Scientists face a problem when it comes to modeling space events inside laboratories: Earth’s gravity tends to get in the way, making it difficult to replicate environments far from our planet.
A newly proposed solution takes the form of a small glass ball, about 3 centimeters (just over an inch) in diameter. Despite its size, the sphere mimics the major forces surrounding giant planets and stars quite well.
By using sound waves as a proxy for gravitational forces, researchers can gather important data on the composition and behavior of space weather like solar flares Which has the potential to affect spaceflight, satellites, and life on Earth.
“Sound fields act like gravity, at least when it comes to driving convection in a gas,” says physicist John Koulakisfrom the University of California, Los Angeles (UCLA).
“Using microwave-generated sound in a spherical beaker of hot plasma, we have achieved a gravitational field 1,000 times stronger than Earth’s.”
The sulfur gas inside the sphere was heated to a temperature of 5,000 degrees Fahrenheit (that is, 2,760 degrees Celsius) to produce sound waves that act like an extremely strong gravitational force, generating currents in the hot, weakly ionized gas (or plasma).
The end result is convection of the plasma, in which the gas cools as it approaches the surface of a body such as a planet, before falling back toward the core, where it heats up again and rises again. The flowing gas generates its own magnetic field, which in stars will form the basis for various forms of space weather.
Many of the conditions inside the glass sphere, such as the way the hotter plasma was held in the center of the sphere, are similar to mechanisms that are supposed to occur in stars. It was very difficult to recreate this kind of result in-lab, and yet it’s now captured on camera.
“People were so interested in trying to model spherical convection with lab experiments that they actually did an experiment on the space shuttle because they couldn’t get a strong enough centripetal force field on Earth,” says physicist Seth Pottermanfrom the University of California.
The basis for the research comes in fact from study In lamps, sound, and hot balls of gas, rather than anything directly related to space. This newfound ability to control the motion of plasma with sound energy could be useful in a range of other fields as well, including studies of our own planet.
For the team, the next step is to scale up the experiment so that it more closely matches conditions in space (particularly in terms of temperature), and to investigate other aspects of the simulation. Essentially, the team needs to look at the experience in more detail and make it last longer.
Right now, there are some types of convective behavior we see around stars and planets that are hard to replicate even with the most powerful computers. With further development, this kind of experiment could take the job.
“What we showed was that our microwave-generated sound system produced gravity so strong that Earth’s gravity was not a factor,” he said. Potterman says. “We don’t need to go into space to do these experiments anymore.”
Research published in Physical review letters.