47 results
1 - The awakening of astronomy
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp 1-16
-
- Chapter
- Export citation
-
Summary
Some 7 million years ago, a group of creatures made its way across the plains of central Africa. Resembling at first a collection of savannah baboons, the 30 or so beings shuffled along as dusk began to fall over a clearing in what we now call Chad. Adult females and flocks of offspring made up the nucleus of this foray, with a few mature males following up and looking for mating opportunities. As darkness began to fall, the group approached a cave that held a common shelter, and light from the Moon blazed down onto what now appeared like black, slumped forms – dirty, disheveled, hairy, and marked by spots of blood from the day's successful hunt.
These earliest hominids, perhaps Sahelanthropus, were the first bipedals, and walked more or less upright. They stand among the earliest creatures known from around the time of the human/chimpanzee divergence, when our ancestors began to make their own lineage that would one day lead to Homo sapiens. As these creatures, primitive by today's standards, shambled back to their nightly caves, they no doubt occasionally looked skyward, at the Moon and the stars. Perhaps they wondered what those lights in the sky meant. Somewhere around this time, some kind of creatures like Sahelanthropus became the first early human ancestors to ponder what space above meant to them.
Human knowledge about astronomy awakened painfully slowly, however. The earliest thoughts about the sky resulting in evidence we can examine were probably related to calendars and monuments, or tools for the planting and harvesting of crops, once humans became farmers. Although they weren't observatories per se, Stonehenge and other ritual Neolithic and Bronze Age sites betray a basic knowledge of the heavens. Egyptian, Spanish, Mexican, Irish, and Scottish stone structures nicely record celestial alignments. Stars no doubt also served as navigational tools for early explorers on land and on water.
Like all sciences, astronomy emerged from a primitive root that stunted progress for centuries – in this case, astrology. But as ideas emerged slowly and the astronomy of Antiquity began to inch forward, astronomy was a science of classification.
13 - The mystery of dark matter
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp 171-183
-
- Chapter
- Export citation
-
Summary
Despite the incredible advances in so many areas of astronomy over the past generation, some things remain works in progress. One of these is the mystery of dark matter, one of the fundamental components of the universe. Cosmological results in 2013 made by the Planck spacecraft team suggest the newest breakdown of the composition (mass-energy) of the universe as 4.9 percent ordinary or baryonic matter, 26.8 percent dark matter, and 68.3 percent dark energy. The story of the nearly opaque mystery of dark energy follows in the next chapter. For now, we'll explore the strange stuff that cosmologists know exists but the nature of which remains murky – dark matter.
In the early part of the twentieth century, not long after the basic cosmic distance scale and the nature of galaxies as separate “island universes” was discovered, astronomers began to stumble on clues from several directions that the bright stuff they saw in the cosmos wasn't the whole story. In 1932, Dutch astronomer Jan H. Oort (1900–1992), later to become famous for his hypothesized cloud of comets surrounding the solar system, was busily studying the motions of stars in the Sun's neighborhood. He determined that the mass of the Milky Way must amount to more than the luminous disk, the halo, and globular clusters. But a short time later, astronomers had serious doubts about the measurements.
Soon thereafter, Swiss astronomer Fritz Zwicky (1898–1974), a colorful, clever, and cantankerous fellow, took up the problem, and Zwicky was an amazing thinker and true innovator. While at the California Institute of Technology, Zwicky studied several clusters of galaxies and found that their masses must have been greater than the visible light they emitted could account for.
In a famous paper published in 1937, Zwicky suggested the possible existence of dark matter, calling it dunkle Materie, and shared the observations he had made over previous years of a variety of galaxy clusters. He didn't really push the idea, but raised it as one possible solution to the observations.
In the grand tradition of nineteenth-century science, Zwicky had become the first astronomer to widely observe and analyze a range of clusters of galaxies, cataloguing them, studying their compositions, and suggesting that some unseen material must be present to explain the orbits of the individual galaxy members, which without the unseen material would fly off into intergalactic space.
Dedication
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp v-vi
-
- Chapter
- Export citation
10 - Here comes Milkomeda
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp 132-144
-
- Chapter
- Export citation
-
Summary
Not only do we now understand the basic structure of our galaxy well, but also recent years have unveiled the fate of the Milky Way. While the universe is expanding and on large scales, objects are moving apart from each other, on smaller scales gravity and local motions can bring objects together. Astronomers have seen evidence of interactions, collisions, and mergers of galaxies in numerous dense groups and clusters of galaxies. In fact, galaxy mergers are common mainly near the dense center of a cluster, contributing to the growth of the most massive galaxy (called a cD galaxy), which lies at the cluster's heart. In such groups, driven by gravity, galaxies eat each other. Larger galaxies can become larger and larger over time, giving these collections of stars, gas, and dust the ability to grow into massive bodies far more massive than their original mass.
We do not live in a dense cluster of galaxies like the Hercules Cluster, the Virgo Cluster, or the Coma Cluster. But even in our loose and small group of galaxies we have experienced – and will experience – mergers. To understand why, you first need to understand the dynamics of our own galaxy group.
Just more than a decade after his discovery of a Cepheid variable star in the Andromeda “nebula,” since known as the Andromeda Galaxy (M31), Edwin P. Hubble defined the nearest galaxies to us as the Local Group of galaxies, explained in his 1936 work The Realm of the Nebulae. The first nine members Hubble identified in our little group were the Milky Way, the Large Magellanic Cloud, the Small Magellanic Cloud, the Andromeda Galaxy, M32, NGC 205, the Pinwheel Galaxy (M33), Barnard's Galaxy (NGC 6822), and IC 1613. He listed as possible members IC 10, IC 342, and NGC 6946. In 1936, Hubble knew of nine members and perhaps as many as twelve.
Nearly 80 years later, we know a vast amount more about the Local Group of galaxies. The Local Group contains at least 50 galaxies, and astronomers are discovering tiny Local Group galaxies every now and then. There may be more than 100 galaxies in the group, spanning a sphere of space some 10 million light-years across.
14 - The bigger mystery of dark energy
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp 184-197
-
- Chapter
- Export citation
-
Summary
As we touched on in the last chapter, the apple cart of cosmology was upset in a brutal and surprising way in 1998, with the observations of distant supernovae, exploding stars, by two big teams of research astronomers. Their discovery revealed the mysterious force that is accelerating the expansion of the cosmos and came to be known as dark energy. This is a crucially important area of cosmology and astrophysics, as recent observational results suggest that approximately two-thirds of the energy/mass of the universe consists of dark energy. So for the last 17 years, astronomers have realized they know very little about what most of the universe is composed of.
The discovery took the astronomy world by storm. But the seeds of the dark energy idea began much farther back in time, to be precise in 1915, actually a century ago. Prior to this, the universe was one of mechanical physics, of Isaac Newton's absolute, predictable cosmos that worked like a clock, independent of other factors. In 1905, German physicist Albert Einstein (1879–1955) began to overturn this, with his Special Theory of Relativity. In 1915, Einstein, late in the year, presented his General Theory of Relativity to an audience in Berlin. Einstein, driven in something of a race with potential competitors, unveiled his equations that not only introduced relativity but also described how space-time is distorted by mass, how mass moves around in gravitational fields, and the many forms of motion in the cosmos as observed by different frames of reference.
Einstein freed the world from seeing the universe in a Newtonian way, a cosmos beset by hard, unchanging geometry and now transformed from fixed coordinate grids to a changing, dynamic system in which space and time are linked and transform in various ways as codependents. That most important Einsteinian equation, E=mc2, was merely the simplest, and it did indeed reveal that matter and energy in the cosmos are coequals, the same thing, in different forms, and that matter can be converted into energy and vice versa. (Your metabolizing this morning's breakfast is one proof of this.) But Einstein provided many other field equations that supported his theories, and he did not ultimately solve them all.
3 - The end of life on Earth
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp 32-46
-
- Chapter
- Export citation
-
Summary
Our planet experienced a very violent early history. As planetesimals, comets, and asteroids crowded the inner solar system and rocked early Earth with numerous collisions, the infant Earth cooled and began to settle down. Unlike the decades-long perception that early Earth was a hot, volcanic mess, coated with numerous flows of lava, evidence now shows that the early history of the planet was dominated by a cool environment and with ample liquid ocean water.
Planetary scientists believe the scene turned somewhat ugly again during the so-called Late-Heavy Bombardment, a hypothesized period 4.1 to 3.8 billion years ago when scads of asteroids and comets rained in on our planet's surface, and on all the other young bodies of the inner solar system. This was long after Earth and the other planets accreted; but evidence for this period of bombardment exists from the Apollo Moon rock samples, which show a majority of melt-rocks on the Moon forming during this window. During this earliest, violent period of planetary formation, life on Earth was probably impossible.
But following the Late Heavy Bombardment, the story soon changed, and one day life arose on Earth. Our planet's age is thought to be about 4.54 billion years, based on the radiometric dating of meteoritic samples along with the oldest known Earth and Moon rocks. The oldest known Earth rocks, specifically, are those dated to 4.4 billion years from the Jack Hills region of Western Australia, betrayed by radioactive impurities in the zircon crystals they contain. The earliest microfossils known on Earth also come from Western Australia, from the so-called Strelley Pool formation, one of the oldest outcrops of sedimentary rock on the planet, and were discovered in 2011. They are primitive cyanobacteria, some 3.4 billion years old, and are the oldest known life we have. Spherical, oval, and tubular shaped, they span a mere hundredth of a millimeter across. Specimens that are more controversial could push the age back to 3.9 billion years, but they are as yet unconfirmed.
Scientists are just beginning to understand the complexity of how life arose on Earth, and how quickly it might have arisen.
6 - Why did Venus turn inside-out?
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp 75-88
-
- Chapter
- Export citation
-
Summary
Venus is unmistakable in our skies. Never straying terribly far from the Sun, it blazes brilliantly in the evening and morning skies, shining as brightly as magnitude –4.6, the most luminous permanent object after the Sun and Moon. Long called Earth's “sister planet,” the similarity is slight. It lies relatively close to us in the solar system, the next planet inward toward the Sun. Like Earth, it is a terrestrial planet, a predominantly rocky body, is about the same size as Earth, just about 95 percent the diameter of our planet, and contains about 82 percent of Earth's mass. But that's where the similarity ends. In most respects, Venus could hardly be any more different than Earth.
On this world that lies about 30 percent closer to the Sun than Earth, ironies abound. They begin even with the planet's name, which comes from the Roman goddess of love and beauty. When this bright and mesmerizing light wandering among the stars was named, the idea might have made sense. But early spacecraft studies of Venus betrayed the hellish nature of the planet.
Venus played a key role in the turning point of understanding the solar system in 1609, when Galileo Galilei observed it with his newly constructed telescope, from Padua, Italy. Galileo watched the planet and sketched it over the course of months, seeing that it underwent phases analogously to the Moon.
But the nature of Venus itself remained largely mysterious until the first spacecraft missions visited the planet in the 1960s. The first such probe, the Soviet Venera 1, was launched in early 1961. Mission successes were slow, from both the Soviet Union and the United States, marked by spacecraft failures. In 1962, the US craft Mariner 2 became the first successful interplanetary mission, measuring the surface temperature of Venus to be a searing 425 °C (800 °F), and ending speculation that the planet might harbor life.
In 1966, the Soviet Venera 3 probe became the first spacecraft to enter the atmosphere and crash land on the surface of another planet.
8 - Planets everywhere…
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp 103-116
-
- Chapter
- Export citation
-
Summary
Few areas of astronomy or astrophysics have been as explosive over recent years as the cottage industry of extrasolar planet discoveries. At the time of writing in early 2015, astronomers know of more than 1,800 planets orbiting more than 1,100 stars other than the Sun, all relatively nearby in the Milky Way Galaxy. The most productive discoverer of exoplanets, NASA's Kepler spacecraft, has produced a total of some 1,000 confirmed exoplanets and 2,900 exoplanet candidates that await confirmation with additional data. The pace of discoveries and confirmations has been so dizzying ‒ especially during the busiest periods of analyzing data from various instruments dedicated to the task ‒ that the count of exoplanets has changed from week to week.
Speculations and crude research on the existence of planets beyond the solar system go back a long way. In the sixteenth century, Italian philosopher Giordano Bruno (1548–1600) speculated on the “infinity of worlds” that should exist out in the vastness of the stars. Similarly, in the conclusion of his fantastic tome Principia Mathematica, Isaac Newton suggested that stars are the centers of systems like the Sun and planets.
The first claims of a detection of exoplanets rolled along in the nineteenth century. Claims of detecting a “dark body” affecting the orbit of the star 70 Ophiuchi, a 4th-magnitude star lying 16.6 light-years distant, stretch back to 1855, when observers at the East India Company's Madras Observatory reported wobbles in the star's position in the sky. Similarly, American astronomer Thomas Jefferson Jackson See (1866–1962), an eccentric underachiever, claimed observations that proved such a body in 70 Oph throughout the 1890s. But these were subsequently discredited. Sixty years later, Dutch astronomer Peter van de Kamp (1901–1995), working at Swarthmore College's Sproul Observatory, claimed detection of a planet orbiting another close star, Barnard's Star. This star, also in Ophiuchus, has the highest degree of motion relative to the background stars in the sky, at a distance of only 6.0 light-years. But the van de Kamp observations also proved to be erroneous.
The first confirmed detection of a planet outside the solar system was announced in 1992, when Polish‒American astronomer Aleksander Wolszczan (1946–) and Canadian–American astronomer Dale Frail described their detection of two planets orbiting the pulsar PSR B1257+12.
Glossary
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp 239-258
-
- Chapter
- Export citation
Contents
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp vii-viii
-
- Chapter
- Export citation
16 - What is the universe's fate?
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp 212-223
-
- Chapter
- Export citation
-
Summary
Astronomy and astrophysics are filled with countless questions, and are slowly gaining some pretty impressive answers. Certainly, one of the most fundamental questions of all, one that stretches back perhaps the longest in philosophical terms in the human mind, is one of the simplest: What will become of the universe?
This elegant question is not an easy one to answer. We know that as we look out into space, we're looking back into time. The distant universe is a snapshot of what existed billions of years ago, and we do not have an accurate picture of many of the objects we see as they really are now, at this exact point in time. Knowing the status of objects in the universe in the “here and now” works very well for our solar system, for Earth, the Sun, and our family of planets, asteroids, and comets. But as we look progressively out even into our Milky Way Galaxy, we begin to see things as they were, more so as distances increase. So how do we predict what will happen well down the road in the universe's future? To predict how the cosmos will end? It is a stupefyingly difficult problem.
To predict the universe's future, astronomers would like to know all about its current physical parameters, as well as the models of cosmology that they believe most strongly in. We have already seen that the current size of the universe is at least 46 billion light-years in each direction from where we are, and that it could be larger yet if cosmic inflation theory is correct, which nearly everyone believes is so. What about the shape of space? According to general relativity, space is curved by a degree set by the average density of matter within it. So exactly how dense the universe is becomes a really big question. Space might be flat, positively curved like a balloon, or negatively curved like an equestrian saddle.
But actually measuring the shape of space is really tough. Measuring distances to and velocities of countless stars and galaxies failed to provide the answer to the universe's shape. Instead, cosmologists now look to the cosmic microwave background radiation, and subtle variabilities within it, to infer the shape of the cosmos.
5 - Where has all the water gone?
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp 61-74
-
- Chapter
- Export citation
-
Summary
Deciphering weather and global climate on another planet is not easy. As anyone knows from watching local news meteorologists, it is not easy right here on Earth. Mars, the Red Planet, is a special partner in the solar system, being a terrestrial world that is relatively close by and characterized by a desert-like climate, sandy dunes, wind storms, polar ice caps, and other features that make it seem similar to various locales on Earth.
But in reality, Mars is terrifically different than our world. With an equatorial diameter of 6,792 kilometers, the Red Planet is slightly more than half Earth's size, and it contains only a tenth of Earth's mass. The martian orbit carries it around the Sun once every 687 days, making its year equivalent to 1.9 Earth years.
Like Earth, Mars is differentiated – that is, it has a dense metallic core overlain by a rocky mantle. The planet's familiar orange color comes from copious amounts of iron oxide, like rust, richly coating the planet's rocks. Mars’ two moons, Phobos and Deimos, were discovered by American astronomer Asaph Hall (1829–1907) at the US Naval Observatory in 1877; they are probably captured asteroids, and measure a mere 27 by 22 by 18 kilometers (Phobos) and 15 by 12 by 10 kilometers (Deimos). Alternatively, some planetary scientists believe they may be pieces of Mars from large impacts.
Over the years, spacecraft missions have added enormously to our understanding of Mars. Missions got off to a rocky start, however. Following a series of unsuccessful missions by the Soviet Union and the failed US probe Mariner 3, the first flyby of Mars took place when the Mariner 4 spacecraft flew past the Red Planet in 1965. Mariner 9 produced a flood of martian imaging in 1971–1972. Substantial progress commenced with the US Viking 1 and Viking 2 landers, which touched down on Mars in 1976 and conducted various experiments. More significantly than the landers, however, were the Viking orbiters, which conducted vast amounts of science after the landers proved somewhat disappointing.
Twenty years later, in 1997, the Americans landed the Mars Pathfinder spacecraft in Chryse Planitia, a smooth circular plain. The craft consisted of the Carl Sagan Memorial Station, named after the then recently deceased astronomer, and a small rover called Sojourner.
Acknowledgments
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp xvii-xviii
-
- Chapter
- Export citation
Preface
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp xi-xvi
-
- Chapter
- Export citation
-
Summary
I was a child of Cosmos.
My youth seemed connected to Carl Sagan. When I was 14, I attended my first “star party” by accident, catching a glimpse of Saturn and other attractions in a small reflecting telescope, and that moment changed the world for me. I became active in the local astronomy club in Oxford, Ohio, a small university town where my father was a professor of organic chemistry at Miami University. The local club needed a writer on deep-sky objects – star clusters, nebulae, and galaxies – and recruited me. Soon I was so entranced with writing about these mysterious creatures of the universe beyond our solar system that I started an amateur publication, Deep Sky Monthly, that had its genesis on the mimeograph machine in my father's chemistry office. It was the summer of 1977, and I was 2 months shy of 16.
During the first months of producing a publication for astronomy enthusiasts, while in high school, I wrote Professor Carl Sagan at Cornell University, letting him know about the publication and seeking career advice. He very graciously replied with the first of a number of letters. This was during his time as a celebrated astronomy figure – he periodically shared enthusiasm with Johnny Carson on The Tonight Show – but before his production of the legendary Cosmos TV program.
On June 6, 1977, Carl wrote me his first letter. His wisdom, encouragement, generosity, and positive spirit during every encounter we had from that moment on were a major factor in my pursuit of astronomy. “I am delighted to hear from a 15-year-old who is already so active in astronomy,” he wrote, and after paragraphs of advice, he closed with “With all good wishes on your career.”
My admiration for Carl Sagan grew throughout our correspondence and I beamed with pride in knowing Carl during the airing of his Cosmos series on PBS TV in 1980. The show premiered on Sunday, September 28, 1980, and I rushed inside after a busy day, a pleasant 72 °F in Oxford, to turn on the TV just in time for that haunting theme music by Vangelis.
“The cosmos is all there is, or ever was, or ever will be,” said Carl in his opening sequence.
The New Cosmos
- Answering Astronomy's Big Questions
- David J. Eicher
- Foreword by Alex Filippenko
-
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015
-
Over the past decade, astronomers, planetary scientists, and cosmologists have answered - or are closing in on the answers to - some of the biggest questions about the universe. David J. Eicher presents a spectacular exploration of the cosmos that provides a balanced and precise view of the latest discoveries. Detailed and entertaining narratives on compelling topics such as how the Sun will die, the end of life on Earth, why Venus turned itself inside-out, the Big Bang Theory, the mysteries of dark matter and dark energy, and the meaning of life in the universe are supported by numerous color illustrations including photos, maps and explanatory diagrams. In each chapter the author sets out the scientific history of a specific question or problem, before tracing the modern observations and evidence in order to solve it. Join David J. Eicher on this fascinating journey through the cosmos!
12 - How large is the universe?
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp 157-170
-
- Chapter
- Export citation
-
Summary
It is absolutely amazing to know that shortly after the Big Bang, the universe was a relatively small, nearly infinitely dense place. It boggles the mind. But that was 13.8 billion years ago. The expanding universe means the entirety of what we know is now incredibly large, and is getting larger every day.
This is one area that two generations of science fiction movies have seriously distorted in the minds of the public at large. The general feeling that technology is pretty good and will know almost no bounds, and that we can almost certainly one day travel between star systems, are pretty much taken on faith. But what the sci-fi movies have failed to communicate, among other things, is that the universe is an INCREDIBLY LARGE place. Even distances between the very nearest objects are staggering, and the distances across the Milky Way Galaxy and certainly between galaxies in the universe are astonishingly huge to living beings stuck on a planet. A model of the Milky Way wherein the Sun is a grain of sand brings this home. On this scale, stars – sand grains – are 6 kilometers apart in the Milky Way's disk and the disk is about 60,000 kilometers across. Now who wants to go traveling from grain to grain?
The concept of the size of the universe has taken a huge stride forward in just the last few years. There was a time not too long ago when astronomers did not know even the approximate size of the cosmos with any degree of accuracy. We still don't know with high precision. The universe may be infinite.
The Big Bang Theory reminds us that once the universe was very small. We know the fastest radiation or any information can travel is the speed of light, 300 million m/s (186,000 miles per second). We also know the universe is 13.8 billion years old. We also know that a light-year is equal to approximately 9.4 trillion kilometers, or 6 trillion miles. In nearly 14 billion years, on first blush, we might expect radiation to expand radially outward to something like 30 billion light-years across.
Index
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp 264-279
-
- Chapter
- Export citation
Bibliography
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp 259-263
-
- Chapter
- Export citation
15 - Black holes are ubiquitous
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp 198-211
-
- Chapter
- Export citation
-
Summary
The best summary line about black holes I've ever heard came from the American theoretical physicist Kip S. Thorne (1940–), who described them during his talk at the first Starmus Festival in 2011: “The brightest objects in the universe – but no light!” That simple statement reveals much about the bizarre nature of black holes, objects of such intense gravity that nothing – not even light – can escape from them. Black holes are certainly among the favorite and most alluring objects in the universe for many astronomy enthusiasts, the subject of almost endless mystery and speculation. The reality of black holes is even stranger than the limited ideas many people have about them.
The knowledge base about black holes is of very recent vintage. When I joined the staff of Astronomy magazine in 1982, black holes were mostly a rumor. (The Milky Way black hole candidate Cygnus X-1 had been identified but not confirmed as a black hole; and astronomers believed quasars contained black holes, but had not yet confirmed that.) That was the case despite the fact that the conceptual ideas for these objects stretch back more than 230 years, to the English natural philosopher and clergyman John Michell (1724–1793). In a 1783 paper he wrote for the Philosophical Transactions of the Royal Society in London, Michell proposed the idea of “dark stars,” objects of such strong gravitational pull that nothing, including light, could escape them, and therefore the stars would be invisible.
In a visionary way, Michell even wrote that because such stars would be invisible, they would have to be detected from their effects on other objects around them, as with stars in a binary system in which one star had become “dark.” Several years after Michell's ideas were published, the great French mathematician and astronomer Pierre-Simon Laplace (1749–1827) also wrote about the same concepts in a book published in 1796.
Yet the evidence for black holes was extraordinarily slow in arriving. And the term black hole was not yet coined until relatively recent times.
Frontmatter
- David J. Eicher
- Foreword by Alex Filippenko, University of California, Berkeley
-
- Book:
- The New Cosmos
- Published online:
- 05 December 2015
- Print publication:
- 03 December 2015, pp i-iv
-
- Chapter
- Export citation