A passing gravitational wave stretches one of LIGO’s four-kilometre arms while squeezing the perpendicular one. The instrument is a Michelson interferometer held on a dark fringe: the two returning laser beams cancel perfectly at the photodetector, so the only light that leaks through is the signature of spacetime itself changing length.
This exhibit plays a black-hole inspiral with the real waveform mathematics — frequency climbing as (t−t_merge)^(−3/8), amplitude as f^(2/3), then merger and ringdown — and lets you hear the chirp as audio. The exaggeration slider scales the visible motion only; drag it down to reality and nothing visibly moves, because the true strain is about 10⁻²¹: a thousandth the width of a proton over four kilometres.
The 2015 detection of GW150914 earned the 2017 Nobel Prize in Physics and opened an entirely new sense for astronomy. It is also the world’s most extreme measurement instrument — in a museum of machines that began with a pendulum, this is the one that listens to spacetime itself.
Specifications
- Instrument
- Michelson interferometer, 4 km arms
- First detection
- GW150914 — 14 September 2015
- Real strain
- h ≈ 10⁻²¹ (≈ 1/10,000 of a proton)
- Simulated
- Inspiral chirp physics, dark-fringe interference, audio
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