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Acoustics and Astronomy
CMB photons being redshifted physically). This sonification shifts the real frequencies by a factor of 1026 upward to match our human hearing range! The universe, even back then, was a big place and the wavelengths that fit within it were huge.
Moving back in closer to home, space physicist Don Gurnett has sonified the plasma density data from the Voyager probe traveling out of the solar system from the heliosphere to in- terstellar space. The pitch and frequency of the sound waves indicated the density of gas surrounding the spacecraft (which was sensed by a plasma probe) and made discern- ing the slow transition much easier. In the heliosphere, the tones were about 300 Hz, corresponding to plasma waves propagating through the (more rarefied) solar wind. When Voyager broke through to the interstellar medium, the fre- quency jumped to 2-3 kHz, making the jump clear to the researchers.
Within the solar system, Timothy Leighton has recom- mended the following excellent NASA website for sonifi- cation, http://acousticstoday.org/space. It features a dozen completely “otherworldly” sounds!
And finally, back at home, MIT’s Building 54 (the “Green Building”) was outfitted with a battery of 35 loudspeakers until mid-September 2017, which translated the temporal variability of the ions and electrons in the ionosphere into acoustic signals that were broadcast outside the building (http://acousticstoday.org/iono). This is a conscious merg- ing of art and science for the MIT community’s and public’s benefit. Given that the music of the universe is a glorious merger of art and science, this is a perfect way to end this story.
Postscript
This article comes from a talk I gave as a member of the Cape Cod Astronomical Society, a very good group of amateur as- tronomers from my home region of Cape Cod. When they learned I did acoustics research and teaching for a living,
one member quipped that “astronomy is a long way from acoustics!” I said that was untrue and would give a lecture to the club to prove it. This article is an expansion of that talk.
Acknowledgments
I thank Drs. Arthur Popper, Timothy Leighton, Anastasia Fi- alkov, and Alan Chave as well as Ms. Joyce Shelley and Mr. James Shelley for their very helpful comments and suggestions.
Biosketch
Jim Lynch is president of the Cape Cod Astronomical Society, editor in chief
of the Acoustical Society of America publications, and senior scientist emeri- tus at the Woods Hole Oceanographic Institution. He is a physicist by train- ing and not an astronomer per se. His
credentials are simply those of a very interested amateur with a science background. He again thanks his reviewers for checking this article.
References
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