Creating the Coldest Matter in the Universe

Creating the Coldest Matter in the Universe
Making the Coldest Matter in the Universe - Shows trapped ytterbium atoms cooled to temperatures approximately 3 billion times colder than deep space (Image credit: Courtesy of Ella Maru Studio/K. Hazzard/Rice University)

To make matter even cooler than the deepest parts of space, far from any stars, a team of scientists has managed to cool it to a billionth of absolute zero degrees.

Interstellar space never gets this cold as it is evenly filled with the cosmic microwave background (CMB).
This event is a form of radiation left over from an event that occurred when the universe was in its infancy, shortly after the Big Bang.

The cooled matter has a temperature just one degree above absolute zero, making it even cooler than the Boomerang Nebula, the coldest known region of space, located 3000 light-years from Earth.

The study, conducted at Kyoto University in Japan, used fermions, the term used by particle physicists to describe any subatomic particle that contributes to the formation of matter, such as electrons, protons, and neutrons. The researchers lowered the temperature of their fermions, or ytterbium atoms, to one billionth of absolute zero, the imaginary point at which all atomic motion would cease.

According to Rice University researcher Kaden Hazzard, who was involved in the study, "if some alien civilizations are not currently performing such experiments, it creates the coldest fermions in the universe whenever this experiment is conducted at Kyoto University."

The team restricted the movement of 300.000 atoms inside an optical lattice, using lasers to cool the material. The experiment simulates a quantum physics paradigm first introduced in 1963 by theoretical physicist John Hubbard. With the help of Hubbard's model, atoms can exhibit a variety of strange quantum phenomena, such as superconductivity, which is the capacity of electrons. In other words, we can say that it can transmit electricity without losing energy.

According to Hazzard, physics is really changing because of the extreme cold. It allows you to observe new phenomena as physics shifts towards a more quantum mechanical framework.

Because of cosmic background radiation, interstellar space could never be this cold. During the universe's initial, rapid expansion following the Big Bang, an event known as "final scattering" produced this homogeneous, evenly distributed radiation.

During the final scattering, electrons began to bond with protons, producing the first atoms of hydrogen, the lightest element known. The universe rapidly lost its unbound electrons as a result of this atom formation. Because electrons scatter photons, the universe was dark before the final scattering. Photons could immediately flow freely in these early hydrogen atoms because the electrons were bound to the protons, making the universe transparent to light.

The final scattering also marked the last time fermions, like protons and photons, had the same temperature.

Photons filled the cosmos at a precise temperature of 454,76 Kelvin, which is equal to minus 270,42 degrees Fahrenheit (minus 2,73 degrees Celsius). This is just 2,73 degrees above absolute zero (0 Kelvin, or minus 459,67 degrees Fahrenheit, or minus 273,15 degrees Celsius).

The Boomerang Nebula, a gas cloud surrounding a dying star in the constellation Centaurus, is significantly cooler than the rest of the cosmos, measuring roughly 1 Kelvin, or minus 457,6 F (minus 272 degrees Celsius).

According to astronomers, the Boomerang Nebula is being cooled by the cold, expanding gas ejected by the dying star at its center. But even the Boomerang Nebula cannot compete with the temperatures reached by the ytterbium atom in the current experiment.

Experiment's team is now building the first instruments that can measure behavior that occurs above one billionth of absolute zero.

"These systems are pretty weird and special," Hazzard said, "but the point is that by researching and understanding them, we can find the essential components that should be present in real materials."

Source: space







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