Astrophysics For People In A Hurry Quotes

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.

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

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 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.

(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.)

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.

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.

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.

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

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.

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.

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

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

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.

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. †

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.

Collectively, these findings tell us it’s conceivable that life began on Mars and later seeded life on Earth, a process known as panspermia.

Dark energy is a mysterious pressure in the vacuum of space that acts in the opposite direction of gravity, forcing the universe to expand faster than it otherwise would.

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.

When Newton breached this philosophical barrier by rendering all motion comprehensible and predictable, some theologians criticized him for leaving nothing for the Creator to do.

Dark matter is a mysterious substance that has gravity but does not interact with light in any known way.

Mount Everest is about as tall as a mountain on Earth can grow before the lower rock layers succumb to their own plasticity under the mountain’s weight.

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.

There’s no doubt about it: more varieties of carbon-based molecules exist than all other kinds of molecules combined.

If all mass has gravity, does all gravity have mass? We don’t know. Maybe there’s nothing wrong with the matter, and it’s the gravity we don’t understand.

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.

…I learned in biology class that more bacteria live and work in one centimeter of my colon, than the number of people who have ever existed in the world. That kind of information makes you think twice about who–or what–is actually in charge.

To picture a pulsar, imagine the mass of the Sun packed into a ball the size of Manhattan. If that’s hard to do, then maybe it’s easier if you imagine stuffing about a billion elephants into a Chapstick casing.

No doubt about it, we’re smarter than every other living creature that ever ran, crawled, or slithered on Earth. But how smart is that?

If all mass has gravity, does all gravity have mass? We don’t know.

Without a doubt, Einstein’s greatest blunder was having declared that lambda was his greatest blunder.

night and day, a hundred billion neutrinos from the Sun pass through each square inch of your body, every second, without a trace of interaction with your body’s atoms.

I don't know about you, but the planet Saturn pops into my mind with every bite of a hamburger I take.

And sometimes I forget that powerful people rarely do all they can to help those who cannot help themselves.

What we know is that the matter we have come to love in the universe—the stuff of stars, planets, and life—is only a light frosting on the cosmic cake, modest buoys afloat in a vast cosmic ocean of something that looks like nothing.

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.

In the beginning, nearly 14 billion years ago, all the space and all the matter and all the energy of the known universe was contained in a volume less than one-trillionth the size of the period that ends this sentence.

Bosons, by the way, are named for the Indian scientist Satyendra Nath Bose.

dark matter is our frenemy.

You need to live in a nation whose government values the search to understand humanity’s place in the universe.

….. Neptune, the outermost planet. No, it’s not Pluto. Get over it.

the universe expands forever in every direction for all of time, taking on the shape of a saddle, in which initially parallel lines diverge.

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.

Explore the universe for what it is, rather than for what it seems.

Celestial happenings, however, don’t limit themselves to what’s convenient for the human retina.

[...] however big our world is - in our hearts, our minds, and our outsized digital maps - the universe is even bigger. A depressing thought to some, but a liberating thought to me.

Without the billion-and-one to a billion imbalance between matter and antimatter, all mass in the universe would have self-annihilated, leaving a cosmos made of photons and nothing else—the ultimate let-there-be-light scenario.

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.

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?

The most accurate measurements to date reveal dark energy as the most prominent thing in town, currently responsible for 68 percent of all the mass-energy in the universe; dark matter comprises 27 percent, with regular matter comprising a mere 5 percent.

I don’t know how Albert would have felt about this, but an unknown element was discovered in the debris of the first hydrogen bomb test in the Eniwetok atoll in the South Pacific, on November 1, 1952, and was named einsteinium in his honour. I might have named it armageddium instead.

In the beginning, nearly fourteen billion years ago, all the space and all the matter and all the energy of the known universe was contained in a volume less than one-trillionth the size of the period that ends this sentence. Conditions

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

But who gets to think that way? Who gets to celebrate this cosmic view of life? Not the migrant farm worker. Not the sweatshop workers. 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.

some of the water you just drank passed through the kidneys of Socrates, Genghis Khan, and Joan of Arc. How

The leptons most familiar to the non-physicist are the electron and perhaps the neutrino; and the most familiar quarks are . . . well, there are no familiar quarks.

Quarks are quirky beasts. Unlike protons, each with an electric charge of +1, and electrons, with a charge of –1, quarks have fractional charges that come in thirds.

The one we call Earth formed in a kind of Goldilocks zone around the Sun, where oceans remain largely in liquid form.

Or what if everything we know and love were just a computer simulation rendered for entertainment by a superintelligent alien species?

where data are sparse, competing ideas abound that are clever and wishful.

You could, in principle, perform this stunt if you managed to let forth a powerful and sustained exhaust of flatulence.

How about methane? It too is chemically unstable, and yes, some of it is anthropogenic, but as we've seen, methane has nonliving agents as well.

The Hubble Space Telescope has spotted aurora near the poles of both Saturn and Jupiter. And on Earth, the aurora borealis and australis (the northern and southern lights) serve as intermittent reminders of how nice it is to have a protective atmosphere.

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.

Until Sir Isaac Newton wrote down the universal law of gravitation, nobody had any reason to presume that the laws of physics at home were the same as everywhere else in the universe. Earth had earthly things going on and the heavens had heavenly things going on.

Helium is widely recognized as an over-the-counter, low-density gas that, when inhaled, temporarily increases the vibrational frequency of your windpipe and larynx, making you sound like Mickey Mouse.

The German physicist Max Planck, after whom these unimaginably small quantities are named, introduced the idea of quantized energy in 1900 and is generally credited as the father of quantum mechanics.

A modern example of this stunning knowledge of nature that Einstein has gifted us, comes from 2016, when gravitational waves were discovered by a specially designed observatory tuned for just this purpose.

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.

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.

From that day on, I began to think of people not as the masters of space and time but as participants in a great cosmic chain of being, with a direct genetic link across species both living and extinct, extending back nearly four billion years to the earliest single-celled organisms on Earth.

In an undistinguished part of the universe (the outskirts of the Virgo Supercluster), in an undistinguished galaxy (the Milky Way), in an undistinguished region (the Orion Arm), an undistinguished star (the Sun) was born.

While most branches of science have ascended in this era, the field of astrophysics persistently rises to the top. I think I know why. At one time or another every one of us has looked up at the night sky and wondered: What does it all mean? How does it all work? And, what is my place in the universe?

But it doesn’t make for good science. 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.

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.

In a trillion or so years, anyone alive in our own galaxy may know nothing of other galaxies. Our observable universe will merely comprise a system of nearby, long-lived stars within the Milky Way. And beyond this starry night will lie an endless void—darkness in the face of the deep.

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.

For reasons I have yet to understand, many people don’t like chemicals, which might explain the perennial movement to rid foods of them. Perhaps sesquipedalian chemical names just sound dangerous. But in that case we should blame the chemists, and not the chemicals themselves. 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.

Other unrelenting skeptics might declare that “seeing is believing”—an approach to life that works well in many endeavors, including mechanical engineering, fishing, and perhaps dating. It’s also good, apparently, for residents of Missouri. But it doesn’t make for good science. 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.

With only one proton in its nucleus, hydrogen is the lightest and simplest element, made entirely during the big bang. Out of the ninety-four naturally occurring elements, hydrogen lays claim to more than two-thirds of all the atoms in the human body, and more than ninety percent of all atoms in the cosmos, on all scales, right on down to the solar system.

We’ve come a long way since Herschel’s experiments with rays that were “unfit for vision,” empowering us to explore the universe for what it is, rather than for what it seems to be. Herschel would be proud. We achieved true cosmic vision only after seeing the unseeable: a dazzlingly rich collection of objects and phenomena across space and across time that we may now dream of in our philosophy.

even a scientist can’t help thinking of the Periodic Table as a zoo of one-of-a-kind animals conceived by Dr. Seuss. How else could we believe that sodium is a poisonous, reactive metal that you can cut with a butter-knife, while pure chlorine is a smelly, deadly gas, yet when added together make sodium chloride, a harmless, biologically essential compound better known as table salt? Or how about hydrogen and oxygen? One is an explosive gas, and the other promotes violent combustion, yet the two combined make liquid water, which puts out fires.

Spheres are indeed fertile theoretical tools that help us gain insight into all manner of astrophysical problems. But one should not be a sphere-zealot. I am reminded of the half-serious joke about how to increase milk production on a farm: An expert in animal husbandry might say, "Consider the role of the cow's diet..." An engineer might say, "Consider the design of the milking machines..." But it's the astrophysicist who says, "Consider a spherical cow...

When something glows from being heated, it emits light in all parts of the spectrum, but will always peak somewhere. For household lamps that still use glowing metal filaments, the bulbs all peak in the infrared, which is the single greatest contributor to their inefficiency as a source of visible light. Our senses detect infrared only in the form of warmth on our skin. The LED revolution in advanced lighting technology creates pure visible light without wasting wattage on invisible parts of the spectrum. That’s how you can get crazy-sounding sentences like: “7 Watts LED replaces 60 Watts Incandescent” on the packaging.

There's a variation of the ever popular multiverse idea in which the multiple universes that comprise it are not separate universes entirely, but isolated, non-interacting pockets of space within one continuous fabric of space time - like multiple ships at sea, far enough away from one another so that their circular horizons do not intersect. As far as any one ship is concerned (without further data), it's the only ship on the ocean, yet they all share the same body of water.

If the rocky ejecta from an impact hails from a planet with life, then microscopic fauna could have stowed away in the rocks’ nooks and crannies. Third, recent evidence suggests that shortly after the formation of our solar system, Mars was wet, and perhaps fertile, even before Earth was. Collectively, these findings tell us it’s conceivable that life began on Mars and later seeded life on Earth, a process known as panspermia. So all Earthlings might—just might—be descendants of Martians.

By day, contrary to common wisdom, you probably won’t see the Great Pyramids at Giza, and you certainly won’t see the Great Wall of China. Their obscurity is partly the result of having been made from the soil and stone of the surrounding landscape. And although the Great Wall is thousands of miles long, it’s only about twenty feet wide—much narrower than the U.S. interstate highways you can barely see from a transcontinental jet. From orbit, with the unaided eye, you would have seen smoke plumes rising from the oil-field fires in Kuwait at the end of the first Persian Gulf War in 1991 and smoke from the burning World Trade Center towers in New York City on September 11, 2001. You will also notice the green–brown boundaries between swaths of irrigated and arid land. Beyond that shortlist, there’s not much else made by humans that’s identifiable from hundreds of miles up in the sky. You can see plenty of natural scenery, though, including hurricanes in the Gulf of Mexico, ice floes in the North Atlantic, and volcanic eruptions wherever they occur.

Only three of the naturally occurring elements were manufactured in the big bang. The rest were forged in the high-temperature hearts and explosive remains of dying stars, enabling subsequent generations of star systems to incorporate this enrichment, forming planets and, in our case, people. For many, the Periodic Table of Chemical Elements is a forgotten oddity—a chart of boxes filled with mysterious, cryptic letters last encountered on the wall of high school chemistry class. As the organizing principle for the chemical behavior of all known and yet-to-be-discovered elements in the universe, the table instead ought to be a cultural icon, a testimony to the enterprise of science as an international human adventure conducted in laboratories, particle accelerators, and on the frontier of the cosmos itself.

Along with osmium and platinum, iridium is one of the three heaviest (densest) elements on the Table—two cubic feet of it weighs as much as a Buick, which makes iridium one of the world’s best paperweights, able to defy all known office fans. Iridium is also the world’s most famous smoking gun. A thin layer of it can be found worldwide at the famous Cretaceous-Paleogene (K-Pg) boundary† in geological strata, dating from sixty-five million years ago. Not so coincidentally, that’s when every land species larger than a carry-on suitcase went extinct, including the legendary dinosaurs. Iridium is rare on Earth’s surface but relatively common in six-mile metallic asteroids, which, upon colliding with Earth, vaporize on impact, scattering their atoms across Earth’s surface. So, whatever might have been your favorite theory for offing the dinosaurs, a killer asteroid the size of Mount Everest from outer space should be at the top of your list.

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. 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.

For the first billion years, the universe continued to expand and cool as matter gravitated into the massive concentrations we call galaxies. Nearly a hundred billion of them formed, each containing hundreds of billions of stars that undergo thermonuclear fusion in their cores. Those stars with more than about ten times the mass of the Sun achieve sufficient pressure and temperature in their cores to manufacture dozens of elements heavier than hydrogen, including those that compose planets and whatever life may thrive upon them. These elements would be stunningly useless were they to remain where they formed. But high-mass stars fortuitously explode, scattering their chemically enriched guts throughout the galaxy. After nine billion years of such enrichment, in an undistinguished part of the universe (the outskirts of the Virgo Supercluster) in an undistinguished galaxy (the Milky Way) in an undistinguished region (the Orion Arm), an undistinguished star (the Sun) was born. The

We use the effect of centrifugal forces on matter to offer insight into the rotation rate of extreme cosmic objects. Consider pulsars. With some rotating at upward of a thousand revolutions per second, we know that they cannot be made of household ingredients, or they would spin themselves apart. In fact, if a pulsar rotated any faster, say 4,500 revolutions per second, its equator would be moving at the speed of light, which tells you that this material is unlike any other. To picture a pulsar, imagine the mass of the Sun packed into a ball the size of Manhattan. If that’s hard to do, then maybe it’s easier if you imagine stuffing about a hundred million elephants into a Chapstick casing. To reach this density, you must compress all the empty space that atoms enjoy around their nucleus and among their orbiting electrons. Doing so will crush nearly all (negatively charged) electrons into (positively charged) protons, creating a ball of (neutrally charged) neutrons with a crazy-high surface gravity. Under such conditions, a neutron star’s mountain range needn’t be any taller than the thickness of a sheet of paper for you to exert more energy climbing it than a rock climber on Earth would exert ascending a three-thousand-mile-high cliff. In short, where gravity is high, the high places tend to fall, filling in the low places—a phenomenon that sounds almost biblical, in preparing the way for the Lord: “Every valley shall be raised up, every mountain and hill made low; the rough ground shall become level, the rugged places a plain” (Isaiah 40:4). That’s a recipe for a sphere if there ever was one. For all these reasons, we expect pulsars to be the most perfectly shaped spheres in the universe.

Another class of universal truths is the conservation laws, where the amount of some measured quantity remains unchanged no matter what. The three most important are the conservation of mass and energy, the conservation of linear and angular momentum, and the conservation of electric charge. These laws are in evidence on Earth, and everywhere we have thought to look—from the domain of particle physics to the large-scale structure of the universe. In spite of this boasting, all is not perfect in paradise. It happens that we cannot see, touch, or taste the source of eighty-five percent of the gravity we measure in the universe. This mysterious dark matter, which remains undetected except for its gravitational pull on matter we see, may be composed of exotic particles that we have yet to discover or identify. A small minority of astrophysicists, however, are unconvinced and have suggested that there is no dark matter—you just need to modify Newton’s law of gravity. Simply add a few components to the equations and all will be well. Perhaps

The stars of the Milky Way galaxy trace a big, flat circle. With a diameter-to-thickness ratio of one thousand to one, our galaxy is flatter than the flattest flapjacks ever made. In fact, its proportions are better represented by a crépe or a tortilla. No, the Milky Way’s disk is not a sphere, but it probably began as one. We can understand the flatness by assuming the galaxy was once a big, spherical, slowly rotating ball of collapsing gas. During the collapse, the ball spun faster and faster, just as spinning figure skaters do when they draw their arms inward to increase their rotation rate. The galaxy naturally flattened pole-to-pole while the increasing centrifugal forces in the middle prevented collapse at midplane. Yes, if the Pillsbury Doughboy were a figure skater, then fast spins would be a high-risk activity. Any stars that happened to be formed within the Milky Way cloud before the collapse maintained large, plunging orbits. The remaining gas, which easily sticks to itself, like a mid-air collision of two hot marshmallows, got pinned at the mid-plane and is responsible for all subsequent generations of stars, including the Sun. The current Milky Way, which is neither collapsing nor expanding, is a gravitationally mature system where one can think of the orbiting stars above and below the disk as the skeletal remains of the original spherical gas cloud. This general flattening of objects that rotate is why Earth’s pole-to-pole diameter is smaller than its diameter at the equator. Not by much: three-tenths of one percent—about twenty-six miles. But Earth is small, mostly solid, and doesn’t rotate all that fast. At twenty-four hours per day, Earth carries anything on its equator at a mere 1,000 miles per hour. Consider the jumbo, fast-rotating, gaseous planet Saturn. Completing a day in just ten and a half hours, its equator revolves at 22,000 miles per hour and its pole-to-pole dimension is a full ten percent flatter than its middle, a difference noticeable even through a small amateur telescope. Flattened spheres are more generally called oblate spheroids, while spheres that are elongated pole-to-pole are called prolate. In everyday life, hamburgers and hot dogs make excellent (although somewhat extreme) examples of each shape. I don’t know about you, but the planet Saturn pops into my mind with every bite of a hamburger I take.