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SUMMARY:第58回NITEP談話会
DTSTART;VALUE=DATE-TIME:20251010T041500Z
DTEND;VALUE=DATE-TIME:20251010T054500Z
DTSTAMP;VALUE=DATE-TIME:20260607T234125Z
UID:indico-event-206@indico.nitep.omu.ac.jp
DESCRIPTION:日時：10/10(金) 13:15-14:45\n場所：F216（中講究室2
 C）\n\n講演者：Yi-Zen Chu (National Central University\, Taiwan\, Pro
 fessor)\n\nTitle: What constitutes a gravitational wave in an expanding un
 iverse?\n\nAbstract: Our understanding of gravitational waves produced by 
 isolated astrophysical systems is primarily based on gravitational perturb
 ation theory off a flat spacetime background. This leads to the common ide
 ntification of gravitational radiation with massless spin-2 waves. In this
  talk\, I will argue that gravitational waves may no longer be solely "spi
 n-2" in character once the background spacetime is our expanding universe 
 instead. As a result of the mixing between gravitational and other degrees
  of freedom\, scalar "spin-0" gravitational waves may exist during the rad
 iation-dominated epoch of our universe\; as well as during its current acc
 elerated expansion phase -- provided the main driver is not the cosmologic
 al constant\, but some extra "Dark Energy" field. Moreover\, during the ra
 diation-dominated era\, spin-0 Cherenkov gravitational waves may even be g
 enerated if its material source were traveling faster than 1/\\sqrt{3}.\n
  \n\nhttps://indico.nitep.omu.ac.jp/event/206/
LOCATION:
URL:https://indico.nitep.omu.ac.jp/event/206/
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