The Big Bang Model is a broadly accepted theory for the origin and evolution of our universe. It postulates that 12 to 14 billion years ago, the portion of the universe we can see today was only a few millimeters across. It has since expanded from this hot dense state into the vast and much cooler cosmos we currently inhabit. We can see remnants of this hot dense matter as the now very cold cosmic microwave background radiation which still pervades the universe and is visible to microwave detectors as a uniform glow across the entire sky.
Foundations of the Big Bang Model
The Big Bang Model rests on two theoretical pillars:
General Relativity
The first key idea dates to 1916 when Einstein developed his General Theory of Relativity which he proposed as a new theory of gravity. His theory generalizes Isaac Newton's original theory of gravity, c. 1680, in that it is supposed to be valid for bodies in motion as well as bodies at rest. Newton's gravity is only valid for bodies at rest or moving very slowly compared to the speed of light (usually not too restrictive an assumption!). A key concept of General Relativity is that gravity is no longer described by a gravitational "field" but rather it is supposed to be a distortion of space and time itself. Physicist John Wheeler put it well when he said "Matter tells space how to curve, and space tells matter how to move." Originally, the theory was able to account for peculiarities in the orbit of Mercury and the bending of light by the Sun, both unexplained in Isaac Newton's theory of gravity. In recent years, the theory has passed a series of rigorous tests.
The Cosmological Principle
After the introduction of General Relativity a number of scientists, including Einstein, tried to apply the new gravitational dynamics to the universe as a whole. At the time this required an assumption about how the matter in the universe was distributed. The simplest assumption to make is that if you viewed the contents of the universe with sufficiently poor vision, it would appear roughly the same everywhere and in every direction. That is, the matter in the universe is homogeneous and isotropic when averaged over very large scales. This is called the Cosmological Principle. This assumption is being tested continuously as we actually observe the distribution of galaxies on ever larger scales. The accompanying picture shows how uniform the distribution of measured galaxies is over a 30° swath of the sky. In addition the cosmic microwave background radiation, the remnant heat from the Big Bang, has a temperature which is highly uniform over the entire sky. This fact strongly supports the notion that the gas which emitted this radiation long ago was very uniformly distributed.
These two ideas form the entire theoretical basis for Big Bang cosmology and lead to very specific predictions for observable properties of the universe.
2006-06-13 16:06:26
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answer #1
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answered by hkyboy96 5
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In the classic 1977 book The First Three Minutes, Nobel Prize-winner Steven Weinberg laid out the physics of what happened just moments after the Big Bang that created our universe. As with most things in physics, that certainly wasn't the end of the story, as attested by the update and reissue of The First Three Minutes in 1993.
Pre-Matter Soup
Until recently, the first hundredth of a second was a bit of a mystery, leaving Weinberg and others unable to describe exactly what the universe would have been like. New experiments at the Relativistic Heavy Ion Collider in Brookhaven National Laboratory have provided physicists with a glimpse through this curtain of high energy, so they can directly observe the sorts of behavior that might have been taking place in this time frame.
At these energies, the quarks that comprise protons and neutrons are not yet joined together, and a dense, superhot mix of quarks and gluons, with some electrons thrown in, is all that can exist in the microseconds before it cools enough to form into the sort of matter particles we observe today.
Pre-Galactic Galaxies
Fast forwarding to after the existence of matter, more information is coming in on the formation of galaxies. It is believed that the earliest galaxies were tiny "dwarf galaxies" that released so much radiation they stripped gas atoms of their electrons. This gas, in turn, heated up and expanded, and thus were able to obtain the mass needed to form the larger galaxies that we know today.
Current telescopes are just now beginning to have the capacity to observe the galaxies from this distant time. Studying the light from quasars, they observe how it passes through the intervening gas clouds. The ionization of these gas clouds is determined by the number of nearby bright galaxies, and if such galaxies are spread around, the ionization level should be constant. It turns out that in galaxies from the period after cosmic reionization there are large fluctuations in this ionization level. The evidence seems to confirm the pre-ionization galaxies were less common and that the post-ionization galaxies have 100 times the mass of the dwarf galaxies. [citation needed]
The next generation of telescopes should be able to see the dwarf galaxies directly, which will help resolve the problem that many astronomical predictions in galaxy formation theory predict more nearby small galaxies than observed.
2006-06-14 02:17:55
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answer #2
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answered by Anonymous
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Universal Studios, a subsidiary of NBC Universal, is a Big Ten movie studio that has production studios and offices located at 100 Universal City Plaza Drive in Universal City, California, an unincorporated area of Los Angeles County between Los Angeles and Burbank. Distribution and other corporate, administrative offices are based in New York City.
The longest-lived Hollywood film production company, Universal Pictures can trace its origins back to the creation in 1909 of a predecessor, the Yankee Film Company. The founder of Universal, Carl Laemmle, was a German Jewish immigrant who had settled in Wisconsin, where he managed a clothing store
[evil grin]
2006-06-13 23:04:01
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answer #3
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answered by umwut? 6
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I assume you mean "How was the universe born?". And the answer is, nobody knows. We can't possibly get direct evidence, so short of a complete theory of the universe, nobody will ever know. And we don't have one. nor do many scientists believe we are likely to get one anytime soon, if ever.
2006-06-13 23:03:56
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answer #4
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answered by Amarkov 4
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as cold is an imaginary force of the absence of heat the infinite cold vacuum imploded or disintegrated as cold falls ever inward creating temperature changes as heat that expands, and so the big bang. More so the slow precession of energy creates the dual particle and compton effects making true and anti matter that fuse into elements and combine into compounds. not that this cold disintegration will ever happen again ... oscillating universe.
2006-06-13 23:22:52
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answer #5
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answered by Anonymous
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The Big Bang, of course.
2006-06-13 23:05:16
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answer #6
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answered by PBarnfeather 3
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of course the big red nebula formed da whole universe,,.. and also da milky way...
2006-06-13 23:04:13
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answer #7
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answered by Katie 3
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