No matter whether theyre big, little, long, short, skinny or fat -- classic stalactites have the same singular shape.
Almost everyone knows that stalactites, formations that hang from the roof of caves, are generally long, slender and pointy. But the uniqueness of their form had gone unrecognized. "Theres only one shape that all stalactites tend to be. The difference is one of magnification -- its either big or its small, but its still the same shape," said researcher Martin Short of the University of Arizona in Tucson.
Short and his colleagues have developed a mathematical theory that explains how stalactites get their shape. "Its an ideal shape in nature and in mathematics that had not been known before," said Raymond Goldstein, a UA physics professor and senior author on the research report. "The Greek philosopher Plato had the concept that there are ideal forms underlying what we see in nature. Although any particular stalactite may have some bumps and ridges that deform it, one might say that within all stalactites is a idealized form trying to get out."
The universality of stalactites had probably been overlooked because the cave formations vary so much in size, said Short, a doctoral candidate in physics at UA. "The result was a surprise," he said. "We had no idea going into this that wed find this basic shape."
An article detailing the findings of Short, Goldstein and their colleagues will be published in an upcoming issue of Physical Review Letters. The Research Corporation and the National Science Foundation funded the research. Other authors on the article are James C. Baygents, a UA associate professor of chemical and environmental engineering; J. Warren Beck, a research scientist in UAs department of physics; David A. Stone, a doctoral candidate in UAs department of soil, water and environmental science; and Rickard S. Toomey, III, science and research manager for Arizona State Parks.
Although people have investigated how cave formations grow, few scientists examined why stalactites have their characteristic shape. After someone suggested that the tubules David Stone was growing in the laboratory resembled some cave formations, Goldstein became intrigued by caves.
He and his colleagues took a field trip to the famed Kartchner Caverns State Park in Benson, Ariz. and were floored by the variety of forms, especially the ripples many structures possess. So Goldstein suggested that his student Martin Short investigate the formation of ripples on stalactites. That task turned out to be extremely difficult, Short said. First he had to learn about the underlying dynamics of stalactite growth.
Stalactites grow when water laden with carbon dioxide and calcium carbonate drips from cracks or holes in the caves ceiling. As a water droplet hangs from the crack, the carbon dioxide escapes, much as a bottle of sparkling water fizzes when opened. As a result, the calcium carbonate comes out of solution and is left behind as a tiny bit of solid calcium carbonate. As each successive drip flows over the minute mineral deposit, the sequence repeats, ultimately forming a stalactite. Because the shape stems from the flow of water over the surface of the growing stalactite, the team turned to the field of fluid dynamics. The researchers developed an equation to describe how a stalactites shape evolves. "Its a general equation of motion for the growth of stalactites," Goldstein said. "Its a geometric law of motion."
Then the researchers plugged the equation into a computer and asked it to "grow" some shapes. To the teams surprise, no matter what shape was used as a starting point, the computers formations lengthened and thickened in a universal manner. The results looked strikingly like classic stalactites. "The computer told us there was something unique to look for, this ideal form," Goldstein said. The researchers then solved their equation of motion and obtained a specific mathematical expression that describes the carrot-like shape of stalactites.
The next step was to test their model against the real thing, so the researchers returned to Kartchner Caverns. "We spent four hours in the cave with cameras and strobe lights and laptops. We took dozens of pictures," said Goldstein.
Because cave formations are delicate, the researchers could not stomp around measuring the stalactites by hand. Instead, the scientists used lasers to project a pair of green dots onto the stalactites from afar and then took pictures of the stalactites. The researchers knew how far apart the green dots were, so the dots served as a scale bar for the pictures. Then the researchers could garner the stalactites dimensions from the pictures. Back in the lab, the researchers analyzed the actual stalactites and compared their shapes to the ideal form predicted by the mathematics. The real and the ideal differed by less than 5 percent. "We calculated the shape mathematically and said, well, we have to go see if this is right," Goldstein said. "And we did. And it was."
Kartchners Toomey said, "Its cool because the research contributes to learning new things about this cave that apply as well to other caves throughout the world," adding, "Missions of state parks include preservation, understanding and education. To have Kartchner and other state parks available for these types of studies helps further these missions." Now, Short and Goldstein say, they finally know enough to figure out what gives stalactites their ripples.
Mari N. Jensen | University of Arizona
NASA examines newly formed Tropical Depression 3W in 3-D
26.04.2017 | NASA/Goddard Space Flight Center
Early organic carbon got deep burial in mantle
25.04.2017 | Rice University
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
26.04.2017 | Life Sciences
26.04.2017 | Physics and Astronomy
26.04.2017 | Earth Sciences