Scientists Say Universe has a “Background Hum”

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Astronomers from around the world on Thursday revealed that they had discovered the first evidence of a long-theorized type of gravitational wave that creates a “background hum” vibrating throughout the universe.

The discovery, made after years of labor by hundreds of scientists utilizing radio telescopes in North America, Europe, China, India, and Australia, was heralded as a huge milestone that opens a new window into the universe.

Gravitational waves are ripples in the fabric of the universe that travel at the speed of light nearly fully unobstructed, as predicted by Albert Einstein more than a century ago.

Their existence was only proven in 2015, when US and Italian observatories detected the first gravitational waves produced by two merging black holes.

These “high-frequency” waves were caused by a single explosive event that sent a powerful, brief burst rippling towards Earth.

However, scientists have been looking for low-frequency gravitational waves, which are considered to be constantly rolling across space like background noise, for decades.

Scientists working at gravitational wave detectors on many continents announced on Thursday that they have finally found substantial evidence of these background waves by banding together under the auspices of the International Pulsar Timing Array project.

Gravitational waves pinch and stretch everything they pass through as they travel through space.

Astronomers examined pulsars, the dead cores of stars that erupted in a supernova explosion, for evidence of this squeezing and stretching at low frequencies.

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Some spin hundreds of times per second, flashing radio wave beams at extraordinarily regular intervals, similar to cosmic lighthouses. Radio telescopes around the world were pointed at 115 pulsars scattered throughout the Milky Way for the new study.

Scientists then examined the exceedingly minuscule changes in pulse timing to look for traces of gravitational waves.

According to Antoine Petiteau, a French astronomer, they were able to “detect changes of less than one millionth of a second over more than 20 years.”

According to Maura McLaughlin of the US Pulsar Search Collaboratory program, they were “awestruck” when they first saw evidence of the waves in 2020.

“Really a magical moment,” she said at a press conference.

According to the experts, the early evidence was consistent with Einstein’s theory of relativity and science’s current knowledge of the cosmos.

However, they stressed that they have not yet officially “detected” the waves because they have not attained the gold standard of five sigma certainty. Five sigma suggests that something is a statistical fluke one in a million times.

Each country or group in the collaboration published their study in a variety of journals on its own. The five sigma level could be attained in a year or two, according to Steve Taylor, chair of North America’s NANOGrav gravitational wave observatory.

The dominant theory holds that the waves are generated by pairs of supermassive black holes at the centers of merging galaxies.

These black holes, unlike those that created the previously reported gravitational waves, are nearly impossibly massive, often billions of times larger than the Sun.

If confirmed, the waves would be “the sum of all of the supermassive black hole binary systems whirling around each other at the cores of galaxies everywhere in the universe,” according to Daniel Reardon, a member of Australia’s Parkes Pulsar Timing Array.

Another idea is that gravitational waves are caused by the fast expansion that occurred within a second of the Big Bang, a phase known as cosmic inflation that scientists are unaware of.

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