Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The dynamo in the Cornfield

07.01.2005


To understand our planet’s magnetic field, Wisconsin scientists are studying a ball of molten metal

In an underground bunker that brushes up against a barnyard on one side and a cornfield on the other, scientists from the University of Wisconsin, Madison, are trying to solve an enduring cosmic mystery: how does the Earth generate its magnetic field--the vast, invisible web that shapes the aurora, makes compass needles point north, and shields us from solar storms? And how do similar fields get generated in almost every other planet in our solar system, as well as in the Sun, other stars, and even entire galaxies?

Their tool is the Madison Dynamo Experiment, a newly operational laboratory model of the Earth’s molten core. Five years in the making, with support provided jointly by the National Science Foundation (NSF) and the Department of Energy, the experiment is the largest of half a dozen such efforts worldwide. And like all the others, says UW physicist Cary Forest, principal investigator on the project, it is designed to fill in some gaping holes in our understanding.



Theory has it that magnetic fields tend to arise spontaneously in any rotating, electrically conducting fluid, explains Forest, whether that fluid is the molten iron in the Earth’s deep interior or the multi-million-degree plasma at the center of the Sun. But empirical evidence is much harder to come by, given that no one has yet figured out how to stick a probe into the core of the Earth, or into the heart of a star.

Thus the gaps. Says Forest, "How fast do the naturally occurring magnetic fields grow? When do they stop growing? What causes them to stop growing? That’s the big one. These are really, really fundamental questions that theory doesn’t address."

And thus the Madison Dynamo Experiment. At its heart is a one-meter-wide, stainless steel sphere that contains about a ton of sodium metal, which serves as the conducting fluid. Sodium metal is a dull, silvery substance that has the consistency of soft cheese at room temperature, and a dangerous habit of reacting violently with moisture and many other things. But sodium also has the advantage of melting at the comparatively low temperature of 98 degrees centigrade, or 208 degrees Fahrenheit, above which it flows like water. (Iron, by contrast, doesn’t melt until 1538 degrees centigrade, or 2800 degrees Fahrenheit.)

When the experiment is in operation, two opposing propellers stir the molten sodium in ways that approximate the flow of molten iron inside the Earth. "At the core of the Earth, it is thought that there are lots of little flows and swirls occurring that contribute to the generation of the planet’s magnetic field," says Forest. But "it’s the details that are important, and with the Madison Dynamo Experiment we can turn the knobs and see what happens."

Indeed, says Forest, with the Madison Dynamo Experiment now operational and generating data, the secrets of how natural dynamos perform will begin to emerge and the limits of current theory can begin to be tested.

Micth Waldrop | EurekAlert!
Further information:
http://www.nsf.gov

More articles from Physics and Astronomy:

nachricht Physicists Design Ultrafocused Pulses
27.07.2017 | Universität Innsbruck

nachricht CCNY physicists master unexplored electron property
26.07.2017 | City College of New York

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Physicists Design Ultrafocused Pulses

Physicists working with researcher Oriol Romero-Isart devised a new simple scheme to theoretically generate arbitrarily short and focused electromagnetic fields. This new tool could be used for precise sensing and in microscopy.

Microwaves, heat radiation, light and X-radiation are examples for electromagnetic waves. Many applications require to focus the electromagnetic fields to...

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

Programming cells with computer-like logic

27.07.2017 | Life Sciences

Identified the component that allows a lethal bacteria to spread resistance to antibiotics

27.07.2017 | Life Sciences

Malaria Already Endemic in the Mediterranean by the Roman Period

27.07.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>