Sometimes scientists need to take a fresh look at fundamentals to improve familiar materials. That means getting down to the basic molecular and atomic structures.
When a research group that calls itself "Liquid Stone" recently did that with cement, it found that what scientists thought they knew about the fundamental structure of that ubiquitous material just isn't so. One team member likens the implications of their new understanding of that structure to the boost biologists got when they discovered the basic structure of the DNA molecule.
Taking a similar fundamental look at the basic dynamics of magnetism, another research team has shown, for the first time, that a gas can be made to behave magnetically like a bar magnet. Team member Wolfgang Ketterle at the Massachusetts Institute of Technology called it "an important discovery, which will advance our understanding of magnetism." That's important in a world where so much technology depends on the use of magnetic materials. Think computer hard drives.
In spelling out the details of this research in the Sept. 18 issue of Science, the MIT team says it appears to have answered the long standing question of whether or not a gas can become "ferromagnetic." That means it can act like solid materials whose crystal structure allows them to become magnetized. The answer is a qualified "yes."
Solid magnets have a basic crystal structure that allows their atomic electrons to line up in the same direction. That constitutes magnetism. The MIT team worked with a form of lithium called lithium-6. Its atoms have the same quantum properties that allow bar magnet electrons to line up like soldiers. The team believes it has shown that, when cooled to almost absolute zero, atoms in a lithium-6 gas can line up the same way. Team member David Pritchard called the evidence "pretty strong" but "not yet a slam dunk." He wants confirmation of its results through further experimentation.
The Liquid Stone group – another MIT team – is even more certain of its conclusions. The technical details were reported earlier this month in the online Proceedings of the National Academy of Sciences. Add water to cement powder and it forms a paste called cement hydrate. Scientists had thought that this paste, which hardens into concrete, had a crystal structure. The team now has shown that its structure actually is part crystal and part amorphous frozen liquid like glass and water ice.
Team member Franz-Josef Ulm considers this insight so fundamentally important he called it finding "the DNA of concrete." He explained: "Now that we have a validated molecular model, we can manipulate the chemical structure to design concrete for strength and environmental qualities, such as the ability to withstand higher pressure or temperatures."
Back to basics is a useful strategy in many areas of life. It's crucial in science and engineering where familiarity can mislead experts when they think they understand the subject they are dealing with. The new insights into magnetism and the structure of cement are the kind of breakthroughs on the research frontier that can save self-assured experts from themselves.
[Editor's note: The original version of this article misstated David Pritchard's name.]