2. And for the three-peat, Planck Collaboration, “Planck 2015 Results. XIII. Cosmological Parameters,” Astronomy & Astrophysics 594 (2016): id.A13.
3. And that number hasn't budged much in the decades we've been measuring it. For example, here's another random paper measuring it: Rachel Mandelbaum et al., “Cosmological Parameter Constraints from Galaxy-Galaxy Lensing and Galaxy Clustering with the SDSS DR7,” Monthly Notices of the Royal Astronomical Society 432 (2013): 1544.
4. Walter Baade and Fritz Zwicky, “On Super-Novae,” Proceedings of the National Academy of Sciences 20 (1934): 254.
5. OK, maybe a lot of finagling. The methods are far from perfect and introduce their own source of uncertainty, as evidenced when, for example, it was applied to a mere seven supernova and produced a very inaccurate result. Saul Perlmutter et al., “Measurements of the Cosmological Parameters Ω and Λ from the First Seven Supernovae at z > = 0.35,” Astrophysical Journal 483 (1997): 565.
6. I present you the two towers of dark energy: Adam Riess et al., “Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant,” Astrophysical Journal 116 (1998): 1009; Saul Perlmutter et al., “Measurements of Ω and Λ from 42 High-Redshift Supernovae,” Astrophysical Journal 517 (1999): 565.
7. Dragan Huterer and Daniel Shafer, “Dark Energy Two Decades After: Observables, Probes, Consistency Tests,” Reports on Progress in Physics 81 (2018): 016901.
8. David Weinberg et al., “Observational Probes of Cosmic Acceleration,” Physics Reports 530 (2013): 87.
CHAPTER 12. THE STELLIFEROUS ERA
1. David Devorkin, “The Origins of the Hertzsprung-Russell Diagram,” Proceedings of the International Astronomical Union, no. 80 (1977): 61.
2. Joe D. Burchfield, Lord Kelvin and the Age of the Earth (Chicago: University of Chicago Press, 1990), pp. 57–80.
3. Frank Dyson, A. S. Eddington, and C. R. Davidson, “A Determination of the Deflection of Light by the Sun's Gravitational Field, from Observations Made at the Solar Eclipse of May 29, 1919,” Philosophical Transactions of the Royal Society A220 (1920): 571.
4. Jeanne R. Wilson, “An Experimental Review of Solar Neutrinos,” Prospects in Neutrino Physics Conference Proceedings (April 16, 2015).
5. Edwin Hubble, “Extra-Galactic Nebulae,” Astrophysical Journal 64 (1936): 321.
6. We'll leave that for scientists like these folks: Mark Vogelsberger et al., “Properties of Galaxies Reproduced by a Hydrodynamic Simulation,” Nature 509 (2014): 177.
CHAPTER 13. THE FALL OF LIGHT
1. Piero Madau and Mark Dickinson, “Cosmic Star-Formation History,” Annual Review of Astronomy and Astrophysics 52 (2014): 415.
2. Jacques Laskar, “Large-Scale Chaos in the Solar System,” Astronomy & Astrophysics 287 (1994): L9.
3. As you might imagine, there isn't exactly a lot of research on the long-term fate of stars and galaxies, if for no other reason than the simple fact that there aren't going to be any observations—at least for a while—to test any hypotheses. Thus the following reference is the go-to standard for most of this story, and in the decades since its publication, there haven't been any major complaints or corrections, except that the authors didn't know that we live in a universe full of dark energy, which does modify the story. Fred Adams and Gregory Laughlin, “A Dying Universe: The Long-Term Fate and Evolution of Astrophysical Objects,” Reviews of Modern Physics 69 (1997): 337.
4. This phenomenon was first figured out by the supremely talented Subramanian Chandrasekhar, “The Maximum Mass of Ideal White Dwarfs,” Astrophysical Journal 75 (1931): 81.
5. Naturally, black holes have a long and storied history worth retelling in another book. Their origins, however, are quite mundane: they appear in one of the simplest solutions of general relativity: Karl Schwarzschild, “Über das Gravitationsfeld eines Massenpunktes nach der Einsteinschen Theorie,” Sitzungsberichte der Königlich Preussischen Akademie der Wissenschaften 7 (1916): 189.
CHAPTER 14. THE LONG WINTER
1. There's continuing and ever-evolving research on this topic, but a solid review can be found in Antonio Riotto, “Theories of Baryogenesis,” (lecture; Summer School in High Energy Physics and Cosmology, Trieste, Italy, June 29–July 17, 1998 [1999]).
2. Sigh, here we go. The usual story is that a particle-antiparticle pair appears in the vacuum of space near an event horizon, with one on the wrong side of the line. It's consumed by the black hole while its partner runs off scot free. This is a “bonus” particle given to the universe, so the energy has to come from somewhere—hence, the black hole loses mass. While this isn't a technically wrong story, I don't think it really represents the underlying mathematics, which is more about the relationship between quantum fields (remember those?) and the sapping of energy from a forming black hole, which leads to its eventual dissolution down the road. But whatever, don't take my word for it. Just read Hawking's original paper on it: Stephen Hawking, “Black Hole Explosions?,” Nature 248 (1974): 30.
3. And the award for most clever article title in these notes goes to Don Page and M. Randall McKee, “Eternity Matters,” Nature 291 (1980): 44.
4. Wendy Freedman, “Correction: Cosmology at a Crossroads,” Nature Astronomy 1 (2017): id. 0169.
5. Alexander Bednyakov et al., “Stability of the Electroweak Vacuum: Gauge Independence and Advanced Precision,” Physics Review Letters 115 (2015): 201802.
6. If you want to go down this particular rabbit hole, you're going to have to follow Max Tegmark, “The Multiverse Hierarchy,” in Universe or Multiverse?, ed. B. Carr (Cambridge: Cambridge University Press, 2007).
EPILOGUE: A GAME OF CHANCE
1. It's the Karman Line, a nice round number close enough to the height where the atmosphere is so thin that normal airplane physics doesn't work so well anymore. Dennis Jenkins, “Schneider Walks the Walk; Extra Feature: A Word about the Definition of Space,” NASA, October 21, 2005, https://www.nasa.gov/centers/dryden/news/X-Press/stories/2005/102105_Schneider.html.
2. You know, plus or minus a few hundred billion. Takahiro Sumi et al., “Upper Bound of Distant Planetary Mass Population Detected by Gravitational Microlensing,” Nature 473 (2011): 349.
3. Rachel Brazi, “Hydrothermal Vents and the Origins of Life,” Chemistry World, April 16, 2017, https://www.chemistryworld.com/feature/hydrothermal-vents-and-the-origins-of-life/3007088.article.
4. Dimitra Atri and Adrian Melott, “Cosmic Rays and Terrestrial Life: A Brief Review,” Astroparticle Physics 53 (2014): 186.
5. Seth Shostak, “Fermi Paradox,” SETI Institute, April 19, 2018, https://www.seti.org/seti-institute/project/fermi-paradox (accessed December 8, 2017).
6. Before you jump on me, I should say that of course interstellar travel is possible. Objects travel from system to system in our galaxy all the time, and we humans have even hurled a few chunks of metal out into the interstellar wastelands. But what we usually mean by “travel”—the same way we might travel by train or plane to another city—is so far beyond the energy generation capabilities of our civilization, and projections of said capabilities into the far, far, far future, that we might as well discount it as a feasible process for all intents and purposes. And it may never be feasible, even if we could harness unimaginable amounts of energy. In short: you're not going to another star, and neither are your kids’ kids’ kids’ kids’ kids’ kids. You can probably safely add a few more generations onto that last sentence. Space is big; don't mess with it.
7. Emily Petroff, “Identifying the Source of Perytons at the Parkes Radio Telescope,” Monthly Notices of the Royal Astronomical Society 451 (2015): 3933.
8. “The Drake Equation Revisited,” Astrobiology Magazine, September 29, 2003, https://www.astrobio.net/alien-life/the-drake-equation-revisited-part-i/.
Adams, Fred C., and Greg Laughlin. The Five Ages of the Universe: Inside the Physics of Eternity. New York: Free Press, 2000.
Bartusiak, Marcia. The Day We Found the Uni
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Berlinski, David. Newton's Gift: How Sir Isaac Newton Unlocked the System of the World. New York: Free Press, 2000.
Carroll, Sean. The Particle at the End of the Universe: How the Hunt for the Higgs Boson Leads Us to the Edge of a New World. Boston: Dutton, 2013.
Cox, Brian, and Jeff Forshaw. The Quantum Universe: Everything That Can Happen Does Happen. London: Allen Lane, 2011.
Davies, Paul. The Eerie Silence: Renewing Our Search for Alien Intelligence. Boston: Mariner, 2010.
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Alpher, Ralph, 100
Andromeda galaxy (nebula), 82, 161, 167–68, 205–206
Cepheid stars in, 78–79
as galaxy, 79–80
anthropic principle, 242
antimatter, 117
balance with matter, 63–64
and charge symmetry, 65, 67
discovery of, 60–62, 112
domination of matter over, 63, 67, 91
energy released by, 61
location of, 62–63
production of excess, 65–66
antiparticles, 114. See also particles
astrologers and astrology, 14, 17, 19, 57
astronomers, 14, 168
astronomy, 14, 57
radio, 190
X-ray, 190
astrophotography, 53
atmosphere
of Earth, 27, 74, 197, 204–205, 232, 234
life's requirement for, 234–35, 240
of planets, 51, 128
of a star, 194–95
of the sun, 205
atomic nuclei, 31, 113. See also fusion
atoms
absorption of radiation by, 109, 130
behavior of, 241, 244
collapse of, 131, 219
helium, 128, 133
hydrogen, 128, 129, 133, 134, 139, 192, 244
nature of, 69, 108, 113, 115
neutral, 110–11
primordial, 95, 98
repulsion of, 30
simple, 139
and spectral lines, 106, 109
See also recombination
baryogenesis, 63, 67
baryon acoustic oscillations, 164, 187
baryons, 71, 113, 117, 197
Bessel, Friedrich, 56–57, 74, 82
big bang model, 91, 94, 97, 101, 118, 120, 128
biosphere, 225
blackbody radiation, 98–99, 101–102, 106
black dwarf stars, 212
black holes
at the end of the universe, 215, 216, 217–18
formation of, 125, 137, 154, 256–57n5
mass of, 148, 253n9, 257n2
in the Milky Way, 137
nature of, 137–38, 141, 212–13, 237
relativity and, 172, 211
supermassive, 137, 200
blazars, 199
Boltzmann constant, 32
Bose, Satyendra Nath, 112
bosons, 35, 112, 117, 221
Brahe, Tycho, 16, 18, 25, 55–56, 57, 79, 82, 178
Bremsstrahlung (“braking radiation”), 150
brown dwarf stars, 148, 211, 212, 213
Bullet Cluster, 153–54, 162
Bunsen, Robert, 51
candles, standard, 177–79, 180, 197
Casimir effect, 131
Cepheid stars, 75–77, 176
chain reactions, 71, 193, 197
charge-parity-time (CPT), 64
clusters
Bullet Cluster, 153–54, 162
collision of, 153
Coma Cluster, 144–46, 161
and the cosmic web, 161–62, 165
dark matter surrounding, 159
demise of, 219
formation of, 170
of galaxies, 144, 146, 148–50
Great Attractor, 167–69, 207
local, 166
Lockyer's sketches of, 46
measurement of, 146, 150–52, 163, 171, 175, 187, 200
Norma Cluster, 169, 170
survival of, 184, 194, 207
Virgo Cluster, 168, 169, 170
Zwicky's study of, 144–46, 148
See also superclusters
COBE (Cosmic Background Explorer), 133
Coma Berenices, 143
Coma Cluster, 144–46, 161
comets, orbit of, 264
Comte, Auguste, 53
Copernicus, Nicolaus, 16, 17, 94, 96
cosmic dawn, 134, 135, 137, 139–41, 165, 202
cosmic distance ladder, 176–77, 180
cosmic evolution. See universe: evolution of
cosmic microwave backg
round (CMB)
detection of, 100–102, 132
exhaustion of, 207–208
formation of, 127
observation of, 122–23, 166, 167, 219, 250n3
cosmic web, 159, 161–63
finite nature of, 169–70
movement of, 165–66
patterns in, 162–64
cosmological constant, 186, 187, 219
cosmological models
big bang model, 91, 94, 97, 101, 118, 120, 128
Brahe's, 18
braneworld, 223
concordance, 188
epicycle geocentric, 16–17
geocentric, 13, 15–16, 18, 166–67
and gravity, 31
heliocentric, 17, 19, 27, 56, 84
messy, 27
Ptolemaic system, 15, 16
steady-state model, 97, 99–100, 101
cosmological principle, perfect, 97, 101
cosmologists, 30, 62, 129–30, 161, 167, 168, 178, 180, 181, 189–90, 199, 206
cosmology/cosmologies
defined, 171
factors governing, 240–41
modern age of, 177
pre-scientific, 15
Coulomb constant, 32, 33
C-symmetry, 64–65
Curtis, Heber, 77–78, 79
curvature, 172–73
dark energy
and accelerated expansion, 182–83, 188, 207
density of, 184, 241
detection of, 186–87, 256n3 (ch. 13)
nature of, 219, 244
phantom, 219
as vacuum energy, 185–86
dark matter
discovery of, 146
evidence for, 149–50
and inflation, 151
nature of, 151–57, 188, 220, 244
deceleration, 181
degeneracy pressure, 211
degenerates, 210
density, 183–84
constant, 97, 184
of dark energy, 184, 241
decrease in, 93
in the early universe, 129–30, 131, 132, 135
energy, 127
high density, 151, 162, 164
infinite, 29
of matter, 128, 183–84
patterns of, 201
of radiation, 94, 183, 235
deuterons, 71
dew point, 68