Fin whale songs recorded on the seafloor have revealed complex temporal interference patterns that initially confounded researchers calculating underwater sound speeds, according to a study published in Physical Review E. Dr. John Spiesberger of the University of Pennsylvania and Dr. Eugene Terray of the Woods Hole Oceanographic Institution found that fin whale vocalisations arrive at acoustic receivers via multiple paths, creating overlapping sound waves that trick measuring instruments into recording speeds ranging from around 1,000 meters per second to 3,000 meters per second instead of the standard 1,500 meters per second.
Two-Path Sound Propagation and Temporal Interference
According to Dr. Spiesberger, the erratic speed calculations stem from fin whale calls traveling to recording equipment through two distinct routes. Some sound waves travel directly from the animal to the receiver, while other waves bounce off the sea surface before arriving, covering a longer distance in the process. When these two wave fronts meet and overlap, they create a phenomenon known as temporal interference. Similar to analog radio or television signal interference where overlapping transmissions distort the output, this acoustic superposition causes the strongest sound point to arrive earlier than expected, throwing off standard sound speed measurements in the water column even though the acoustic waves themselves maintain a constant velocity.
Did you know?
Fin whale (Balaenoptera physalus) songs are among the loudest biological sounds in the ocean. According to research published in Science by Dr. Vaclav Kuna and Dr. John Nabelek of Oregon State University, these infrasonic calls can exceed the volume of a rocket launch and penetrate deep into the Earth’s crust.
TOSSIT Acoustic Recorders Enable Long-Term Seabed Monitoring
To capture long-term fin whale audio without disrupting marine life, researchers deployed autonomous underwater recording devices named TOSSIT, developed by the Woods Hole Oceanographic Institution. As detailed in Physical Review E, these units are simply tossed overboard from boats without needing divers or surface tether lines. Each device features a plastic frame with buoyant foam, a hydrophone, and an acoustic release system that drops the unit to the seafloor at depths down to 500 meters. Operating without mooring ropes eliminates entanglement risks for marine mammals and cuts down mechanical noise in the recordings.
Einstein’s Theory of Relativity and Apparent Superluminal Speed
According to Dr. Spiesberger and Dr. Terray, the temporal interference observed in fin whale acoustics mirrors theoretical mechanics involving light waves and Albert Einstein’s special theory of relativity, which dictates that no matter or information can travel faster than light. Light waves can theoretically superimpose so that their peak energy points appear to travel faster than light speed, while individual photons maintain their constant velocity. This does not violate physics because the fast-moving peak carries no actual information; if data could be transmitted through that specific point, it could theoretically arrive ahead of its causal trigger and break universal cause-and-effect laws.
Mapping Ocean Sediments with Fin Whale Calls
Complementing acoustic propagation studies, research published in Science by Dr. Vaclav Kuna and Dr. John Nabelek demonstrated that fin whale vocalizations can replace air-gun seismic surveys, which historically disrupted marine life. Monitoring the Blanco Fracture Zone off the Oregon coast using 54 ocean-bottom seismometers, Dr. Kuna and Dr. Nabelek analyzed how fin whale songs penetrate the seafloor. By comparing direct sound waves with seismic waves bouncing off sediment-basalt boundaries, the researchers calculated sediment thicknesses ranging from 380 to 650 meters over 1.8 kilometers of basaltic crust.
Frequently Asked Questions
How fast does sound normally travel in seawater?
According to research outlined in Physical Review E, the baseline speed of sound in seawater is approximately 1,500 meters per second.
Do fin whale songs violate the speed of light?
No. While interference patterns can create points of energy that appear to move faster than normal wave or light speeds, no information is transferred through those points, preserving Einstein’s theory of relativity and causal laws.
Why do scientists use TOSSIT recorders instead of tethered instruments?
TOSSIT units operate without surface ropes, preventing marine mammal entanglement and reducing ambient mechanical noise in deep-sea acoustic recordings.
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