Black Holes — From Dark Stars to Ringing Spacetime

Black Holes — from dark stars to ringing spacetime Throw a ball up and it comes back. Throw it fast enough and it never does. What if even light could not escape? This video follows that question from John Michell’s “dark stars” of 1783, through Einstein, Schwarzschild, Chandrasekhar and Oppenheimer, to the first black-hole images, the first gravitational-wave chirp, Hawking radiation, and what astronomers are finding today. The moving physics is computed, not hand-drawn: a ray-traced black hole (exact light paths in Schwarzschild spacetime), the exact redshift of a falling probe, a numerical solution of the Regge–Wheeler wave equation for the ringdown, and the acoustic wave equation for a sonic horizon. Each sound comes from the same numbers as its picture. CHAPTERS 0:00 The everyday puzzle 1:00 Dark stars (1783) 2:00 Einstein and Schwarzschild (1915) 3:19 Gravity slows time 4:17 The absurd star (1930s) 5:16 Collapse (1939) 5:53 The event horizon 7:28 Quasars and Cygnus X-1 8:27 What a black hole looks like 9:18 Weighing the black hole at the center of the Milky Way 10:20 Hearing black holes merge 11:22 The ringdown 12:20 Not so black 13:13 A black hole for sound 13:48 Black holes today 15:17 References NOTES The GW150914 sound is a model waveform (3.5 post-Newtonian inspiral joined to the ringdown of the final 62-solar-mass Kerr black hole), not detector data. The falling-probe demo uses a 12,000-solar-mass black hole so the fade lasts a few seconds. The ringdown simulation reproduces the known l = 2 quasinormal frequency to better than 1% (ωGM/c³ ≈ 0.373 − 0.088i vs 0.3737 − 0.0890i). The EHT-style rings, the “black hole star” and the LISA sketch are illustrations, not data. REFERENCES 1. J. Michell, Phil. Trans. R. Soc. Lond. 74, 35 (1784) doi:10.1098/rstl.1784.0008 2. P.-S. Laplace, Exposition du système du monde (Paris, 1796) 3. A. Einstein, Sitzungsber. Preuss. Akad. Wiss. Berlin, 844 (1915) 4. K. Schwarzschild, Sitzungsber. Preuss. Akad. Wiss. Berlin, 189 (1916); English translation: arXiv:physics/9905030 5. L. Flamm, Phys. Z. 17, 448 (1916) 6. N. Ashby, Living Rev. Relativ. 6, 1 (2003) doi:10.12942/lrr-2003-1 7. S. Chandrasekhar, ApJ 74, 81 (1931) doi:10.1086/143324 8. J. R. Oppenheimer & H. Snyder, Phys. Rev. 56, 455 (1939) doi:10.1103/PhysRev.56.455 9. G. Lemaître, Ann. Soc. Sci. Bruxelles A53, 51 (1933) 10. D. Finkelstein, Phys. Rev. 110, 965 (1958) doi:10.1103/PhysRev.110.965 11. R. Penrose, PRL 14, 57 (1965) doi:10.1103/PhysRevLett.14.57 12. R. P. Kerr, PRL 11, 237 (1963) doi:10.1103/PhysRevLett.11.237 13. J. M. Bardeen, in Black Holes (Les Houches 1972), eds. C. DeWitt & B. S. DeWitt (Gordon and Breach, 1973) 14. A. Ewing, Science News-Letter 85, 39 (18 January 1964) doi:10.2307/3947428 15. M. Schmidt, Nature 197, 1040 (1963) doi:10.1038/1971040a0 16. E. E. Salpeter, ApJ 140, 796 (1964) doi:10.1086/147973 17. Ya. B. Zel’dovich, Sov. Phys. Dokl. 9, 195 (1964) 18. D. Lynden-Bell, Nature 223, 690 (1969) doi:10.1038/223690a0 19. B. L. Webster & P. Murdin, Nature 235, 37 (1972) doi:10.1038/235037a0 20. C. T. Bolton, Nature 235, 271 (1972) doi:10.1038/235271b0 21. J.-P. Luminet, A&A 75, 228 (1979) 22. GRAVITY Collaboration, A&A 615, L15 (2018) doi:10.1051/0004-6361/201833718 23. EHT Collaboration, ApJL 875, L1 (2019) doi:10.3847/2041-8213/ab0ec7 24. EHT Collaboration, ApJL 930, L12 (2022) doi:10.3847/2041-8213/ac6674 25. EHT Collaboration, A&A 681, A79 (2024) doi:10.1051/0004-6361/202347932 26. B. P. Abbott et al., PRL 116, 061102 (2016) doi:10.1103/PhysRevLett.116.061102 27. T. Regge & J. A. Wheeler, Phys. Rev. 108, 1063 (1957) doi:10.1103/PhysRev.108.1063 28. F. J. Zerilli, PRL 24, 737 (1970) doi:10.1103/PhysRevLett.24.737 29. C. V. Vishveshwara, Nature 227, 936 (1970) doi:10.1038/227936a0 30. E. W. Leaver, Proc. R. Soc. Lond. A 402, 285 (1985) doi:10.1098/rspa.1985.0119 31. J. D. Bekenstein, Phys. Rev. D 7, 2333 (1973) doi:10.1103/PhysRevD.7.2333 32. S. W. Hawking, Nature 248, 30 (1974) doi:10.1038/248030a0 33. S. W. Hawking, Commun. Math. Phys. 43, 199 (1975) doi:10.1007/BF02345020 34. W. G. Unruh, PRL 46, 1351 (1981) doi:10.1103/PhysRevLett.46.1351 35. J. R. Muñoz de Nova, K. Golubkov, V. I. Kolobov & J. Steinhauer, Nature 569, 688 (2019) doi:10.1038/s41586-019-1241-0 36. LIGO, Virgo & KAGRA, PRL 135, 111403 (2025) doi:10.1103/kw5g-d732 37. R. P. Naidu et al., Nature 656, 329 (2026) doi:10.1038/s41586-026-10846-4 38. LIGO Laboratory, “LIGO-Virgo-KAGRA complete the fourth observing run” (18 November 2025): https://www.ligo.caltech.edu/news/lig... 39. ESA, “Capturing the ripples of spacetime: LISA gets go-ahead” (January 2024): https://www.esa.int/Science_Explorati... 40. Methods — L. Blanchet, Living Rev. Relativ. 17, 2 (2014) doi:10.12942/lrr-2014-2 41. Methods — E. Berti, V. Cardoso & C. M. Will, Phys. Rev. D 73, 064030 (2006) doi:10.1103/PhysRevD.73.064030