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April 14, 2014 • Volume 29
In this Issue
There is an excellent video on YouTube which will help you visualize the discovery of gravitational waves for your students.
On March 17, 2014, John Kovac announced to the world that he and his team of radio astronomers had found the imprint of gravitational waves from the Big Bang that created our universe 13.8 billion years ago. They did so by looking at the cosmic microwave background (CMB), or microwave background radiation, sometimes called the “afterglow” of the Big Bang, using BICEP2, a radiotelescope experiment based at the South Pole. The discovery has been hailed as a milestone in science, but the concepts involved will be unfamiliar to many people. How can you explain it to your students?
Start with what they know - Albert Einstein & Gravity. Einstein predicted gravitational waves, but he also calculated that they would be extremely feeble, so much so that he thought they would never be detected. BICEP2′s findings are the most convincing evidence — short of direct detection — that gravitational waves actually exist.
According to Einstein’s theory of relativity, gravity is how mass curves the shape of space. But this curving does not always stay near the massive body. In particular, Einstein realized that the deformation can propagate throughout the Universe, just as seismic waves propagate in Earth’s crust. Unlike seismic waves, however, gravitational waves can travel in empty space — and they do so at the speed of light.
The gravitational waves are the confirmation of yet another theory-inflation. According to this theory, the Universe underwent a brief period of exponential expansion during its first moments of its existence. During inflation, the Universe’s temperature — and thus the energies reached by elementary particles — were trillions of times higher than can be achieved in any laboratory, even in particle accelerators such as the Large Hadron Collider at CERN.
Because inflation is a quantum phenomenon and gravitational waves are part of classical physics, gravitational waves establish a link between the two, and could be the first evidence that gravity has a quantum nature just like other forces of nature.
The 2014 Polar Vortex that began in January brought heavy snowfall to parts of Canada and swept across the Midwest to the eastern seaboard of the United States. Temperatures fell to unprecedented levels, and low temperature records were broken across the U.S. Business, school, and road closures, as well as mass flight cancellations, were common. Altogether, more than 200 million people were affected in an area ranging from the Rocky Mountains to the Atlantic Ocean and extending south to include roughly 187 million residents of the continental United States.
Americans did get by – except for an unlucky few – thanks in large measure to nuclear power, which was able to stand up to the challenging conditions where other power sources could not, and which chipped in with a much higher share of the supply than normal.
It seems that America’s nuclear power stations, more so than its over-challenged gas-fired and coal-fired plants, kept us warm, the lights on, and businesses running.
To bring you the story in more detail, check out “Polar Vortex – Nuclear Saves the Day” by scientist James Conca (Forbes Magazine)
The Shroud of Turin is a centuries-old linen cloth – one of the world’s most famous relics. It contains a faint impression of the front and back of a human body, along with blood, dirt and water stains from age. Many Roman Catholics believe the impressions were left by the body of Jesus after his crucifixion.
Skeptics believe the 14-foot cloth was faked during medieval times. Scientists have used various methods, including carbon dating, to test the authenticity of the fabric, and some results have supported the belief that the cloth is a medieval forgery. But there might be new evidence to support the view that the shroud is real.
What is radiocarbon dating?
Comparing the amount of C-14 in a dead organism to available levels in the atmosphere, produces an estimate of when that organism died.
Radiocarbon dating works well for some archaeological finds, but it has limitations: it can be used to date only organic materials less than about 60,000 years old. However, there are other dating methods that use radioactive isotopes, such as argon 40 to argon 39, potassium-argon (K-Ar), uranium-lead (U-Pb), rubidium-strontium (Rb-St), that can be used to date non-organic materials (such as rocks) and older materials (up to billions of years old).
One of these radioisotopes is K-40, which is found in volcanic rock. After the volcanic rock cools off, its potassium-40 decays into Ar-40 with a 1.25-billion-year half-life. It is possible to measure the ratio of potassium-40 to argon-40 and estimate a rock’s age, but this method is imprecise. Then, scientists discovered in the 1960s that they could irradiate a rock sample with neutrons and thereby convert the potassium-40 to argon-39, an isotope not normally found in nature and easier to measure. Though more intricate, this process yields more precise dates. For example, scientists at the University of California at Berkeley were able to date samples from the 79 A.D. eruption of the volcano Vesuvius to within seven years of the event.
Can other natural disasters affect dating methods? While some consider the Shroud of Turin a miracle, others search for a more scientific explanation for its existence, and researchers from the Politecnico di Torino have come up with a theory that they believe might provide some answers. They say that it is possible that neutron emissions from an earthquake around the time of Jesus’ death could have created the image, as well as affected radiocarbon levels that suggested the shroud was a forgery from medieval times. Read more about this discovery at the link below.
In this activity, created by the Astronomical Society of the Pacific, students will learn about nuclear fusion and how radiation is generated by stars, using marshmallows as a model.
In this Issue
Teach Nuclear Science with Confidence Detecting Radiation in Our Radioactive World June 14 / Reno, NV
This full-day workshop will prepare attendees to teach the basics about radiation, how we detect radiation, and uses of nuclear science and technology in society. Teachers who complete the workshop will receive a wealth of materials – background information, hands-on activities,
The Science of Nuclear Energy & Radiation Virginia Commonwealth University July 14 / Virginia
This four-day teacher workshop includes: 4 Continuing Education units, meals, accommodations on campus, teaching materials, and Geiger-Muller counter.
Registration Fee: $75
National Nuclear Science Week October 20 - 24, 2014 NuclearScienceWeek.org
For information about the week and ideas for activities to recognize the importance of nuclear science and technology in daily life.
Sign up for ReActions™, the e-newsletter for educators that offers teaching ideas about nuclear science and technology. It is published electronically between September and May.Sign Up
Center for Nuclear Science and Technology Information of the American Nuclear Society
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