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Credit: SOHO���������������������������������������������������������������������� ��Credit:
Ed Fomalont (NRAO) et al., VLA, NRAO, AUI, NSF
Left: A double layer explodes from the Sun, accelerating
tons of plasma into space in a �coronal mass ejection�.
Right: Radio-noisy double layers (shown in orange) on each side of Fornax A dwarf
the active galaxy between
them. The thin filaments
that connect the galaxy to the double layers
and transmit the
electrical power to drive
their radiation are not visible in this
image.
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Jul 01, 2005
Seeing More Electricity in Space
As laboratory research documents the behavior of plasma, many unexplained events in nature become understandable. Electrical �double layers� are a powerful example, offering the most efficient answers to many observational mysteries. In these cases, popular speculations based on pure mathematics are no longer useful.
The pinching of plasma into filaments is due to both magnetic and electric forces. We can detect the magnetic fields at a distance and understand why the filaments behave as they do. But another common formation in plasma is purely electrical. We can only detect it by sending a probe through it.
Anthony Peratt, an associate of Nobel Laureate Hannes Alfven, describes this formation in his textbook, The Physics of the Plasma Universe. He writes about �...two thin and close regions of opposite charge excess which give rise to a potential drop....� The two regions are called a �double layer�. Because we�re familiar with the idea that positive and negative charges attract each other, the idea that a layer of positive charges could persist close to a layer of negative charges is counterintuitive.
But these �thin and close regions of opposite charge� don�t just lie isolated in space: They form in a current�in a flow of charged particles�and they act as part of a filamentary circuit.
Double layers originate in a chicken-and-egg kind of ambiguity. Fluctuations in the charge density and particle velocity of a current will produce a potential drop; a potential drop will accelerate charged particles and produce fluctuations in density and velocity.
In a current, negative electrons stream in one direction and positive ions stream in the opposite direction. A potential drop will increase the velocity of particles on the �downstream� side�electrons move faster on one side of the potential drop, ions on the other.
The increased velocity means that the density decreases. To maintain charge neutrality in the circuit, other particles with the same charge are �trapped� on the downstream side. These trapped particles make up the layers of the double layer, with electrons on one side, ions on the other, and an electric field�the potential drop�between them.
With the ebb and flow of the many conditions in a filament (density, velocity, composition, temperature, etc.), double layers can form and dissipate. And the amplitudes of variations in these conditions can become large. A double layer can accelerate particles to cosmic-ray energies. It is �radio noisy�, radiating across a wide band of frequencies. It accelerates particles in beams. It can exert pressure on the plasma and expand across the magnetic field. It may explode and draw inductive energy from the filamentary circuit, releasing vastly more energy than was present in the double layer itself.
Because double layers dissipate energy�by accelerating matter and emitting radiation�they must be powered by an external source. The ability of Birkeland filaments to transmit electrical power over great distances means that the source could be many light-years�hundreds or thousands of light-years�away.
In the plasma universe, energetic events cannot be explained by reference to local conditions only. The effects of an entire circuit�which may encompass a whole galaxy or cluster of galaxies�must be considered. For this reason, while the prevailing scientific view allows only for isolated galactic and stellar islands in space, the electric view emphasizes connectivity.
(In the image of Fornax A above, for example, a tiny but energy-dense plasmoid at the center of the galaxy discharges energy along oppositely-directed Birkeland filaments (invisible in this image) into the radio lobes. Diffuse currents loop back from the lobes to the spiral arms, where their increasing density triggers star formation as they return to the central plasmoid.)
Irving Langmuir, one of the early pioneers in the study of plasma, discovered double layers in his laboratory in the 1920s. Hannes Alfven, the father of plasma cosmology, proposed their existence in cosmic settings in 1958. Double layers in space weren�t discovered until 1978, when artificial satellites orbited through them and measured the characteristic changes in their electric fields.
This fact is undeniable. But the traditional theories of astrophysics�gas kinetics and gravity and particle physics�provide no electrical framework to make this fact meaningful. And meaningless facts are simply ignored. They are often not even perceived.
The phenomenon of double layers became a ghost that haunts conventional astrophysics. Astrophysicists can detect and recognize the existence of magnetic fields in space. They use the conceptual tools of magnetohydrodynamics (MHD�the physics of fluids that are affected by magnetic forces) to explain magnetic influences on gases.
But because double layers are purely electrical and can only be detected by sending a probe through them, conventional astrophysicists are unable to recognize their existence. Because the electric field in Birkeland filaments is aligned with the magnetic field (field-aligned currents), the electric field in double layers is also aligned with the magnetic field and MHD doesn�t apply. Astrophysicists� concepts have created a blind spot in their percepts.
Astrophysicists see only the double layers� effects, and so they are at a loss to explain them. Energetic events occur without commensurate causes, as if a poltergeist were loose in the universe. In the left image above, loops of filaments on the sun suddenly expand and explode, throwing off massive bubbles of plasma that accelerate to significant fractions of the speed of light. Jets from opposite poles of a galaxy end in energetic clouds (right image above) that radiate copiously in radio and x-ray wavelengths.
(The text in the last link�written from the conventional point of view�displays astrophysicists� blind spot: The attempt at explanation begins with �plasma� but regresses to �gas� and ends with the �belief� that� magnetism can somehow explain the anomalous acceleration and collimation.)
Conventional theorists grasp at mathematical artifacts�such as black holes and magnetic reconnection�to fill in their empirical blind spot. But science is based on fact, not artifact. And the fact is that double layers can be produced in a laboratory and directly detected in space. Black holes and magnetic reconnection can�t.
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