How Do We Hear Spacetime?

How can a laser measure a passing gravitational wave—and why can a signal from empty space become something we hear? Follow the complete chain from changing spacetime to calibrated evidence, black-hole chirps, neutron-star collisions, pulsar timing and the planned LISA observatory. This episode explains both what the measurements reveal and what they cannot establish. No acoustic sound travels from a black-hole collision through the vacuum. Audible representations are produced locally from a measured or modeled signal. CHAPTERS 00:00 A message with no light 02:15 What a wave carries 04:44 A circle of freely falling beads 07:11 Why your ruler does not erase the signal 09:45 How small is the change? 12:09 Why a laser has a phase 14:39 A long instrument with repeated light 17:14 Mirrors that must fall and stay put 19:48 The Earth is a noisy place 22:34 What quantum noise means here 25:12 Why two observatories matter 27:45 The shape called a chirp 30:23 A useful mass that is not either mass 33:06 The first signal, revisited carefully 35:43 Filtering is not inventing a signal 38:16 Looking for a pattern without forcing it 41:02 What a false alarm rate actually says 43:47 Turning strain into sound 46:14 When a waveform is also a map 48:55 A collision that brought light with it 51:38 The race that was not a simple race 54:07 What matter added to the story 56:56 Distance without a familiar candle 59:46 The evidence before direct detection 1:02:25 A galaxy used as an instrument 1:05:10 The low frequency background 1:07:56 The missing middle and LISA 1:10:39 Testing a prediction against an alternative 1:13:20 What we have not heard 1:16:06 Which events make it into the catalog? 1:18:57 Rebuilding the experiment on paper 1:21:37 Hearing as a new way of knowing SELECTED PRIMARY SOURCES GW150914 discovery: https://arxiv.org/abs/1602.03837 Advanced LIGO: https://arxiv.org/abs/1411.4547 Detector noise and signal extraction: https://arxiv.org/abs/1908.11170 GW170817: https://arxiv.org/abs/1710.05832 Multi-messenger observations: https://arxiv.org/abs/1710.05833 Gamma-ray timing: https://dcc.ligo.org/P1700308/public NANOGrav 15-year background evidence (2023): https://arxiv.org/abs/2306.16213 ESA LISA factsheet: https://www.esa.int/Science_Explorati... Event examples retain their historical dates and approximate original estimates. Hypotheses, inferred source properties and future observing goals are distinguished from established measurements. This is not a live discovery-count update. Production: synthetic Michael narration; original educational schematics and an AI-generated artistic cover. Distortions and teaching curves are schematic, not measured event data or real observational imagery. No original detector audio is presented. No professor or on-screen avatar. Subscribe to Orbit Minute for careful, accessible science and the questions that make the universe worth exploring.