Subtitled: StarTalk’s Guide to Who We Are, How We Got Here, and Where We’re Going
(National Geographic, 2021, 311pp, including 22pp acknowledgements, further reading, illustrations credits, index, and about the authors.)
Like Tyson’s one-year later book, TO INFINITY AND BEYOND (reviewed here), this is a heavily illustrated book published by National Geographic and associated with his podcast StarTalk (https://startalkmedia.com/) which I only see snippets of on Facebook. The coauthors of the two books are different; the later one was Lindsey Nyx Walker, this one is the rather more prominent James Trefil, an author of books and photography books himself.
This one is more fundamental that the 2023 book, focusing on the basic big questions about humanity, our place in the universe, the size and age of the universe, and its past and future. My notes here are a little sketchy, but they should provide the gist.
The book is in a sense admirably concise in summarizing our current state of knowledge on a range of topics, and is more up-to-date on certain issues than similar books in my library. Rather than a list of key points, I’ll just list the ten topics that the book explores;
- Our place in the universe
- How we know what we know
- How the universe got to be this way
- How old the universe is
- What the universe is made of
- What life is
- Whether we’re alone in the universe
- How it all began
- How it will end
- What nothingness actually is
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Detailed Notes
1, What Is Our Place in the Universe?
About Newton & Aristotle; epicycles; the Almagest; the shape and size of the Earth; Eratosthenes. Parallax; the distance ladder, first rung. Hipparchus. Galileo, 1610, telescope. Size of solar system. Next rung: Henrietta Leavitt and Cepheid variables.
By the early 20th c, the Milky Way was known to be 100,000 light years across. Spiral nebulae were know, without knowing what they were. Mount Wilson telescope found Cepheid variables in the Andromeda Nebula; thus the spiral nebulae were other galaxies, and the Milky Way was just one galaxy among many. Types classified. Hubble discovered galaxies were hurtling away from one another. Redshift of light from a galaxy indicates its distance from the Milky Way. By late 20th, some hundred billion galaxies were know.
Darwin and Freud also removed humanity from the center of creation. By same point, we can assume the laws of nature are true everywhere.
2, How do we know what we know?
How the night sky looked. About archaeoastronomy, the recent study of how ancient peoples understood the sky, via artifacts like Stonehenge.
Astronomy was a naked-eye science for millennia. Tycho and others used long tubes to make measurements of objects’ positions more accurate. Then Galileo pointed the telescope; what he saw, p50.
How visible light is part of the EM (electromagnetic) spectrum; all of it but visible light and radio are blocked by our atmosphere, 54-55. So we can use radio astronomy to search for ETs.
Sciences go through phases: astronomy plus spectography became astrophysics. Two Germans; putting telescopes in space, at the LaGrange points. Sending spacecraft to other planets.
Now we use neutrinos and gravitational waves.
About the big observatories: Maui, Chile. Hubble went up in 1980. The Webb and ELT under construction, p70
3, How did the universe get to be this way?
Hubble discovered the redshift, and thus the expansion of the universe. And from that the Big Bang was deduced. The Doppler effect provided the speed of the expansion.
The history of the universe has six phase changes: melting, freezing, vaporization, condensation, sublimation, deposition.
Consider the expanding universe from an age of one minute. By this time elementary particles have been formed. By age 3 minutes protons and neutrons can bond; this is a phase transition. Hydrogen, helium, lithium, but after 45 seconds these become too far apart for more collisions to occur. This was the fourth state of matter, plasma.
By 380,000 years old atoms formed that were able to remain stable. Then galaxies and stars began to form. Radiation escaped (to be cosmic background) and the universe became transparent. Like sugar dissolving in iced tea.
How particles spread so far apart that they were able to clump into matter was solved by the discovery of dark matter. It has gravity but doesn’t interact with EM. Gravity pulls together objects like stars and planets. They heat; fusion begins, giving off energy.
The first stars appeared at around 300 million years. Stars end as white dwarfs or neutron stars (the result of a supernova explosion) or black holes.
Laplace developed the nebula hypothesis for the formation of solar systems. With rocky planets closer in, gaseous ones farther out. The ‘frost line’ in between.
But not everything is so simple. Dozens of early bodies in the inner solar system likely collided with each other, some becoming rogue planets, until only a few were left. Possibly many of them.
The outer planets too likely caromed around the solar system. P93. Shuffling around the inner planets. Triggering a reign of comets that perhaps provided all the water on Earth.
Beyond the planets, the Kuiper belt. Eris, only slightly smaller than Pluto. Beyond them, the Oort cloud.
Ch4, How old is the universe?
Arranged as 6 surprises.
The common answer now is 13.8 billion years. But while that light traveled to us, it has still been expanding; thus it’s now about 45 billion years ly in every direction. How much of the actual universe can we perceive?
Surprise #1: cosmic background radiation. Objects above absolute zero radiate EM waves: the hotter the object, the shorter the wavelength. The 1964 discovery of the CMB (cosmic microwave background) was direct evidence for the big bang.
Surprise #2: the message in the microwaves. The consistency of the CMB indicates the universe hadn’t expanded much. This is the horizon problem.
Surprise #3: the inflationary universe. This relies on the study of elementary particles. Alan Guth’s idea was when the universe was a tiny fraction of a second old, it froze. It was so small uniformity of temperature was easy.
Surprise #4: temperature differences in the CMB. Measurements give us an age for the universe at 13.8b.
The astronomical distance ladder. The large-scale structure of the universe. Recall parallax, then Cepheid variables. They work out to about 100 million ly.
Surprise #5: dark energy. The next rung in the ladder is a Type 1A supernova. White dwarfs in binary star systems. Studying these led to discovery that expansion of the universe is speeding up, not slowing down. The force doing this was dubbed “dark energy.” And this study led to a 12.5bya universe. But this disagrees with the other estimate.
The tension. Our measurements aren’t perfect. So maybe we’re measuring the wrong thing, 117b. Sometimes equipment is to blame. Other reasons; accuracy versus precision. The two measurements have both become more precise over the years.
Surprise #6: dark matter. Dubbed to explain gravitation movements of galaxies. Perhaps should be called dark gravity.
Formations of the universe. Having now plotted positions of more than a million galaxies, we can see they’re not evenly spaced. There are pockets, like those in a sponge. The largest structure known is the ‘Great Wall’, p125.
[[ never heard the term ‘frozen’ w/respect to the early universe. Also how they mapped the larger universe—by measuring distances to over a million galaxies. ]]
Ch5, What is the universe made of?
It seems the world is made up of zillions of different materials. Consider a library, or a book. Books are made of words, with rules about sentences, paragraphs, and so on; different words indicate the existence of languages; they’re made up of letters. And so on: very complex.
In the Middle Ages was alchemy. By the 18th century it became chemistry. The idea of elements. In 1776 only 22 pure elements were known; the ancients had known of 12 of these. The law of multiple proportions was seen.
Where did the elements come from, beyond hydrogen, helium, and lithium? Recall the formation of the solar system. The sun can fuse elements up to carbon. More massive stars, up to iron. When a star collapses into a supernova, elements up to uranium are generated. Heavier elements can be generated only in labs.
John Dalton introduced modern atomic theory in 1808. Mendeleev developed the periodic table, though no one knew how it worked.
The simplicity of this theory began to unravel in 1897 when electrons were discovered. Showing that atoms were not indivisible. Rutherford shot particles at gold in 1911, and only 1/10 of 1% bounced back. Thus ‘proton’ and nucleus. And predicted the neutron. So the universe was made up of just three particles…
Until cosmic rays were detected. Experiments with them turned up the positron, the muon. And more. Most of them short-lived.
Then came particle accelerators. The cyclotron. Berkeley. Synchrotron. Now the LHC.
By the 1960s things were getting complex, with so many new particles. They were explained in terms of more elementary particles, the quarks. Which can’t be pulled apart. Is there another layer down? Glossary p147.
Are there more layers? Two ideas: string theory and loop quantum gravity. The first entails 10 or 26 dimensions. In the latter, space itself is a weave of interlocking loops. They explain how the various particles are related to one another, but there’s no actual evidence for either theory.
Ch6, What is life?
No clear definition. Three ways: by list; by history; by thermodynamics.
A list might include cells, ability to reproduce, and so on. By history: having evolved by natural selection. Or, a system maintained by a flow of energy.
By the end of the 19th century it was understood that life arose from life. But how did it originate?
The experiment that changed everything was in 1952, Stanley Miller and Harold Urey. Some of their details were wrong but the experiment has been repeated many times with wide varieties of conditions.
Then there are meteorites falling on earth. They contain amino acids. The 2007 Stardust mission visited a comet, also containing organic particles.
RNA poses a chicken and egg problem; which came first? In the 1980s an experiment found that RNA could act as the enzymes necessary…
Once the first cell appeared, natural selection took over. Which drives biodiversity. The process would work everywhere, but different planets would have different results.
It took two billion years for symbiosis to lead to the complexity of life we see today. Around 800 million years ago came multi-celled life. Complexity grew just as the interstate highway system grew from simple beginnings.
Technology is an outcome of intelligence. Yet it doesn’t take much of a brain to produce complex behavior. Does intelligence always lead to technology?
Is synthetic life possible? Moore’s law. Paperclips. Kurzweil. Quantum computing. If machines outperformed humans we might encounter the singularity. Authors consider von Neumann probes the likeliest artificial life form we might encounter.
Life on earth mostly inhabits areas between the freezing and boiling points of water. Chemical reactions slow down by half as the temp dropped 10c. Life on Titan would take months for what an organism on earth would take a minute. At the opposite extreme we don’t expect to find organisms in molten lava. Still, there are microbes that exist in boiling water: extremophiles, like tube worms, discovered in 1977. Tardigrades.
Ch7, Are we alone in the universe?
We are limited to the kinds of life we know. Once there were plants and animals. Now we know four other branches of life (fungi, etc). but they are all carbon-based. Alien life might look like nothing on earth.
Life not like us might be based on another element, e.g. silicon. Or it could arise in a liquid environment other than water, e.g. Titan. Or a lava planet.
Humans have long imagined other forms of life, even in the sun p187 or in the moon. Or in the rings of Saturn. There are many spherical worlds, but only one form of life known. And so we presume other life would be carbon based in liquid water, because that’s all we know. Biases p191: carbon; water; surface; stellar; chemical. [[ obviously sf writers have challenged all of these. ]]
Searching for ET life is distinct from SETI (intelligence). What Earth was like over its history, p195. We search for signals; but this limits how long earth has been ‘visible’.
Drake equation. Example values yield various results.
Is technology inevitable? (Sidebar about the ‘wow’ signal in 1977 p201). Maybe not; the dinosaurs didn’t.
SETI. Began in 1959. Where to look, and for what? Nearby sunlike stars; hydrogen signals. SETI@home began in the late 1990s. but no evidence has been found. But the search must go on.
Every star has a continuously inhabitable zone, or Goldilocks zone. This presumes liquid water is required.
Fermi paradox, p206. Known for doing quick estimates. Various answers: there aren’t any; we’re in a zoo; earthlike planets are rare; or civilizations wipe themselves out.
In 1963 Kardashev proposed a scale of three Types of civilizations, p210. If Type 2 or 3 civilizations existed, how would we see them?
Ch8, How did it all begin?
The earliest events in the history of the universe require understanding cosmology and elementary particle physics. See timeline below.
The bricks of ordinary matter are six quarks and six leptons. And just four forces operate on them. Less familiar are the strong and weak force. Strong holds protons together. Weak triggers radioactivity.
The inside of atoms is the study of quantum mechanics. Heinsenberg uncertainty. Virtual particles. The exchange of virtual particles generates forces. Three such particles correspond to three of the forces; gravity is the missing one.
Things were simpler in the early universe. So were the four forces originally just a single force? This is the unified field theory. The increase in temperature unified the forces.
Next, quark confinement at 10^-5 second. Forces between quarks increase the farther away they get.
At 10^-10 sec, the forces unified. Before this point, there were three forces: strong, gravity, and electroweak. After this time the third became electromagnetic and weak. We’ve seen this in the Large Hadron Collider. Earlier than this we cannot test.
Then, back to 10^-35. The six quarks and six leptons showed up. We have no theory about what happened earlier than that. Before this time there were only two forces: gravity, and the strong unified with electroweak.
There are ideas: e.g. that final unification occurred at 10^-43. The Planck time. Before this the entire universe was tiny enough to be controlled by quantum mechanics.
Why is there matter at all? All the antimatter is gone.
Grand scenario p232-3.
14by: age of universe
10^-43: before this time, just one force; afterward, two forces, gravity, strong/electroweak.
10^-35: expansion; slightly more matter than antimatter; three forces: gravity, strong, electroweak.
10^-10: now all four forces.
10^-5 sec: quarks form elementary particles; no quarks exist on their own.
3m later: nuclei of atoms survive, up to lithium; then Hubble expansion spreads them too far apart to build heavier nuclei.
380,000 later: plasma cooled for atoms to form; universe becomes transparent; matter clumps to stars and galaxies (where dark matter is found)
That’s all we know so far. Questions remain: what happened earlier than 10^-43? How does gravity resolve with QM? And what was the nature of the initial event?
Ch9, How will it all end?
First we think about the sun: at equilibrium for billions of years, balancing gravity with energy from fusion. In another 5by the hydrogen for fusion will run out. Then will follow nuclear reactions that turn the helium ash to carbon, and burning of the unfused hydrogen around the core. It will turn into a red giant, engulfing Mercury and Venus at least. Then gravity will compress what’s left, until countered by the outward pressure of leftover electrons, and the sun will become a white dwarf.
The sun has gradually been brightening all the while. How will that affect earth? Ice ages will come and go. Continents will continue to shift, reuniting in just another 250my.
A billion yrs from now the planet’s average temp will be higher than our body temp. Greenhouse effect. Continents will lock into place. Eventually the rocky surface will liquefy into a lava ocean. And so on.
An unpredictable doomsday is volcanoes. Vast supervolcanoes. There are 20 in the world; the most familiar is the one in Yellowstone.
Another activity is igneous provinces, e.g. the Deccan Traps, and Siberian Traps; their timing matches two mass extinctions.
Another: Impact. Meteor Crater in Arizona, 50,000 years ago. The worst we know of was the event 65mya—another mass extinction.
There are NASA program to detect Earth-threatening objects.
Occasionally galaxies collide; ours and Andromeda will collide in a few billion years. Though galaxies are mostly empty space. eventually the two will settle down into one jumbo galaxy.
Is the Hubble expansion open, closed, or flat? All the evidence points to a flat universe.
What is the composition of the universe? Baryonic matter, 5%. Dark matter: 27%. Dark energy: 68%. There are two theoretical contenders for the last of these: the energy of empty space; or something called “quintessence.”
If dark energy is finite, expansion will slow but never end.
But if it increases, expansion will accelerate, leading to the Big Rip in some 22by. Stars will separate, then solar systems, then atoms, leaving only elementary particles.
This is the end of our theoretical knowledge.
What would an observer see? Two timelines, 261, with or without the Big Rip.
Ch10, What does nothing have to do with everything?
We need to understand the existence of nothing. Aristotle considers it absence of air. Theologians considered it absence of God. In 1654 a German scientist demonstrated the existence of a vacuum.
Until QM, vacuum was thought to be a region of space with nothing in it. The uncertainty principle changed that. Virtual particles. So now a vacuum is full of particles that pop in and out of existence. With no gain or loss of net energy.
Perhaps the entire universe is a quantum fluctuation. How could such a massive thing as the universe last? But you can create energy and also negative energy.
Cosmogenesis is the idea that the universe began with the quantum vacuum. Like a ball rolling down a hill, p274. Energy stored in a false vacuum triggers the big bang.
Before the big bang. What existed before? Maybe the question is nonsense, like the north pole question. Or maybe the answer is, the quantum vacuum. How would we tell? What can we measure?
The multiverse is like a large collection of bubbles that never touch each other. Each with its own laws of physics and constants of nature. This would explain the fine-tuning problem. A very narrow range of possible values allows life to exist. Recall the Texas sharp-shooter fallacy.
Max Tegmark defined four categories of multiverses.
Level 1: like scattered ships at sea. Like science fiction’s parallel universes.
Level 2: a multiverse contains bubble universes, with slightly different laws and constants.
Level 3: many worlds hypothesis.
Level 4: all the multiverses associated with all possible mathematical structures. E.g. like time running backward.
Is this really science? Ockham’s razor. How can we test any of this? Proponents say existing theories imply the multiverses, even if there’s much we can’t verify.
Keep asking questions, and keep looking up.
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