Friday, July 23, 2010

Electric Universe: Everything I needed to know about science I learned from watching Star Trek?

or “How pseudo-science learns from Sci-fi technobabble”

Engineer: “Captain, we can stop the flow with a concentrated beam of chronoton particles”
First Officer: “Aren't chronoton particles notoriously unstable?”
Engineer: “Not if we modulate it with a high-frequency pulse of tachyons.”

Anyone who's a fan of television or movie science fiction has doubtless seen a similar scene.  A catastrophe is averted by judicious manipulation of terminology.  Those of us familiar with the science snicker a little at scenes like these.

Many of these types of shows have inspired this author, and many others, to pursue careers in the sciences and engineering.  But while television science fiction has inspired some to actually learn more science, it seems to have convinced others that most of science is manipulation of sophisticated-sounding terminology.

In dealing with pseudo-scientific claims, I have frequently encountered this kind terminology manipulation, usually with present-day scientific terms.  However, using the terminology does not mean the speaker understands the concepts and implications behind the terminology.

As an example, I'll take a close look at a comment recently posted in this blog under the post “Scott Rebuttal. II. The Peratt Galaxy Model vs. the Cosmic Microwave Background".  Any reasonable response would be way to long for the comments so I decided to make it a regular posting.
Commenter: "Is it to be assumed that electrons within a Birkeland current move in circular and spiraling motions? A circular motion at least, would indicate that the internally induced magnetic fields are more important than the ones driving the Birkeland current in the first place. Now, the Birkeland currents are per definition initially field alligned, and the additional induced magnetic fields (a collective cylindrical one), would be surrounding the Birkeland current, seen from a classical point of view. However, it is the Debye shielding that prevents the effect you propose are happening (that otherwise would produce cyclotron radiation). For this reason, it seems likely that Birkeland currents can be in “dark mode“ until they interact with considerable densities of plasmas or gases, seen as glow mode in various wavelengths (double helix above Milkyway centre?) or as auroras."
In an attempt to salvage the Peratt galaxy model, the commenter has assembled an explanation which makes use of some real scientific terminology.  It reads really impressive, even logical, every bit as good as the techobabble on television sci-fi.  However, while they use the terms, I will now point out how they misuse the concepts that they represent as well as the consequences of those concepts.  Each of the errors has, at its root, the notion that the terms we use to describe physical processes are somehow isolated, like the 'black boxes' of engineering - that the processes do not depend on more fundamental processes - and that these underlying processes interact in ways that limit the applicability of 'black box' processes. 

The commenter's explanation has three major failures.

1) “electrons within a Birkeland current move in circular and spiraling motions? A circular motion at least, would indicate that the internally induced magnetic fields are more important than the ones driving the Birkeland current in the first place.”
Charged particles in ANY magnetic field move in circular/spiraling motions. Depending on the density, the particles may not complete a full circle before they scatter off a neighboring particle, but they still move in curving trajectories.

There are two sources of magnetic fields in the Birkeland current configuration.  There is the field component along the axis of the current path, usually labelled the z-axis.  This is the main field of the Birkeland current and has to come from some other source (rarely specified in EU literature).  As the charges flow along the z-axis, that current induces an additional magnetic field, called the azimuthal field. 

Another important thing to note is that for a current to exist, the charge carriers in the Birkeland current, ions and electrons, must travel at different speeds.  In an electric field, the force on an electron and proton are the same (but opposite in direction).  However, the electron will accelerate about 1800 times faster due to its proportionally smaller mass.   Therefore, electromagnetic, as well as thermal mechanisms, have ions and electrons traveling at different mean speeds.  If the electrons and protons travel at about the same velocity (magnitude AND direction), the net current flow becomes zero, and the entire system fails.  The plasma becomes indistinguishable from a hot cloud of plasma.

Birkeland currents still require a magnetic field to align along their direction of travel.  For the Earth & planetary magnetospheres, this field is provided by the planetary magnetic dipole field.  What is the source of this field in Peratt's galaxy model?  This would have to be a HUGE structure to be a source of magnetic field lines that can stretch across several hundred million light-years of the cosmos.  I've yet to find anything in EU or plasma cosmology literature identifying the nature of this large-scale magnetic field.

All known cosmic Birkeland currents are relatively low current density, they do not themselves produce a significant magnetic field relative to the field aligned along their axis.  If the current-induced field becomes large, the plasma confinement becomes unstable.  This is well established observationally and experimentally.  Therefore the commenter's claim that the induced (azimuthal) magnetic field is more important than the driving field (z-axis) immediately leads to an unstable configuration.

2) “it is the Debye shielding that prevents the effect you propose”. 
First, I didn't propose synchrotron radiation would occur in the configuration advocated by Dr. Peratt.  Peratt himself recognized that synchrotron radiation would be generated by the electrons moving in a magnetic field, as referenced in the original blog post.  This process is well established, observationally & experimentally.

Debye screening surrounds a positive charge center with more mobile negative charges to give a net charge of ZERO beyond some useful distance scale.  Debye screening relies on the light electrons having a roughly isotropic (uniform in all directions) velocity relative to the heavier, slower moving ions.  This configuration gives electrons a net velocity of zero with respect to the ions and therefore the system has NO net current flow.  But if your net current is zero, then so is your magnetic confinement mechanism, as noted above.  Your Birkeland current is no longer confined by the magnetic field and becomes nothing but a blob of hot plasma.

If electrons have a net relative velocity with respect to the ions, as is needed for a current, then they can no longer form a uniform cloud around the ions to screen them.  Debye screening no longer applies.  Peratt's galaxy model relies on 30keV electrons as part of the main current stream.  This is substantially above the ionization energies of even the innermost electrons in atoms with atomic numbers up to iron.  Hydrogen, the most abundant interstellar element, has a 13.6 eV ionization potential, while iron needs about 7keV to liberate the innermost electron.  The electrons in Peratt's current stream will barely feel any influence from the ions and therefore cannot change their motion substantially to screen them.

So suppose you want to claim that the electrons slow down around the ions and screen them?  To get electrons moving in a bulk current flow to an isotropic distribution relative to the ions requires the electrons loose energy.  This will occur by either collisions or scattering.  Both of these processes can generate photons, by either exciting atoms or bremsstrahlung(wikipedia).  I did a test calculation using Peratt's parameters which suggests there is very little energy loss via bremsstrahlung but I need to check this against other sources.

In fact there are numerous other processes, in addition to bremsstrahlung mentioned above, that can come into play that would make the Birkeland currents detectable.  Electrons interact strongly with photons.  If space were full of streams of electrons required by the Peratt model, they would Compton scatter (wikipedia),  or Thomson scatter (wikipedia) in the case of non-relativistic electrons, off background photons, changing their energy. 

The bottom line is that any interaction that alters the charged particle flows, results in energy being transferred between particles, which generates more emission.  This makes the mechanism fail or you see emission as the kinetic energy of the electrons is converted to photons (most likely in the radio, microwave to infrared regions of the spectrum). 

3) “Birkeland currents can be in 'dark mode' until they interact with considerable densities of plasmas or gases”
The “dark mode” term in regards to gas discharges is a laboratory description which refers to a lack of emission in the range of visible light.  But even in the 'dark current', electrons and ions are still moving in the gas, accelerating & colliding through this region, it is just their emission is not in the range of visible light.  These configurations emit in radio to infrared frequencies, depending on the gases and voltages involved.  The commenter uses the term as if “dark mode” is still a mysterious process (perhaps trying to draw an analogy with Dark Matter?).  These processes in gas discharges have been heavily studied in the laboratory and even computer simulations.  There is a large body of scientific literature on this topic which the EU supporters routinely ignore.

In the final analysis, any mechanism that can hide these Birkeland currents also basically kills them.  To hide behind the 'dark mode' claim ignores that fact known cosmic Birkeland currents emit in the radio band, such as the magnetosphere of Jupiter (Wikipedia),

Thursday, July 8, 2010

Electric Universe: More data refuting the EU galaxy model

This is a followup to Still no electric currents powering the galaxies....

A new full-sky dataset has been released that creates more problems for the Electric Universe (EU) supporters clinging to the galaxy model formerly advocated by Anthony Peratt of LANL (see Scott Rebuttal. II. The Peratt Galaxy Model vs. the Cosmic Microwave Background).

As noted in the previous posts, one of the predictions of the Peratt galaxy model is that these galaxy-powering current streams should be strong emitters of synchrotron radiation in the microwave band, at an energy density level equivalent to the cosmic microwave background radiation. They were expected to appear as spaghetti-like streams across the sky. You would expect to see these structures clearly associated with the nearer galaxies.

The Planck satellite (Wikipedia, ESA) has been operating at the Sun-Earth L2 point for six months now and has published a preliminary skymap of their data. The sky survey will eventually improve on the WMAP results with about three times higher angular resolution and ten times higher sensitivity in the microwave band. The two instruments on the satellite are the LFI (Low Frequency Instrument), covering 30-70 GHz, and HFI (High Frequency Instrument), covering 100-857 GHz. Note that these frequencies are beyond the 1.42GHz emission of neutral hydrogen gas (Wikipedia), sometimes labelled HI, so direct HI contamination is avoided.

On the BBC news site, Planck telescope reveals ancient cosmic light, the story includes a checkbox on the graphic where you can overlay locations of some better known objects, such as the Andromeda galaxy and the Magellanic clouds. In the graphic, the blue/white structures are from the HFI channels and reveal dust and gas in the Milky Way.  Many of these HFI bands will be used to determine the concentration of this foreground material so the its contribution to the LFI channels can be calculated and subtracted, leaving a net CMB map.

Another cool web-tool for exploring this dataset online is Chromoscope. Turn on the sky labels by pressing the letter 'l'. Then zoom in close to the locations of the Andromeda galaxy or the Magellanic clouds. Using the vertical controller in the upper right, you can step through different all-sky datasets from radio wavelengths to gamma-rays. In all these wavelengths, these extragalactic objects don't exhibit the connection to long structures required by the EU galaxy model.

Here's a snapshot from Chromoscope of the region around the Andromeda galaxy.

Thursday, July 1, 2010

Electric Universe: Pulsars & "Planetary Magnetospheres"

One of the popular claims of the Electric Universe advocates is that the pulsar analysis and model described in Healy & Peratt (1995) concluded that a compact object, in particular, a neutron star, was not needed to explain many pulsar observations.  This statement can be found at: Supernova 1987A Decoded.  Near the bottom of the page, we find two paragraphs
The 1995 analysis he refers to is “Radiation Properties of Pulsar Magnetospheres: Observation, Theory, and Experiment” by Kevin Healy and Anthony Peratt. Healy and Peratt concluded, “Our results support the ‘planetary magnetosphere’ view, where the extent of the magnetosphere, not emission points on a rotating surface, determines the pulsar emission.”
In other words, we do not require a hypothetical super-condensed object to form a pulsar. A normal stellar remnant undergoing periodic discharges will suffice. Plasma cosmology has the virtue of not requiring neutron stars or black holes to explain compact sources of radiation.
While these two paragraphs are occasionally misleadingly presented as one quote in some discussion forums (link), the paragraph in bold is NOT in Healy & Peratt.  The 'planetary magnetosphere' concept Healy & Peratt reference is Michel (1982).  Some aspects of this are even described in Section 4 of Healy & Peratt, including a footnote noting the similarities between pulsar emission and the decametric radio emission of Jupiter.   

More details can be found in Wikipedia: Jupiter as a pulsar and in T.W. Hill and A.J. Dressler (1995) or Sections 1.4 and 7.2 of Michel(1991).

Three key points from these relevant to the planetary magnetosphere model for pulsars:

1) The primary mechanism is  rotating magnetic dipole, the magnetic axis, B, is offset from the rotational axis, omega, (as in the figure below), embedded in a plasma.

2) The pulse periods are still driven by the rotation period of the object.  Millisecond pulse periods still require a rapidly rotating, and therefore very compact, object.

3) The radiation mechanisms for pulsars still require strong magnetic fields.  The comparison to planetary magnetospheres is connected to the actual  radiation mechanism of the particles moving along the magnetic field lines (Birkeland currents).

The bottom line is that Healy & Peratt (1995) does not rule out the need for a compact object, such as a neutron star, to explain the timing characteristics of pulsars.  The primary point of their paper is that the source of emission is in the pulsar magnetosphere, making the analogy with emission from Jupiter's magnetosphere.

A large amount of Michel (1982) deals with electrodynamics of a plasma in a rotating magnetic dipole field, independent of the nature of the central object, the details of which provide a boundary condition for the system, and therefore may have applications to other “Electric Sun” claims.   Also examines some unconventional pulsar mechanisms examined.
  1. Michel, F. Curtis.  “Theory of Neutron Star Magnetospheres”  University of Chicago Press, 1991.
  2. Hill, T. W.; Dessler,  A. J. Space Physics and Astronomy Converge in Exploration of Jupiter's Magnetosphere. Earth in Space, Vol. 8, No. 2, Oct 1995, p.6. 1995
  3. Healy, K.R. & Peratt, A.L.  Radiation Properties of Pulsar Magnetospheres: Observation, Theory, and Experiment.  Astrophysics & Space Science, 227:229–253, May 1995.
  4. Michel, F.C. Theory of pulsar magnetospheres. Reviews of Modern Physics, 54:1–66, January 1982.