A team of researchers has cooled matter to a billionth of absolute zero degrees, far cooler than any star, even in the deepest depths of space.
Interstellar space never gets this cold due to the fact that it is evenly filled. cosmic microwave background (CMB) is a form of radiation left over from an event that occurred shortly after the event. Big Bang When Universe was in its infancy. The cooled matter is even colder than the coldest known region of space. Boomerang Nebula3,000 in light years From Earth, which has a temperature just one degree above absolute zero.
The experiment, conducted at Kyoto University in Japan, used fermions, which particle physicists call any particle that makes up matter, including electrons, protons and neutrons. The team cooled their fermions — atoms of the element ytterbium — to about one billionth of absolute zero, the hypothetical temperature at which all atomic motion would cease.
“If an alien civilization isn’t currently doing experiments like this, it makes the coldest fermions in the universe whenever that experiment runs at Kyoto University,” said Rice University researcher Kaden Hazzard, who was involved in the study. Declaration (opens in new tab).
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The team used lasers to cool the matter by restricting the movement of 300,000 atoms in an optical lattice. The experiment simulates a model quantum physics It was first proposed by theoretical physicist John Hubbard in 1963. The model, called the Hubbard model, allows atoms to display unusual quantum properties, including the collective behavior between atoms. electrons such as superconductivity (the ability to conduct electricity without loss of energy).
“The payoff of this chill is that the physics really change,” Hazzard said. “Physics starts to become more quantum mechanics and allows you to see new phenomena.”
‘Fossil’ radiation that keeps space warm
Interstellar space can never get this cold because of the presence of the CMB. This evenly distributed and uniform radiation was created by an event called final scattering, which occurred during the first rapid expansion of the universe shortly after the Big Bang.
During the final scattering, electrons began to bond with protons, forming the first atoms of hydrogen, the lightest element available. As a result of this atom formation, the universe rapidly lost its loose electrons. And because electrons scatter photons, before the final scattering, the universe was opaque to light. With electrons bound to protons in these early hydrogen atoms, photons could suddenly travel freely and make the universe transparent to light. The final scattering also marked the last moment when fermions such as protons and photons had the same temperature.
As a result of the final scattering, photons filled the universe at a specific temperature of 2.73 Kelvin, which is equal to minus 454.76 degrees Fahrenheit (minus 270.42 degrees Celsius), which is only 2.73 degrees above absolute zero – 0 Kelvin, or minus 459.67 degrees F (minus 459.67 degrees F). 273.15 degrees C).
There is one region in the known universe, the Boomerang Nebula, a gas cloud surrounding a dying planet. stale In the constellation Centaurus, which is even cooler than the rest of the universe – about 1 Kelvin, or minus 457.6 ⁰F (minus 272⁰ C). Astronomers believe that the Boomerang Nebula is being cooled by the cold, and the gas emitted by the dying star is expanding at the center of the nebula. But even the Boomerang Nebula can’t compete with the temperatures of the ytterbium atom in the latest experiment.
The team behind this experiment is currently trying to develop the first tools that can measure behavior occurring above one billionth of absolute zero.
“These systems are pretty exotic and special, but by studying and understanding them, we hope we can identify the key components that should be in real materials,” Hazzard said.
The team’s research was published in September. 1 inch Nature Physics (opens in new tab).
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