Gravitational waves

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Propagating distortions of spacetime itself, produced by accelerating mass distributions with a changing quadrupole moment and travelling at the speed of light. Einstein derived them from the linearised field equations shortly after general relativity and then doubted for decades whether they were physical rather than an artefact of coordinates. Their reality was established indirectly first: the orbit of the binary pulsar PSR B1913+16, discovered by Hulse and Taylor in 1974, decays at precisely the rate general relativity predicts for energy lost to radiation. Direct detection required measuring a strain of order one part in ten to the twenty-first - a length change smaller than a proton across a four-kilometre arm. Because they interact with matter so weakly, gravitational waves pass through everything between the source and the detector unabsorbed, which is exactly why they carry information about a region no light ever leaves. Not a place on Earth.

A node is not a place. Drawing it on a map would assert something about the world that no stored fact supports.