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SUMMARY:Piotr Chrusciel (University of Wien)
DTSTART:20200428T173000Z
DTEND:20200428T183000Z
DTSTAMP:20260422T212923Z
UID:BHIColloq/1
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/BHIColloq/1/
 ">Mass\, and its positivity?\, for solutions of Einstein equations with ne
 gative cosmological constant.</a>\nby Piotr Chrusciel (University of Wien)
  as part of BHI Colloquium\n\n\nAbstract\nI will review the notion of mass
  for solutions of vacuum Einstein equations with negative cosmological con
 stant\, discuss some standard examples\, and outline the proof of positivi
 ty for solutions with spherical topology at infinity.\n
LOCATION:https://researchseminars.org/talk/BHIColloq/1/
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BEGIN:VEVENT
SUMMARY:Martin Lesourd (BHI\, Harvard)
DTSTART:20200512T173000Z
DTEND:20200512T183000Z
DTSTAMP:20260422T212923Z
UID:BHIColloq/2
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/BHIColloq/2/
 ">How Do Black Holes Form?</a>\nby Martin Lesourd (BHI\, Harvard) as part 
 of BHI Colloquium\n\n\nAbstract\nMathematical General Relativity is held t
 ogether by a couple of deep conjectures. Many mathematicians like to think
  that by proving these (or finding counterexamples)\, they will finally be
  able to underpin (or challenge) the beliefs that Physicists and Astrophys
 icists have held for decades. Arguably the grandest such example is the ''
 Final State Conjecture'': generic vacuum spacetimes undergoing gravitation
 al collapse will eventually resemble the Kerr solution in their exterior. 
 At present\, there is not a single example of this conjecture\, nor a sing
 le vacuum spacetime with a complete future asymptotic region describing bl
 ack hole formation. I will review what is known\, and describe some work (
 still in progress) with Athanasiou in this direction.\n
LOCATION:https://researchseminars.org/talk/BHIColloq/2/
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BEGIN:VEVENT
SUMMARY:Frederic Vincent (Paris Meudon Observatory)
DTSTART:20200512T173000Z
DTEND:20200512T183000Z
DTSTAMP:20260422T212923Z
UID:BHIColloq/3
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/BHIColloq/3/
 ">What can we infer from black hole images?</a>\nby Frederic Vincent (Pari
 s Meudon Observatory) as part of BHI Colloquium\n\n\nAbstract\nThe recent 
 Event Horizon Telescope (EHT) millimeter image of the vicinity of the supe
 rmassive compact object M87* at the center of the galaxy M87 is a breakthr
 ough. It is important to investigate what can and what cannot be inferred 
 from such images. In this talk I will discuss a simple geometric model of 
 the region of the accretion flow immediately surrounding M87*. I will use 
 this model to discuss the highly-lensed features of EHT-like images\, ofte
 n loosely referred to as the "photon ring". I will discuss whether such fe
 atures can be used as clean probes of the nature of the underlying spaceti
 me. I will also discuss various EHT-like images of M87*\, assuming this ob
 ject is various kinds of compact alternatives to the standard black hole. 
 This will allow discussing to what extent can EHT-like images help constra
 in the nature of the compact objects at the center of M87 or our Milky Way
 .\n
LOCATION:https://researchseminars.org/talk/BHIColloq/3/
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