One thing I don&#x27;t quite understand - how can the &quot;chirp&quot; from LIGO be unambiguously categorized as extraterrestrial in origin? The waveform shown onscreen in the NYtimes video looks like an extremely noisy signal - not sure if that&#x27;s the actual sampled data or just an artistic rendition. Couldn&#x27;t there be a variety of physical disturbances that explain a sine-tone sweep like that, given how sensitive the instrument is to physical vibrations?