BLOGS

A researcher holds the scaffolding with tiny copper foils attached. These copper pieces will be struck with lasers, heating them to thousands of degrees Fahrenheit.

Credit: Hiroshi Sawada

Topics: Applied Physics, Lasers, Materials Science, Plasma, Radiation, Thermodynamics

For the first time, researchers monitor the heat progression in laser-created plasma that occurs in only a few trillionths of a second.

A team of researchers supported by the U.S. National Science Foundation has developed a new method of tracking the ultra-fast heat progression in warm, dense matter plasmas — the type of matter created when metals are struck with high-powered lasers. Published in Nature Communications, the results of this study will help researchers better understand not only how plasma forms when metal is heated by high-powered lasers but also what's happening within the cores of giant planets and even aid in the development of fast ignition laser fusion with energy-generating potential here on Earth.

The research team aimed a high-powered laser at very thin strips of copper, which heated to 200,000 degrees Fahrenheit and momentarily shifted to a warm, dense matter plasma state before exploding. At the same time, the researchers used ultrashort-duration X-ray pulses from an X-ray free-electron laser to capture images of the copper's transformation down to a few picoseconds or trillionths of a second. By doing so, the researchers were able to observe the ultra-fast and microscopic transformation of matter.

"These findings shed new light on fundamental properties of plasmas in the warm dense matter state," says Vyacheslav Lukin, NSF program director for Plasma Physics. "The new methods to probe the plasma developed by this international team of researchers may also inform future experiments at extremely high-powered lasers, such as the NSF ZEUS Laser Facility."

Researchers track plasma creation using a novel ultra-fast laser method, National Science Foundation

Credit: Public Domain

Topics: Applied Physics, Education, History, Materials Science, Philosophy, Radiation, Research

We take for granted that Earth is very old, almost incomprehensibly so. But for much of human history, estimates of Earth’s age were scattershot at best. In February 1907, a chemist named Bertram Boltwood published a paper in the American Journal of Science detailing a novel method of dating rocks that would radically change these estimates. In mineral samples gathered from around the globe, he compared lead and uranium levels to determine the minerals’ ages. One was a bombshell: A sample of the mineral thorianite from Sri Lanka (known in Boltwood’s day as Ceylon) yielded an age of 2.2 billion years, suggesting that Earth must be at least that old as well. While Boltwood was off by more than 2 billion years (Earth is now estimated to be about 4.5 billion years old), his method undergirds one of today’s best-known radiometric dating techniques.

In the Christian world, Biblical cosmology placed Earth’s age at around 6,000 years, but fossil and geology discoveries began to upend this idea in the 1700s. In 1862, physicist William Thomson, better known as Lord Kelvin, used Earth’s supposed rate of cooling and the assumption that it had started out hot and molten to estimate that it had formed between 20 and 400 million years ago. He later whittled that down to 20-40 million years, an estimate that rankled Charles Darwin and other “natural philosophers” who believed life’s evolutionary history must be much longer. “Many philosophers are not yet willing to admit that we know enough of the constitution of the universe and of the interior of our globe to speculate with safety on its past duration,” Darwin wrote. Geologists also saw this timeframe as much too short to have shaped Earth’s many layers.

Lord Kelvin and other physicists continued studies of Earth’s heat, but a new concept — radioactivity — was about to topple these pursuits. In the 1890s, Henri Becquerel discovered radioactivity, and the Curies discovered the radioactive elements radium and polonium. Still, wrote physicist Alois F. Kovarik in a 1929 biographical sketch of Boltwood, “Radioactivity at that time was not a science as yet, but merely represented a collection of new facts which showed only little connection with each other.”

February 1907: Bertram Boltwood Estimates Earth is at Least 2.2 Billion Years Old, Tess Joosse, American Physical Society

Image Source: Link Below

Topics: Astrophysics, Interstellar, Plasma, Supernovae, Radiation

Scientists have found new evidence that Earth has been moving through the remains of exploded stars for at least the last 33,000 years.

In a new study published in the journal Proceedings of the National Academy of Sciences, a team of Australian researchers describes how they extracted a special isotope of iron called iron-60 from five deep-sea sediment samples using mass spectrometry.

That’s illuminating because as the researchers wrote in their paper, the isotope is “predominantly produced in massive stars and ejected in supernova explosions.” In other words, iron-60 is left over after a star explodes.

And because iron-60 is radioactive and decays in 15 million years, the theory is that our planet is continuously being dusted with the stuff as it’s moving through the “Local Interstellar Cloud,” a region of unclear origins made up of gas, dust, and plasma.

Scientists: Earth Moving Through Radioactive Debris of Exploded Stars, Victor Tangermann, Futurism