Latest news with #BénédicteRey
Japan Today
01-08-2025
- Science
- Japan Today
Physicists still divided about quantum world, 100 years on
Quantum mechanics have led to the development of vast amounts of tech, such as lasers or transistors used phones By Bénédicte Rey The theory of quantum mechanics has transformed daily life since being proposed a century ago, yet how it works remains a mystery -- and physicists are deeply divided about what is actually going on, a survey in the journal Nature said Wednesday. "Shut up and calculate!" is a famous quote in quantum physics that illustrates the frustration of scientists struggling to unravel one of the world's great paradoxes. For the last century, equations based on quantum mechanics have consistently and accurately described the behavior of extremely small objects. However, no one knows what is happening in the physical reality behind the mathematics. The problem started at the turn of the 20th century, when scientists realised that the classical principles of physics did not apply to things on the level on atoms. Bafflingly, photons and electrons appear to behave like both particles and waves. They can also be in different positions simultaneously -- and have different speeds or levels of energy. In 1925, Austrian physicist Erwin Schroedinger and Germany's Werner Heisenberg developed a set of complex mathematical tools that describe quantum mechanics using probabilities. This "wave function" made it possible to predict the results of measurements of a particle. These equations led to the development of a huge amount of modern technology, including lasers, LED lights, MRI scanners and the transistors used in computers and phones. But the question remained: what exactly is happening in the world beyond the maths? To mark the 100th year of quantum mechanics, many of the world's leading physicists gathered last month on the German island of Heligoland, where Heisenberg wrote his famous equation. More than 1,100 of them responded to a survey conducted by the leading scientific journal Nature. The results showed there is a "striking lack of consensus among physicists about what quantum theory says about reality", Nature said in a statement. More than a third -- 36 percent -- of the respondents favoured the mostly widely accepted theory, known as the Copenhagen interpretation. In the classical world, everything has defined properties -- such as position or speed -- whether we observe them or not. But this is not the case in the quantum realm, according to the Copenhagen interpretation developed by Heisenberg and Danish physicist Niels Bohr in the 1920s. It is only when an observer measures a quantum object that it settles on a specific state from the possible options, goes the theory. This is described as its wave function "collapsing" into a single possibility. The most famous depiction of this idea is Schroedinger's cat, which remains simultaneously alive and dead in a box -- until someone peeks inside. The Copenhagen interpretation "is the simplest we have", Brazilian physics philosopher Decio Krause told Nature after responding to the survey. Despite the theory's problems -- such as not explaining why measurement has this effect -- the alternatives "present other problems which, to me, are worse," he said. Enter the multiverse But the majority of the physicists supported other ideas. Fifteen percent of the respondents opted for the "many worlds" interpretation, one of several theories in physics that propose we live in a multiverse. It asserts that the wave function does not collapse, but instead branches off into as many universes as there are possible outcomes. So when an observer measures a particle, they get the position for their world -- but it is in all other possible positions across many parallel universes. "It requires a dramatic readjustment of our intuitions about the world, but to me that's just what we should expect from a fundamental theory of reality," US theoretical physicist Sean Carroll said in the survey. The quantum experts were split on other big questions facing the field. Is there some kind of boundary between the quantum and classical worlds, where the laws of physics suddenly change? Forty-five percent of the physicists responded yes to this question -- and the exact same percentage responded no. Just 24 percent said they were confident the quantum interpretation they chose was correct. And three quarters believed that it will be replaced by a more comprehensive theory one day. © 2025 AFP
Japan Today
04-06-2025
- Science
- Japan Today
Huge planet discovered orbiting tiny star puzzles scientists
An artist's illustration of an exoplanet and its star By Bénédicte Rey Astronomers announced Wednesday they have discovered a massive planet orbiting a tiny star, a bizarre pairing that has stumped scientists. Most of the stars across the Milky Way are small red dwarfs like TOI-6894, which has only 20 percent the mass of our Sun. It had not been thought possible that such puny, weak stars could provide the conditions needed to form and host huge planets. But an international team of astronomers have detected the unmistakable signature of a gas giant planet orbiting the undersized TOI-6894, according to a study in the journal Nature Astronomy. This makes the star the smallest star yet known to host a gas giant. The planet has a slightly larger radius than Saturn, but only half its mass. It orbits its star in a little over three days. The astronomers discovered the planet when searching through more than 91,000 low-mass red dwarfs observed by NASA's TESS space telescope. Its existence was then confirmed by ground-based telescopes, including Chile's Very Large Telescope. "The fact that this star hosts a giant planet has big implications for the total number of giant planets we estimate exist in our galaxy," study co-author Daniel Bayliss of the UK's Warwick University said in a statement. Another co-author, Vincent Van Eylen, of University College London, said it was an "intriguing discovery". "We don't really understand how a star with so little mass can form such a massive planet!" he said. "This is one of the goals of the search for more exoplanets. By finding planetary systems different from our solar system, we can test our models and better understand how our own solar system formed." The most prominent theory for how planets form is called core accretion. The process begins when a ring of gas and dust -- called a protoplanetary disc -- which surrounds a newly formed star builds up into a planetary core. This core attracts more gas that forms an atmosphere, eventually snowballing into a gas giant. Under this theory, it is difficult for low-mass stars to host giant planets because there is not enough gas and dust to begin building a core in the first place. A rival theory proposes that these planets instead form when their protoplanetary disc becomes gravitationally unstable and breaks up, with the collapsing gas and dust forming a planet. However neither theory seems to explain the existence of the newly discovered planet, TOI-6894b, the researchers said. The planet also interests scientists because it is strangely cold. Most of the gas giants discovered outside our Solar System so far have been what are known as "hot Jupiters", where temperatures soar well over 1,000 degrees Celsius. But the newly discovered planet appears to be under 150C, the researchers said. "Temperatures are low enough that atmospheric observations could even show us ammonia, which would be the first time it is found in an exoplanet atmosphere," said study co-author Amaury Triaud of Birmingham University. The James Webb space telescope is scheduled to turn its powerful gaze towards the planet in the next year, which could help uncover some more mysteries of this strange planet. © 2025 AFP
