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- Gravity’s Engines: How Bubble-Blowing Black Holes Rule Galaxies, Stars and Life in the Cosmos!
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The only way to detect these lords of gravity is by looking for the energy from the shock waves created as they gulp down matter. Thanks to X-ray telescopes like the Chandra Space Telescope, astronomers have found energy coming from the hearts of galaxies, including our own Milky Way. After a quick, nontechnical overview of how black holes are created, Scharf discusses how they power galactic dynamics. The most massive grow dim relatively quickly, exhausting their food supply, while a smaller black hole can burn for billions of years, varying from simmering beast to blazing pyre and back.
They cast off ripples of energy, pushing galactic dust and gases outward and slowing stellar formation. Scharf s explanations are vivid and accessible, evoking the awe of cosmic grandeur in a way that s as humbling as it is fascinating. The Copernicus Complex. The Zoomable Universe.
For others it is more a means to an end, a way to provision ourselves with the things that bring comfort, joy, and even some peace. Nonetheless, we should all consider taking just a moment now and then to stop and gaze skyward. As tiny as we are, our lives are tied intricately into an amazing and grand cosmos. This is our heritage. We should be proud and satisfied with our place in it, and never put aside our curiosity about it. A computer sits among the coffee-stained papers scattered across my desk. Its screen has been blank all morning. Suddenly it lights up and displays a pixelated image.
A message is coming in from space. With chilled eyes it has patiently tracked a tiny patch of the cosmos, a speck of sky close to the constellation Auriga—the Charioteer. In this direction is a glorious view for a spotter peering into the abyss in the hope of finding treasure. This remarkable instrument is called Chandra.
Decades of work went into its construction, with hundreds of people toiling in multiple countries. The blood, sweat, love, and tears of a highly technological civilization produced the smooth surfaces and exquisitely precise devices inside it. Careers started and ended while it grew from a dream into a reality. Now it has captured a whiff of something from the deep. Photons, particles of light, have found their way down through its mirrors and filters, forming an image on the silicon sensor of a digital camera.
That image, encoded as a stream of data, has passed to Earth, first beamed as microwaves to a ground station and then relayed around the globe.
Processed and sent on across a continent, another journey through hundreds of miles of wires and fiber optics, it finally re-forms as a monochrome picture on a screen in my small and untidy office ten floors above the streets of twenty-first-century Manhattan. Patience is a hard-won lesson.
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Yet there, amid the rough noise of the image, is a structure. I can see a pinpoint of light surrounded by something else—a fuzzy streak jutting out to the left and right. It looks like a small dragonfly pinned to a piece of cardboard. Something is very curious about this image. It has the flavor of a new species.
Traffic out on the street echoes noisily up the canyon of buildings, but for an instant it rings hollow. My mind is not in this world anymore, but away in a very, very distant corner of the universe.
Gravity's engines : how bubble-blowing black holes rule
Twelve billion years ago, the photons that made this image began their journey. They are X-rays, invisible to human eyes, but able to penetrate through our soft bodies. For 12 billion years they have passed unimpeded through the cosmos.
But as they have traveled, the universe has changed; space itself has expanded, stretching the photon waveforms and cooling them to a lower energy. When they set out there is no star called the Sun, no planet called Earth.
When Earth forms, these photons are already ancient, 7-billion-year-old particles that have traversed vast stretches of the cosmos. Time passes. Somewhere on Earth a complex set of molecular structures begins to self-replicate: life begins. Two billion years later, the photons start to enter the very outer regions of what we might call the known universe. Here are the great superclusters and web-like structures of galaxies that we have mapped. Spanning tens of millions to hundreds of millions of light-years, these forms are the skeletons upon which galaxies and stars are coalescing, molded by gravity—millions of galaxies, and quintillions of stars, strung through the cosmos.
On Earth, microbial evolution has just given rise to the first cells of a new type of life—the Eukarya, our direct ancestors. These busy microscopic creatures swim off in search of food. A billion more years go by. The photons enter truly known space, a realm where our instruments have mapped great walls of galaxies and huge empty voids. Here are structures with familiar names and calling cards, like Abell and Zwicky , huge gravitational swarms of galaxies known as clusters. On Earth the very first true multicellular life emerges, and the air is filling with oxygen.
The chemistry of this element is ferocious. New types of metabolism are evolving in response—a revolution is under way. Just million years later, the dry surfaces of Earth are covered by something exotic: plants that use the molecular tools of photosynthesis. A strange, greenish tint appears across the supercontinent Gondwana, the largest body of land on the planet. The photons continue their patient journey, passing through regions that will be increasingly familiar to as yet unevolved astronomers.
Nearby are the great galaxy clusters we will name for the constellations in which we see them: Coma, Centaurus, and Hydra. Onward the photons fly, and from the point of view of an observer standing to the side as they race past, our galaxy is now one of thousands of patches of light in the sky ahead. It takes them another million years to reach our Local Group, a ragtag band of galaxies. It is not a particularly remarkable place, perhaps a total of a few trillion or so stars altogether. On Earth many great periods of life have come and gone.
The dinosaurs have not been seen for almost 60 million years. The continents and oceans have changed dramatically, and the contours of our modern world are clearly visible. Birds and mammals are swarming across the globe.
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In the next few million years, the photons descend into the gravity well of our galactic neighborhood. The Milky Way, like most galaxies, has a supermassive black hole at its core. It is an active black hole, but fortunately spews that energy away from the Earth, sparing us from bursts of X-rays and gamma rays that are not conducive to life. Black holes are clearly more than astronomical curiosities that stimulate the imagination.
They are objects that have made the universe we live in possible.