Astrophysics for People in a Hurry

The universe is under no obligation to make sense to you. —NDT

We are stardust brought to life, then empowered by the universe to figure itself out—and we have only just begun.

The power and beauty of physical laws is that they apply everywhere, whether or not you choose to believe in them. In other words, after the laws of physics, everything else is opinion.

We do not simply live in this universe. The universe lives within us.

People who believe they are ignorant of nothing have neither looked for, nor stumbled upon, the boundary between what is known and unknown in the universe.

Yes, Einstein was a badass.

Looking more closely at Earth’s atmospheric fingerprints, human biomarkers will also include sulfuric, carbonic, and nitric acids, and other components of smog from the burning of fossil fuels. If the curious aliens happen to be socially, culturally, and technologically more advanced than we are, then they will surely interpret these biomarkers as convincing evidence for the absence of intelligent life on Earth.

Every cup that passes through a single person and eventually rejoins the world’s water supply holds enough molecules to mix 1,500 of them into every other cup of water in the world. No way around it: some of the water you just drank passed through the kidneys of Socrates, Genghis Khan, and Joan of Arc. How about air? Also vital. A single breathful draws in more air molecules than there are breathfuls of air in Earth’s entire atmosphere. That means some of the air you just breathed passed through the lungs of Napoleon, Beethoven, Lincoln, and Billy the Kid.

For reasons I have yet to understand, many people don’t like chemicals, which might explain the perennial movement to rid foods of them. <...> Personally, I am quite comfortable with chemicals, anywhere in the universe. My favorite stars, as well as my best friends, are all made of them.

Science is not just about seeing, it’s about measuring, preferably with something that’s not your own eyes, which are inextricably conjoined with the baggage of your brain. That baggage is more often than not a satchel of preconceived ideas, post-conceived notions, and outright bias.

The gravitational waves of the first detection were generated by a collision of black holes in a galaxy 1.3 billion light-years away, and at a time when Earth was teeming with simple, single-celled organisms. While the ripple moved through space in all directions, Earth would, after another 800 million years, evolve complex life, including flowers and dinosaurs and flying creatures, as well as a branch of vertebrates called mammals. Among the mammals, a sub-branch would evolve frontal lobes and complex thought to accompany them. We call them primates. A single branch of these primates would develop a genetic mutation that allowed speech, and that branch—Homo Sapiens—would invent agriculture and civilization and philosophy and art and science. All in the last ten thousand years. Ultimately, one of its twentieth-century scientists would invent relativity out of his head, and predict the existence of gravitational waves. A century later, technology capable of seeing these waves would finally catch up with the prediction, just days before that gravity wave, which had been traveling for 1.3 billion years, washed over Earth and was detected.Yes, Einstein was a badass.

At least once a week, if not once a day, we might each ponder what cosmic truths lie undiscovered before us, perhaps awaiting the arrival of a clever thinker, an ingenious experiment, or an innovative space mission to reveal them. We might further ponder how those discoveries may one day transform life on Earth.Absent such curiosity, we are no different from the provincial farmer who expresses no need to venture beyond the county line, because his forty acres meet all his needs. Yet if all our predecessors had felt that way, the farmer would instead be a cave dweller, chasing down his dinner with a stick and a rock.

In other words, after the laws of physics, everything else is opinion.

Matter tells space how to curve; space tells matter how to move.Ӡ

Of all the sciences cultivated by mankind, Astronomy is acknowledged to be, and undoubtedly is, the most sublime, the most interesting, and the most useful. For, by knowledge derived from this science, not only the bulk of the Earth is discovered . . . ; but our very faculties are enlarged with the grandeur of the ideas it conveys, our minds exalted above [their] low contracted prejudices." JAMES FERGUSON, 1757† Long before anyone knew that the universe had a beginning, before we knew that the nearest large galaxy lies two million light-years from Earth, before we knew how stars work or whether atoms exist, James Ferguson’s enthusiastic introduction to his favorite science rang true. Yet his words, apart from their eighteenth-century flourish, could have been written yesterday. But who gets to think that way? Who gets to celebrate this cosmic view of life? Not the migrant farmworker. Not the sweatshop worker. Certainly not the homeless person rummaging through the trash for food. You need the luxury of time not spent on mere survival. You need to live in a nation whose government values the search to understand humanity’s place in the universe. You need a society in which intellectual pursuit can take you to the frontiers of discovery, and in which news of your discoveries can be routinely disseminated.

Time to get cosmic. There are more stars in the universe than grains of sand on any beach, more stars than seconds have passed since Earth formed, more stars than words and sounds ever uttered by all the humans who ever lived.

(An artist coworker of mine once asked whether alien life forms from Europa would be called Europeans. The absence of any other plausible answer forced me to say yes.)

Earth’s Moon is about 1/ 400th the diameter of the Sun, but it is also 1/ 400th as far from us, making the Sun and the Moon the same size on the sky—a coincidence not shared by any other planet–moon combination in the solar system, allowing for uniquely photogenic total solar eclipses.

The cosmic perspective shows Earth to be a mote. But it’s a precious mote and, for the moment, it’s the only home we have.

What we do know, and what we can assert without further hesitation, is that the universe had a beginning. The universe continues to evolve. And yes, every one of our body’s atoms is traceable to the big bang and to the thermonuclear furnaces within high-mass stars that exploded more than five billion years ago. We are stardust brought to life, then empowered by the universe to figure itself out—and we have only just begun. †

The cosmic perspective comes from the frontiers of science, yet it is not solely the provenance of the scientist. It belongs to everyone.The cosmic perspective is humble.The cosmic perspective is spiritual, even redemptive, but not religious.The cosmic perspective enables us to grasp, in the same thought, the large and the small.The cosmic perspective opens our minds to extraordinary ideas but does not leave them so open that our brains spill out, making us susceptible to believing anything we're told.The cosmic perspective opens our eyes to the universe, not as a benevolent cradle designed to nurture life but as a cold, lonely, hazardous place, forcing us to reassess the value of all humans to one another.The cosmic perspective shows Earth to be a mote. But it's a precious mote and, for the moment, it's the only home we have.The cosmic perspective finds beauty in the images of planets, moons, stars, and nebulae, but also celebrates the laws of physics that shape them.The cosmic perspective enables us to see beyond our circumstances, allowing us to transcend the primal search for food, shelter, and a mate.The cosmic perspective reminds us that in space, where there is no air, a flag will not wave, an indication that perhaps flag-waving and space exploration do not mix. The cosmic perspective not only embraces our genetic kinship with all life on Earth but also values our chemical kinship with any yet-to-be discovered life in the universe, as well as our atomic kinship with the universe itself.

The power and beauty of physical laws is that they apply everywhere, whether or not you choose to believe in them.

During our brief stay on planet Earth, we owe ourselves and our descendants the opportunity to explore - in part because it's fun to do. But there's a far nobler reason. The day our knowledge of the cosmos ceases to expand, we risk regressing to the childish view that the universe figuratively and literally revolves around us. In that bleak world, arms-bearing, resource-hungry people and nations would be prone to act on their 'low contracted prejudices.' And that would be the last gasp of human enlightenment - until the rise of a visionary new culture that could once again embrace, rather than fear, the cosmic perspective.

If a huge genetic gap separated us from our closest relative in the animal kingdom, we could justifiably celebrate our brilliance. We might be entitled to walk around thinking we’re distant and distinct from our fellow creatures. But no such gap exists. Instead, we are one with the rest of nature, fitting neither above nor below, but within.

A few years ago I was having a hot-cocoa nightcap at a dessert shop in Pasadena, California. Ordered it with whipped cream, of course. When it arrived at the table, I saw no trace of the stuff. After I told the waiter that my cocoa had no whipped cream, he asserted I couldn’t see it because it sank to the bottom. But whipped cream has low density, and floats on all liquids that humans consume. So I offered the waiter two possible explanations: either somebody forgot to add the whipped cream to my hot cocoa or the universal laws of physics were different in his restaurant. Unconvinced, he defiantly brought over a dollop of whipped cream to demonstrate his claim. After bobbing once or twice the whipped cream rose to the top, safely afloat. What better proof do you need of the universality of physical law?

Nonetheless, they remind us that ignorance is the natural state of mind for a research scientist.

And yes, every one of our body's atoms is traceable to the big bang and to the thermonuclear furnaces within high-mass stars that exploded more than five billion years ago.We are stardust brought to life, then empowered by the universe to figure itself out - and we have only just begun.

Consider an adult who tends to the traumas of a child: spilled milk, a broken toy, a scraped knee. As adults we know that kids have no clue of what constitutes a genuine problem, because inexperience greatly limits their childhood perspective. Children do not yet know that the world doesn’t revolve around them. As grown-ups, dare we admit to ourselves that we, too, have a collective immaturity of view? Dare we admit that our thoughts and behaviors spring from a belief that the world revolves around us? Apparently not. Yet evidence abounds. Part the curtains of society’s racial, ethnic, religious, national, and cultural conflicts, and you find the human ego turning the knobs and pulling the levers. Now imagine a world in which everyone, but especially people with power and influence, holds an expanded view of our place in the cosmos. With that perspective, our problems would shrink—or never arise at all—and we could celebrate our earthly differences while shunning the behavior of our predecessors who slaughtered one another because of them.

The cosmic perspective opens our minds to extraordinary ideas but does not leave them so open that our brains spill out, making us susceptible to believing anything we’re told. The

But what if the universe was always there, in a state or condition we have yet to identify—a multiverse, for instance, that continually births universes? Or what if the universe just popped into existence from nothing? Or what if everything we know and love were just a computer simulation rendered for entertainment by a superintelligent alien species? These philosophically fun ideas usually satisfy nobody. Nonetheless, they remind us that ignorance is the natural state of mind for a research scientist. People who believe they are ignorant of nothing have neither looked for, nor stumbled upon, the boundary between what is known and unknown in the universe. What we do know, and what we can assert without