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Our Cosmic Habitat

Our Cosmic Habitat

Copyright Date: 2001
Pages: 224
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  • Book Info
    Our Cosmic Habitat
    Book Description:

    Our universe seems strangely ''biophilic,'' or hospitable to life. Is this happenstance, providence, or coincidence? According to cosmologist Martin Rees, the answer depends on the answer to another question, the one posed by Einstein's famous remark: ''What interests me most is whether God could have made the world differently.'' This highly engaging book explores the fascinating consequences of the answer being ''yes.'' Rees explores the notion that our universe is just a part of a vast ''multiverse,'' or ensemble of universes, in which most of the other universes are lifeless. What we call the laws of nature would then be no more than local bylaws, imposed in the aftermath of our own Big Bang. In this scenario, our cosmic habitat would be a special, possibly unique universe where the prevailing laws of physics allowed life to emerge.

    Rees begins by exploring the nature of our solar system and examining a range of related issues such as whether our universe is or isn't infinite. He asks, for example: How likely is life? How credible is the Big Bang theory? Rees then peers into the long-range cosmic future before tracing the causal chain backward to the beginning. He concludes by trying to untangle the paradoxical notion that our entire universe, stretching 10 billion light-years in all directions, emerged from an infinitesimal speck.

    As Rees argues, we may already have intimations of other universes. But the fate of the multiverse concept depends on the still-unknown bedrock nature of space and time on scales a trillion trillion times smaller than atoms, in the realm governed by the quantum physics of gravity. Expanding our comprehension of the cosmos, Our Cosmic Habitat will be read and enjoyed by all those--scientists and nonscientists alike--who are as fascinated by the universe we inhabit as is the author himself.

    eISBN: 978-1-4008-4107-3
    Subjects: Astronomy

Table of Contents

  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-viii)
    (pp. ix-x)
  4. PROLOGUE “Could God Have Made the World Any Differently?”
    (pp. xi-xviii)

    The preeminent mystery is why anything exists at all. What breathes life into the equations of physics, and actualized them in a real cosmos? Such questions lie beyond science, however: they are the province of philosophers and theologians. For science, the overarching problem is to understand how a genesis event so simple that it can be described by a short recipe seems to have led, 13 billion years later, to the complex cosmos of which we are a part. Was the outcome “natural,” or should we be surprised at what happened? Could there be other universes? Scientists are now addressing...

  5. PART I From Big Bang to Biospheres

    • CHAPTER 1 Planets and Stars
      (pp. 3-14)

      “Whilst this planet has been cycling on according to the fixed law of gravity, from so simple a beginning, forms most wonderful . . . have been and are being evolved.” These are the famous closing words of Charles Darwin’sOn the Origin of Species.

      Darwin’s genius was to recognize how “natural selection of favored variations” could have transformed primordial life (formed, he surmised, in a “warm little pond”) into the amazing varieties of creatures that crawl, swim, or fly on Earth. But this emergence—a higgledy-piggledy process, proceeding without any guiding hand—is inherently very slow. Darwin guessed that...

    • CHAPTER 2 Life and Intelligence
      (pp. 15-34)

      An iconic image from the 1960s was the first photograph of the entire round Earth, taken from our Moon. Our habitat of land, oceans, and clouds was revealed as a thin, delicate-seeming glaze. Our home planet—the “third rock from the Sun”—is very special. The beauty and vulnerability of “spaceship Earth” contrasts with the stark and sterile moonscape on which the astronauts left their footprints. It may take more than twenty years before we can hang on our walls a poster of another Earth, but when we can, it will surely have even more impact than the classic picture...

    • CHAPTER 3 Atoms, Stars, and Galaxies
      (pp. 35-48)

      The French philosopher Auguste Comte averred in 1835 that, while we might learn the sizes and motions of stars, we would never know what they were made of.Within just twenty years, this pessimism proved misplaced.

      Newton’s famous experiment with a prism had shown that sunlight could be split into a spectrum, displaying all the colors of the rainbow. Early in the nineteenth century, the German optician Josef von Fraunhofer used a more elaborate instrument to display the Sun’s spectrum as a ribbon of light that he could then analyze with a microscope. He found that it was crossed by many...

    • CHAPTER 4 Extragalactic Perspective
      (pp. 49-64)

      We live in a disk-shaped Galaxy that contains 100 billion stars. The Sun orbits around the central hub at a distance of 25,000 light-years, taking 200 million years to make a complete circuit (a galactic year). But our Galaxy is just one among many; for example,Andromeda, its nearest neighbor, lies about 2 million light-years away. To an observer on Andromeda, our Galaxy would look roughly as Andromeda looks to us—a vast, slowly swirling disk of stars and gas, seemingly oval shaped because it is viewed obliquely.

      Galaxies are the basic ingredients of the large-scale universe, just as individual stars...

    • CHAPTER 5 Pregalactic History
      (pp. 65-86)

      The Hubble Deep Field images offer a portrait of the era when galaxies were newly forming. But what about still earlier cosmic history, before even the first star formed? Some seventy years ago, Georges Lemaître, a Belgian priest who was also a mathematician and an mit graduate, pioneered the idea that everything began in a dense state. He called this the “primeval atom”; but that phrase never caught on. Nor did the word “ylem” introduced by the boisterous Russian-American, George Gamow. These coinages were usurped by “Big Bang”—a flippant term that Fred Hoyle introduced in the 1950s as a...

    • CHAPTER 6 Black Holes and Time Machines
      (pp. 87-96)

      Every since the beginning, gravity has been making our universe less and less uniform and building up ever-larger contrasts of density and temperature. In the end, gravity overwhelms all the other forces in stars, and in anything larger, even though the effects of rotation and nuclear energy delay its final victory.

      There are some entities in which gravity has already triumphed over all other forces. These are black holes—objects that have collapsed so far that no light or any other signal can escape them, but that nonetheless leave imprints, distortions of space and time, frozen in the space they’ve...

  6. PART II The Beginning and the End

    • CHAPTER 7 Deceleration or Acceleration?
      (pp. 99-112)

      In August 1999, a total solar eclipse was visible from south-west England. I viewed it from Cornwall through intermittent clouds. For me it was simply an environmental experience, shared with thousands of New Age cultists, astrology devotees, and the like. But the spectacle triggered some simpleminded thoughts.

      It reminded me, first, that astronomy is by far the oldest quantitative science. Eclipses could be predicted, at least approximately, in the first millennium b.c. For several centuries, the Babylonians recorded celestial events on cuneiform tablets, and thousands of these records can now be seen in the British Museum. They stretched over a...

    • CHAPTER 8 The Long-Range Future
      (pp. 113-122)

      Five billion years from now, when the Sun dies, the galaxies will be more widely dispersed and intrinsically somewhat fainter because their stellar population will have aged, and less gas will survive to form bright new stars. But what might happen still farther ahead? We can’t predict what role life will eventually carve out for itself: it could become extinct, or it could achieve such dominance that it can influence the entire cosmos. The latter is the province of science fiction, but it can’t be dismissed as absurd. After all, it has taken little more than one billion years for...

    • CHAPTER 9 How Things Began: The First Millisecond
      (pp. 123-138)

      Astronomy and cosmology have a high profile and a positive image, in contrast to the ambivalence with which the public perceives, for instance, genetics or nuclear science. The essence of the new discoveries and concepts in these cosmic sciences can be conveyed, free of technicalities, to a wide general audience. I am uneasy, however, about the media’s portrayal of the subject: all too often, claims are hyped up, only to be retracted later, with the retraction usually being more subdued.When this happens, it is often the scientists themselves (or their press offices) who are at fault, not the journalists: indeed,...

  7. PART III Fundamentals and Conjectures

    • CHAPTER 10 Cosmos and Microworld
      (pp. 141-156)

      Everything astronomers can see, stretching out to distances of 10 billion light-years, emerged from an infinitesimal speck. This astonishing idea becomes easier to swallow if we realize that, in a sense, the universe’s net energy can be zero. Everything has an energy equal tomc², according to Einstein’s famous equation. But everything also has negative energy because of gravity.We on Earth have an energy deficit compared to an astronaut in space. But the deficit due to all the masses in the universe added together could amount tominus mc². In other words, the universe makes for itself a gravitational pit...

    • CHAPTER 11 Laws and Bylaws in the Multiverse
      (pp. 157-182)

      I described in chapter 9 how the entire domain astronomers observe, extending at least 10 billion light-years, could have inflated from an infinitesimal speck; moreover, the inflationary growth could have led to a universe so large that its extent requires a million-digit number to express it. But even this vast expanse of space may not be everything there is: patches where inflation does not end may grow fast enough to provide the seeds for other Big Bangs. If so, our Big Bang wasn’t the only one but may even be part of an eternally reproducing cosmos.

      There are other conjectures...

  8. APPENDIX Scales of Structure
    (pp. 183-186)
    (pp. 187-196)
  10. INDEX
    (pp. 197-205)