I noticed this entry in the colloquium listing about a month ago and began preparing (which is why I haven't been keeping this blog very up-to-date). I contacted a few people I knew in the GSFC education groups to see if they were interested in attending but none of the people I contacted were actually in attendance.
At the colloquium, there were about 50-60 in attendance (about half the auditorium capacity). As part of his opening, Dr. Scott asked for a show of hands of number of astronomers/astrophysicists vs. engineers in audience. Maybe 10-15 hands were raised for each group. I'm not sure about those who did not raise their hands. Perhaps they were software programmers of which there are many at GSFC supporting the scientific mission.
Dr. Scott noted that this day was the anniversary of Robert Goddard's first liquid fuel rocket launch in 1926.
After opening with mention of a number of historical figures in plasma physics, Dr. Scott went into a presentation of plasma observations and principles that were covered in the book and which I discuss in my analysis (http://www.crankastronomy.org/anomalies/electriccosmos.html)
Complaint: Electric fields are not zero in plasmas
My response: This is an artifact of the ideal MHD approximation, where particle collisions dominate, resistivity is small (conductivity is very high, infinite in the ideal limit), and the length scales are much longer than the Lamor radius. It is still around for pedagogical reasons but most modern researchers try to find ways to relax the limiting assumptions. It's still gets a fair amount of use in press releases and education sites due to its simplicity.
Complaint: Illustrating magnetic fields by lines.
My response: I wish there were a better way to represent vector fields over a large region. This becomes even more problematic when the vector field varies in time. Interestingly, he made a few caveats that I had not read in his material but was mentioned in my analysis.
Complaint: Magnetic fields do not 'move things around'
My response: Generally true, but spatially varying magnetic fields will look like time varying magnetic fields to moving particles which means the particle will see an electric field in its own frame. This can change particle energies. In some of my historical explorations, I've come across some interesting history of the “moving line theory” misconception in electromagnetism.
- W.G.F Swann, “Unipolar Induction”. Phys. Rev. 15, 365 - 398 (1920) (http://dx.doi.org/10.1103/PhysRev.15.365)
- D.L Webster. “Schiff's Charges and Currents in Rotating Matter”. American Journal of Physics, 31:590–597, August 1963 (http://dx.doi.org/10.1119/1.1969688)
- D.L. Webster. “Relativity of Moving Circuits and Magnets”. American Journal of Physics, 29:262–268, April 1961 (http://dx.doi.org/10.1119/1.1937738)
He mentions a number of other topics
- Why don't double layers slam together? He claims this is because they are created by a dynamical process, in particular, current flows. But the problem is actually more complex than this. Double layers tend to form in regions where the differences between the electron & ion velocities are the largest. This is why they tend to form around the electrodes themselves, hence Langmuir's justification for calling the 'sheaths'.
- A double layer in the chromosphere of the Sun may be a contributor to the solar flare particle acceleration mechanism. I actually have no problem with this. It is an consequence of the Pannekoek-Rosseland field. As mentioned in my analysis, this field has been known, but largely forgotten by the wider community, since the 1920s. (see R. Wildt, “Note on stellar ionization and electric fields”. MNRAS 97. 225-231 (1937). http://adsabs.harvard.edu/abs/1937MNRAS..97..225W or J Vranjes and M Y Tanaka. “On Gravity Induced Electric Field in Space Plasmas”. Phys. Scr. 71 325-328 (2005). http://dx.doi.org/10.1238/Physica.Regular.071a00325 )
- Structures in planetary nebulae as possible double layers. During this part, he seemed to paraphrase the statement in my analysis “It Looks like ‘X’ so it must be ‘X’”
- Alfven's galaxy model
- Peratt's galaxy model
- Galaxies along filamentary structures
- Pulsars as relaxation oscillators: Dr. Scott claims that these oscillators exhibit the same high period stability as pulsars. Pulsar fractional period variations have values on the order of 1e-14 to 1e-16, more stable than atomic clocks! Is Dr. Scott claiming this kind of precision for commercially available relaxation oscillators?? (http://en.wikipedia.org/wiki/Relaxation_oscillator)
- The problem with the decay of free neutrons and the nuclear 'line of stability'. He tries to refute the rebuttal that this is held together by pressure but doesn't seem to recognize that a 1.4 solar mass sphere of neutronium is at a lower energy state than the same mass sphere of protons or nuclei and free electrons. Once the pressure is sufficiently high, as is the case with several solar masses of matter 'above' it, this fact favors formation of the neutronium.
I decided to ask about the Peratt galaxy model. My question consisted of two parts:
- What powers the currents which form the galaxies? His comment from the earlier question suggested that they had no idea where these currents could come from. Yet isn't that as big, perhaps even a larger mystery than 'Dark Matter'? Which is simpler, perhaps a particle which interacts so weakly that our technology can't currently detect it, or gigantic, invisible EMF generators floating around in the cosmos. I can't recall getting a definitive response on this as Dr. Scott's responses began to lead into question 2.
- Around 1990, Peratt began to examine the production of synchrotron radiation by these currents, in a attempt to see if a background created by them could explain the cosmic microwave background radiation (CMB) observed. (Note that we did not have an all-sky microwave map from COBE until 1993, and it had fairly low angular resolution.) He obtained numbers that could produce fluxes on the order of the CMB but this also implied we should see the current streams from nearer spiral galaxies (such as M31 and M33) clearly overlaid over the more distant background in the CMB maps, especially the higher resolution WMAP data. Some aspects of the paper also suggest Peratt's model would require much larger fluctuations in the CMB than measured by COBE. Peratt's model suggests streams on the order of 350 megaparsecs in length. For nearby galaxies, we should see these stretched across the sky. We don't see this at all, which suggests these galactic scale Birkeland currents do not exist. One member of the audience suggested this might be due to 'beaming' of the emission as in pulsars. However, in pulsars, the particle motions are believed to be highly-relativistic which beams the emission (energies in millions of electron volts). Peratt's electrons streams are non-relativistic, about 30 kiloelectron volts. Dr. Scott asked if I didn't believe Birkeland currents were real. My response was that we've clearly identified them in Earth's magnetosphere and even some of the systems which energize them with particles, it was galactic-scale currents capable of forming galaxies that is not supported by the observations.
After some 'splinter group' discussions, one of the colloquium organizers suggested I introduce myself to Dr. Scott. We had some discussions covering topics such as the detrimental effects of 'big science' and funding pressures on innovative research. We also had some 'shop talk' complaints about the multitude of units (esu, emu, mks) used in the electrodynamics community. Dr. Scott signed my copy of “The Electric Sky”, we shook hands and agreed to be “friendly enemies”. He also mentioned that his rebuttal to my analysis would soon be online.
The next day, one of the engineering colloquium organizers relayed a message that Dr. Scott wanted me to know that “he didn't hate me.”
I invite others in attendance at this colloquium to leave comments, Dr. Scott as well.
(Editing note: Opps! Had the year wrong in the opening date.)
Update: 1/28/2014: fixed broken link.