Could their tremendous power be harnessed?
Here on Earth, we have it pretty good — lush greenery, deep oceans, breathable air, and a liveable average planetary temperature of 59 degrees Fahrenheit. However, other locations in the universe can be quite hostile, experiencing violent collisions, enormous nuclear reactions, and gigantic explosions.
How these processes unfold and what they tell us about the universe is still a bit of a mystery, but now humans are asking the question: Could this power be harnessed for the benefit of humankind?
To find out, researchers from the Department of Energy’s SLAC National Accelerator Laboratory performed three sophisticated experiments to create violent cosmic conditions in the lab, shining light on meteor impacts, the cores of giant planets, and cosmic particle accelerators a million times more powerful than the Large Hadron Collider located in Geneva, Switzerland.
Markings for Meteor Impacts
High pressures can turn a soft form of carbon, like graphite, into an extremely hard form of carbon — diamond. But could the same thing happen when a meteor hits graphite in the ground?
Scientists have predicted that it could, and that these impacts may even be powerful enough to produce a form of diamond called Lonsdaleite, which is even harder than regular diamond.
Siegfried Glenzer, head of SLAC's High Energy Density Science Division, and his colleagues, heated the surface of graphite with a powerful optical laser pulse that set off a shock wave, rapidly compressing it. By shining bright, ultrafast X-rays through the sample, the researchers were able to see how the shock changed the graphite's atomic structure.
"We saw that lonsdaleite formed for certain graphite samples within a few billionths of a second and at a pressure of about 200 gigapascals — 2 million times the atmospheric pressure at sea level," said Dominik Kraus, lead author of the paper published on March 14 in Nature Communications.
"These results strongly support the idea that violent impacts can synthesize this form of diamond, and that traces of it in the ground could help identify meteor impact sites."
Turning Hydrogen into Metal
At high pressures and temperatures within gas giants like Jupiter — whose interior is largely made of liquid hydrogen — this hydrogen is believed to switch from its “normal” electrically-insulating state into a metallic-conducting one.
Glenzer and colleagues performed an experiment at Lawrence Livermore National Laboratory (LLNL), where they used a high-power Janus laser to rapidly compress and heat a sample of liquid deuterium — a heavy form of hydrogen — to create a burst of X-rays.
The team saw that, at a pressure of 250,000 atmospheres and a temperature of 7,000 degrees Fahrenheit, deuterium transitioned from a neutral, insulating fluid to an ionized, metallic one.
"Understanding this process provides new details about planet formation and the evolution of the solar system," said Glenzer, co-principal investigator of the study published on April 15 in Nature Communications.
Building a Cosmic Accelerator
Within the universe, powerful cosmic particle accelerators exist near supermassive black holes, where streams of ionized gas, called plasma, are propelled hundreds of thousands of light-years into space. The energy in this plasma can convert into a few extremely energetic particles, which produce brief but intense bursts of gamma rays that can be detected on Earth.
Scientists want to know how this process works because it could lead to fresh ideas for building better accelerators.
Researchers believe one of the predominant forces behind cosmic accelerators is "magnetic reconnection" — a process where magnetic field lines in plasmas break and reconnect in a different way, releasing energy.
Frederico Fiúza, a researcher from SLAC's High Energy Density Science Division, and his team, ran several computer simulations that predicted how particles would behave.
"We determined key parameters for the required detectors, including the energy range they should operate in, the energy resolution they should have, and where they must be located in the experiment," said the study's lead author, Samuel Totorica, a PhD student at Stanford University and SLAC.
The researchers are waiting until the 11th International Conference on High Energy Density Laboratory Astrophysics, held May 16-20, to discuss the results of their study published March 3 in Physical Review Letters.