"Curiosity may have killed the cat, but with all due respect, the cat was going to die anyway."

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We used to think the Earth was the divine centre of the universe. It turned out to be a speck of dust orbiting a massive burning star. That star turned out to be a speck of dust among hundreds of billions of stars in our galaxy, and that galaxy turned out to be a speck of dust among two trillion galaxies in the observable universe. Our whole universe might be a speck of dust too, but we can’t know for sure.Humanity, which for most of our history seemed so special and superior to all other life forms, turned out to have the same soupy origin as every one of the 8.7 million other species on our planet: whether in the wet oceans, the smoky sky, or rocketed to our world from an asteroid storm of planetary crossbreeding.In other words, our atoms have the same backstory as the rest of the solar system, smashed together in the core of a star as it blew itself to pieces. And these particles have the same backstory as the entire rest of the universe. All of us, and everything in the cosmos, burst out of nothing when the vacuum of space itself suddenly fell apart.It seemed that life on Earth was the only possibility. Now there are theories in which there could be life across the universe: in roiling far off skies, in oceans of liquid methane, in burning lakes of molten lava, in the chilling void of empty space, and even deep inside stars themselves. There are more planets out there in the universe than there are grains of sand on all the Earth’s beaches, deserts, and sand dunes combined. It’s pretty hard to imagine that nowhere else in the cosmos has even a speck of life. Our galaxy cluster is silently being dragged toward a huge unknown object, and we have no idea why. The entire universe is way larger than the edge of what we can see, and we have no idea how much further it goes.But none of it will matter in the end because, trillions of years from now, our cosmos will either rip itself to shreds, crush itself into nothing, or expand forever into oblivion, leaving no trace of our existence. Our universe could even recreate itself over again in the distant future. Perhaps all of this has already happened, and you’ve already read this book. In that case, no refunds.If none of the previous paragraphs were even slightly unsettling to you, we might have a serious problem.
Since we’re in such a stupendously huge universe, we’re faced with the sad fact that we’ll never be able to grasp it all. The human brain is, after all, only a kilogram of cells in our heads. Most of the universe lies far beyond our reach, either in places too distant to access, too small to observe, too large to comprehend, too far in the past to see, or too far in the future to visualize.Some people find it chilling, saddening, and somewhat daunting. Others find it thrilling, riveting, exciting, and awe-inspiring. Depending on how you feel about it, this book is either going to be awesome, or a genuine horror story that’s based on our actual reality. Again, no refunds.No wonder the scientists during the Age of Enlightenment––an era of philosophical and reform in the 1600s and 1700s that included the development of the concept of free speech and thought––had such a hard time getting their point across. For two thousand years following the creation of Aristotle’s geocentric model of the universe, people gleefully put Earth at the centre of the entire cosmos. They believed that crystal spheres surrounded the planet, fixing the planets and the stars in their twirling paths around us.Nobody ever imagined that there was anything wrong with this idea, firstly because it made sense based on what we could see, and secondly because there was a ready-made system at Rome's Campo de’ Fiori to burn people at the stake for going against such things. During the Middle Ages, a quick way to end up there was to say that the theories put forth by the Roman Catholic Church were wrong. Giordano Bruno, who theorized that the stars in the sky were actually their own suns with solar systems of planets, was excommunicated and exiled three times, then burned at the stake in 1600 for distributing his heretical views.Basically, anyone who was foolhardy enough to suggest that our world was not the divine centre of the cosmos was pushing their luck, especially given the religious dogma at the time.While it was known that the planets occasionally looped around in their paths across the sky, the geocentric crystal-sphere model of our universe couldn’t explain it, except with a ridiculously complex system of spheres within spheres within spheres that rotated throughout the year. It looked like a gear clock on steroids.Copernicus saw a simpler, but weird and controversial solution: maybe that looping pattern was just what happened when our Earth went along its orbit around the Sun and passed other planets in their looping orbits. Was it possible that the Earth wasn’t the divine centre of everything?For his own sake, Copernicus kept quiet about his discovery until 1543, the year he died. A few decades later, in 1610, Galileo Galilei had the audacity to publicly spread the idea––and for doing so, he was put under lifetime house arrest by the Roman Inquisition.But this paradigm entered public consciousness and changed our concept of the universe forever. Perhaps our position as its special centrepiece wasn’t the best explanation for reality after all. Copernicus ushered in a brand-new way of thinking about our place in the universe: simplicity is better than human-centrism. The best explanations of the universe were now the simplest and most concise ideas, and science was no longer required to conform to common beliefs; it was dared to defy them. The universe was never so simple ever again.Even as our sense of cosmic specialness was crushed, we kept assuming we were finally done after each new discovery.At the turn of the 20th century, the excitement of earlier scientific discoveries had been fading into memory for over a hundred years. The physicist Lord Kelvin is quoted saying in 1900, for example, “There is nothing new to be discovered in physics now. All that remains is more and more precise measurement.”Of course, as we now know, we hadn’t quite discovered everything just yet. Despite being a famed physicist for his work in the field of thermodynamics, Kelvin couldn’t have imagined the discoveries that were going to be made in the next century as scientists began searching for the constants of our universe. Electrons were discovered; special relativity was formulated; the speed of light became a constant; space and time became relative; the atomic nucleus was found; our galaxy was mapped for the first time and turned out to be over a million times larger than previously thought; other galaxies were discovered beyond our own; the universe was found to be expanding; and the Big Bang theory was first proposed.And all this was only discovered in the first three decades of the 1900s. At this point, the universe is the ultimate antidote to the human ego.For most of the day, we aren’t thinking about our place in the universe. You probably don’t think about the fact that you’re standing at a dramatic angle on a curved portion of a massive sphere. You don’t enter a town and declare that the houses and buildings are protruding from the side of the Earth, even if you happen to live at the equator. No police officer would give you a speeding ticket because you were rotating around the Earth’s axis at a thousand kilometres per hour. It sounds ridiculous to say, “I’d like to meet you after the Earth rotates us into its umbral shadow and obscures the Sun.” Of course, we find it easier to say “I’d like to meet you after sunset.”When someone asks you, “What’s up?” you are expected to say something like, “Not much, you?” People tend to give you a weird look if you say something like, “The direction opposite the centre of the Earth, as defined by human society.”Our bodies never needed the ability to see where we are in the bigger picture. We evolved two eyes so we could see depth and perspective—an effect known as binocular disparity. That works great when you’re trying to run from creatures that are trying to eat you. It also works great when you’re trying to run after food you want to eat. But at larger distances, perspective disappears. Studies have found that we can’t really see perspective in anything farther than twenty metres away.Unfortunately, the universe is slightly further than twenty metres away.
The cosmos offers a perspective that literally flips our world upside down. Humanity is only a very small part of an enormous story that goes billions of years into the past, trillions of years into the future, deep into the subatomic realm, and out to the furthest galaxies.Most of our universe is inaccessible, but through observation and inquiry, a little speculation, and the power of scientific imagination, we can make it there. In fact, we can go absolutely anywhere.Just wait for a day when you can see both the Moon and the Sun in the daytime sky, tilt your head so that both of them are lying in a flat line, and you’ve just oriented yourself with the rest of the solar system. You’re standing on the curved surface of a giant sphere, at an awkward angle, whether you like it or not!
With that said, welcome to the universe.