Natalie Wolchover writes:

Anytime astronomers figure out a new way of looking for magnetic fields in ever more remote regions of the cosmos, inexplicably, they find them.

These force fields — the same entities that emanate from fridge magnets — surround Earth, the sun and all galaxies. Twenty years ago, astronomers started to detect magnetism permeating entire galaxy clusters, including the space between one galaxy and the next. Invisible field lines swoop through intergalactic space like the grooves of a fingerprint.

Last year, astronomers finally managed to examine a far sparser region of space — the expanse between galaxy clusters. There, they discovered the largest magnetic field yet: 10 million light-years of magnetized space spanning the entire length of this “filament” of the cosmic web. A second magnetized filament has already been spotted elsewhere in the cosmos by means of the same techniques. “We are just looking at the tip of the iceberg, probably,” said Federica Govoni of the National Institute for Astrophysics in Cagliari, Italy, who led the first detection.

The question is: Where did these enormous magnetic fields come from?

“It clearly cannot be related to the activity of single galaxies or single explosions or, I don’t know, winds from supernovae,” said Franco Vazza, an astrophysicist at the University of Bologna who makes state-of-the-art computer simulations of cosmic magnetic fields. “This goes much beyond that.”

One possibility is that cosmic magnetism is primordial, tracing all the way back to the birth of the universe. In that case, weak magnetism should exist everywhere, even in the “voids” of the cosmic web — the very darkest, emptiest regions of the universe. The omnipresent magnetism would have seeded the stronger fields that blossomed in galaxies and clusters. [Continue reading…]