The Little Book of Cosmology Hardcover – April 7, 2020

I am taking a course in Cosmology by Dr. Brian Keating Phd. from the Peterson Academy online. This was one of recommended supplementary reading and is concise, coherent and an excellent complement to the course. I highly recommend it if interested in this subject.

This is a short book describing the evolution of the Universe since the Big Bang and its composition. How do we know all this stuff? The Cosmic Microwave Background (CMB) can tell us a lot. The CMB is a black body radiation remnant from the time (400,000 years after the Big Bang) when the Universe had cooled enough to allow the formation of hydrogen atoms and the decoupling of photons from electrons so that they could roam free. CMB is in itself evidence for the Big Bang but in addition we get additional information from the minor anisotropy and polarization of the CMB, and add the composition of the elements (hydrogen, helium, lithium, and heavier elements), redshifts of galaxies, gravity lensing, and we can tell quite a bit about the evolution of the Universe and where it is heading. It’s fascinating science detective work. This eventually leads to the Standard Model of Cosmology, which is something I’ve never heard of before, but it’s cool.I found the facts about the size and age of the Universe, the early giant stars in the Universe, dark energy and dark matter, very interesting. The book is filled with basic and fascinating facts that I did not know. Because of the CMB (rather than particle accelerator experiments) we know roughly the mass (rest mass) of neutrinos. We know why dark energy can’t be space dust, or rogue planetoids, or black holes or neutrinos, so what is it? The book explains why it can’t be any of those. There’s a lot we can know because of the CMB and other information, and some things we don’t know. Finding out what we do know was quite exciting and finding out what the mysterious “what we don’t know” was equally exciting. Again, the focus is on CMB and how it is measured, it tells us a lot.The book is easy to read and require no degree in physics or mathematics. I admit I have a degree in Engineering Physics, and I am also interested in astronomy and cosmology, but I can tell it was light reading. It is a truly popular science book like those that Neil De Grasse Tyson writes, and it was short but very informative. There’s a lot of information you can extract from CMB. It was a fun short read for anyone interested in the mysteries of the Universe.

Many people likely go through their lives and never fully appreciate the situation in which they find themselves. They may occasionally acknowledge the Moon's luminous presence, but not consider what its presence implies, basically, that all known human activity has occurred on a relatively tiny cosmic body floating somewhere within a vast and incomprehensible something that we call "the universe." So many questions about the absolute state of the human condition remain that even the question "where are we?" doesn't seem to have a definitive answer. Sure, we live on Earth, but we also live in the universe and from that larger perspective, we don't really know where we are or how we ultimately arrived here in our "interesting" predicament. Interest in such questions may have also waned somewhat since the once awe-inspiring night sky, from which an incalculable number of stars used to shine, has largely fallen victim to light pollution, especially in heavily populated areas. Anyone seeking the pinnacle of existential experiences should find a very isolated and unlit location and, after the sun sets, look up. Also make sure to look down because, in many such situations, the ancient starlight will cast a delicate glow upon the ground. Many people will want to know more after seeing such a beautifully startling sight. Some may eventually discover the term "cosmology," which denotes the science of the universe's creation and development. Though a full understanding of this rapidly evolving science does require a significant mathematical and astronomical background, popular books, accessible to just about anyone, exist for those who haven't yet tread those rocky paths. One such book, "The Little Book of Cosmology," provides an excellent non-technical introduction to this vast subject. Plus, at some one hundred pages, it definitely qualifies as "little."To help illuminate its contents, the book includes not only highly accessible prose, but also numerous diagrams, charts and even full color plates. A short preface outlines the agenda: a discussion of modern cosmology, namely, the "Standard Model" with a particular focus on the 2.725 Kelvin, or "3K," cosmic microwave background radiation (CMB), and a basic structural model of the universe made up of 5% atomic material, 25% "dark matter" and 70% "dark energy." It also claims, somewhat astonishingly, that understanding the "remarkably simple" universe remains far easier than understanding the overwhelming complexities of the single planet Earth. Some may also find comfort at the promise of encountering only basic math, nothing much beyond "distance = speed x time," and only a light treatment of Relativity Theory. That said, the book does delve slightly deeper into technical territory than, say, Neil DeGrasse Tyson's excellent "Astrophysics for People in a Hurry," which includes pretty much no mathematics, but also covers a wider breadth of material. Arguably, "The Little Book of Cosmology" provides a great follow-up for those who read DeGrasse Tyson's primer and desire a somewhat deeper dive into this particular branch of astronomy."The Basics," the book's first of five chapters, opens by stating the known universe's size as "really, really big!" It then gives some perspective by referencing "nearby" objects, such as the Moon that sits 250,000 miles, or "1.3 light seconds," away and the Sun at 93 million miles, or "8 light minutes," away. The numbers explode in volume from there: our galaxy, the Milky Way, contains 100 billion stars and has a diameter of 100,000 light years. Given that humans have, so far, only traveled to the Moon, the cosmic equivalent of our backyard garden shed, some may find this information sobering. Not only that, the Milky Way doesn't even qualify as the largest galaxy in its 6 million light year diameter "local group" of around 50 galaxies. That distinction goes to the Andromeda galaxy. The Hubble Deep Field gives an even more awe-inspiring glance of just how many galaxies exist: a 300 hour exposure of a tiny piece of the sky revealed around 10,000 galaxies. Extrapolating that figure to the entire "observable universe" implies that it contains around 100 billion galaxies total, a nearly incomprehensible number. This calculation holds given the universe's homogeneity and isotropy, meaning that the universe tends to look the same from just about any viewpoint. Despite this, the universe also expands, or "makes space," at an increasing and inconstant rate by the Hubble-Lemaitre law of 15 miles per second for every million light years distance. So objects further away move faster than those situated closer. This suggests a past "compact" universe and the WMAP and Planck satellites measure the universe's age as between 13.7 to 13.9 billion years old (the book uses 13.8). The Big Bang began all space and time, but a few physics-defying early time intervals remain nebulous. The constant speed of light also limits our view of the known universe, so we can only see a sphere of about 27.6 billion light years across. No one knows whether the universe goes on infinitely, but the cosmological model works just as well assuming an infinite universe. Such vast distances also mean that we see faraway objects as they existed long ago in time, or equivalent to the age of the light that reaches Earth. As such, visible light acts as a kind of "time machine," at least for the past.The next chapter, "The Composition and Evolution of the Cosmos," introduces the CMB, "a fossil in primordial light," as a prime example of one of the universe's three main components, radiation. Representing the heat remaining from the Big Bang as "blackbody radiation," it has slight temperature variations throughout its mass. Its current state, the most distant observable light, suggests a hot early universe in thermal equilibrium. The universe has become drastically less compact over time, even becoming a "quark-gluon plasma" some 25 millionths of a second after the Big Bang, reaching temperatures of more than a billion Kelvin. Cooling gradually allowed matter, made up of protons, neutrons and electrons and the universe's second main component, to form. All known matter originated from this phase of the universe. Elusive neutrinos also emerged from radioactive decay, but "dark matter," first proposed in 1933, still remains completely unknown, but given observations, something must exist to account for obvious gaps in the motions and velocities of observed objects. Inconstant "dark energy," the universe's third main component, also has no explanation, but it serves as a placeholder for an energy density or "pressure" in space quantified as the "cosmological constant." This force will eventually push all visible galaxies completely out of view. The details of galaxy formation remain a puzzle, but a model exists for how the process begins, which involves the clumping and cooling of dark matter and electron scattering over some 400,000 years and allows enough cooling for Hydrogen atom formation. Then CMB photons decouple and roam the universe and more clumping occurred, leading to the lighting of the first stars and ending the universe's "dark ages." Fusion formed Carbon, Nitrogen and Oxygen, which supernovae eventually shot throughout the universe, which much later led to the formation of life on Earth. We came from the stars, or, as one prominent astronomer once put it, "their nuclear waste." The book quotes Joni Mitchell's 1970 song "Woodstock," "we are stardust, billion year old carbon," but corrects it to "13.8 billion year old carbon."Chapter 3, "Mapping the Cosmic Microwave Background," probably qualifies as the book's most difficult chapter, or at least the one that will likely require the most careful reading. After a short discussion of Penzas and Wilson's 1965 discovery of the CMB, it discusses the importance of plotting hot and cold spots of the CMB from WMAP and Planck, the CMB "anisotropy," and how a graphing of this phenomenon can "determine the composition of the universe." It calls the graph, shown in figure 3.3, "one of the most important plots in cosmology." The curve's smooth line even represents the standard model of cosmology, so any model of the universe must conform to this plot. Many of the fine details of this chapter defy easy summary. The next chapter, "The Standard Model of Cosmology," begins by describing the shape of the universe, derived from the CMB hot/cold mapping and the Hubble Constant, as "flat" since the geometry from the calculations results in a 180 degree triangle. This same process, using high-school geometry, eliminates a saddle-shaped or a spherical-shaped universe. But the first instants of the universe have not yet revealed their secrets and no theory yet exists "that combines gravity with the standard model of particle physics." Research on "inflation" theory continues, which posits extremely rapid expansion in "a billionth of a billionth of a billionth of a billionth of a second" and fits well with a flat geometry. Quantum fluctuations, verified in laboratories, may provide the "seeds of structure formation." The chapter concludes with other ways of looking at the universe besides through the CMB and the "six parameters" of the standard model, which provides a tidy summary of the material covered throughout the book, with a few additions. A short fifth and final chapter, "The Frontiers of Cosmology," discusses five possible items that could effect the standard model, including neutrinos, gravitational waves, structure formation and basic physics and The Sunyaev-Zel'dovich (SZ) effect and clusters of galaxies. Not surprisingly, the book concludes that "from a cosmic point of view, Earth is insignificant," but an immense amount still remains to learn from the CMB, not to mention about dark matter, dark energy and the possibility of multiverses. Nonetheless, the standard model presents "a powerful and predictive model with open questions.""The Little Book of Cosmology" won't reveal the meaning of life or anything about "why" the universe began, but it can illuminate certain aspects of the human condition gleaned from scientific investigation involving observation, experiment and measurement. From this perspective, humanity does not sit at the center of the universe, nor does it seem particularly important or influential for the larger cosmos. The eventual fate of our solar system, all alone in an empty hyper-expanded space, may not sound particularly appealing, either. Such stark reflections may cause the interminable question "what does it all mean?" to ring louder for many. In the end, we don't really know and cosmology doesn't promise any answers to these questions, but it can provide some perspective. Existential concerns aside, the book does clearly demonstrate the impressive efforts made toward understanding the universe and the amazing strides that cosmology has made in just the last few decades. Yet as certain elements of the universe become comprehensible, new quandaries seem to always emerge. This process will likely continue for some time and some long-standing cherished theories may someday become modified or possibly even discarded. An understanding of this process and the science underlying it requires some basic foundational knowledge and, ideally, an effective entry point. "The Little Book of Cosmology," though a little challenging in places, will provide stalwart readers a valuable glimpse into the latest science around the origin and development of the universe that we find ourselves inhabiting.

I am not a scientist, but I have read many books on physics, astronomy and cosmology. This book provided me with many details I was missing in my previous readings. Writing style is excellent for the topic, examples are clarifying and plates/graphs provide visual backup. Of course, Kindle books lose a lot of the effect of the visuals, but I was able to make out the details better in this book than most.If you have an interest in this topic either as a beginner or are reasonably conversant in the topic, this is a good book to read and keep for reference.

This book by Lyman Page is probably the most compact version of our understanding of modern cosmology. I thoroughly enjoyed reading and re-reading this short book. Page explains a lot without dwelling too long on any one topic.... but make no mistake ... everything is covered and the book is very nicely written.

Mostly from the view of the CMB (Cosmic Microwave Background) the radiation bouncing around the universe since shortly after the Big Bang began everything. But a lot can be understood from this portion of the electromagnetic spectrum.