“Background noise” of gravitational waves: a discovery…

Several officials made it clear Thursday that the first detection of “background noise” of gravitational waves announced Wednesday by several science teams from around the world is a transcendent discovery that “shatters our fixed perception of the universe.”

The deputy director of the National Science Foundation’s (NSF) Mathematical and Physical Sciences Directorate, Sean Jones, explained Thursday during a presentation that our perception of the universe until now has been based on images produced by telescopes such as Hubble or, more recently, James Webb.

However, thanks to the new use of a galactic network of neutron stars – known as pulsars – to detect very low-frequency gravitational waves, we can see “a bustling, undulating universe, enlivened by a cosmic symphony of gravitational waves.”

Scientists are not yet sure of the causes of these massive distortions of space-time, although their main suspicion is that they come from pairs of supermassive black holes, which are systems formed when two galaxies merge into one and have a mass equivalent to thousands of millions of suns.

But there are more theories. According to Kip Thorne, one of the world’s most famous astrophysicists and Nobel Prize laureate in physics, the “background noise” could be caused by the remnants of the Big Bang, the starting point from which the entire universe was formed.

For Thorne, the “Holy Grail” for the NANOGrav team, an association of scientists from across the United States that is one of the groups announcing its advances this week, will be extracting information from these waves to better understand the origin of our world.

galaxy detector

To detect these low-frequency waves, which can take up to a decade to repeat themselves, NANOGrav scientists — like several agencies in China, Australia, Europe and India — tapped into a “galactic-scale detector,” in Sean Jones’ words.

Using emissions from the remnants of stars that have depleted their energy, shrunk to the size of a city, and spin hundreds of times per second, scientists have been able to detect these variations in space-time caused by gravitational waves.

This is ‘hacking’ on a galactic scale.

Each time one of these emissions reaches Earth, it is measured using radio telescopes, which makes it possible to detect the differences in space separating it from our planet.

Einstein’s theories of general relativity, published more than a hundred years ago, predict a unique pattern of variability in the emissions from these pulsars, and it is this pattern that scientists at NANOGrav and beyond have detected with astonishing accuracy.

job for 15 years

It’s been more than 15 years of work since the team began recording emissions from nearly 70 pulsars, separated by thousands of light-years across the Milky Way, in 2007.

Not only that: our understanding of pulsars, which are used here as a kind of ultra-accurate cosmic clock, builds on the work of astrophysicists like Jocelyn Bell Burnell, who in the 1960s detected the first radio signal from one of these objects.

The scientist, who was present by videoconference during the presentation, joked that at the time no one could have imagined her discovery would end up being used to detect gravitational waves.

Using pulsar networks to study these differences in time and space holds promise for progress in our understanding of the early universe, although it remains to be seen how much this process can be improved.

So far, science has relied on specialized, ultra-precision instruments, such as the Laser Interferometer Gravitational-Wave Observatory, or LIGO, which detected waves from the collision of two black holes in 2016 and earned its founders — Kip Thorne among them — the Nobel Prize in 2017.

However, the use of pulsars makes it possible to detect objects at much lower frequencies, which opens the door to new discoveries about the very first moments of our universe and can reveal new fundamental laws of physics.

Everything will depend on the level of refinement of this method, the scientists explained, and their next step will be to identify the individual elements of this cosmic “background noise”.

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