Mysterious quantum forces unraveled-MIT researchers find a way to calculate...Casimir forces...

[OKIsItJustMe]

http://web.mit.edu/newsoffice/2010/casimir-0511.html

Mysterious quantum forces unraveled

MIT researchers find a way to calculate the effects of Casimir forces, offering a way to keep micromachines’ parts from sticking together.

Larry Hardesty, MIT News Office

May 11, 2010

Discovered in 1948, Casimir forces are complicated quantum forces that affect only objects that are very, very close together. They’re so subtle that for most of the 60-odd years since their discovery, engineers have safely ignored them. But in the age of tiny electromechanical devices like the accelerometers in the iPhone or the micromirrors in digital projectors, Casimir forces have emerged as troublemakers, since they can cause micromachines’ tiny moving parts to stick together.

MIT researchers have developed a powerful new tool for calculating the effects of Casimir forces, with ramifications for both basic physics and the design of microelectromechanical systems (MEMS). One of the researchers’ most recent discoveries using the new tool was a way to arrange tiny objects so that the ordinarily attractive Casimir forces become repulsive. If engineers can design MEMS so that the Casimir forces actually prevent their moving parts from sticking together — rather than causing them to stick — it could cut down substantially on the failure rate of existing MEMS. It could also help enable new, affordable MEMS devices, like tiny medical or scientific sensors, or microfluidics devices that enable hundreds of chemical or biological experiments to be performed in parallel.

...

Calculating the incalculable

In a paper appearing this week in Proceedings of the National Academy of Sciences, Johnson, physics PhD students Alexander McCauley and Alejandro Rodriguez (the paper’s lead author), and John Joannopoulos, the Francis Wright Davis Professor of Physics, describe a way to solve Casimir-force equations for any number of objects, with any conceivable shape.

The researchers’ insight is that the effects of Casimir forces on objects 100 nanometers apart can be precisely modeled using objects 100,000 times as big, 100,000 times as far apart, immersed in a fluid that conducts electricity. Instead of calculating the forces exerted by tiny particles flashing into existence around the tiny objects, the researchers calculate the strength of an electromagnetic field at various points around the much larger ones. In their paper, they prove that these computations are mathematically equivalent.

...

[ClarkUSA]

1. Another step forward to the realization of an humanity wedded to nanomachinery.

Yesterday's science fiction is tomorrow's everyday reality. Gotta love it. :D

[UndertheOcean]

2. It is always the Graduate Students that do the grunt work ! Congrats to Alexander

and Alejandro on the breakthrough .

[HughMoran]

3. Pretty cool

I wonder what made them consider using an electrically conductive fluid and 10^5 scaling? Do they understand the physics or was this a bit of common sense and empirical experimentation?

[Confusious]

8. they did the math

In their paper, they prove that these computations are mathematically equivalent.

Einstein predicted "gravitational lensing" years before anyone saw it.

According to general relativity, mass "warps" space-time to create gravitational fields and therefore bend light as a result. This theory was confirmed in 1919 during a solar eclipse, when Arthur Eddington observed the light from stars passing close to the sun was slightly bent, so that stars appeared slightly out of position.

Einstein realized that it was also possible for astronomical objects to bend light, and that under the correct conditions, one would observe multiple images of a single source, called a gravitational lens or sometimes a gravitational mirage.

However, as he only considered gravitational lensing by single stars, he concluded that the phenomenon would most likely remain unobserved for the foreseeable future. In 1937, Fritz Zwicky first considered the case where a galaxy could act as a source, something that according to his calculations should be well within the reach of observations.

It was not until 1979 that the first gravitational lens would be discovered. It became known as the "Twin QSO" since it initially looked like two identical quasistellar objects; it is officially named SBS 0957+561. This gravitational lens was discovered accidentally by Dennis Walsh, Bob Carswell, and Ray Weymann using the Kitt Peak National Observatory 2.1 meter telescope.

It was all predicted in the math.

[gateley]

4. This stuff is way over my head and education, but I am always fascinated! Thanks! nt

[OKIsItJustMe]

6. You're welcome

If you read the stuff you don't understand, you will gain understanding.

[gateley]

7. I seem to get a SENSE of it, and I find it exciting. nt

[quiet.american]

5. Interesting stuff. What I'm really waiting for is the capacity to beam myself home from work, tho'.

:) Goodbye, subways! I'll be first in line when they come up with that.