The Discovery of Gravitational Radiation and Why It Matters

Gravitational wave signal detected by LIGO.
Image credit: LIGO, NSF, Aurore Simonnet (Sonoma State U.)

This Wednesday, the Laser Interferometer Gravitational Wave Observatory (LIGO) announced the second detection of gravitational radiation emanating from a merger of two black holes. This follows the initial discovery of gravitational radiation in February [1]. But why should any of that matter to you? We can't feel our bodies being squeezed by gravitational waves. The discovery of gravitational waves is important because it confirms that the laws of physics work the way we always thought they did. We've been talking about gravitational waves since the early 20th century, when Einstein first posited that the force of gravity might interact directly with space and time [2]. This concept of space and time interwoven as a “fabric” began with his theory of general relativity, and wasn't confirmed until February of 2016 (and again on Wednesday). The detection of gravitational waves doesn't just confirm Einstein's theory on space-time; it also confirms the existence of black hole mergers - extraordinarily energetic events in which two dead stars, each much larger than our Sun, enter a “death spiral” and eventually collide with one another. We're seeing the universe not only in electromagnetic radiation that propagates through space (light), but in gravitational radiation that propagates through the very fabric of space-time itself. It's like discovering a new color, or a new frequency of sound. This amazing technology ushers in a new era of astronomy, where we can now see the universe in an entirely different way.

Laura Haney (@LauraVican)
Signal to Noise Co-founder and COO
PhD, Physics and Astronomy

[1] P. Abbott et al. (LIGO Scientific Collaboration and Virgo Collaboration), Observation of Gravitational Waves from a Binary Black Hole Merger. Phys. Rev. Lett. 116, 061102 (2016).

[2] Einstein, A.: Über Gravitationswellen. In: Sitzungsberichte der Königlich Preussischen Akademie der Wissenschaften Berlin (1918), 154–167. [English translation]