A platform of gold adds color to nature's fundamental forces

When dust sticks to a surface or a lizard sits on a ceiling, it is due to "nature's invisible glue." Researchers at Chalmers University of Technology, Sweden, have now discovered a quick and easy way to study the hidden forces that bind the smallest objects in the universe together. Using gold, salt water and light, they have created a platform on which the forces can be seen through colors. The research is published in the journal Proceedings of the National Academy of Sciences. In the lab at Chalmers, doctoral student Michaela Hošková shows a glass container filled with millions of micrometer-sized gold flakes in a salt solution. Using a pipette, she picks up a drop of the solution and places it on a gold-coated glass plate in an optical microscope.

I got to see my best friend in person for the first time and it was without a doubt the best week of my life. I'm not exaggerating in the slightest when I say leaving felt like ripping away a piece of my soul. But now I always have a piece of them to carry with me. I love you, Sam.

Introduction In quantum field theory, vacuum energy is the zero-point energy of all the fields in space. This includes both the electromagnetic field and the other fundamental fields. It’s the lowest possible energy that a quantum mechanical physical system may have and is the energy of empty space. Zero-Point Energy The notion of vacuum energy is closely related to the concept of zero-point…

A New Explanation For Dark Energy: The Matter In Our Universe

“What's the electromagnetic force of empty space? It's nothing, of course. With no charges, no currents, and no matter to influence, it really is zero; that's not a trick. But if you put two metal plates a finite distance apart, and then ask what the electromagnetic force is, you'll find that it isn't zero! Due to the fact that some of the vacuum fluctuation modes are forbidden due to the boundaries of the plates, we not only predict but measure a non-zero force between these plates, arising from nothing other than empty space itself. As it turns out, all of the forces, including the gravitational force, exhibit a Casimir effect as well.”

Ever since we first discovered that the expansion of the Universe is accelerating, scientists have puzzles as to what’s causing it. Although we’ve measured it precisely and concluded that it’s uniform, static in time, and equivalent in its form to a cosmological constant, we still don’t know why it exists. Moreover, any attempts to calculate what its magnitude should be give nonsensical answers that are a factor of 10^120 too large. Speculations have abounded that it might be due to an additional force or field in the Universe, or that there should be some experiments or measurements we could make that would surface an anomaly in dark energy. But perhaps the solution lies in a different place entirely: in calculating the Casimir effect for the gravitational force. The Universe isn’t truly empty, but contains huge amounts of matter, and it might be the interplay between the Universe’s large-scale structure and the gravitational fields that exist everywhere in space that causes dark energy to arise.

Researchers find a way to make Casimir effect attract or repulse depending on gap size

A team of researchers from the University of California at Berkeley and Lawrence Berkeley National Laboratory has found a way to make the Casimir effect attract or repulse depending on the size of the gap between two objects. In their paper published in the journal Science, the group describes their technique and possible applications.

The Casimir effect, first proposed by Hendrik Casimir back in 1948, is the phenomenon in which two tiny surfaces in close proximity experience a force that pulls them closer together. Quantum fluctuations inside and outside of the gap push against the plates, but because those pushing from the outside are stronger, they create an attractive forcebetween the two plates. The Casimir effect is more than a curiosity, because it can create problems in nanotechnology applications.

Just two years after Casimir first proposed the effect, others in the field began making predictions about ways to counter it—making it repulsive rather than attractive, for example, in the case of fluids and plates made of lower refractive metals. Then, in 2010, a team at MIT suggested that it should be possible to counter both attractive and repulsive effects to create a state of equilibrium between the two plates. In this new effort, the researchers report that they have done just that.

The Casimir torque: Scientists measure previously unexamined tiny force

Researchers from the University of Maryland have for the first time measured an effect that was predicted more than 40 years ago, called the Casimir torque.

When placed together in a vacuum less than the diameter of a bacterium (one micron) apart, two pieces of metal attract each other. This is called the Casimir effect. The Casimir torque—a related phenomenon that is caused by the same quantum electromagnetic effects that attract the materials—pushes the materials into a spin. Because it is such a tiny effect, the Casimir torque has been difficult to study. The research team, which includes members from UMD's departments of electrical and computer engineering and physics and Institute for Research in Electronics and Applied Physics, has built an apparatus to measure the decades-old prediction of this phenomenon and published their results in the December 20th issue of the journal Nature.

"This is an interesting situation where industry is using something because it works, but the mechanism is not well-understood," said Jeremy Munday, the leader of the research. "For LCD displays, for example, we know how to create twisted liquid crystals, but we don't really know why they twist. Our study proves that the Casimir torque is a crucial component of liquid crystal alignment. It is the first to quantify the contribution of the Casimir effect, but is not the first to prove that it contributes."

The device places a liquid crystal just tens of nanometers from a solid crystal. With a polarizing microscope, the researchers then observed how the liquid crystal twists to match the solid's crystalline axis.