The universe's first magnetic fields were 'comparable' to the human brain — and still linger within the 'cosmic web'

The universe's first magnetic fields may have been much weaker than we first imagined — and were roughly equivalent to the strength of the magnetic activity within the human brain, according to a new study.

Researchers used hundreds of thousands of computer simulations to examine the remnants of these ancient magnetic fields, which still reside within the "cosmic web" billions of years later.

Magnetism is a natural force generated by the movements of electrical charges and has existed since the early days after the Big Bang, when the infant universe was full of jostling electrically charged particles. Experts have long suspected that the initial magnetic fields created by these particles, known as primordial magnetic fields, were much weaker than those created by complex cosmic objects that exist today, such as stars, black holes and planets.

But in the new study, published Aug. 13 in the journal Physical Review Letters, researchers have revealed that these primordial fields may have been even weaker than they previously imagined. Using exhaustive computer simulations, the team constrained an upper limit on these fields' magnetic strength and found that they likely maxed out at 0.00000000002 gauss, which is billions of times weaker than a standard fridge magnet (~100 gauss).

Such magnetic fields are "comparable to magnetism generated by [the electrical activity of] neurons in the human brain," the researchers wrote in a statement.

Despite their weakness, remnants of these magnetic fields still reside within the intergalactic cosmic web — a mysterious, sprawling structure that permeates the entire known universe — and this was key to uncovering the new findings.

Related: Scientists share groundbreaking image of the 'cosmic web' connecting 2 galaxies near the dawn of time

The cosmic web is an expansive network of ghostly filaments that connect all the galaxies in the universe like a giant 3D spider's web. There is still a lot we don't know about the cosmic web, including what it is really made of. However, in recent years, scientists have started to image this gigantic structure properly and have begun to map it out in detail.

One of the biggest mysteries about the cosmic web is why it has its own magnetic fields. This is especially confusing in regions of space in-between galaxies, where the web is isolated within large expanses of nothingness.

"Our hypothesis was that this [magnetism] could be a legacy of events occurring in cosmic epochs during the birth of the universe," study lead author Mak Pavičević, a doctoral candidate at the International School for Advanced Studies (SISSA) in Trieste, Italy, and co-author Matteo Viel, an astrophysicist at SISSA, jointly said in the statement. "This is what we sought to ascertain with our work."

Their team believes that the earliest primordial magnetic fields could have been caught up in the initial inflation of the universe and later become intertwined with the cosmic web as it grew in the expanding spaces between galaxies.

In the study, the researchers used approximately 250,000 computer simulations, based on observational data of the cosmic web, to reverse engineer this supposed series of events, allowing them to set "strict limits on the intensity of magnetic fields formed in the very early moments of the universe," Pavičević and Viel said.

These findings are still theoretical as there is currently no way of directly observing primordial magnetic fields. However, the researchers claim that the results align with recent findings concerning the cosmic microwave background (CMB), which is the radiation leftover from the Big Bang, although it is unclear which specific findings they are referring to.

The study team also notes that continued observations of the cosmic web with the James Webb Space Telescope (JWST) could allow them to create more powerful simulations to further test their hypothesis in the future.