Illustration of Alfvén wave

1942 Alfvén wave

The book of science

Tom Sharp

Hannes Alfvén electromagnetism Illustration of Alfvén wave

Alfvén wave

A magnetic field induces currents in a moving conductive fluid, which affect the magnetic field. These waves help explain the earth’s geomagnetic dynamo, the behaviors of the solar wind, and the sun’s magnetic fields. They help explain sunspots, solar flares, why the sun doesn’t spin in proportion to its mass, and why the sun’s corona is so much hotter than its surface.

Random waves

Random motion in the convection zone of the sun produces waves that carry energy into the sun’s corona. We say it’s random, but what we mean is chaotic; we have no way to predict it; it’s too complex. Over a longer time, life is also “random,” that is, unpredictable, which doesn’t stop us from describing its side effects.

Not to be confused

Alfvén, not elfin or elvish, not supernatural, fairy-like, impish, puckish, or mischievous. Similarly, not Alvin, the mischievous chimpmunk, although frequency has something to do with it. Frequently at a frequency orthogonal to our main direction, we push the possibilities.

Hannes Alfvén proposed that plasmas with magnetic and electric fields pervade space, causing “a network of currents which transfer energy and momentum over large or very large distances.”

The existence of the sunspot cycle shows that the motions in the convection zone are not entirely random.

See also in The book of science:

Readings in wikipedia: