Science has never been more popular. This is reflected in the news, where cosmic discoveries are making headlines on a regular basis, but it’s also seen in our culture. Many of today’s most popular TV shows and movies are either based on a scientific premise, or feature scientists as main characters. There is a particular field of science, however, that invariably receives more attention than any other: astrophysics. We are naturally drawn to this field because it deals with some of our biggest questions about how the universe works, and what our place is within it. If you have an interest in learning more about the cosmos, but you’re short on time, this book was written for you.

It all began about 14 billion years ago: the matter, space, and energy of our entire universe was contained in a space one-trillionth the size of the period at the end of this sentence. Where exactly this tiny all-containing entity came from, we don’t know. But it burst forth, and within a trillionth of a second, gravity and quantum mechanics were already at odds and four distinct forces— atomic energy, gravity, radioactive decay, and electromagnetism—were already at play. Within a millionth of a second, the universe was already the size of our Solar System, and subatomic particles like quarks and leptons had emerged and were interacting with their anti-matter complements in a trillion-degree Kelvin cauldron. Before the universe was one-second-old, quarks cooled and bonded, forming heavy particles called hadrons, as well as protons and neutrons. Before it was two minutes old, the universe was already several light-years wide, and the temperature was only 100 million degrees.

For the next 380,000 years, the universe continued to expand and the cauldron of electrons and photons were free to move about—until the temperature dropped to 3,000 degrees Kelvin, or half the Sun’s temperature, at which point the electrons began combining with atomic nuclei.

Within a billion years of the universe’s beginning, galaxies had begun to form, and so did stars— billions and billions of them. From these stars issued materials heavier than helium and hydrogen, enabling the formation of matter that would eventually cluster into planets. As stars exploded, they scattered their chemically-rich and diverse debris across galaxies. In one pocket of the universe, at the edge of a Virgo Cluster, in the Milky Way galaxy, in the region known as the Orion Arm, a small star which we now know as the Sun formed with heavy enough material to pull a collection of comets and planets into its gravitational field.

One of the planets we now call Earth coalesced and fell under the Sun’s gravitational spell. Not just anywhere, though: Earth ended up in what scientists call the “Goldilocks zone” where its distance from the Sun allowed for the large liquid bodies on the planet’s surface to stay in mostly liquid form. Any closer to the sun and the oceans would have evaporated; any farther, the oceans would be frozen solid. The conditions were “just right” for life.

Scientists have yet to discover exactly how life emerged from non-life, but somehow from the organic matter in the oceans simple bacteria emerged. Scientists theorize that they must have required no oxygen to thrive, and were also able to give off oxygen as a by-product. Eventually, these bacteria produced sufficient oxygen molecules to support aerobic organisms and the production of a protective ozone shield around the Earth that protected life from the Sun’s molecule-destroying UV photons.

This story of an expanding universe and the development of all that now exists is the greatest story every told. Scientists have yet to discover how life came from non-living matter but refuse to settle for the religious cop-out of a Creator.

To get a sense of how big the universe is, and all that it contains, scientists usually speak in terms of galaxies. By recent count, there are likely as many as 100 billion galaxies, each containing billions upon billions of stars. The nearest galaxies to our own Milky Way are over 180,000 light-years from us. They were actually discovered by world explorer Ferdinand Magellan in a 1519 voyage—that’s before the invention of the telescope! We can think of these galaxies as cities at night view from the air: bright spots amidst the dark of surrounding countryside. As with the dark of the countryside, however, there is actually a lot going on in the void between these celestial clusters of stars and planets. Some of the most important and interesting discussions among astrophysicists deal with these spaces between the galaxies.

Thanks to modern technology and recent theories, we have been able to detect the presence of objects and phenomena never before possible: dwarf galaxies, exploding runaway stars, dark matter, and dark energy—to name a few.

The author’s first essay about the universe was actually about the presence of dwarf galaxies, called “The Galaxy and the Seven Dwarfs.” The title points to something still more fascinating than the fact that there are mini galaxies around—there are far more of them than galaxies proper.

So why are we just now discovering them? Part of the reason is that they are significantly smaller clusters, with far fewer stars. This makes the dwarf galaxies appear dimmer and easy to miss. Scientists speculate that because they have as few as one million stars instead of hundreds of billions like other galaxies, the chances of their discovery are about 100 thousand times slimmer.

Gravity is the most clearly evidenced force around us, and yet it remains one of the biggest enigmas. The most brilliant mind of the past millennium was undoubtedly Isaac Newton. He discovered that gravity has the ability to influence action at a distance, that it is the force that attracts objects. Not only did he realize this, but he was able to express gravity’s influence on mass in mathematical terms. The most brilliant mind of the past century was Albert Einstein. He modified Newton’s calculations about gravitational pull when he realized that the curve in space-time bends light rays as they pass over a massive object.

Even with these monumental contributions, many questions remain. For almost a century, the world has awaited another Newton or Einstein to make sense of the fact that the vast majority (85 percent) of the gravitational force in the universe that we’ve managed to calculate is derived from entities that do not respond to the energy and matter we’re familiar with.

The Swiss-American physicist Fritz Zwicky was the first to bring up this problem of “missing mass” in the 1930s. He identified the odd phenomenon in the movement of galaxies in the Coma Bernices, an enormous cluster of galaxies 300 million light-years away from our own. Zwicky observed that galaxies were moving at high enough velocities to break away from their orbital circuits and go hurtling off into space—but they didn’t for some reason. If Earth were moving just 1.4 times faster than its current speed, it’d slip off the track, but these galaxies weren’t getting derailed from their courses: they stayed on their circuits, flying at speeds far beyond their “escape velocities,” which indicated that there was far more mass present than could be observed with the tools at science’s disposal.

There is a mysterious, invisible mass keeping the stars in their orbits. The common name that astrophysicists now employ for this is “dark matter.” The word “dark” does not indicate its appearance, but that it is something all together different than anything we’ve known. We are no closer to figuring it out because astrophysicists can’t analyze what they can’t observe.

For most people, the periodic table of elements is a relic from grade school chemistry. But this seeming hodgepodge of numbers and letters comes to life when we put them in context. Think about sodium chloride, or table salt: sodium is a toxic metal and chloride is an odorous, lethal gas, but together, they season your meal. Then there’s water, comprised of elements that, by themselves, allow for combustion and are highly flammable, but together, constitute a life-sustaining substance that we drink everyday. 

In the beginning, there were only three elements. The Big Bang unleashed hydrogen, helium, and lithium into an ever-expanding universe. Hydrogen is the lightest and simplest of all the elements. It comprises 75 percent of your body mass and 90 percent of all matter in the universe.

A distant second to hydrogen is helium, a gaseous substance that, in addition to elevating vibrational frequency in the windpipe and vocal pitch, comprises 10 percent of the universe’s atoms. There’s far more of it than all of the other elements put together. A distant third in prevalence to hydrogen and helium is lithium, which comprises about one percent of all atoms in the universe.

In 2000 the Hayden Planetarium of New York City offered an exhibit called Passport to the Universe, which puts our relation to time and space in the universe into perspective. It shows us that we humans are carbon-rich specks on a pale blue dot in a vast galaxy, and that life on Earth has only been around for the slightest fraction of the universe’s lifetime. In fact, if the universe’s life were a calendar year, human history would only begin in the final seconds of 11:59 PM on December 31.

One Ivy League university professor asked to collaborate with the Planetarium in order to investigate the psychological effects of the exhibit on the public. He found that the majority of the public were depressed by the exhibit, and he himself confided that it was the most demoralizing experience of his life.

The professor’s perspective is shaped by ego and an inflated view of humanity’s importance in the grand scheme of things. This is understandable, given how society tends to elevate humanity, and assign it a significance that transcends the natural order. But it is precisely this, that humanity has a position within the great cosmic chain of being, a role to play, neither more or less vital than that of climates or plants or animals, that we have a sense of significance. We are intimately connected to the universe. Particles of the same water that you drink have passed through the kidneys of Buddha, Aristotle, and Newton. Particles of the same air you breathe have passed through the lungs of Alexander the Great, Confucius, and Bach. We are connected to the very earliest life forms to ever emerge. We are all comprised of star debris whose origin can be traced back to the very beginning of existence.

This cosmic perspective is based upon the solid foundation of empirical knowledge, but it also lays the groundwork for wisdom, humility, open-mindedness, spirituality—not to be confused with religion—and an openness to finding beauty in everything from planets to prokaryotes. Not only are we in the universe, but the universe is within us. Now that is an inspiring thought.

These insights are just an introduction. If you're ready to dive deeper, pick up a copy of Astrophysics for People in a Hurry here. And since we get a commission on every sale, your purchase will help keep this newsletter free.