translation: GoogleTranslate/doxa-louise
A breakthrough in quantum physics made in space
More than a second of observation in space, versus milliseconds on Earth: overcoming the limits of gravity, scientists have succeeded, aboard the International Space Station (ISS), a performance in quantum physics helping to better understand the fascinating mechanics that governs the microscopic world.
The feat was achieved at the Cold Atom Laboratory, a space microlaboratory installed by NASA on board the ISS in 2018, dedicated to experiments on atoms at temperatures of extreme cold, close to absolute zero, i.e. -273.2 ° C, reports a study published Thursday in the journal Nature .
Operating remotely from Earth, physicists have generated “Bose-Einstein condensates”, ultra-cold gases that form a new state of matter (the “fifth state” after solid, liquid, gas and plasma), predicted in the 1920s by Albert Einstein and the Indian mathematician Satyendranath Bose, and observed for the first time in 1995.
These gases are an aggregate of several tens of thousands of atoms which, cooled at very low temperatures, become inseparable from each other to form only one single wave, and all react in the same way at the same time. This is a quantum, mechanical property, governing the world of the infinitely small, according to which a particle (atom, ion, photon, etc.) or a group of particles can be found in several states at the same time , which can overlap and intertwine, forming a linked system, regardless of the distance between them.
But these amazing properties are very difficult to observe, because they disappear on contact with the outside world. Also, to maintain an atom in a quantum state, it is necessary to stabilize it, therefore to slow down its speed while cooling it. In the laboratory, this manipulation is hampered by Earth's gravity, which inevitably accelerates atoms.
Hence the idea of turning to space where microgravity (or microweight) no longer pulls towards the Earth and allows to recreate the conditions of a free fall. Result: “Quantum atoms are trapped by a combination of magnetic fields and lasers; they "float" longer, more than a second, instead of the generally achievable tens of milliseconds, "Kamal Oudrhiri, one of the study's authors, told AFP.
"Unbelievable!"
This extended observation time, which allows more precise measurements, will even soon pass to five seconds, ensures this space engineering specialist at NASA.Because the Cold Atom Laboratory is capable of reproducing the conditions allowing these measurements for "12 hours in a row" - a feat compared to experiments of the same type simulating microgravity (in particular parabolic flights in zero gravity) which do not exceed a few minutes , specifies the scientist.
"What they managed to do in orbit is incredible!" reacted Daniel Hennequin, physicist specializing in quantum at the CNRS. "This will allow us to better understand quantum mechanics, a science which we will soon celebrate 100 years, which has never been called into question by experimentation, but to which we have never understood anything because it is completely counter-intuitive, ”he comments.
Bose-Einstein condensates, large "objects" visible to the naked eye, straddle the border between the microscopic world, governed by quantum mechanics, and the macroscopic world, governed by "classical" physics, but "whose theory tells us that it is also quantum ", continues the scientist.
The Austrian physicist Erwin Schrödinger (1887-1961) had thus imagined an experiment where a cat enclosed in a box with a vial of poison would be both dead and alive at the same time. "With the condensates, we are getting near the kitten," quips Daniel Hennequin.
A better understanding of this fifth state of matter could in particular shed light on one of the great mysteries of the Universe, dark matter, this invisible mass that populates galaxies, but with unexplained effects, predicts Kamal Oudrhiri.
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