To Infinity and Beyond: A Journey of Cosmic Discovery

“Cave paintings and rock carvings that date back 40,000 years or more capture not only animals and hunters but also comets, meteors, and constellations in enough detail to track Earth’s slow wobble on its axis.”

The authors emphasize throughout the book that the desire to explore space is an innate characteristic in humans—thus, the cosmic journey is something of a birthright. Humanity has looked to the heavens for thousands of years for answers to scientific, philosophical, and psychological questions. The questions of where humanity comes from and where is it going are inextricable from the odyssey.

“Emboldened with the discovery that air has a measurable weight and that the weight lessens with altitude, Earthlings soon contrived new ways to buoy our way through the skies above, and soar like Icarus before his final moments.”

Mythology inspires science: The notion of flight, technologically impossible for the ancients, still yet sparked their imagination. With the advent of modern science and a greater understanding of how the atmosphere works, those stories transform into reality—though not necessarily as the original tales would have it. Here, the authors use an allusion to the Greek myth of Icarus, who flew too close to the sun and perished as a result.

“At Earth’s equator, where the surface moves the fastest, the centrifugal force is the strongest. So, why aren’t Ecuadorians, Singaporeans, Galápagos giant tortoises, and other equatorial residents clinging to the ground with Velcro for fear of flying off? One word: gravity. However, that doesn’t mean the centrifugal force is absent. It shows up in people’s reduced weight. Everyone weighs a bit less than they would anywhere else in the world.”

The authors use vivid, humorous language here to illustrate how gravity works. Gravity is one of the most important forces in the universe, as the authors repeatedly note, and they use easy-to-grasp language and examples to convey its effect to their general audience.

“And so, astronauts are weightless in orbit—not because space has a magical property that erases the force of gravity, but because they remain in free fall in an orbit Isaac Newton first described almost three and a half centuries ago.”

Manned spaceflight must achieve escape velocity to break through Earth’s gravity field. These speeds form a hyperbolic trajectory, wherein the vessel (like the International Space Station) travels at such a speed that its free fall toward the Earth is counteracted by that speed. This is what causes weightlessness. Spaceflight is not magic; rather, it is informed by the fundamental laws of physics, established for centuries.

“With the miniaturization of hardware, satellites have become smaller, cheaper, and ever more indispensable to science and society.”

While technological developments have been highly beneficial for humanity in certain ways (cell phones, laptops, more efficient communications), they have also led to ecological problems here on Earth and potentially severe problems in outer space. The proliferation of satellites—many of them dead—in orbit around the Earth has created a plethora of what is called space junk. The Kessler effect suggests that if satellites begin crashing into one another, breaking into smaller pieces, the bits of debris could coalesce into an impenetrable band of junk through which no spacecraft could travel.

“Five years after the last Moonwalk, humanity set course on its greatest journey into the cosmos, yet not one person was on board. Instead, two humble space probes named Voyager 1 and Voyager 2 carried testimonies to the existence of an intelligent species inhabiting the third rock from the sun.”

In accordance with humanity’s “fantasy of ascending upward, outward, and onward into the universe” (80), the Voyager mission set out on a very simple, yet incredibly ambitious, project of discovery and possible contact with alien species. These space probes are ambassadors of Earth, traveling with what was considered the best cultural artifacts of human creativity at the time. The idea of humanity’s smallness in the face of the vast universe is emphasized through figurative language here, which describes Earth as “the third rock from the sun.”

“From the moment Earth was dethroned from its position as the perfect, unmoving center of the universe, new technologies and advancements in mathematics began recasting our cosmic identity into a tale incalculably more thrilling, improbable, and humbling than ever before imagined.”

This suggests that identity is inextricably linked to storytelling (“tale”) and that the story humanity tells about itself is no longer framed just by terrestrial existence here on Earth but by Earth’s position in the larger universe. Our sun is not the only sun around which planets orbit, and the Earth is not the only planet in the zone wherein life appears possible. The Milky Way galaxy does not occupy anything like a central position within the larger universe. Galaxies are not rushing away from Earth; rather, the entire universe is expanding, and Earth is only one small piece of that larger cosmic dance.

“For most of human history, the world was simply how it appeared and felt. The scientific method—the urge to test a hypothesis via repeated experimentation—didn’t take hold until the 17th century.”

The authors emphasize that the five senses are not always adequate for understanding the phenomena one encounters—especially when one encounters the subatomic world or deals with quantum physics. Rather, the scientific method of testing hypotheses to determine a theory is a reliable way to explain natural phenomena.

“What we call ‘Mercury in retrograde’ is a function of our perspective on the sun and the planet, not a reversal in Mercury’s orbital direction. There’s nothing unusual about Mercury’s movement during those times, other than the human urge to assign it meaning—an urge traceable to a time of ignorance, when we all thought the universe revolved around us.”

It took centuries for the heliocentric view of the solar system to become accepted fact; the idea that Earth was at the center of things was necessary to support certain philosophical ideologies and spiritual beliefs. The notion that Earth is singular, without equal, still yet informs some worldviews—here, the authors discuss, Mercury retrograde, a popular notion in astrology. The search for meaning does not only reside in the desire for exploration but also in the need to understand one’s place in the universe. The authors look to science to explain phenomena, but they implicitly acknowledge that humans look to other sources for meaning as well such as stories, religion, culture, and art.

“Mars comes with an Earth 2.0 starter pack: a bit of atmosphere, some gravity, and (we think) reservoirs of water ice beneath the surface, luring as permafrost. Just add heat. Some assembly required.”

The authors tackle the prospect of terraforming Mars should Earth become too overcrowded, polluted, or wracked by extreme weather due to climate change. The authors conclude that the ethical conundrums in embarking on such a project—geopolitical struggles; colonizing another planet possibly inhabited by microbial life—not to mention the technological impediments to such an enormous undertaking make such a prospect unfeasible. Instead, they argue that Earth should be humanity’s first priority. This quotation also showcases the authors’ use of humor in dealing with heavy subjects.

“Combine the possibility of deepwater vents with the evidence already established of a warm salty liquid ocean, rife with organic molecules, and the idea of a world teeming with alien life transcends science fiction.”

Saturn’s moon, Enceladus, contains the elements that are believed to be necessary for supporting life—though the images that have been sent to Earth are only from space. No probe has landed on its surface as of yet. Again, the ideas first dreamed up in stories—here in science fiction—often inspire the science that follows.

“At its current velocity, logging more than 900,000 miles a day, Voyager 1—the fastest human-made thing in the universe—will need another 300 years before it arrives at the outskirts of that shell [the Oort cloud], and another 30,000 years to traverse it. By then, the Voyagers, Pioneers, and New Horizons will be long dead, their metallic remains an ode to the ambitions of humanity.”

This reveals the absolutely mind-boggling distances and depths involved in exploring the universe. The Oort cloud, a shell of comets numbering in the trillions, is something that scientists can see via powerful space telescopes, yet it lies far beyond where the fastest humanmade spacecraft have. This celestial phenomenon itself is so large that a spacecraft utilizing today’s technology would need a timespan equivalent to six times the whole of recorded human history to move beyond it.

“Humanity’s ideas about where and what space is began with the sky—blue and vast and mysterious as the seas. We called it the aerial ocean. At various times in history, descriptions and assumptions about the sea were bestowed on the sky and, later, on the entirety of space beyond.”

The connection between the sea and space is emphasized in the use of nautical terms to describe spacecraft and aerial navigation. The deep oceans are as inhospitable to human exploration as outer space; humans cannot survive without specialized equipment, protection, and their own oxygen supply. It is not a coincidence that many of science fiction’s alien monsters (and some rare friendlies) possess attributes similar to sea creatures like tentacles, snapping beaks, rows of teeth, and greenish or bluish skin.

“The inextricable history of the (first) Cold War and the 1960s moon shot, of World War II and the V-2 rocket, of World War I and the aeroplane all serve as stark reminders that aeronautical and astronautical technologies often advance in the service of war.”

Science does not take place in a vacuum; its work is implicated in the maelstrom of war, and with increasing technological sophistication comes ever more destructive weapons. The context in which scientific advancement occurs is morally and ethically significant. The intentions with which scientific exploration is carried out also warrant scrutiny.

“If the universe is infinite, then even if luminosity decreases with distance, a single photon from a sufficient portion of the universe’s infinitude of stars would yield a white night sky. Think of our magic-pebble slingshot. If you launched infinite pebbles from infinite slingshots, your target would take on onslaught of pebbles to every square inch of its body, no matter where it moved.”

Many people believe that since the night sky is dark, the universe must be finite—the authors use an analogy here to illustrate the concept of infinity and why it’s incompatible with the black sky. This leads to the understanding that the universe is expanding, which in turn confirms that the universe possesses a finite beginning. The authors also emphasize that this demonstrates the limits of human knowledge: the observable universe.

“NASA’s 2009 Kepler mission launched with a single directive: to hunt for Earthlike planets within a Sunlike star’s habitable zone, also called the ‘Goldilocks zone.’ This is the orbital region around a star where a planet will find itself at just the right temperature—not too cold, not too hot—to sustain liquid water on its surface, a prerequisite for life exactly as we know it.”

The discovery of exoplanets in the 1990s led to the revitalization of the search for extraterrestrial life. The Kepler mission confirmed the existence of nearly 3,000 exoplanets within the Milky Way, and estimates suggest that there may be up to 11 billion earthlike planets orbiting sunlike stars within the galaxy. Again, science turns to stories—here, the nursery rhyme about Goldilocks and the three bears—for inspiration. As much as science relies on evidence and experiments, it also turns to human creativity and culture for insight.

“An interstellar ark represents the ultimate conquest of nearly every hardship Earthlings collectively face today, ranging from a self-sustainable, equitable food system to psychological well-being.”

Science must grapple with the moral and ethical implications of its research and missions. Sending humans to the farthest reaches of space would require a multigenerational commitment, and the equitable division of resources would be crucial to the mission’s success. There are also the ethical implications of effectively exiling future generations, who did not consent to the journey from their home planet.

“But even if we can advance robotics to create the perfect android—something that can replicate human abilities and mimic creative thought—the urge to explore remains firmly embedded, as it always has, in the human psyche. If robotic exploration could satisfy that urge, then why are we determined to set up colonies on the moon and Mars?”

While the ethical dilemmas of sending humans to space for years or decades (or for life) are difficult to reconcile, the authors point out that robots would not be an acceptable substitute. They suggest that there is something fundamentally and uniquely human about the desire to explore and understand. As much as the authors resist the notion that Earth is a unique or exceptional planet in the context of the universe, they insist on it for humanity itself.

“Cosmic discoveries across the three centuries following Galileo’s seminal observations of the universe continually dismantled humanity’s egocentric worldviews. In the 20th century, when Einstein introduced his new theories of the universe, our reality expanded further, through another dimension entirely: time.”

While the first three sections of the book deal with more familiar realms of space exploration such as Earth’s atmosphere, the solar system, and new understandings about interstellar space, the final section of the book reaches out into theoretical territory. The mathematical equations, initiated by Einstein’s theory of relativity and expanded by the fields of quantum mechanics and string theory, conceptually allow for time travel, wormholes, and entanglement (wherein particles can be in two places at once). This is made possible by the understanding that space and time are inextricably linked in the fabric of a dynamic cosmos.

“A worldline is the mapped trajectory, including the time coordinate, of any object, whether a particle or a person. A party happens because the worldlines of all the attendees intersect. What that simply, but profoundly, means is that everybody managed to occupy the same space at the same time.”

The authors use the idea of a party as an analogy to explain worldlines. Worldlines intersect on the spacetime continuum, creating maps of interactions between space, time, and matter. However, this does not indicate that space and time behave the same way, even though they are both woven into the fabric of spacetime. Humans can travel through space, but they cannot travel through time. While the speed of light is a constant (and informs interspatial distances as well as intergalactic speeds), time itself fluctuates. Thus, worldlines are unique, discrete plotted points on a map that are unreproducible.

“If an Intergalactic Space Olympics took place in Newton’s universe, and if alien and human viewers across myriad planets could all witness the events from home, everyone would agree on the duration of the 200-meter dash. But in Einstein’s universe, every zone of spacetime would clock a different winning time from that measured by the official timers at the Olympics. The sprint that might take 20 seconds from the point of view of the sprinters could carry on for years from the point of view of an alien world.”

The authors use a familiar scenario—a set race during the Olympics—to describe the complex idea of spacetime. Looking into deep space is like traveling into the past because the light from distant stars takes years, decades, or even millennia to reach Earth. Thus, what scientists are seeing are messages from the past. This quotation also emphasizes the crux of Einstein’s theory: time is relative.

“All told, the detection of muons on Earth’s surface is the best, naturally occurring, constant, and directly measurable evidence we have for time dilation. And it dilates by the exact amount predicted by relativity. There’s simply no other explanation for why this little smidge of matter could ever survive a descent to Earth.”

Time dilation explains the difference between the experience of time by objects traveling at different speeds or exhibiting different fields of gravity. Time dilation explains why astronauts age a fraction of a second more slowly while they speed above the Earth in orbit. Muons, minuscule particles that exist for a fraction of a fraction of a second (as in particle accelerator experiments), can yet survive all the way from outer space and through Earth’s atmosphere. Time passes differently there than it does here.

“The x-rays detected were the energetic death throes of swirling stellar matter, shredding into its component atoms as it superheated to millions of degrees, forming a luminous accretion disk—that glowing halo around the rim of a black hole. The dying star unmasked a cosmic monster, other disguised in nothingness, as it gobbled down its atomic meal.”

The authors use a vivid metaphor to describe the gravitational pull of a black hole, the hungry remains of a dying star. The juxtaposition between the halo of light (angelic) and the voracious gravitational force (monstrous) reveals the tendency of humans to assign meaning and metaphor to natural phenomena. That halo is not part of the black hole itself but rather the glow of “the matter that has yet to fall in” (270)—a final celestial signal.