Tuesday, March 27, 2012

James Cameron Explores the Mariana Trench

The Mariana Trench in comparison with Mount Everest.
James Cameron, the director of mega blockbusters Avatar and Titanic, has reached the depths of the Mariana Trench, a decent of nearly 11 km below sea level. He accomplished this in a 7.3-meter submersible designed to reach the bottom of Challenger Deep, the deepest place on Earth. Cameron is the first person to explore Challenger Deep—located south of Guam in the Pacific Ocean—in a single-person submersible, and recorded this incredible feat on March 26, 2012.
   Upon resurfacing, Cameron was cheered by his team members. “We all did it, I was just the [unlucky one] that had to get crammed in here to go take the ride,” Cameron exclaimed. Speaking to reporters, Cameron described his journey: “My feeling was one of complete isolation from all of humanity. I felt as though literally in the space of one day, I’ve gone to another planet and come back.”
   The dive follows seven years of planning, including the design and construction of a specialized submarine that could withstand the incredible pressure at the ocean floor, which actually squeezes the sub so much that it reduces its overall length by several centimeters.
   It took Cameron 2 hours and 37 minutes to reach the bottom and only 70 minute to come back up. Cameron spent a little more than three hours at the bottom of the Mariana Trench before returning. A malfunction in the hydraulic system kept him from bringing back most of his sediment sample. He wasn’t able to close the sample door and lost most of it on the trip back to the surface. Still, Cameron was hopeful that some new microbial species would be found in what he was able to bring back.
   The Mariana Trench is so remote that we don’t know even the basic of what is down there, other than small invertebrates and arthropods. Scientists do not know, for example, if there are any fish that far down. The only other time that Challenger Deep has been explored was in 1960 when Jacques Piccard, a Swiss oceanographer, and Don Walsh, a U.S. Navy captain, explored the bottom for 20 minutes in the bathyscaphe Trieste. They also had to cut their mission short when they found cracks developing in their viewing window. Piccard passed away in 2008, but Walsh was one of the team members on hand for Cameron’s historic dive.

Monday, March 26, 2012

The Higgs Field

A simulated event in the Large Hadron Collider
where two protons collide to produce a Higgs boson.
Recently, there has been a lot of chatter amongst physicists about the Higgs boson. But what is it? In 1964, a physicist named Peter Higgs proposed the existence of an energy field that permeated the entire universe. We now call this energy field the Higgs field. The reason he proposed this field is that nobody understood why some subatomic particles were very massive while other had little or no mass. The energy field that Higgs proposed would interact with the subatomic particles and give them their mass. Very massive particles would interact a lot with the field, while massless particles wouldn’t interact at all. 
   To better understand the idea we can use an analogy of swimmers in the ocean. If we think of the ocean as a Higgs field, then a fish, being streamlined, only interacts slightly with the field and can move through it very easily. A fish, therefore, would be similar to a low-mass particle. In contrast, if you or I were to try and swim through the same water, we would move much more slowly. We would represent a massive particle because we interact a lot with the water.
   The lightest of the subatomic particles is the electron, and the heaviest is the top quark, which weighs about as much as an entire gold atom, or about 350,000 times more than the electron. The thinking is not that the top quark is more massive because it is bigger. In fact, it’s the same size as an electron, but more massive because it interacts more strongly with the Higgs field. If the Higgs field didn’t exist, neither of these particles would have any mass at all.
   For some reason, we don’t hear much about the Higgs field, but rather the Higgs boson. The two are related because the Higgs boson is the smallest part of the Higgs field. We can use our water analogy to understand this better. We all know what water is. If you are in the ocean, you know that water is a continuous medium that is all around you. We also know that water is made of molecules. Once you realize that water is composed of countless water molecules you can begin to appreciate the Higgs boson. The Higgs field consists of countless Higgs bosons.
   Keep in mind that the Higgs boson has not been discovered yet. Even so, physicists are currently studying data taken from particle accelerators such as the Large Hadron Collider at CERN, in Geneva, Switzerland, and we should have an answer soon. If it is confirmed we will have the final piece of the jigsaw puzzle known as the Standard Model in place. If not, well, then things get really interesting!

Sunday, March 18, 2012

Thor’s Nuclear Hammer

Use of thorium instead of uranium may be breakthrough in energy production. Recently, India has announced their intent to produce nuclear power using thorium. The thorium reactor under development would be the first of its kind.
   The development of workable, industrial-scale thorium reactors has for decades been a dream for nuclear engineers and environmentalists alike with the hope that it becomes a major alternative to fossil fuels. Thorium has considerable advantages over uranium. Thorium is more abundant and using it does not involve releasing large quantities of carbon dioxide, making it less harmful to the climate than fossil fuels.
   The Bhabha Atomic Research Center (BARC) in Mumbai is finalizing the site for construction of a new large-scale experimental reactor. If all goes according to plan, the reactor could be operational by the end of the decade. The reactor is designed to produce 300 megawatts of electricity—about one fourth of the output of a typical nuclear plant.

   Producing a workable thorium reactor would be a huge breakthrough in energy production. Using thorium—a moderately radioactive element named after Thor, the Norse god of thunder—as a source for nuclear power is not new technology. Early research carried out in the U.S. during the 1950s and 60s was promising, but abandoned in favor of using uranium. Some believe this is at least partly because nuclear power programs in developed countries produce plutonium as a byproduct which can be used to create nuclear weapons. Unlike uranium, thorium reactors do not produce plutonium. Also, the waste from thorium reactors is less dangerous and remains radioactive for hundreds rather than thousands of years. For governments worried about nuclear waste and the possibility of terrorists getting their hands on plutonium, this is a distinct advantage. 
   Another reason for the attention on thorium is that the world’s supply of uranium is being rapidly depleted. Thorium is more than three times as abundant and contains 200 times as much energy density compared to uranium. India has the largest thorium deposits in the world, nearly 40% of the world’s supply, giving them additional incentive to develop the technology for export.
   One potential problem is that thorium reactors need a trigger fuel to initiate operation. Usually plutonium is used as a trigger fuel, but that could pose a problem for import and export. New reactors will eventually be developed to use low-enriched uranium as a trigger fuel which will make it much easier to market the technology abroad.
   Kirk Sorensen, a spokesperson for Teledyne Brown Engineering and former NASA aerospace engineer, sums up thorium’s potential “Conflicts that we see today based around energy could go away. Thorium energy sources don’t emit carbon dioxide or greenhouse gasses, and don’t produce dangerous waste. It could enable us to have cleaner water, cleaner air, and less intrusion on our environment.”

Friday, March 9, 2012

A Better Battery

Schematic of a magnesium (Mg)/antimony (Sb) battery
made of three liquid layers and running at 700 °C.

One of the cutting-edge areas of study in chemistry today is materials chemistry for battery development. Researchers at Massachusetts Institute of Technology have developed a new type of battery that could provide affordable, large-scale energy storage. Current batteries are unable to meet the low-cost, long-lifespan demands for supplementing our electrical power grid. This new type of battery would make it economical for utility companies to integrate wind and solar power with more traditional sources because they could store the electricity from these intermittent sources.
   Led by Materials Chemistry Professor Dr. Donald Sadoway, the MIT team has developed a liquid-metal based battery made from antimony, magnesium, and a mixture of magnesium-, potassium-, and sodium-chloride salt. Heated to more than 700 °C, these materials melt; and because they have variable densities, they settle into three distinct layers. The top (negative) magnesium layer and the bottom (positive) antimony layer form the electrodes of the battery, and the middle molten salt layer is the electrolyte. An electrolyte is a medium through which charged particles flow as the battery is charged or discharged.
   As the battery discharges, the magnesium atoms ionize, losing two electrons to the external circuit, and travel through the electrolyte to the positive electrode where they pick up two electrons and change back to ordinary magnesium, forming an alloy with antimony. Charging the battery runs the process in reverse, driving magnesium out of the alloy and back across the electrolyte to the negative electrode.
   While most batteries do not work well at high temperatures, this system needs high temperatures to run. Dr. Sadoway’s was inspired by his earlier work on the electrochemistry of industrial aluminum smelting. Sadoway says his new battery process is like running a smelter in reverse.
   Why magnesium and antimony? There are a couple good reasons, first of which are their different densities which allows for stratification. Also, both elements display good electrochemical properties. But most import, both are relatively abundant and inexpensive elements compared to other elements that have been tried. That keeps the cost of the batteries low. They have achieved up 69% energy efficiency with this setup.
   The team isn’t the first to research liquid-battery systems, but Dr. Sadoway says he and his team are the first to produce a working storage system in this way. Over the past few years, they have scaled up their experiment from about 4 cm in diameter to a 15 cm prototype with 200 times more storage capacity than their original version. Currently, they are focusing their efforts on improving the insulation and heating of the containers that hold the molten materials to reduce the operating temperature and cut energy costs. According to Sadoway, if they can commercialize the technology, “…it could be a game-changer”.

Monday, March 5, 2012

Cretaceous Park

A comparison of deinonychus (above)
and velociraptor (below). 

Even though the movie Jurassic Park was ground breaking for its time, it got a lot of its facts wrong, especially with velociraptor. Velociraptors were not as large as what was shown in the movie. They were actually only about 1 meter tall and 2 meters long, most of which was tail. Adults weighed about 9-14 kilograms, looking somewhat like a turkey with a long tail. Velociraptors were similar to birds in many ways. They had feathers, hollow bones, and a wishbone. They also built nests. The more that we learn about these animals the more we see them as prehistoric birds.
   Fossil evidence suggests that velociraptors were solitary creatures and did not hunt in packs, as portrayed in the film. There is a famous fossil specimen of velociraptor locked in combat with protoceratops, a small horned dinosaur about the size of a sheep, but no pack of velociraptors engaging in this or any other hunt has ever been found. Velociraptors were also not found in Montana or even the United States, as the movie suggests. They have only been found in Mongolia.
   Another myth that I would like to dispel is that velociraptors were intelligent. Certainly not smarter than dolphins or primates, as suggested in the movie. The velociraptors in Jurassic Park were actually modeled after deinonychus, a larger cousin to velociraptor which also was feathered. Deinonychus did occasionally hunt in packs and was probably a bit more intelligent, but that is a relative term when talking about dinosaurs!
   Velociraptors had bird-like claws. Its middle claw was retractable and could extend out to about 8 cm for slashing and stabbing its prey. This was velociraptor’s main weapon, similar to the spurs on a rooster. Because velociraptor hunted, it was probably warm blooded. Cold blooded animals don’t usually hunt, instead preferring to wait for their prey to come to them.
   But the largest myth perpetrated by the movie is contained in its title. Velociraptor lived during the late Cretaceous, about 70 million years AFTER the end of the Jurassic period. Maybe Cretaceous Park just didn’t have the same ring to it.