MSGID: 1:317/3 64951ff2   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Einstein and Euler put to the test at the edge of the Universe    
      
     Date:   
         June 22, 2023   
     Source:   
         Universite' de Gene`ve   
     Summary:   
         The cosmos is a unique laboratory for testing the laws of physics,   
         in particular those of Euler and Einstein. Euler described the   
         movements of celestial objects, while Einstein described the   
         way in which celestial objects distort the Universe. Since the   
         discovery of dark matter and the acceleration of the Universe's   
         expansion, the validity of their equations has been put to the   
         test: are they capable of explaining these mysterious phenomena? A   
         team has developed the first method to find out. It considers a   
         never-before-used measure: time distortion.   
      
      
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   FULL STORY   
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   The cosmos is a unique laboratory for testing the laws of physics, in   
   particular those of Euler and Einstein. Euler described the movements of   
   celestial objects, while Einstein described the way in which celestial   
   objects distort the Universe. Since the discovery of dark matter and the   
   acceleration of the Universe's expansion, the validity of their equations   
   has been put to the test: are they capable of explaining these mysterious   
   phenomena? A team from the University of Geneva (UNIGE) has developed   
   the first method to find out. It considers a never-before-used measure:   
   time distortion. The results are published in Nature Astronomy.   
      
   The theories of Leonhard Euler (1707-1783) and Albert Einstein (1879-1955)   
   revolutionised our understanding of the Universe. With the famous   
   equation that bears his name, Euler gave scientists a powerful tool for   
   calculating the movements of galaxies in the Universe. With his theory   
   of general relativity, Einstein demonstrated that the Universe is not   
   a static framework: it can be distorted by star clusters and galaxies.   
      
   Physicists have tested these equations in all sorts of ways, which have   
   so far proved successful. However, two discoveries continue to put these   
   models to the test: the acceleration of the Universe's expansion and the   
   existence of invisible dark matter, which is thought to account for 85%   
   of all matter in the cosmos. Do these mysterious phenomena still obey   
   the equations of Einstein and Euler? Researchers are still unable to   
   answer this question.   
      
   The missing ingredient "The problem is that current cosmological   
   data do not allow us to differentiate between a theory that breaks   
   Einstein's equations and one that breaks Euler's equation. This is what   
   we demonstrate in our study. We also present a mathematical method for   
   solving this problem. This is the culmination of ten years of research,"   
   explains Camille Bonvin, associate professor in the Department of   
   Theoretical Physics in the UNIGE Faculty of Science and first author of   
   the study.   
      
   Researchers were unable to differentiate between the validity of these two   
   equations at the very edge of the Universe because they were missing an   
   "ingredient": the measurement of time distortion. "Until then, we only   
   knew how to measure the speed of celestial objects and the sum of the   
   distortion of time and space. We have developed a method for accessing   
   this additional measurement, and it's a first," says Camille Bonvin.   
      
   If the time distortion is not equal to the sum of time and space --   
   i.e. the result produced by the theory of general relativity -- this   
   means that Einstein's model does not work. If the time distortion does   
   not correspond to the speed of the galaxies calculated with the Euler   
   equation, this means that the latter is not valid. "This will allow   
   us to discover whether new forces or matter, which violate these two   
   theories, exist in the Universe," explains Levon Pogosian, professor   
   in the Department of Physics at Simon Fraser University, in Canada,   
   and co-author of the study.   
      
   Reality check These results will make a crucial contribution to several   
   missions whose aim is to determine the origin of the accelerated expansion   
   of the Universe and the nature of dark matter. These include the EUCLID   
   space telescope, which will be launched in July 2023 by the European   
   Space Agency (ESA), in collaboration with the UNIGE, and the Dark Energy   
   Spectroscopic Instrument (DESI), which began its 5-year mission in 2021   
   in Arizona. There is also the international SKA (Square Kilometre Array)   
   giant radio telescope project in South Africa and Australia, which will   
   begin observations in 2028/29.   
      
   "Our method will be integrated into these different missions. This is   
   already the case for DESI, whom we have become external collaborators   
   thanks to this research," Camille Bonvin enthuses. The research team has   
   successfully tested its model on synthetic catalogues of galaxies. The   
   next stage will involve testing it using the first data supplied by   
   DESI, as well as identifying the obstacles and minimising the systematic   
   features that could hamper its application.   
      
       * RELATED_TOPICS   
             o Space_&_Time   
                   # Cosmology # Astrophysics # Big_Bang # Dark_Matter   
             o Matter_&_Energy   
                   # Quantum_Physics # Physics # Albert_Einstein #   
                   Nuclear_Energy   
       * RELATED_TERMS   
             o Ultimate_fate_of_the_universe o Shape_of_the_Universe o   
             Physical_cosmology o Astronomy o Dark_energy o Dark_matter o   
             Introduction_to_general_relativity o General_relativity   
      
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   Story Source: Materials provided by Universite'_de_Gene`ve. Note:   
   Content may be edited for style and length.   
      
      
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   Journal Reference:   
      1. Bonvin, C., Pogosian, L. Modified Einstein versus modified Euler   
      for dark   
         matter. Nat Astron, 2023 DOI: 10.1038/s41550-023-02003-y   
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   Link to news story:   
   https://www.sciencedaily.com/releases/2023/06/230622120924.htm   
      
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