2.6. An Epoch of Discovery 33
References 34
The Radio Sun and Planets 35
3.1. War Secrets 35
3.2. The Plasma Sun 35
3.3. Solar Radio Emission 37
3.4. The Quiet Sun 37
3.5. Solar Radio Bursts 37
3.6. Radio Signals from the Planets 38
3.7. JupiterÌs Radio Bursts 38
3.8. JupiterÌs Radiation Belts 39
3.9. The Planets as Radio Sources 41
3.10. Planetary Radar 41
The Galactic Radio Nebulae 45
4.1. The Supernova-Stardeath 45
4.2. Recent "Guest Stars" 46
4.3. Cassiopeia A 47
4.4. Supernovae of Type I and Type II 47
4.5. Supernovae and Life 49
4.6. Emission Nebulae-Star Birth 50
4.7. HII Regions 51
4.8. Planetary Nebulae 51
Radio Waves from the Milky Way 52
5.1. "A Steady Hiss Type Static of Unknown Origin" 52
5.2. Receiver Noise-"Listening" to Radio Sources 52
5.3. Grote Reber Maps the Milky Way 54
5.4. A Radio Map of the Whole Sky 54
5.5. The Appearance of the Radio Sky 55
5.6. Polarization of the Galactic Radio Waves 56
5.7. "Normal" Galaxies 56
5.8. A Note on Distances 57
5.9. The Shape of the Milky Way Galaxy 57
5.10. The Center of the Milky Way 58
5.11. Close-up Radio View of the Galactic Center 59
5.12. The Very Center and the Black Hole 61
Interstellar Hydrogen 63
6.1. Clouds of Destiny 63
6.2. Generation of the 21-cm Spectral Line 63
6.3. Observations of Interstellar Neutral Hydrogen 64
6.4. An Image of Interstellar Hydrogen 64
6.5. Seeing into the Depths of Space 65
6.6. Anomalous Velocity Hydrogen 67
6.7. Interstellar Magnetic Fields 67
6.8. Neutral Hydrogen in Other Galaxies 68
Interstellar Molecules 71
7.1. Chemical Factories in Space 71
7.2. What is a Molecule? 74
7.3. Molecular Spectral Lines 74
7.4. Masers in Space 75
7.5. Mega-Masers 78
7.6. Giant Molecular Clouds 78
7.7. The Stages Immediately Following Star Birth 79
Pulsars 81
8.1. Scintillation of Radio Sources 81
8.2. The Discovery of Pulsars 81
8.3. Where are the Pulsars? 83
8.4. Formation of Neutron Stars 84
8.5. Binary Pulsars-Nature's Fabulous Space Labs 86
8.6. Millisecond Pulsars 88
8.7. What Pulse Timing Tells Us? 89
8.8. Pulsars in Globular Clusters 90
The Galactic Superstars 91
9.1. The Curious Object SS433 91
9.2. A Black Hole and its Accretion Disk 93
9.3. Precession of the Accretion Disk 94
9.4. Radio Stars 95
9.5. Novae 97
9.6. Other Superstars 98
Radio Galaxies 99
10.1. On Finding Distances in Astronomy 99
10.2. Chaos in Distant Galaxies 99
10.3. The Largest "Things" in the Universe 100
10.4. Cygnus A 100
10.5. The Radio Emitting Jets 101
Quasars 108
11.1. The Discovery of Quasars 108
11.2. Brightness Variations 109
11.3. Parent Galaxies 110
11.4. Quasars: The Modern View 111
The Grand Unification: Active Galactic Nuclei 114
12.1. Cosmic Jets 114
12.2. Seyfert Galaxies 116
12.3. The Energy Diet of a Jet 116
12.4. Faster than Light-Superluminal Motions 117
12.5. Active Galactic Nuclei 118
12.6. Black Holes 119
12.7. Precession 121
12.8. Galactic Cannibalism 122
Beyond the Quasars-Radio Cosmology 124
13.1. A Cosmic Perspective 124
13.2. Radio Astronomy and Cosmology 125
13.3. The Microwave Background 126
13.4. Beyond the Big Bang-Multiple Universes 127
13.5. How Smooth is Space? 128
13.6. Missing Mass (Dark Matter?) 130
13.7. Gravitational Lenses 131
On The Radio Astronomical Quest For Extraterrestrial Intelligence 134
14.1. "And Now for Something Completely Different" 134
14.2. The Harsh Realities of the SETI Equation - A Modern Heresy 135
Radio Telescopes: The Future 142
15.1. Bigger and Better 143
15.2. Low-Noise Receivers 145
15.3. SMA - The Submillimeter Array 145
15.4. Planned Arrays 145
15.4.1. ALMA - The Atacama Large Millimeter/ Submillimeter Array 146
15.4.2. LOFAR - Low Frequency Array 148
15.4.3. SKA - The Square Kilometer Array 149
15.4.4. PAPER - Portable Array to Probe the Epoch of Ionization 150
What's It All About? 152
16.1. Expecting the Unexpected 152
16.2. Are We Still Open to the Unexpected? 153
16.3. How Much Longer Will Radio Astronomy Last? 153
16.4. So, What's It All About? 154
Appendix 157
A.1. "Seeing" Radio Waves 157
A.2. The Electromagnetic Spectrum 157
A.2.1. Wavelength and Frequency 158
A.2.2. The Wavelength Range of the Electromagnetic Spectrum 158
A.2.3. Atmospheric Windows 158
A.2.4. Spectral Lines 159
A.2.5. The Redshift and the Doppler Effect 159
A.2.6. Velocities in Radio Astronomy 159
A.3. The Brightness of Radio Sources 160
A.4. Radio Spectra - Identifying the Emission Mechanism 160
A.5. Notation 161
A.6. Position Measurement and Angular Accuracy 161
A.7. Astronomical Coordinate Systems 162
A.8. Astronomical Distances - Looking Back in Time 163
A.9. Keeping Things (Radio) Quiet 163
Index 164