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Title: Positive geometry for graviton scattering amplitudes
Plain: Gravity amplitudes lack the cyclic ordering of particles that the gauge-theory shapes rely on. No shape whose volume-like form gives graviton scattering is known.
Precise: Find a positive geometry whose canonical form equals tree-level n-graviton amplitudes of Einstein gravity or $N=8$ supergravity in $D = 4$ for all helicity sectors, or the loop integrands of $N=8$ supergravity; or prove that gravity amplitudes cannot be canonical forms in the standard sense.
Settled by: An explicit geometry reproducing all tree-level graviton amplitudes, or a proof of impossibility.
Kind: well-posed
Answer type: identification
References: (empty)
Literature status: open
Status note: (empty)
Posed since: (empty)