Page 12 - AT Sept 3 2020
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A12   SCIENCE
               Thursday 3 sepTember 2020
            Cosmic Legos: Black holes merge into never before seen size




            By SETH BORENSTEIN                                                                                                  said, but this new discovery
            AP Science Writer                                                                                                   may offer a clue.
            Black  holes  are  getting                                                                                          Perhaps, like playing Legos,
            stranger — even to astrono-                                                                                         smaller  blocks  combine
            mers.  They've  now  detect-                                                                                        to  make  bigger  ones  and
            ed  the  signal  from  a  long                                                                                      those  combine  to  make
            ago violent collision of two                                                                                        even bigger ones, said Har-
            black holes that created a                                                                                          vard astronomer Avi Loeb,
            new one of a size that had                                                                                          who  wasn't  part  of  the
            never been seen before.                                                                                             study  but  said  the  results
            "It's the biggest bang since                                                                                        chart  new  astronomical
            the  Big  Bang  observed  by                                                                                        territory.
            humanity,"  said  Caltech                                                                                           And  indeed  the  bigger
            physicist  Alan  Weinstein,                                                                                         of  the  two  black  holes  in-
            who was part of the discov-                                                                                         volved  in  this  crash  could
            ery team.                                                                                                           have been the result of an
            Black  holes  are  compact                                                                                          earlier  merger,  both  Wein-
            regions of space so densely                                                                                         stein and Christensen said,
            packed that not even light                                                                                          further  bolstering  that  the-
            can  escape.  Until  now,                                                                                           ory.
            astronomers  only  had  ob-                                                                                         "It's  conceivable  that  this
            served  them  in  two  gen-                                                                                         pair of black holes formed
            eral  sizes.  There  are  "small"                                                                                   entirely  differently,  possi-
            ones  called  stellar  black   This illustration provided by LIGO/Caltech in September 2020 depicts two black holes of about 66   bly in a dense system with
            holes  that  are  formed     and 85 solar masses spiralling into each other to form the GW190521 black hole.  Associated Press  lots  of  dead  stars  whizzing
            when a star collapses and                                                                                           about,  which  allows  one
            are about the size of small  tensen, research director of  space  that  travels  at  the  Weinstein  said.  "It  really  black  hole  to  capture  an-
            cities. And there are super-  the French National Centre  speed  of  light.  It  was  that  doesn't sound like much on  other during a fly by," said
            massive  black  holes  that  for Scientific Research.     wave  that  physicists  in  the  a speaker."              Barnard  College  astrono-
            are millions, maybe billions,  Then  in  May  2019  two  de-  United  States  and  Europe,  This crash happened about  mer  Janna  Levin,  who
            of times more massive than  tectors  picked  up  a  signal  using detectors called LIGO  7  billion  years  ago,  when  wasn't part of the research
            our sun and around which  that  turned  out  to  be  the  and  Virgo,  captured  last  the  universe  was  about  and  is  author  of  the  book
            entire galaxies revolve.     energy  from  two  stellar  year. After deciphering the  half  its  current  age,  but  is  "Black Hole Survival Guide."
            According  to  astronomers'  black  holes  —  each  large  signal  and  checking  their  only  being  detected  now  On  the  other  hand,  sci-
            calculations,  anything  in  for  a  stellar  black  hole  —  work,  scientists  published  because  it  is  incredibly  far  entists  can't  quite  explain
            between didn't quite make  crashing  into  each  other.  the  results  Wednesday  in  away.  Black hole collisions  how  merged  black  holes,
            sense,  because  stars  that  One was 66 times the mass  Physical Review Letters and  have  been  observed  be-     flying  around  the  universe,
            grew  too  big  before  col-  of our sun and the other a  Astrophysical  Journal  Let-  fore,  but  the  black  holes  would meet so many others
            lapse   would    essentially  husky 85 times the mass of  ters.Because the detectors  involved  were  smaller  to  to  merge  again  and  grow
            consume themselves, leav-    the sun. The end result: The  allow  scientists  to  pick  up  begin with and even after  ever  bigger.  It  could  in-
            ing no black holes.          first  ever  discovered  inter-  the  gravitational  waves  as  the merger didn't grow be-  stead be that supermassive
            Star   collapses   couldn't  mediate black hole, at 142  audio signals, scientists ac-  yond the size of typical stel-  black holes were formed in
            create  stellar  black  holes  times the mass of the sun.   tually  heard  the  collision.  lar black holes.        the  immediate  aftermath
            much bigger than 70 times  Lost in the collision was an  For  all  the  violence  and  Scientists  still  don't  know  of the Big Bang.
            the mass of our sun, scien-  enormous  amount  of  en-    drama,  the  signal  lasted  how  supermassive  black  "In  astrophysics  we're  al-
            tists  thought,  according  ergy in the form of a gravi-  only one-tenth of a second.  holes at the center of gal-  ways  faced  with  surprises,"
            to  physicist  Nelson  Chris-  tational  wave,  a  ripple  in  "It  just  sounds  like  a  thud,"  axies  formed,  Christensen  Weinstein said.q

              Can I use a face shield instead of a mask?



              By The Associated Press
              Can I use a face shield instead of a mask?
              No. Health officials don't recommend the clear plastic barriers as a sub-
              stitute for masks because of the lack of research on whether they keep
              an infected person from spreading viral droplets to others.
              However, those who want extra protection may want to wear a face
              shield in addition to a mask.
              Face shields have the added benefit of protecting your eyes and dis-
              couraging you from touching your face by acting as a physical barrier,
              says Christopher Sulmonte, project administrator of the biocontainment
              unit at Johns Hopkins Hospital.
              Meanwhile, the available research so far indicates that the best face
              shields for preventing viral spread are hooded or wrap around the sides
              and bottom of the face, according to the U.S. Centers for Disease Con-
              trol and Prevention. That's because those shields leave less space for
              droplets from sneezing, coughing and talking to escape.
              If you do wear a reusable face shield in addition to a mask, the CDC   A Congressman Aldo Davila, wearing a face mask and face shield amid the
              notes the importance of cleaning it after each use. The agency also   COVID-19  pandemic,  waits  outside  the  presidential  office  with  Indigenous
                                                                                    leaders,  hoping  for  a  meeting  with  President  Alejandro  Giammattei  in
              says you should wash your hands before and after taking it off, and   Guatemala City, Friday, Aug. 21, 2020.
              avoid touching your face while removing it.q                                                                                Associated Press
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