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Stargazers spot dark energy
"Doug Freyburger" wrote in message ... Wayne Throop wrote: ::: To result in an 'increased rate of separation' they either need to ::: REPEL each other or be under some other form of acceleration. :: Really? Yes. No. That's the deal with the expanding universe. The amount of space between here and there grows without any acceleration of either object. The question is whether the accelerating expansion is because the amount of space is growing faster or if there's now so much space between here and there that there's more of it to expand. Dark energy increased dramatically in the universe at the very same time life evolved on Earth. Anyone care to speculate on the source of that 'cosmic coincidence'? And btw, gravity does NOT always attract, most forms of matter are self-repulsive. Hence, the matter spreads itself out as thinly as possible, making it rather difficult to spot ....hence the term dark. But dark matter and energy cannot be directly observed, only known by the ...effects, for the very same reason we can only know things like market forces and gravity by their effects. As they are all emergent system properties. "Emergence and Evolution - Constraints on Form" "Again on a Solar System or Galactic level interactions of a different form (gravitational and electromagnetic) lead to emergent structure, suggesting that the concept of 'external selection' is simply a convenient simplification in what is always essentially a two way process. Self-regulation by feedback mechanisms seems to be a feature of every level of evolution, a hierarchy of order, emergent from initial disorder." http://calresco.org/emerge.htm But what dark matter and dark energy are really telling us is just how little we know. Don't for a minute think anyone has a handle on reality. All the great discoveries are just around the corner. Everything is about to change. Quotes below from the director of theoretical science at Princeton, a founder of inflationary theory, and one of the top cosmologists in the world. A Quintessential Introduction to Dark Energy Paul J. Steinhardt (selected quotes) "We live at a special moment in cosmic history: the transition between a decelerating, matter-dominated Universe and an accelerating, dark-energy-dominated Universe." "Most of the energy in the universe consists of some form of dark energy that is gravitationally self-repulsive and that is causing the expansion rate of the universe to accelerate." "Most of the energy in the universe is not "matter." For its first 300 years, physics has focused on the properties of matter and radiation, including dark matter. Now we know that they represent less than 30% of the composition of the universe. The rest consists of something we know virtually nothing about." "Most of the energy in the universe is not gravitationally attractive. We are probably the last generation to have been taught that gravity always attracts," "Why did the Universe begin to accelerate just as humans started to evolve? Cosmic acceleration and human evolution are both linked to the onset of matter domination. The k-essence component has the property that it only behaves as a negative pressure component after matter/radiation equality, so that it can only overtake the matter density and induce cosmic acceleration after the matter has dominated the Universe for some period, at about the present epoch." "The two logical possibilities for dark energy are the cosmological constant and quintessence. The cosmological constant was first introduced by Einstein for the purpose of constructing a static model of the universe." "Quintessence is a dynamical, evolving, spatially inhomogeneous component with negative pressure." "In the current context, quintessence would be the fifth dynamical component that has influenced the evolution of the universe, in addition to the previously known baryons, leptons, photons, and dark matter. "If space is uniform, then should not the same be true for time? Hubble's discovery that the Universe is expanding taught us that the Universe is evolving, but the notion was that the evolution has been steady over the last 15 billion years with no remarkable changes. We now know that time is anti-Copernican." Fine-tuning, cosmic coincidence, and the quintessential solution "Whatever form the dark energy takes, two new cosmological problems arise. First, the component must have a tiny energy density (ca. 10¡47 GeV4) today. How does this small value arise from a microphysical theory? We will refer to this puzzle as the Fine-tuning problem'." "A second problem arises when the cosmological model is extrapolated back in time to the very early Universe, at the end of inflation, say. The quintessence energy density decreases at a different rate from the matter density, and their ratio shrinks by many orders of magnitude as we extrapolate back in time. The observations tell us that, somehow, the ratio was set initially just right so that now, fifteen billion years later, the ratio is of order unity. Accounting for the special ratio in the early Universe will be referred to as the `coincidence problem' (Steinhardt 1997)." "The fine-tuning and cosmic coincidence problems are vexing. They are often posed as a paradox: why should the acceleration begin just as humans evolve? In desperation, some cosmologists and physicists have given renewed attention to anthropic models." "Should we believe, as most cosmologists suggest, that this is the last missing piece of the puzzle and our understanding of the universe is virtually complete? Or have we just uncovered a deep dark secret that will revolutionize our whole view of the universe and our place in it? I must confess to my own prejudice that the latter seems more likely." http://www.physics.princeton.edu/~steinh/steinhardt.pdf The key words on all of the above is ...."in desperation" He's correct in that last assumption. Our view of the universe is about to /completely/ change. The stunning 'cosmic coincidences' require an entirely different world view to explain. The fundamental constants of the universe /must evolve/ to explain the observations. Just as the larger sample better shows the underlying patterns of behavior, the most complex the universe has to offer best shows fundamental law. And the most complex the universe has to offer is...LIFE! Life explains the universe not the other way around. Assuming that reducing to the simplest parts the universe for fundamental law is an erroneous assumption driven out of necessity, not logic. Jonathan s |
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Stargazers spot dark energy
"David Spain" wrote in message ... Doug Freyburger wrote: Wayne Throop wrote: ::: To result in an 'increased rate of separation' they either need to ::: REPEL each other or be under some other form of acceleration. :: Really? Yes. No. That's the deal with the expanding universe. The amount of space between here and there grows without any acceleration of either object. The question is whether the accelerating expansion is because the amount of space is growing faster or if there's now so much space between here and there that there's more of it to expand. And I can't help but believe this is also intertwined with the 2nd Law Of Thermodynamics. We are not only expanding, we are cooling too. The universe initially inflated from radiation pressure. As the ratio of matter increased, the rate of inflation slows. But just recently, at about the same time life on Earth evolved, the universe arrived at the tipping point between radiation/matter equality. At this tipping point a ...new force for a second period of universal inflation greatly increased...dark energy. Which is self repulsive, providing the force for this second round of inflation. Dark energy existed before this tipping point, but at minuscule levels. And dark energy will dissipate quickly after the tipping point, as it's unstable. But near the tipping point, dark energy becomes a primary variable for the future evolution of the universe. This universe-wide balance between energy and matter coincides with a second, but much slower, period of inflation due to the emergence of self-repulsive dark energy. Also coinciding with the start of life on Earth. Dark energy and life? Cosmic coincidence? Or cause and effect? The question then becomes, how in the world could the state of the distant reaches of the universe effect the evolution of life on Earth? How is life connected to the cosmos? We'll never understand the co-evolutionary relationship with physics, but only through...Darwin. Just pretend that's in fact true, for a moment, and try to imagine the implications for science and religion. For a new world-view. That biological evolution is just as pervasive and inherent to the universe as gravity. After all, gravity and fitness follow inverse-square law behavior. Why shouldn't there be a universal process of evolution? s Dave (now colder than when I started typing this) Spain |
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Stargazers spot dark energy
Jonathan wrote:
Stuff from Steinhardt... I like Steinhardt, I mostly agree with him; Physics is at another one of those major crossroads, like it was back in the late 19th century. You know, 19th century physicists also believed that with Maxwell's equations and the work of Newton all behind us it was just a simple matter of mopping up the remaining spots and gathering the results of the Michelson-Morely experiments to fill in the holes and determine where our inertial reference frame was in regards to the universal frame. But unlike Steinhardt, I'm not worried about 'Quintessence'. We need to study and think hard about what could be going on near and around the Planck 'interval'. My money is on positive quantum vacuum energy. This would force an expanding universe, and probably an accelerating one at that, sets the direction for the arrow of time to be 'away from quantum foam', forces the 2nd Law of Thermodynamcs, and dooms the ultimate fate of the universe to be devoid of energy, since space-time will eventually face what I'd call 'destructure' and cannot support it. My 2 cents... Dave |
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Stargazers spot dark energy
In alt.philosophy David Spain wrote:
.... We need to study and think hard about what could be going on near and around the Planck 'interval'. My money is on positive quantum vacuum energy. This would force an expanding universe, and probably an accelerating one at that, sets the direction for the arrow of time to be 'away from quantum foam', forces the 2nd Law of Thermodynamcs, and dooms the ultimate fate of the universe to be devoid of energy, since space-time will eventually face what I'd call 'destructure' and cannot support it. .... There may be something to the idea. If you look at the mathematics of random walks -- a simple example is the scenario of a drunk on a bridge; 1/2 the time staggering toward one shore, 1/2 the time to the opposite shore -- you find that in 1D (i.e. the bridge example) the "average position" of the drunk remains where they started; in 2d (the "drunk on the playground" the same; but in 3d and higher the average position drifts away from the starting point. The same kind of thing -- or possibly some more arcane consequence of the relevant mathematics -- happening at small scales or even cosmological scales could account for an expansion "force". Similarly, there may also be a "quantum" explanation for the "dark matter" -- perhaps some analog of gravitation related to zero-point energy. Of course, the cosmos itself may be warped without the need for any mass/energy (or other) to do the job. -- They said it was only luck. But the more I practised, the luckier I got. -- Gary Player [and others] |
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