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Detached9 · 06-01-2002, 02:39 PM

Most cosmologists today believe that the universe we inhabit exploded into being some 15 billion years ago in a titanic fireball called the big bang. Contrary to popular belief, the modern big bang theory does not state that a concentrated lump of matter located at some particular point in space suddenly exploded, sending fragments rushing away at high speed; rather, it holds that space itself, along with time, came into being at the moment of the big bang. The birth of the universe is said to have happened in the following manner (P. Davies & J. Gribbin, The Matter Myth, Simon & Schuster/ Touchstone, 1992, pp. 162-73). In the beginning, a tiny bubble of spacetime, a billion-trillion-trillionth of a centimeter across, popped spontaneously into existence out of nothing as the result of a random quantum fluctuation. It was seized by an intense anti-gravitational force which caused it to expand with explosive rapidity. In scarcely more than a billion-trillion-trillionth of a second the universe swelled to about 10 to the negative 33rd cm, the size of a grapefruit. The anti-gravitational force then disappeared, and the inflationary phase of accelerating expansion came to an abrupt halt amid a burst of heat. The heat energy and gravitational energy of expanding space then produced matter and, as the universe cooled, more and more structure began to "freeze out" -- first nuclei, then atoms, and finally galaxies, stars, and planets. (Cosmology and The Big Bang, <a href="http://www.theosophy-nw.org/theosnw/science/prat-bng.htm)" target="_blank">http://www.theosophy-nw.org/theosnw/science/prat-bng.htm)</a>

Is this an explanation for the origin of the universe? I'm confused. Are they stating that this is one of the theories set forth in regards to the origin of the universe, or are they stating that this is THE explanation for the origin of the universe?

Does anyone know of the validity of this explanation?

Friar Bellows · 06-01-2002, 05:09 PM

Well, for one thing, it must have been a very lean year for the fruit growers if they were producing grapefruits of size "10 to the negative 33rd cm".

For a better exposition on Modern Cosmology see:

<a href="http://www.astro.ucla.edu/~wright/cosmolog.htm" target="_blank">Ned Wright's Cosmology Tutorial</a>

eh · 06-02-2002, 07:07 AM

Yeah it's the inflation scenario. The universe does not pop out of nothing, as the author was to lazy to point out. For the the quantum flucutation to occur, one assumes a pre existing vacuum. So the big bang is really when the first bubble of vacuum energy started expanding, and the birth of our visible universe comes after.

NumberTenOx · 06-02-2002, 08:00 AM

Also check out <a href="http://nedwww.ipac.caltech.edu/level5/Guth/Guth_contents.html" target="_blank">this Caltech page</a>. Here are a few excerpts:

Quote:

There are many versions of inflationary theories but generically they assume that some small patch of the early Universe somehow came to be in a false vacuum state. Various possibilities have been discussed, including supercooling during a phase transition in the early Universe, or a purely random fluctuation of the fields. A chance fluctuation seems reasonable even if the probability is low, since the inflating region will enlarge by many orders of magnitude, while the non-inflating regions will remain microscopic. Inflation is a wildfire that will inevitably take over the forest, as long as there is some chance that it will start.

Once a patch of the early Universe is in the false vacuum state, the repulsive gravitational effect drives the patch into an inflationary period of exponential expansion. To produce a universe with the special features of the Big Bang discussed above, the expansion factor must be at least about 10**25. There is no upper limit to the amount of expansion. Eventually the false vacuum decays, and the energy that had been locked in it is released. This energy produces a hot, uniform, soup of particles, which is exactly the assumed starting point of the traditional Big Bang theory. At this point the inflationary theory joins onto the older theory, maintaining all the successes for which the Big Bang theory is believed.

In the inflationary theory the Universe begins incredibly small, perhaps as small as 10**24cm, a hundred billion times smaller than a proton. The expansion takes place while the false vacuum maintains a nearly constant energy density, which means that the total energy increases by the cube of the linear expansion factor, or at least a factor of 10**75. Although this sounds like a blatant violation of energy conservation, it is in fact consistent with physics as we know it.

The resolution to the energy paradox lies in the subtle behavior of gravity. Although it has not been widely appreciated, Newtonian physics unambiguously implies that the energy of a gravitational field is always negative a fact which holds also in general relativity. The Newtonian argument closely parallels the derivation of the energy density of an electrostatic field, except that the answer has the opposite sign because the force law has the opposite sign: two positive masses attract, while two positive charges repel. The possibility that the negative energy of gravity could balance the positive energy for the matter of the Universe was suggested as early as 1932 by Richard Tolman, although a viable mechanism for the energy transfer was not known.

During inflation, while the energy of matter increases by a factor of 10**75 or more, the energy of the gravitational field becomes more and more negative to compensate. The total energy - matter plus gravitational - remains constant and very small, and could even be exactly zero. Conservation of energy places no limit on how much the Universe can inflate, as there is no limit to the amount of negative energy that can be stored in the gravitational field.

This borrowing of energy from the gravitational field gives the inflationary paradigm an entirely different perspective from the classical Big Bang theory, in which all the particles in the Universe (or at least their precursors) were assumed to be in place from the start. Inflation provides a mechanism by which the entire Universe can develop from just a few ounces of primordial matter. Inflation is radically at odds with the old dictum of Democritus and Lucretius, "Nothing can be created from nothing" If inflation is right, everything can be created from nothing, or at least from very little. If inflation is right, the Universe can properly be called the ultimate free lunch.

So, this theory shows how the universe might have grown from a very small amount of matter, spontaneously occurring in a vacuum. However, the existence of the primordial vacuum is still a prerequisite.

Pretty cool, huh?

06-01-2002, 02:39 PM	#1
Detached9 Regular Member Join Date: Mar 2001 Posts: 341	The Big Bang Most cosmologists today believe that the universe we inhabit exploded into being some 15 billion years ago in a titanic fireball called the big bang. Contrary to popular belief, the modern big bang theory does not state that a concentrated lump of matter located at some particular point in space suddenly exploded, sending fragments rushing away at high speed; rather, it holds that space itself, along with time, came into being at the moment of the big bang. The birth of the universe is said to have happened in the following manner (P. Davies & J. Gribbin, The Matter Myth, Simon & Schuster/ Touchstone, 1992, pp. 162-73). In the beginning, a tiny bubble of spacetime, a billion-trillion-trillionth of a centimeter across, popped spontaneously into existence out of nothing as the result of a random quantum fluctuation. It was seized by an intense anti-gravitational force which caused it to expand with explosive rapidity. In scarcely more than a billion-trillion-trillionth of a second the universe swelled to about 10 to the negative 33rd cm, the size of a grapefruit. The anti-gravitational force then disappeared, and the inflationary phase of accelerating expansion came to an abrupt halt amid a burst of heat. The heat energy and gravitational energy of expanding space then produced matter and, as the universe cooled, more and more structure began to "freeze out" -- first nuclei, then atoms, and finally galaxies, stars, and planets. (Cosmology and The Big Bang, <a href="http://www.theosophy-nw.org/theosnw/science/prat-bng.htm)" target="_blank">http://www.theosophy-nw.org/theosnw/science/prat-bng.htm)</a> Is this an explanation for the origin of the universe? I'm confused. Are they stating that this is one of the theories set forth in regards to the origin of the universe, or are they stating that this is THE explanation for the origin of the universe? Does anyone know of the validity of this explanation?

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06-01-2002, 05:09 PM	#2
Friar Bellows Veteran Member Join Date: Apr 2001 Location: arse-end of the world Posts: 2,305	Well, for one thing, it must have been a very lean year for the fruit growers if they were producing grapefruits of size "10 to the negative 33rd cm". For a better exposition on Modern Cosmology see: <a href="http://www.astro.ucla.edu/~wright/cosmolog.htm" target="_blank">Ned Wright's Cosmology Tutorial</a>

06-02-2002, 07:07 AM	#3
eh Senior Member Join Date: Sep 2000 Location: Canada Posts: 624	Yeah it's the inflation scenario. The universe does not pop out of nothing, as the author was to lazy to point out. For the the quantum flucutation to occur, one assumes a pre existing vacuum. So the big bang is really when the first bubble of vacuum energy started expanding, and the birth of our visible universe comes after.

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