Event Horizon Telescope
Event Horizon Telescope
One-line summary: A planet-spanning array of ~8 observatories that, by catching the same wavefront of light simultaneously, imaged the shadow of a black hole's event horizon.
What it is
A global interferometer — not a single dish but ~8 radio observatories spread across Earth (South Pole, Chile, and elsewhere) whose data are combined to synthesize an aperture effectively "as big as the Earth." Explicitly not a NASA mission (michelle-thaller flags this). See the method chain in earth-sized-interferometry-to-black-hole-image.
Why it matters to science
It produced the first image of a black hole's event-horizon shadow — a measurement Thaller "would have bet" was impossible. It is her headline example of physics done "right on the fuzzy edge of being possible," and of black-holes as observable rather than purely theoretical objects.
Key facts
- Works by interferometry: all telescopes must catch the same wavefront / same photon of light at once; being off by "one millionth of a meter" would ruin the image.
- Synchronization must account for Earth's curvature, rotation, and each site's altitude.
- Data volume was too large for the South Pole's network link — they shipped physical hard drives and replayed them together.
- The black "shadow" imaged is slightly larger than the event horizon itself, because space and time curve light around the hole.
- "They did it. They fucking did it." — and have since repeated it.
Open questions
- What, if anything, is inside a black hole? "All the equations blow up." (see black-holes)