In high school, my friends and I were hooked on the sitcom Happy Days. We were roughly the same age as the characters and learning similar life lessons. There was a club of teenage girls in the show who wore jackets that read “Magnets: We Attract.”
Magnetism has been attracting a lot of scientific attention lately. In an earlier story, we talked about our planet’s magnetic field. It’s not as stable as you might think, and it’s still mysterious in many ways. We work with magnets and compasses every day, so we tend to take magnetism for granted. Yet, there are actually quite a few things that scientists still can’t explain about magnetic fields.
Electromagnetism is one of the Fundamental forces
There are four fundamental forces in the universe, gravity, the strong nuclear force, the weak nuclear force and electromagnetism. Of these, magnets are the earliest discovery. We’ve known about them for as long as anyone can remember.
The first person to make a formal study of magnetic fields was Petrus Peregrinus de Malcourt in 1269. He was the one who decided to name the two points where the lines in magnetic fields cross “poles,” after the North and South Poles of the planet. Scientists refined their ideas about magnetism and electricity over the centuries that followed.
Next year will mark the 200th anniversary of Hans Christian Orsted’s discovery that a length of wire with electricity flowing through it has a magnetic field wrapped around it. In 1831, Michael Faraday discovered that if he changed a magnetic field, a new electric field would encircle it. Scientists call that induction.
Between 1861 and 1865, James Clark Maxwell explained and united all the theories around magnetism and electricity in his famous equations. Richard Feynman merged electromagnetism with quantum mechanics in his Quantum Electrodynamics (QED) theory.
There are unimaginably vast electromagnetic fields floating in space.
The earth, the sun and the other planets in the solar system, except for Venus and Mars, all have magnetic fields. Mars and Venus have other, less conventional forms of magnetism as well. At this point, for cosmologists, there is something much harder to explain. There are unimaginably vast electromagnetic fields floating in space.
Some of these fields are bigger than a cluster of galaxies. Just as a reminder, there are several hundred billion stars in a galaxy and more than 1,000 galaxies in a cluster. Cosmic magnetic fields are hard to study.
We can’t see a magnetic field here on earth, we only perceive its effects. It works the same way in outer space. Astronomers can’t observe a magnetic field with an optical telescope. All they can do is try to detect the radiation from these fields.
the largest ever radio telescope called the Square Kilometre Array (SKA)
An international project is underway to build the largest ever radio telescope called the Square Kilometre Array (SKA). One of its plans will be to detect the radiation generated by cosmic magnetism. It will have the sensitivity and resolution to map out these massive magnetic fields. Scientists expect it to discover things we can’t even predict at this point. However, as I write this, construction hasn’t started yet.
The biggest mystery about these vast cosmic magnetic fields is where they came from. One idea is that the magnetism formed in the very early universe. According to cosmology’s Standard Model, there was a minute fraction of a second during which space itself expanded exponentially. It’s called the inflationary period, but it was shorter than the blink of an eye. They speculate that there was some sort of inflation particle that caused this and that interaction with this particle enhanced the existing magnetic fields.
Other scientists have challenged this idea because they believed that any magnetic fields created during the inflationary period would have faded out. During the more stable, ongoing expansion of the universe that followed, skeptics argued that the frequencies would shift in the red direction. This would be due to the doppler effect and it would change the magnetism into faint radiation.
The biggest mystery about these vast cosmic magnetic fields is where they came from
Researchers at the International Centre for Theoretical Physics and the University of Southern Denmark have published new findings. They show that the behaviour of magnetic fields after the inflationary period would have been different than previously thought. The University is having some fun touting this because Orsted came from Southern Denmark.
Assuming that the fields were strong enough near the very beginning of the universe, and based on Faraday’s induction discovery, magnetic fields from the inflationary period would have survived. In fact, they would be 37 orders of magnitude stronger than the skeptics calculated.
This might explain how the immense magnetic fields we seem to have detected formed and survived. As Professor Martin S. Sloth put it, “This opens a new door to our understanding of the origin of cosmic magnetic fields.”
“This opens a new door to our understanding of the origin of cosmic magnetic fields”
We can never fully understand the universe without first understanding how cosmic magnetic fields work. These mammoth fields don’t merely fill interstellar space.
They determine how dense cosmic rays become and how they get distributed. They’re needed to get stars to form. They affect the pressure of interstellar gas. They even determine how galaxies and galaxy clusters develop and progress.
To understand the universe and our place in it, we need a better grasp of electromagnetism as a fundamental force. We’re hoping that this new discovery can be confirmed empirically by the Square Kilometre Array. Filling in the gaps in the Standard Model will give us the complete story and help make our lives more meaningful.
We always have more to learn if we dare to
University of Southern Denmark
Square Kilometre Array
Early cosmological evolution of primordial electromagnetic fields