MSGID: 1:317/3 643633df   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    New findings that map the universe's cosmic growth support Einstein's   
   theory of gravity    
    Significant breakthrough in understanding the evolution of the universe   
      
      
     Date:   
         April 11, 2023   
     Source:   
         Princeton University   
     Summary:   
         Research by the Atacama Cosmology Telescope collaboration has   
         culminated in a groundbreaking new image that reveals the most   
         detailed map of dark matter distributed across a quarter of the   
         entire sky, reaching deep into the cosmos. Findings provide further   
         support to Einstein's theory of general relativity, which has been   
         the foundation of the standard model of cosmology for more than   
         a century, and offers new methods to demystify dark matter.   
      
      
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   FULL STORY   
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   For millennia, humans have been fascinated by the mysteries of the cosmos.   
      
      
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   Unlike ancient philosophers imagining the universe's origins, modern   
   cosmologists use quantitative tools to gain insights into the universe's   
   evolution and structure. Modern cosmology dates back to the early 20th   
   century, with the development of Albert Einstein's theory of general   
   relativity.   
      
   Now, researchers from the Atacama Cosmology Telescope (ACT) collaboration   
   have created a groundbreaking new image that reveals the most detailed   
   map of dark matter distributed across a quarter of the entire sky,   
   extending deep into the cosmos. What's more, it confirms Einstein's   
   theory of how massive structures grow and bend light, over the entire   
   14-billion-year life span of the universe.   
      
   "We have mapped the invisible dark matter across the sky to the largest   
   distances, and clearly see features of this invisible world that   
   are hundreds of millions of light-years across, says Blake Sherwin,   
   professor of cosmology at the University of Cambridge, where he leads   
   a group of ACT researchers. "It looks just as our theories predict."   
   Despite making up 85% of the universe and influencing its evolution,   
   dark matter has been hard to detect because it doesn't interact with   
   light or other forms of electromagnetic radiation. As far as we know   
   dark matter only interacts with gravity.   
      
   To track it down, the more than 160 collaborators who have built and   
   gathered data from the National Science Foundation's Atacama Cosmology   
   Telescope in the high Chilean Andes observe light emanating following   
   the dawn of the universe's formation, the Big Bang -- when the universe   
   was only 380,000 years old.   
      
   Cosmologists often refer to this diffuse light that fills our entire   
   universe as the "baby picture of the universe," but formally, it is   
   known as the cosmic microwave background radiation (CMB).   
      
   The team tracks how the gravitational pull of large, heavy structures   
   including dark matter warps the CMB on its 14-billion-year journey to us,   
   like how a magnifying glass bends light as it passes through its lens.   
      
   "We've made a new mass map using distortions of light left over   
   from the Big Bang," says Mathew Madhavacheril, assistant professor   
   in the Department of Physics and Astronomy at the University of   
   Pennsylvania. "Remarkably, it provides measurements that show that both   
   the 'lumpiness' of the universe, and the rate at which it is growing   
   after 14 billion years of evolution, are just what you'd expect from   
   our standard model of cosmology based on Einstein's theory of gravity."   
   Sherwin adds, "our results also provide new insights into an ongoing   
   debate some have called 'The Crisis in Cosmology,'"explaining that this   
   crisis stems from recent measurements that use a different background   
   light, one emitted from stars in galaxies rather than the CMB. These have   
   produced results that suggest the dark matter was not lumpy enough under   
   the standard model of cosmology and led to concerns that the model may be   
   broken. However, the team's latest results from ACT were able to precisely   
   assess that the vast lumps seen in this image are the exact right size.   
      
   "When I first saw them, our measurements were in such good agreement   
   with the underlying theory that it took me a moment to process the   
   results," says Cambridge Ph.D. student Frank Qu, part of the research   
   team. "It will be interesting to see how this possible discrepancy between   
   different measurements will be resolved."  "The CMB lensing data rivals   
   more conventional surveys of the visible light from galaxies in their   
   ability to trace the sum of what is out there," says Suzanne Staggs,   
   director of ACT and Henry DeWolf Smyth Professor of Physics at Princeton   
   University. "Together, the CMB lensing and the best optical surveys are   
   clarifying the evolution of all the mass in the universe."  "When we   
   proposed this experiment in 2003, we had no idea the full extent of   
   information that could be extracted from our telescope," says Mark Devlin,   
   the Reese Flower Professor of Astronomy at the University of Pennsylvania   
   and the deputy director of ACT. "We owe this to the cleverness of the   
   theorists, the many people who built new instruments to make our telescope   
   more sensitive, and the new analysis techniques our team came up with."   
   ACT, which operated for 15 years, was decommissioned in September 2022.   
      
   Nevertheless, more papers presenting results from the final set of   
   observations are expected to be submitted soon, and the Simons Observatory   
   will conduct future observations at the same site, with a new telescope   
   slated to begin operations in 2024. This new instrument will be capable   
   of mapping the sky almost 10 times faster than ACT.   
      
       * RELATED_TOPICS   
             o Space_&_Time   
                   # Cosmology # Big_Bang # Astrophysics # Astronomy #   
                   Dark_Matter # Black_Holes # Space_Telescopes # Cosmic_Rays   
       * RELATED_TERMS   
             o Physical_cosmology o Dark_energy o Dark_matter   
             o Albert_Einstein o Ultimate_fate_of_the_universe o   
             Shape_of_the_Universe o Cosmic_microwave_background_radiation   
             o General_relativity   
      
   ==========================================================================   
   Story Source: Materials provided by Princeton_University. Original   
   written by Liz Fuller- Wright (Nathi Magubane from the University of   
   Pennsylvania contributed to this story). Note: Content may be edited   
   for style and length.   
      
      
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   Related Multimedia:   
       * Stephan's_Quintet   
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   Link to news story:   
   https://www.sciencedaily.com/releases/2023/04/230411105938.htm   
      
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