How foamy is spacetime?

Maybe not as foamy as some scientists thought, as a fresh look at a quasar first observed in 1998 by the Hubble Space Telescope (HST) shows. Physicists observed a diffraction pattern called an Airy ring around the image of a distant quasar-like object. This ring persuades physicists that the light from this distant object has traveled through a relatively calm – rather than extremely frothy – spacetime.

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