ASCS: Tom Bridgman: The REAL Electric Universe
... I went through some of Tom Bridgman's material and I'll try to post the best of it here, starting with his version of electrical effects in the universe. Of those he mentions, the Pannoekoek-Rosseland Field sounds the most interesting to me. I think the Pulsars and Gamma Ray Bursts are the most likely misunderstood processes listed here. GRBs are likely much closer than conventionally estimated, so they're much smaller than claimed. Pulsar pulses seem more likely to be electrical pulses, than lighthouse beams, especially since the pulse signals are said to greatly resemble lightning signals. Charles has other ideas about pulsars though.The REAL Electric Universehttp://dealingwithcreationisminastronomy.blogspot.com/2009/~Friday, August 21, 2009
- Many EU advocates try to claim that astrophysics ignores the effects of electric fields and currents as possible drivers of astrophysical phenomena. - ... Yet electric currents and fields are discussed throughout the professional astrophysical literature, predating much of the Electric Universe.
This mechanism of charge separation and resulting electric field generation was first recognized back in the 1920s. Gravitational stratification of plasma gives light electrons a larger scale height than heavy ions. This generates a weak charge separation and small electric field, forming a structure similar to a weak double layer. The presence of dust can significantly strengthen the field. There are a number of astrophysical environments where this process is believed to act:
solar atmosphere and out into the solar wind
planetary ionospheres (This configuration contributes to the Birkeland currents identified in planetary magnetospheres)
galactic disk 'atmospheres'
possible source of seed fields for stellar dynamo processes
Offset Rotating Magnetic Dipoles:
A dipole magnet at rest just produces a magnetic field. But if the dipole is rotated and the magnetic axis of the dipole is tilted from the rotation axis, the magnetic field at any point near the magnet changes, which by Maxwell's equations, produces an electric field. Because Maxwell's equations are Lorentz invariant, the easiest way to find the values of this electric field is to transform the magnetic dipole into a rotating coordinate system. This system is a popular demonstration of how to treat relativity in rotating coordinate systems and dates back to the 1930s. Here's some areas in the astrophysical literature where this process is important:
- The strong magnetic fields of fast-rotating neutron stars (~10^10 gauss) generate very strong electric fields in the charged plasma environment around them.
Ionospheric & Magnetospheric physics:
- This configuration is another contribution to the Birkeland currents identified in planetary magnetospheres.
Charge-separation by radiation pressure:
- Photons interact with electrons more strongly than protons and can accelerate electrons away.
Driver of stellar winds:
- In the stellar wind outflow, the electrons will get an extra boost outward due to momentum transfer by scattering from the outflowing photons.
- High-energy photons can create a charge separation in the interstellar medium (ISM)
Currents: Sunspot and active region processes:
- Some of these currents may initially be generated by the Pannekoek-Rosseland field.
All these mechanisms create the charge separations and currents using energy from other processes, usually gravity. The charge-separation itself is not the original energy process but can create non-thermal distributions of charged particles.
The Electric Universe
February 16th, 2012 --- This may be somewhat of a repeat of the above.
Podcaster: W.T. Bridgman
- Description: The How, Where, and Why of electric fields in space – a short introduction.
- First, let's consider the case of a plasma bound by gravity where the negatively-charged electrons and positively-charged ions have the same temperature, so their average kinetic energy is the same. Ions are at least 1800 times heavier than the electrons, so at the same energy, the ions must move much more slowly than the electrons. As any child knows from playing ball, in a gravitational field, a faster moving particle can travel much higher than a slower moving particle. This means the faster moving electrons can form a thin 'atmosphere' around the ions. This charge separation generates an electric field, forming a structure sometimes called a 'double layer' by laboratory plasma researchers. This process was recognized independently by Rosseland and Pannekoek in the early 1920s and is sometimes called the Pannekoek-Rosseland field. This discovery actually predates Langmuir defining the term 'plasma' for ionized gases. While Pannekoek and Rosseland examined the simple case of electron and ion gases at the same temperature, this process operates in far more general cases. The presence of dust can significantly strengthen the electric field since the charges adhere to the dust particles and dramatically increases the effective mass of the charge.
- There are a number of astrophysical environments where astronomers think this process is operating:
The atmosphere of the Sun and out into the solar wind
Planetary ionospheres. The electric field contributes to the Birkeland currents that have been identified in planetary magnetospheres.
Galaxies are surrounded by very thin ionized gas that transitions to the even less dense intergalactic medium, essentially a galaxy 'atmosphere'.
Accretion disks around black holes and neutron stars.
- These types of configurations generate a very small electric field, but can do so over a very large region. This makes it possible to accelerate charged particles to very high energy. These configurations only operate a very low current. This is because a large amount of charge transfer would eventually reduce the charge difference, reducing the electric field, and eventually canceling the electric field.
- Basically, this process operates anywhere that plasmas can be confined under gravity. This process may actually be the source of the 'seed fields' which are needed to start processes such as the magnetic dynamo in the Sun and other stars.
- Next, consider a simple magnetic dipole, much like the classic demonstration of a bar magnet surrounded by iron filings which many people have seen. A dipole magnet at rest just produces a static magnetic field. But if the dipole is rotating and the magnetic axis of the dipole is tilted from the rotation axis, then the magnetic field measured at any point near the magnet changes with time. According to Maxwell's equations, a changing magnetic field produces an electric field, a process called induction. This is also a consequence of the relativistic invariance of Maxwell's equations. In fact, the easiest way to find the values of this electric field in this configuration is to transform the magnetic dipole into a rotating coordinate system. This offset rotating magnetic dipole was a popular demonstration of how to treat relativity in rotating coordinate systems and dates back to the 1930s. Here's some areas in the astrophysical literature where this process is important:
- Pulsars: The strong magnetic fields of fast-rotating neutron stars (about a billion gauss) can generate very strong electric fields in the charged plasma environment around them, an excellent mechanism for particle acceleration.
- Ionospheric & Magnetospheric physics, driven by planetary magnetic fields: Because the induced electric fields are roughly parallel to the magnetic field, this configuration is another contributor to the Birkeland currents identified in planetary magnetospheres.
- Another type of electric field configuration can form because photons interact with electrons much more strongly than protons. The shininess of metals is actually due to the weakly bound outer electrons of metallic atoms as they are hit by photons. When electrons are in free space, collisions with photons can transfer energy to the electrons and increase their velocity. This process is called Thomson scattering at low energies, and Compton scattering at high energies. This process also enables electrons to separate from ions to the point that the average force from the photons balances with the electric field produced by the charge separation. There are a couple of environments where astronomers think this process can act:
- As a driver of stellar winds. In the stellar wind outflow, especially for high-temperature O and B-type stars that emit strongly in the ultraviolet, the electrons can get an extra boost outward due to momentum transfer by scattering with the outflowing photons.
- Gamma-ray bursts: High-energy X- and gamma-ray photons can create a charge separation in the ionized gas of the interstellar medium.
- So with all these examples, why don't astronomers talk about cosmic electric fields more? There are several key reasons.
- Electric fields are very difficult to measure with remote sensing technologies. George Ellery Hale tried to measure electric fields on the Sun as early as 1915 but was only able to place an upper limit on the strength of such a field. Measurement techniques have improved since then, but still, it's difficult to talk about it if you can't reliably measure it in the first place.
- Since matter is normally electrically neutral in bulk quantities, it takes at least as much energy to separate the positive and negative charges in neutral matter as you obtain when the charges recombine. This is because energy is conserved and the fact that moving charges radiate photons, resulting in an additional energy loss in both the separation and recombination process.
- If an electric field is created purely by charge separation with no additional forces keeping the charges apart, it can't last very long in free space. Opposite charges attract each other and eventually they will move to cancel the electric field.
- The flip side of this cancellation process is that for a time, the moving charges create an electric current. Electric currents create magnetic fields, and since the current changes with time, so does the magnetic field. And the process can repeat, maintaining this field for quite some time after the original current is gone. Magnetic fields are much easier to detect with remote sensing techniques. Since the magnetic field is easy to tie back to actual observations, astronomers principally talk about the magnetic field, and use Maxwell's equations and plasma physics to infer the electric fields behind them.