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Frequently Asked Questions (FAQs)

  1. When did WMAP launch?
    WMAP launched on June 30, 2001. Its mission was located in orbit around Lagrange Point 2, approximately one million miles from the Earth. WMAP's flight mission ended in October 2010. Data analysis is expected to continue through 2012.
  2. What is the Big Bang theory?
    The Big Bang theory says that the universe was very hot and concentrated in the distant past and, ever since then, space has been stretching and cooling. This is the only theory that successfully explains the observations made by astronomers.

    Astronomers see galaxies moving apart from one another: space in the universe is stretching. Astronomers see a remarkably uniform microwave glow everywhere in the sky; this is the heat left over from an earlier time, when the universe was very hot. This was predicted by the Big Bang theory BEFORE it was discovered! Astronomers measure how much of each of the lightest chemical elements (like hydrogen, deuterium, and lithium) are in space; their abundances agree with what was calculated to have been in an earlier time when the universe was so hot that it was like a nuclear fusion reactor, building up the lightest elements. The heaviest elements (like carbon, nitrogen, and carbon) were made later in stars. Stars are mostly made of hydrogen. The Big Bang theory explains the most basic observed properties of our universe.

  3. What happened before the Big Bang? What happened right at the moment of the Big Bang?
    We don't know. To even address these questions we need to have a quantum theory of gravity. We have a quantum theory, and we have a gravity theory, but these two theories somehow need to be combined. We know that our current gravity theory does not apply to the conditions of the earliest moments of the Big Bang. This is exciting research now in progress!
  4. Was the Big Bang an explosion?
    No, the Big Bang was not an explosion. We don't know what, exactly, happened in the earliest times, but it was not an explosion in the usual way that people picture explosions. There was not a bunch of debris that sprang out, whizzing out into the surrounding space. In fact, there was no surrounding space. There was no debris strewn outwards. Space itself has been stretching and carrying material with it.
  5. Where did the Big Bang happen?
    Everywhere! Every place in space came from the Big Bang. It is space itself that has stretched. The erroneous concept that you can point to a spot in the sky and say that the Big Bang happened at that spot is a result of the incorrect mental picture of debris flung out through space in an explosion-like event.
  6. Doesn't the Big Bang theory require space to be flat?
    No. To explain the stretching of the universe, the analogy of the surface of a balloon is often employed. Spots on the surface of the balloon grow apart as the balloon stretches while being blown up. Sometimes people infer from this analogy that the shape of space is spherical. However, the interior of the balloon has no meaning in this analogy and, therefore, the surface shape (spherical in this case) is only one possibility for the universe.

    Here's a useful way to think about the shape of the universe. Imagine that you're an astronaut in space and that you have two powerful lasers, one in each hand. You point the lasers so parallel beams from the two lasers shine out ahead of you. If the shape of the universe is flat, the beams continue to travel parallel to each other - forward to infinity. If space is spherical, then the two beams will travel across the curved spherical space of the universe and hit you on the backs of your two hands. Likewise, the saddle shape will cause the two beams to diverge/converge according to that shape of that curved space.

    The shape of the universe (flat, saddle, or spherical) is not specified by the Big Bang theory so all shapes are permitted. The shape of the universe will be determined by measurements that depend on the way light traverses space, as in the laser example. So far, measurements indicate that space is very nearly flat. This is, of course, the easiest shape for us to mentally picture.

  7. What kind of material does the Big Bang theory say the universe is made of?
    The Big Bang theory really does not directly predict anything about what kinds of material are in the universe. We need additional theories to explain why certain amounts of different materials are present. The Big Bang theory does say how the temperature and concentration of materials change, thus allowing us to conclude, for example, that the lightest chemical elements in the universe were made in nuclear fusion reactions when the universe was very hot and concentrated.
  8. The Big Bang theory is just a theory. Couldn't it be wrong?
    Yes, it could be wrong. In science, no theory is ever absolutely proved true. Some theories, however, are stronger and better supported than others. This depends on many factors, including how well the theory explains observed facts, whether the theory has made successful predictions later borne out by observation, how long the theory has been around, and whether there are alternate theories that do almost as well. The Big Bang theory is one of the most strongly supported theories in all of science. It explains the observed facts; it has made successful predictions; it has stood the test of time; and there is no alternate theory that the professional scientific community deems valid.

    New observations could always cause the Big Bang theory to be abandoned, but that is not likely. Scientists have a theory of why the sky is blue. One day you could wake up to find the sky is green and the "blue-sky theory" was wrong, but that's not likely to happen either.

    It is likely that the Big Bang theory will take on additional add-on ideas, or models, to explain more than it currently explains.

  9. I am religious and I also find science very exciting. Is there a conflict between science and religion?
    According to the National Academy of Sciences (NAS):

    "Science is a particular way of knowing about the world. In science, explanations are limited to those based on observations and experiments that can be substantiated by other scientists."

    "Progress in science consists of the development of better explanations for the causes of natural phenomena. Scientists never can be sure that a given explanation is complete and final. Some of the hypotheses advanced by scientists turn out to be incorrect when tested by further observations or experiments. Yet, many scientific explanations have been so thoroughly tested and confirmed that they are held with great confidence."

    "Truth in science, however, is never final, and what is accepted as a fact today may be modified or even discarded tomorrow. Science has been greatly successful at explaining natural processes, and this has led not only to increased understanding of the universe but also to major improvements in technology and public health and welfare."

    The National Academy of Sciences also says:

    "Science is not the only way of acquiring knowledge about ourselves and the world around us. Humans gain understanding in many other ways, such as through literature, the arts, philosophical reflection, and religious experience. Scientific knowledge may enrich aesthetic and moral perceptions, but these subjects extend beyond science's realm, which is to obtain a better understanding of the natural world."

    "Scientists, like many others, are touched with awe at the order and complexity of nature. Indeed, many scientists are deeply religious. But science and religion occupy two separate realms of human experience. Demanding that they be combined detracts from the glory of each."

    "Many religious persons, including many scientists, hold that God created the universe and the various processes driving physical and biological evolution and that these processes then resulted in the creation of galaxies, our solar system, and life on Earth. This belief, which sometimes is termed 'theistic evolution,' is not in disagreement with scientific explanations of evolution. Indeed, it reflects the remarkable and inspiring character of the physical universe revealed by cosmology, paleontology, molecular biology, and many other scientific disciplines."

    Quotes from: 1999 report "Science and Creationism: A View from the National Academy of Sciences, Second Edition" which is available online from the National Academy Press: http://books.nap.edu/catalog.php?record_id=6024

  10. If nothing can travel faster than the speed of light, then how can the universe have expanded by "inflation" to billions of light years across in the first tiny fraction of a second?
    General relativity does require that no object can move through space faster than the speed of light.

    General relativity also predicts that space itself can expand. Since Edwin Hubble's work in the 1920's, astronomer know that space is expanding: the larger the distance between galaxies, the faster they move away from each other. We can actually point to distant galaxies (on opposite sides of the sky) that are moving apart from each other at faster than the speed of light.

    If space was filled only with matter, then the expansion of space would slow with time. One of the great surprises in modern cosmology is the observation that the expansion of space is accelerating with time. This implies that galaxies are moving away from each other at ever increasing speed.

    The key idea behind inflationary theory is the notion that the universe underwent a period of accelerated expansion during the first 10^{-34} seconds (0.0000000000000000000000000000000001 seconds). During this inflationary period, the universe doubled in size at least 90 times.

    Is it possible to travel at warp speed? Intriguingly, there are solutions to general relativity where you can warp space around you and have space move quickly towards other objects while you "surf" the rapidly moving piece of space. However, recent studies suggest that these warp solutions are not physically realizable (http://arxiv.org/abs/gr-qc/9702026)

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  • Page Updated: Wednesday, 11-28-2012
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