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DTSTART;TZID=America/New_York:20191009T103000
DTEND;TZID=America/New_York:20191009T120000
DTSTAMP:20240212T180524Z
CREATED:20240212T110952Z
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UID:10002041-1570617000-1570622400@cmsa.fas.harvard.edu
SUMMARY:10/9/2019 Quantum Matter Seminar
DESCRIPTION:
URL:https://cmsa.fas.harvard.edu/event/10-9-2019-quantum-matter-seminar/
LOCATION:MA
CATEGORIES:Quantum Matter,Seminars
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BEGIN:VEVENT
DTSTART;TZID=America/New_York:20191009T151500
DTEND;TZID=America/New_York:20191009T161500
DTSTAMP:20240221T103022Z
CREATED:20240212T111415Z
LAST-MODIFIED:20240221T103022Z
UID:10002048-1570634100-1570637700@cmsa.fas.harvard.edu
SUMMARY:10/9/2019 RM & PT Seminar
DESCRIPTION:
URL:https://cmsa.fas.harvard.edu/event/10-9-2019-rm-pt-seminar/
LOCATION:MA
CATEGORIES:Colloquia & Seminar,Seminars
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BEGIN:VEVENT
DTSTART;TZID=America/New_York:20191009T163000
DTEND;TZID=America/New_York:20191009T173000
DTSTAMP:20240514T175345Z
CREATED:20240212T101721Z
LAST-MODIFIED:20240514T175345Z
UID:10001968-1570638600-1570642200@cmsa.fas.harvard.edu
SUMMARY:Global Existence and Scattering for Einstein's equations and related equations satisfying the weak null condition
DESCRIPTION:Speaker: Hans Lindblad (Johns Hopkins University) \nTitle:  Global Existence and Scattering for Einstein’s equations and related equations satisfying the weak null condition \nAbstract: Einstein’s equations in harmonic or wave coordinates are a system of nonlinear wave equations for a Lorentzian metric\, that in addition satisfy the preserved wave coordinate condition. Christodoulou-Klainerman proved global existence for Einstein vacuum equations for small asymptotically flat initial data. Their proof avoids using coordinates since it was believed the metric in harmonic coordinates would blow up for large times. John had noticed that solutions to some nonlinear wave equations blow up for small data\, whereas Klainerman came up with the ‘null condition’\, that guaranteed global existence for small data. However Einstein’s equations do not satisfy the null condition. Hormander introduced a simplified asymptotic system by neglecting angular derivatives which we expect decay faster due to the rotational invariance\, and used it to study blowup. I showed that the asymptotic system corresponding to the quasilinear part of Einstein’s equations does not blow up and gave an example of a nonlinear equation of this form that has global solutions even though it does not satisfy the null condition. Together with Rodnianski we introduced the ‘weak null condition’ requiring that the corresponding asymptotic system have global solutions and we showed that Einstein’s equations in wave coordinates satisfy the weak null condition and we proved global existence for this system. Our method reduced the proof to a fraction and has now been used to prove global existence also with matter fields. \nRecently I derived precise asymptotics for the metric which involves logarithmic corrections to the radiation field of solutions of linear wave equations. We are further imposing these asymptotics at infinity and solve the equations backwards to obtain global solutions with given data at infinity.
URL:https://cmsa.fas.harvard.edu/event/10-9-2019-colloquium/
LOCATION:MA
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-10.09.19-2-789x1024-1.png
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