Magnetism, the Underestimated Force
An essential presence in the evolution of the universe
When we look at the universe, gravity tends to dominate the explanation. It keeps planets in orbit, governs the formation of stars, shapes galaxies, and determines the behavior of some of the most extreme objects known to science. Light, meanwhile, allows us to witness events that occurred billions of years ago, carrying information across distances almost impossible to imagine. Yet between the structures gravity helps create and the distant worlds light brings into view, another fundamental presence receives considerably less attention: magnetism.
Our familiarity with magnetism usually begins with ordinary objects. Magnets attract certain metals, compasses respond to Earth’s magnetic field, and electric motors transform electromagnetic interactions into movement. We know that the Sun has magnetic activity, that solar flares can disrupt technological systems, and that some planets possess magnetic fields while others do not. These familiar manifestations, however, reveal only a fraction of magnetism’s physical reach. Beyond solid materials and planetary environments, magnetic fields extend through stellar atmospheres, clouds of interstellar gas, entire galaxies, and regions of space where matter is so sparse that we instinctively imagine almost nothing exists.
Magnetism is not an independent force added to electricity. Both are manifestations of electromagnetism, one of the four fundamental interactions recognized by modern physics. Electric charges, moving particles, currents, and the intrinsic magnetic properties of electrons all contribute to magnetic phenomena. Relativity goes further, showing that electric and magnetic fields are components of a unified physical description, with their apparent separation depending partly on the observer’s motion. But the universality of electromagnetism does not imply that magnetic fields must be equally strong or organized everywhere. Their particular configurations emerge from the conditions and history of the systems in which they exist.
This distinction becomes especially important when we move beyond solid matter and consider plasma. Much of the visible matter in stars and throughout the environments surrounding galaxies exists in an ionized state, containing freely moving charged particles. These particles respond to electromagnetic fields, while their collective motion can generate, amplify, distort, and redistribute those same fields. Rotation, compression, turbulence, and electrical currents become part of a continuing interaction in which matter changes magnetism and magnetism changes the behavior of matter. The relationship is neither passive nor unidirectional.
Star formation offers a revealing example. Gravity draws enormous clouds of gas together, allowing regions of increasing density to develop into stars. Yet the process is not governed by gravitational attraction alone. Magnetic fields can resist contraction, influence the movement of gas, and help redistribute angular momentum. Their importance varies with the density, turbulence, and physical conditions of each region, but they contribute to determining how stellar formation unfolds. Gravity provides much of the overall tendency toward collapse; magnetic interactions help establish the circumstances under which that collapse proceeds.
The relationship becomes even more dramatic around black holes. Matter falling toward these objects can release extraordinary amounts of energy before crossing the event horizon. The X-rays detected from systems such as Cygnus X-1 do not escape from inside the black hole. They originate in the surrounding environment, where hot plasma, energetic particles, and electromagnetic processes transform gravitationally released energy into radiation. Magnetic fields also influence the flow of material through accretion disks and can participate in launching relativistic jets that extend far beyond their sources. Some of the energy concentrated by gravity is consequently carried outward through processes in which magnetism plays an essential role.
Magnetars reveal another extreme expression of this interaction. These compact neutron stars contain masses comparable to that of the Sun within bodies only a few dozen kilometers across. Their gravity is immense, but their magnetic fields are even more remarkable in comparison with familiar terrestrial conditions, reaching intensities vastly beyond those produced by human technology. Such fields can generate stresses within the star, contribute to powerful high-energy outbursts, and influence how radiation travels through the surrounding vacuum. Their strength cannot be explained simply by the star’s current rotation or mass. It reflects the complex physical history through which the object formed and evolved.
What makes these examples significant is not their extremity alone, but the different ways gravity and magnetism participate in the same processes. Gravity dominates the formation of large-scale cosmic structures, while magnetic fields can strongly influence the behavior of electrically active matter within them. A magnetic field does not have to rival gravity across an entire region to become decisive for the plasma occupying part of that region. Its influence depends on intensity, geometry, duration, spatial extent, and the properties of the matter with which it interacts. Even relatively weak fields can acquire considerable dynamical importance when they extend over immense distances and participate in processes lasting millions or billions of years.
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This changes the way we imagine the space between astronomical objects. Between stars and galaxies, we do not encounter a simple absence of substance interrupted by isolated luminous bodies. There are diffuse gases, energetic particles, plasma, and magnetic fields distributed across enormous regions. Within galaxy clusters, magnetism participates in the dynamics of the hot material surrounding their member galaxies. Beyond those environments, astronomers are investigating magnetic fields associated with the filaments of the cosmic web itself. That does not mean the universe is held together by a single continuous magnetic network. It means that the space separating visible structures also contains physical configurations that influence how ordinary matter behaves.
Interestingly, the light through which we observe the universe is also one of the principal ways we discover these otherwise invisible fields. Radiation emitted by aligned dust grains can carry information about magnetic orientation, while radio waves crossing magnetized plasma may experience a measurable rotation of their polarization. By examining such changes, astronomers reconstruct properties of fields located at distances no spacecraft could realistically traverse. Light therefore tells us more than where it originated. It also carries traces of the environments through which it traveled.
These methods have already revealed magnetism remarkably early in cosmic history. In 2023, observations made with the ALMA telescope identified an organized magnetic field in the distant galaxy known as 9io9, seen as it existed when the universe was approximately 2.5 billion years old. The discovery demonstrated that large-scale magnetic organization was already present in galaxies long before the universe reached its current age. It also raised a question that remains difficult to answer: how quickly can such organization emerge, and what processes were responsible for establishing it?
Part of the answer may lie in the capacity of magnetic fields to retain characteristics of earlier physical conditions. Some stars possess what are considered fossil magnetic fields, configurations that survived from previous stages of their evolution. Elsewhere, existing fields are compressed, twisted, amplified, and reorganized as matter moves through changing environments. Their present structure may consequently preserve partial evidence of events no longer directly observable. This is not memory in the sense of an untouched record. Magnetic configurations evolve, lose energy, and undergo transformations of their own. Nevertheless, they can retain physical information about processes that shaped them long ago.
The possibility becomes especially intriguing when extended toward the beginning of cosmic history. Electromagnetism belongs to the fundamental framework of known physics, but the existence of that interaction does not tell us when the first persistent cosmic magnetic fields appeared. Some theories propose that magnetic fields originated during processes in the primordial universe, perhaps through mechanisms associated with cosmic inflation or transitions between different physical states. Other explanations place their emergence later, as plasma movements, turbulence, and the formation of the earliest structures created conditions favorable to magnetic generation and amplification. Weak primordial fields might also have been strengthened through subsequent cosmic evolution.
The cosmic microwave background provides a way to investigate part of this history. Released when the universe was approximately 380,000 years old, this radiation preserves information about conditions preceding the first stars. Magnetic fields present during those early stages could have left measurable signatures in the radiation’s distribution and polarization. Observations have established constraints on various primordial magnetic-field models, but have not yet confirmed that such fields existed. The distinction matters because discovering magnetism in an ancient galaxy is not equivalent to demonstrating that it originated during the earliest moments of the Big Bang.
There is also a deeper question concerning the relationship between magnetic fields and the fundamental interactions themselves. Modern physics describes electromagnetism and the weak nuclear interaction within a unified electroweak framework, whose low-energy manifestation emerged as the early universe cooled and its physical conditions changed. Whether all fundamental interactions, including gravity, share a still deeper origin remains unresolved. The possibility of primordial magnetism intersects with these investigations, although magnetic fields alone would not establish that such an overarching unification occurred. What they might provide are additional traces of physical processes taking place before familiar cosmic structures existed.
None of this diminishes gravity’s central importance. Its influence is indispensable to understanding the large-scale distribution of matter, including the gravitational role attributed to dark matter, the formation of galaxies, and the geometry of spacetime itself. Magnetism does not replace that explanation, nor does it offer a universal solution to the unknowns surrounding dark energy or cosmic expansion. Its significance emerges from a different role: the movement, transformation, and organization of electrically active matter within the evolving gravitational structure of the universe. These processes cannot always be understood adequately when electromagnetic interactions are treated as secondary details.
The imbalance in public attention may have as much to do with perception as with physics. Galaxies have recognizable forms, stars shine, and black holes can be studied through gravitational effects and the radiation emitted by their surroundings. Magnetic fields rarely offer such immediate visual identities. Their structures must often be reconstructed from indirect measurements, interpreted through models, and represented in ways that make otherwise invisible relationships comprehensible. The very methods required to observe them can reinforce the impression that they belong behind the scenes, even when they participate directly in the phenomena taking place before us.
There is something revealing about this difference between what attracts our attention and what helps determine physical behavior. We naturally recognize objects before relationships, visible structures before distributed processes, and spectacular events before the quieter conditions that make them possible. Yet much of the universe operates through interactions that do not present themselves as isolated objects. Magnetic fields can extend beyond the bodies associated with them, evolve with moving matter, and persist as part of the physical history of environments whose visible appearance has changed completely.
As astronomical instruments become more sensitive to polarization, plasma dynamics, and the faint magnetic signatures of intergalactic space, a more complete picture of cosmic evolution begins to emerge. The universe is not simply an arrangement of massive bodies whose positions are determined by gravity. It is also an environment in which fields and matter continuously influence one another, redistributing energy, shaping movement, and sometimes preserving traces of events that occurred billions of years ago.
Perhaps magnetism has remained underestimated because its influence is often embedded within phenomena whose most visible features are attributed to something else. We notice the star, the galaxy, the black hole, or the radiation, while the electromagnetic relationships involved in their behavior remain less apparent. Recognizing those relationships does not reveal a different universe. It allows us to perceive more of the one we already inhabit, including a dimension of its history and organization that we are still learning how to observe.
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