[align=center]The Force of Empty Space[/align][align=center][:-][/align][align=center]

[/align][align=center][/align][align=center]Phys. Rev. Lett. 81, 4549
Sensitive sphere. This 200-µm-diameter sphere mounted on a cantilever was brought to within 100 nm of a flat surface (not shown) to detect the elusive Casimir force.
According to quantum mechanics, the vacuum is not empty, but teeming with virtual particles that constantly wink in and out of existence. One strange consequence of this sea of activity is the Casimir effect: Two flat metal surfaces automatically attract one another if they get close enough. The Casimir force is so weak that it has rarely been detected at all, but now a team reports in the 23 November PRL that they have made the most precise measurement ever of the phenomenon. They claim that their technique, using an atomic force microscope, has the capacity to test the strangest aspects of the Casimir effect, ones that have never before been tested.
The simplest explanation of the Casimir effect is that the two metal plates attract because their reflective surfaces exclude virtual photons of wavelengths longer than the separation distance. This reduces the energy density between the plates compared with that outside, and--like external air pressure tending to collapse a slightly evacuated vessel--the Casimir force pulls the plates toward one another. But the most puzzling aspect of the theory is that the force depends on geometry: If the plates are replaced by hemispherical shells, the force is repulsive. Spherical surfaces somehow "enhance" the number of virtual photons. There is no simple or intuitive way to tell which way the force will go before carrying out the complicated calculations.
Since the discovery of the theory by Casimir 50 years ago, there have been only two previous documented detections of the effect. One was in 1958 and had 100% uncertainty, and the second was last year [Phys. Rev. Lett. 78, 5 (1997)], when the theory was verified to within 5%. Umar Mohideen and Anushree Roy, of the University of California at Riverside, claim their new results verify the theory to within 1%.
Mohideen and Roy exploited the exquisite sensitivity of the atomic force microscope (AFM), which can sense forces as small as 10-18 newtons. In an AFM, the force causes a slight deflection of a microscopic cantilever, which is detected with a laser system. The team affixed an aluminum-plated, 200-µm-diameter sphere to the cantilever and recorded the deflection as it approached a flat, aluminum-plated surface to within 100 nm. They corrected the raw data for several small effects, including the electrostatic force between the surfaces caused by a small excess charge on the sphere. Because the approach was so close, the team also had to correct the theoretical curve to account for the microscopic roughness of the metal surfaces, which they measured using the AFM in a more traditional mode. They applied a further correction to the ideal theory to account for the lack of perfectly reflecting surfaces.
Mohideen says the new method is superior to previous ones because the electrostatic corrections to the data amounted to only a few percent of the size of the Casimir force, whereas in the previous experiment, those corrections were 5 times the Casimir force. But the real importance of the new technique, says Mohideen, is that its precision can be dramatically improved, allowing studies of the weird geometry dependence of the Casimir effect and even its predicted dependence on temperature.
[i]Lawrence Ford, of Tufts University in Medford, MA, says the work is important b

 

Did the add "the mind of" in front of Space in those last few sentences or did it already say that?
That whole article is way over my head. I didnt even try to pretend I knew what they were talking about. lol

 

space! you lost me on the first sentance...lol..way over my head, was that english?

 

[align=center] [/align][align=center][/align][align=center]LOL ~ LOL `Matt & Mod Wiz[/align]


[hr]


[align=center]"This is a test.The `Space Stationis conducting a test of the Emergency MCFWeb System. This is only a test.[/align][align=center]Please don't panic, this is only a test" [/align]

[/align][align=center]Test conducted to see what member's are[/align][align=center]clicking/reading/contributing[/align][align=center]to the MCF.[/align][align=center]We shall return to regular forum activities[/align][align=center]in 3-2-1 = Now[/align][align=center][/align][align=center]Go EnJoy your `Journeyon the MCF,[/align][align=center]and we shall
calculate, & evaluate your intense input byyour [/align][/align]
[/align][align=center][/align][align=center]Thank You for complying to the rules[/align][align=center]of the MCF.[/align][align=center][/align]

 

Dark Matter and Dark Energy: One and the Same?
By Robert Roy Britt
Senior Science Writer
posted: 07:00 am ET
12 July 2004


Dark matter and dark energy are two of the most vexing problems in science today. Together they dominate the universe, comprising some 96 percent of all mass and energy.


But nobody knows what either is. It's tempting to consider them products of the same unknown phenomenon, something theorist Robert Scherrer suggests. The professor of physics at Vanderbilt University says "k-essence" is behind it all.


Dark matter was invoked decades ago to explain why galaxies hold together. Given regular matter alone, galaxies might never have formed, and today they would fly apart. So there must be some unknown stuff that forms invisible clumps to act as gravitational glue.


Dark energy hit the scene in the late 1990s when astronomers discovered the universe is not just expanding, but racing out at an ever-faster pace. Some hidden force, a sort of anti-gravity, must be pushing galaxies apart from one another in this accelerated expansion.


Separate theories have been devised to try and solve each mystery.
To explain dark energy, for example, theorists have re-employed a "cosmological constant" that Einstein first introduced as a fudge factor to balance the force of gravity. Einstein called the cosmological constant a great blunder and retracted it. Yet many theorists now are comfortable re-employing it to account for the effects of dark energy. But it does not reveal what the force is.


Scherrer agrees two explanations might be necessary, but he's also bothered by that complexity.


'Embarrassing'
"It is somewhat embarrassing to have two different unknown sources for the dominant forms of matter and energy in the universe," he said in an e-mail interview. "On the other hand, that may just be the way things are. We don't get to pick the universe we live in."


To explain it all in one fell swoop, Scherrer invokes an exotic form of energy called a scalar field. It's a bit like an electric or magnetic field, with energy and pressure and a magnitude. But a scalar field has no direction. A scalar field is thought to have been behind inflation, the less-than-a-second period after the Big Bang when the universe expanded many billions of times before settling into a more reasonable rate of growth.

Scherrer borrows from work by Princeton University's Paul Steinhardt, V. Slava Mukhanov at the University of Munich and Christian Armendáriz Picón of the University of Chicago, relying on a specific type of second-generation scalar field they envisioned called k-essence, short for kinetic-energy-driven quintessence.

K-essence changes behavior over time in Scherrer's model, clumping early on to help form galaxies, and now forcing the universe apart. Right now, dark matter has a density that decreases as the universe expands, he explained, while dark energy has a density that stays constant as the universe expands.


"That means that at very early times, the dark matter 'piece' of the k-essence is the dominant one," Scherrer said. "As the universe expands and the density of the dark matter 'piece' of the k-essence decreases, it eventually falls below the density of the dark energy 'piece,' and the k- essence behaves more like dark energy."

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Uh-hunh. Uh-hunh. I see.
So that's the reason birds poop on my car right after Iwash it.

Interesting.

 

^^^LMAO!!

 

 

 

I just wanted to pay homage to 2nd Gen's.