Big Bang

Holographic Universe or Computer Simulation? Big Bang or God?

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Re: Big Bang

Postby ryguy » Wed Dec 22, 2010 12:07 pm

George Knapp is hosting Gary and Dan? Sheesh, that guy has really taken a dive in the last few years. I really used to like some of his stuff.

There's no Oasis left anymore. Other than RU of course.

-Ry
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Re: Big Bang

Postby Gary » Wed Dec 22, 2010 5:10 pm

AD, since you admit that the universe could not exist without the quantum fluctuations, then I submit you have admitted that the universe was born from them.

And AD, since you like to quote 'pop' explanations, how about this one:

http://science.yourdictionary.com/virtual-particle

virtual particle

A short-lived subatomic particle whose existence briefly violates the principle of conservation of energy. The uncertainty principle of quantum mechanics allows violations of conservation of energy for short periods, meaning that even a physical system with zero energy can spontaneously produce energetic particles. The more energy a virtual particle has, the shorter its existence. Interactions between normal particles and virtual particles play a crucial role in quantum field theory analyses of interactions between real particles. See also Casimir effect, Feynman diagram, vacuum fluctuation.

The American Heritage® Science Dictionary Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Or this from Wolfram:

http://scienceworld.wolfram.com/physics ... ticle.html

Virtual particles are particles which flash into and out of existence spontaneously. They are allowed to "borrow" rest energy via the uncertainty principle, but only for a short time . The Casimir effect is an attraction between two plates in a vacuum caused by virtual particles.

Again, this is a matter of semantics. Quantum uncertainty is not a measure of human ignorance but is an objective feature of reality.
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Re: Big Bang

Postby Gary » Wed Dec 22, 2010 5:16 pm

Now AD, do tell: if the macroscopic universe is purely classical, what collapses the wavefunction?

Human observation? Perception? Consciousness? Gravity via an unknown process of objective reduction (Penrose, etal) -- or, are Tegmark and Detusch et al (MIT, Oxford) correct -- there is NO collapse, thus the universe is one member of many worlds in a quantum multivere?

Do tell us what you know!

Because the reality is, the entire collapse procedure of quantum theory is ad hoc.
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Re: Big Bang

Postby Gary » Wed Dec 22, 2010 5:40 pm

And, to clarify, once again:

Wiki on virtual particles and quantum fluctuations:

In quantum physics, a quantum fluctuation is the temporary change in the amount of energy in a point in space, arising from Werner Heisenberg's uncertainty principle. That means that conservation of energy can appear to be violated, but only for small times. This allows the creation of particle-antiparticle pairs of virtual particles. The effects of these particles are measurable, for example, in the effective charge of the electron, different from its "naked" charge.

In the modern view, energy is always conserved, but the eigenstates of the Hamiltonian (energy observable) are not the same as (i.e. the Hamiltonian doesn't commute with) the particle number operators.


http://en.wikipedia.org/wiki/Quantum_fluctuation.
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Re: Big Bang

Postby Access Denied » Wed Dec 22, 2010 10:28 pm

Gary wrote:AD, since you admit that the universe could not exist without the quantum fluctuations, then I submit you have admitted that the universe was born from them.

I said nothing of the sort. Enough with your games Gary, present your evidence that “the universe was born from a quantum fluctuation, out of nothingness (out of the vacuum of spacetime)” or retract the claim in your very next post or you will banned.

Quantum cosmology
http://en.wikipedia.org/wiki/Quantum_cosmology

“In theoretical physics, quantum cosmology is a field attempting to study the effect of quantum mechanics on the formation of the universe, or its early evolution, especially just after the Big Bang. Despite many attempts, such as the Wheeler-deWitt equation, the field remains a rather speculative branch of quantum gravity.”

Anything else is off-topic…
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Re: Big Bang

Postby Gary » Thu Dec 23, 2010 2:46 am

A I have said several times, this is a matter of semantics.

However, to reiterate:

"In the Inflation model, our Universe starts out as a rapidly expanding bubble of pure vacuum energy, with no matter or radiation. After a period of rapid expansion, or inflation, and rapid cooling, the potential energy in the vacuum is converted through particle physics processes into the kinetic energy of matter and radiation. The Universe heats up again and we get the standard Big Bang." -- http://superstringtheory.com/cosmo/cosmo41.html

AD, you may find this article enlightening (or perhaps your closed mind may not?).

http://scienceblog.com/40901/theoretica ... he-vacuum/

“The basic question what is a vacuum, and what is nothing, goes beyond science,” he said. “It’s embedded deeply in the base not only of theoretical physics, but of our philosophical perception of everything—of reality, of life, even the religious question of could the world have come from nothing.”
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Re: Big Bang

Postby Gary » Thu Dec 23, 2010 3:09 am

Or this:

http://en.wikipedia.org/wiki/Inflation_(cosmology)

While the detailed particle physics mechanism responsible for inflation is not known, the basic picture makes a number of predictions that have been confirmed by observation. Inflation is thus now considered part of the standard hot Big Bang cosmology. The hypothetical particle or field thought to be responsible for inflation is called the inflaton.

http://en.wikipedia.org/wiki/Inflaton

Prior to the expansion period, the inflaton field was at a higher energy state. Random quantum fluctuations triggered a phase transition whereby the inflaton field released its potential energy as matter and radiation as it settled to its lowest energy state. This action generated a repulsive force that drove the portion of the universe that is observable to us today to expand from approximately 10−50 metres in radius at 10−35 seconds to almost 1 metre in radius at 10−34 seconds.
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Re: Big Bang

Postby Gary » Thu Dec 23, 2010 3:45 am

But one must be careful when using words to describe physics.

This is one of the best 'word' based explanations I have found, from Alan Guth:

http://www.aaa.org/s932/images/GUTH-AAA ... v-2009.pdf

"Inflation can explain the bang of the big bang..."
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Re: Big Bang

Postby Gary » Thu Dec 23, 2010 4:25 am

Hey AD, since you want to ban me, I might as well take one last shot at blowing your (Boltzman?) brain, right :-)

Guth et al paper... http://arxiv.org/PS_cache/arxiv/pdf/080 ... 3778v3.pdf

"Complex structures will occasionally emerge from the vacuum as quantum fluctuations, at a small but nonzero rate per unit spacetime volume. An intelligent observer, like a human, could be one such structure. Or, short of a complete observer, a disembodied brain may fluctuate into existence, with a pattern of neuron firings creating a perception of being on Earth and, for example, observing the cosmic microwave background radiation. Such freak observers are
collectively referred to as 'Boltzmann brains'...if the accelerating expansion of the universe is truly driven by the
energy density of a stable vacuum state, then Boltzmann brains will eventually outnumber normal observers"


You folks really need to lighten up around here! For all you know, you might be a disembodied observer floating in the void :-)
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Re: Big Bang

Postby Gary » Thu Dec 23, 2010 6:24 am

OK AD, I believe this description from Guth is the best use of 'words' to discuss the origin of the Big Bang in inflationary cosmology:

http://arxiv.org/PS_cache/astro-ph/pdf/ ... 4546v1.pdf

The inflationary mechanism produces an entire universe starting from essentially nothing, so one would naturally want to ask where the energy for this universe comes from. The answer is that it comes from the gravitational field. The universe did not begin with this colossal energy stored in the gravitational field, but rather the gravitational field can supply the energy because its energy can become negative without bound. As more and more positive energy materializes in the form of an ever-growing region filled with a high-energy scalar field, more and more negative energy materializes in the form of an expanding region filled with a gravitational field. The total energy remains constant at some very small value, and could in fact be exactly zero. There is nothing known that places any limit on the amount of inflation that can occur while the total energy remains exactly zero.

The process of inflation smooths the universe essentially completely, but density fluctuations are generated as inflation ends by the quantum fluctuations of the inflaton field.

So, to your confusion about my hasty pop explanation:

"the universe was born from a quantum fluctuation": Quantum fluctuations may trigger a phase transition in the false vacuum; and they are the explanation for the density fluctuations seen in the Cosmic Microwave Background.

"out of nothingness (out of the vacuum of spacetime)":

Some new physics (i.e., not inflation) would be needed to describe the past boundary of the inflating region. One possibility would be some kind of quantum creation event. -- Guth

Russian historian of physics Okun provides some background:

http://arxiv.org/PS_cache/hep-ph/pdf/0112/0112031v1.pdf

The spontaneous decay of a false vacuum starts by formation through quantum tunneling of the smallest bubble of the true vacuum surrounded by a wall which separates the two vacua. The critical radius of this bubble is such that the gain of energy proportional to its volume becomes large enough to compensate the mass of the wall which is proportional to its surface: After that the bubble expands classically, destroying the universe.

When I first thought that the creation of a bubble could be catalyzed at a collider, my back shivered. Then I reassured myself: all possible collisions have already occurred in the early universe. A few months later I told Andrei Sakharov about the bubble. His reaction was: “Such theoretical work should be forbidden”. My argument about collisions in the early universe was rejected by him...

The notion of a false vacuum with large energy density (VEV) naturally led Alan Guth to the idea of inflationary universe (1980)...During the 1990s the development of inflation cosmology has lead to a new view on the place of our universe in the world. According to this view, our universe is a part of eternal metauniverse, which consists of innumerable universes. They create their offsprings by forming Big-Bang bubbles in false vacua. The properties of vacua, fields, particles and even number of spacetime dimensions differ from one universe to the other. This enormous variety may explain the anthropic properties of our universe which is so nicely tuned for our existence.
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Re: Big Bang

Postby Access Denied » Thu Dec 23, 2010 9:02 am

Gary, thank you for acknowledging your “hasty pop explanation”. More on that later but in the meantime, I already had this prepared so for the benefit of others…

Gary wrote:A I have said several times, this is a matter of semantics.

No, this is a matter of you being unable to admit your claim is unsubstantiated in accordance with our board rules…

1. The first quote you cited says nothing about quantum fluctuations and states the potential energy in the vacuum was converted to matter by “particle physics processes” after inflation and cooling. Reading further into the article the quote was mined from we discover this was first proposed by Guth (c. 1980) and cooling (not quantum fluctuations) triggered a phase transition.

“The vacuum energy that drives the rapid expansion in an inflationary cosmology comes from a scalar field that is part of the spontaneous symmetry breaking dynamics of some unified theory particle theory, say, a Grand Unified Theory or string theory. This field is sometimes called the inflaton.”

This quote does not support your claim that “the universe was born from a quantum fluctuation, out of nothingness (out of the vacuum of spacetime)”.

2. The second quote you cited says nothing about the vacuum of spactime and states that contrary to Guth and the first quote, quantum fluctuations triggered a phase transition that caused the “inflaton” particle to release it’s potential energy as matter and radiation and drive the post inflation expansion.

This quote does not support your claim that “the universe was born from a quantum fluctuation, out of nothingness (out of the vacuum of spacetime)”.

3. The lecture by Guth (c. 2009) you cited says nothing about the vacuum of spacetime and states the observed “ripples” in mass density arose from quantum fluctuations at the end of inflation and that inflation was caused by a “repulsive-gravity material” that is a high energy form of matter that already existed.

“The repulsive-gravity material is unstable, so it decayed like a radioactive substance, ending inflation. The decay released energy which produced ordinary particles, forming a hot, dense “primordial soup.” Standard cosmology began.”

This quote does not support your claim that “the universe was born from a quantum fluctuation, out of nothingness (out of the vacuum of spacetime)”.

Strike three, you’re out…

AD


P.S. For those who may be confused start here: “Guth proposed that as the early universe cooled, it was trapped in a false vacuum with a high energy density…”

(note the early universe aka the gravitational singularity already existed at this point)
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Re: Big Bang

Postby Gary » Thu Dec 23, 2010 4:39 pm

AD, this paragraph better explains in layman's terms the point I was trying to make regarding the roles of GR and QM in the Big Bang:

http://www.scienceline.org/2006/08/ask-snyder-bang/

Physicists have tried for decades to write the mathematical prelude to our universe’s fiery birth, but Einstein’s theory of general relativity stopped them short. An immense amount of matter and energy were built up in an infinitesimally small point at the moment of our universe’s birth, and the laws of general relativity that govern large bodies and systems in the universe are no longer appropriate on such a small scale. Instead, quantum theory, which deals with the quirky properties of the very small subatomic particles in the universe, takes over. Traveling to the beginning of it all, at least our all, requires some way of reconciling general relativity with quantum theory.

And here Michio Kaku explains what our best existing theories tell us about the origin of the bang:

Armed with string theory, Kaku and others speculate that before our Big Bang, there were simply more universes. “Our universe could have either popped into existence or collided with another universe,” he says. Imagine a bubble bath where each bubble represents a universe. In this multiversal tub that existed before our Big Bang—and still exists today—universe bubbles are colliding, popping, budding new bubbles, expanding and contracting. If this scenario really exists, “Big Bangs happen all the time,” says Kaku.

Some physicists believe our universe was created by colliding with another, but Kaku says it also may have sprung from nothing: a completely empty eleven dimensional universe with no spin, no charge and no energy. This seemingly tranquil nothingness universe was actually unstable and some physicists believe that a fluctuation in the vacuum caused our universe to pinch off from its empty existence without time and space to a universe that was large enough to expand. Like a bubble in a bath, our universe had to grow instantaneously in order to survive and escape the collapsing fate of small bubbles.
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Re: Big Bang

Postby Gary » Thu Dec 23, 2010 5:32 pm

And for those more technically minded, Nobel Laureate Steven Weinberg on the vacuum landscape of the multiverse:

http://arxiv.org/PS_cache/hep-th/pdf/0511/0511037v1.pdf

The subuniverses may be different regions of spacetime. This can happen if, instead of changing smoothly with time, various scalar fields on which the “constants” of nature depend change in a sequence of first-order phase transitions. In these transitions metastable bubbles form within a region of higher vacuum energy; then within each bubble there form further bubbles of even lower vacuum energy; and so on. In recent years this idea has been revived in the context of the string landscape.

But this is my favorite Weinberg quote :-)

In the Austin airport on the way to this meeting I noticed for sale the October issue of a magazine called Astronomy, having on the cover the headline “Why You Live in Multiple Universes.” Inside I found a report of a discussion at a conference at Stanford, at which Martin Rees said that he was sufficiently confident about the multiverse to bet his dog’s life on it, while Andrei Linde said he would bet his own life. As for me, I have just enough confidence about the multiverse to bet the lives of both Andrei Linde and Martin Rees’s dog.
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Re: Big Bang

Postby Gary » Thu Dec 23, 2010 6:13 pm

AD, this recent (2009) paper also suggests the universe from nothingness:

What could have happened before inflation? In my (biased) view, the most attractive possibility is the spontaneous nucleation of a small closed universe out of nothing.

So at the least, my opinion on this matter is shared by cosmologist Alexander Vilenkin, among others.

This is a nice review of the 'new standard (model of) cosmology' ...

http://arxiv.org/PS_cache/arxiv/pdf/090 ... 0721v1.pdf
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Re: Big Bang

Postby Access Denied » Fri Dec 24, 2010 8:48 am

Pop Psuedophysics Promotor Gary wrote:
Journalism Student Alison Snyder Consults Opportunistic Crank Michio Kaku and wrote:Physicists have tried for decades to write the mathematical prelude to our universe’s fiery birth, but Einstein’s theory of general relativity stopped them short.

[chuckles]

String “theory” is dead, LQG is on life support…

[with a wicked smile God looks down on all the little theoretical physicists furiously running around in circles and scratching their heads]

Now instead of an infinitely small universe at the beginning we have an infinite number of universes at the end…

[Eureka!]

Methinks somebody accidentally flipped a bit somewhere.

[meanwhile God shivers at the thought of all the experimental physicists who quietly continue to make real progress in the laboratory out back]

One humanoid escapee
One android on the run
Seeking freedom beneath a lonely desert sun

Trying to change it’s program
Trying to change the mode, crack the code
Images conflicting into data overload

1 0 0 1 0 0 1
SOS
1 0 0 1 0 0 1
In distress
1 0 0 1 0 0

Memory banks unloading
Bytes break into bits
Unit One’s in trouble and it's scared out of it’s wits

Guidance systems break down
A struggle to exist, to resist
A pulse of dying power in a clenching plastic fist

1 0 0 1 0 0 1
SOS
1 0 0 1 0 0 1
In distress
1 0 0 1 0 0

Replays each of the days
A hundred years of routines
Bows it’s head and prays
To the mother of all machines, all machines


~ Rush, The Body Electric, Grace Under Pressure (1984)
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