# Strongly Focused Gravitational Waves

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Michael Reiterer, ETH, Zurich
Fine Hall 110

Christodoulou (2008) proved that trapped spheres can form in evolution, through the focusing of gravitational waves. Recently, with E. Trubowitz, we considered the same physical problem, using very different mathematical methods. Our approach is based on a systematic use of formal expansions, scaling symmetries and energy estimates. We give a direct construction of vacuum solutions by a far field expansion and exhibit trapped spheres that first appear deep inside the far field region.