Hardcore astrophysicists have been chained to their computers for the past 15 years in search of a “hum.” They’re breaking out the Champaign because they finally found it. It’s been independently confirmed that the background noise of the universe has been detected.
The slow cycle hum of reality
“We’ve been on a mission for the last 15 years to find a low-pitch hum of gravitational waves,” Michael Lam relates. He’s an astrophysicist at the SETI Institute and a member of the North American Nanohertz Observatory for Gravitational Waves.
Multiple teams of scientists around the world have “independently found compelling evidence for long-theorized space-time waves.”
It took data from “telescopes across the planet” to pick up the quiet hum of reality. Confirming the signs of a “gravitational wave background” quickly “sent a thrill through the astrophysics community, which has been buzzing for days.”
It also affirms “an astounding implication of Albert Einstein’s general theory of relativity that until now has been far too subtle to detect.”
Einstein revealed that space is anything but empty and time doesn’t “march smoothly forward.” The reality of our modern multiverse involves “gravitational interactions of massive objects.” Things only get interesting to the guys who study the background hum when they involve the merger of “supermassive black holes.”
Gravitational monsters huge enough to “regularly ripple the fabric of space and time.” The gravity waves may be strong but they’re slow. The power in your walls, that feeds the appliances, is an audible 60 cycles per second. These scientists are listening for music where the waves have years between the peaks.
Earth bobs like a cork
As explained by professor Lam, “what we measure is the Earth kind of moving in this sea. It’s bobbing around — and it’s not just bobbing up and down, its bobbing in all directions.” They knew it would make some sort of hum but proving that is a challenge.
To do it, they start with pulsars. Those are some nifty objects in their own right. Since they can’t be seen in the visible spectrum, astronomers had no idea they were even there until the radio telescopes were invented.
Pulsars are ultradense neutron stars. They spin rapidly, “hundreds of revolutions per second.” While they’re doing that, they emit “radio waves in a steady pulse.” As steady as an atomic clock. NANOGrav mapped 68 of them. To find the hum of the cosmic dynamo they had to poke and stroke their keyboards until their wrists got numb but they persevered, convinced “that low-frequency gravitational waves could throw off the arrival of pulsar signals.” The ripples are slow ones.
Imagine sitting at the beach and watching a wave roll in to shore. Then, be prepared to wait years for the next wave to come swelling in. “Such low-frequency ripples can have crests separated by years, so the search for subtle swells in the sea of space-time required patience. The deviation in the pulsar data is so slight that it took 15 years of observations to come up with solid evidence of these gravitational waves.”
The key to the puzzle is the fact that the center of almost every galaxy has a “supermassive” black hole at the center. Not just an ordinary garden variety baby black hole that gets created by a collapsing star. These ones have been around for awhile and matured. Professor Lam and his team were only interested in the most cannibalistic ones which have eaten a number of their rivals. They have gravitational magic.
As one extraordinarily massive black hole sucks in another, they swirl around each other in a cosmic dance of death. “Over time, energy leaks from the dance party, as it were, and the supermassive black holes ease closer together, their orbital period shortening to just a few decades. At that point, the wavelengths begin to reach the frequencies detectable by NANOGrav.” That’s how they heard the hum.
