Scientists Hear a Black Hole’s “Ringing” for the First Time

For the first time, scientists have isolated distinct tones from a newborn black hole’s ringing.

Key Takeaways:

1. Researchers have successfully detected specific tones in the ringing of a newly formed black hole.
2. The findings support Einstein’s theory that a black hole’s ringing reveals its mass and spin.
3. The study provides the first direct test of the no-hair theorem, reinforcing the idea that black holes have only three observable properties.
4. Scientists used data from the 2015 GW150914 gravitational wave detection to extract the black hole’s vibrational frequencies.
5. Future improvements in gravitational wave detectors could reveal even more details or challenge Einstein’s predictions.

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For the first time, scientists have detected distinct tones in the gravitational waves emitted by a newly formed black hole, confirming a key prediction of Einstein’s general relativity. The study, published in Physical Review Letters, strengthens the idea that black holes lack any observable features beyond mass, spin, and electric charge—known as the “no-hair theorem.”

Echoes of a Cosmic Collision

The discovery stems from the first-ever detection of gravitational waves on September 14, 2015, an event known as GW150914. These waves, recorded by LIGO (Laser Interferometer Gravitational-wave Observatory), originated from the merger of two massive black holes. Scientists had long theorized that a newly formed black hole should “ring” like a struck bell, but until now, isolating these reverberations from the noise of the initial collision seemed impossible.

Researchers from MIT and other institutions, led by NASA Einstein Fellow Maximiliano Isi, found a way to extract these signals from the chaotic aftermath. By analyzing the last few milliseconds of GW150914’s signal, they identified two distinct tones—each with a specific pitch and decay rate. Using Einstein’s equations, they calculated the black hole’s mass and spin based on these tones, and their results matched previous measurements. This confirms that black holes exhibit only the properties predicted by general relativity.

A New Era of Black Hole Science

This breakthrough not only verifies Einstein’s theory but also opens new possibilities for studying black holes. Before this study, scientists assumed that detecting multiple vibrational tones required much more sensitive instruments than currently available. Now, researchers know that even existing data can reveal crucial information about black holes.

As gravitational wave detectors improve, scientists may discover tones that deviate from Einstein’s predictions—potentially indicating exotic objects like wormholes or boson stars. According to Isi, “In the future, we’ll have better detectors on Earth and in space… and if black holes don’t ring as Einstein predicts, we’ll have a chance to see it.”

For now, the findings reinforce the idea that black holes are “bald,” meaning they lack any extra properties beyond mass, spin, and charge. But as technology advances, the search continues for any hidden complexities lurking within these cosmic giants.