The Plasma Universe of Hannes Alfvén

Editor’s note: the following article has just been published in the October-December issue of Edge Science.

In the 20th century no scientist added more to our knowledge of electromagnetism in space than Hannes Alfvén (1908–1995). His insights changed the picture of the universe, revealing the profound effects of charged particle movement at all scales of observation. But recognition never came quickly, and never easily, and mainstream journals typically regarded Alfvén as an outsider, often rejecting his submissions. In retrospect, Alfvén’s difficulties in gaining acceptance can only highlight the inertia of institutionalized ideas in the sciences, reminding us of the obstacles faced by all of history’s great scientific innovators.

Awarded the Nobel Prize in 1970 for his contribution to physics, Alfvén emerged as a towering critic of directions in astronomy, cosmology, and astrophysics. Though he was surely not correct on everything he proposed, decades of space exploration eventually confirmed a lifetime of observations and hypotheses, often with implications that many space scientists did not want to hear. “In the world of specialized science,” wrote plasma scientist Anthony Peratt, “Alfvén was an enigma. Regarded as a heretic by many physicists, Alfvén made contributions to physics that today are being applied in the development of particle beam accelerators, controlled thermonuclear fusion, hypersonic flight, rocket propulsion, and the braking of reentering space vehicles.”1

But Alfvén’s impact reached far beyond new technologies. He devoted much of his life to the study of plasma, a highly conductive, elementary form of matter characterized by the presence of freely moving charged particles, not just electrically neutral atoms. Normal gases become plasma through heating and partial ionization as some percentage of the atoms give up one or more of their constituent electrons. Often called “the fourth state of matter” after solids, liquids, and gases, plasma is now known to constitute well over 99 percent of the observed universe.

Alfven is the acknowledged father of “plasma cosmology,” a new way of seeing formative processes in the heavens. Proponents of plasma cosmology suggest that vast but invisible electric currents play a fundamental role in organizing cosmic structure, from galaxies and galactic clusters down to stars and planets. The Big Bang hypothesis, black holes, dark matter, and dark energy are only a few of today’s popular cosmological themes disputed by scientists working with this new perspective. Many central tenets of plasma cosmology emerged from laboratory experiments with plasma and electric discharge, and it was Alfvén himself who showed that plasma behavior in the laboratory can be scaled up to galactic dimensions: vast regions of plasma in space behave similary to plasma on earth.

Underscoring the enormity of ignoring cosmic electromagnetic effects in cosmology is the fact that the electric force between charged particles is some 39 orders of magnitude (a thousand trillion trillion trillion) times stronger than the gravitational force. In comparative terms, gravity is incomprehensibly weak; a hand-held magnet will raise a small metallic sphere against the entire gravity of the Earth.

Alfvén’s documentation of laboratory plasma experiments eventually made it impossible to ignore the role of electricity in space. He explained the auroras based on the work of his predecessor Kristian Birkeland; correctly described the Van Allen radiation belts; identified previously unrecognized electromagnetic attributes of Earth’s magnetosphere; explained the structure of comet tails; and much more.

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