Sunday, May 27, 2012

Electric Universe: Peer Review Exercise 3

This is the third of five posts devoted to providing a more professional peer-review of the "Special Issue" of the Bentham Open Astronomy Journal (BOAJ) devoted to Plasma Cosmology and Electric Universe (PC/EU).  While BOAJ claims to be a peer-reviewed journal, we'll see in the upcoming posts that the quality of the peer-review process for this issue was very questionable.  Each of the articles exposed in these reviews exhibit many fundamental errors in physics (especially electromagnetism) and astronomy.  Many of the unchallenged mistakes are at levels which could be identified by an undergraduate physics student or possibly even a competent EE undergraduate.

Review report by W.T. Bridgman and Nereid.
Quotes from the article discussed are in blue.

Article Reviewed:
Electric Currents Key to Magnetic Phenomena

Donald E. Scott

What is the point of equation 3?  It is not used anywhere in the paper.
"Magnetic fields that obey equation (1) cannot exist in the absence of the current density, J, which is their cause." 
This equation can also be true if J is zero and dE/dt is non-zero, yet Scott ignores this case, which is strange considering Scott mentions the term, but not its implications. 

Maxwell added the dE/dt term to Ampere's Law to solve a problem in configurations such as capacitors.  It is sometimes called the "displacement current" (wikipedia), but does not correspond to an actual charge flow.  This case is vital for the propagation of electromagnetic waves, where electric and magnetic fields repeatedly regenerate each other, far from their original source.  This process continues to operate even after the original current source (antenna) is turned off!  While some type of current may be required to get the field started, there are configurations where a changing magnetic field can be maintained via this term, long after the original current is gone.  We can examine the interaction of electromagnetic waves with matter independent of the original source of the electromagnetic wave.  See additional references:
Dr. Scott repeats this error
"Magnetic fields are created by and moved around by electric currents – nothing else."
This is a strange oversight for an electrical engineer to make.  Even odder is this is NOT the first time Dr. Scott has made such wrong statements about Maxwell's equations (see Scott Rebuttal. IV. 'Open' magnetic field lines).

Apparently he did not check any of this with anyone with any actual expertise in using Maxwell's equations at a more fundamental level.  This is made more annoying by the fact that Dr. Scott's fundamental thesis is accusing others of not understanding Maxwell's equations!
"There are no bar magnets in space." 
Planetary dipoles can be treated as bar magnets if the time scale is small compared to the intrinsic variation of the field.  Even bar magnets are not permanent on sufficiently long time scales at temperatures above absolute zero.

III.  Enigmatic Plasma motions.
In Scott's description of magnetic reconnection, he totally ignores the role of the plasma itself in the electromagnetic field.  The field is created by charged particle motion (ions & electrons).  But the field influences the motion of the charges via the Lorentz force.  This causes the particle distribution to change, which drives changes in the electric & magnetic fields (a feedback mechanism).  Dr. Scott made this same error in "The Electric Sky" and has failed to correct it  ("The Electric Sky - Short Circuited" 2008 Draft, pg 36-37).

Dr. Scott's complaints about descriptions of magnetic fields are from popularizations??  Apart from the Parker reference in Physics Today, all of Scott's complaints are from popularizations.  Scott concludes his (brief) criticism of Parker's paper like this:
"In light of the previous example, we offer a possible explanatory mechanism in Fig. (3), below." 
This is the same "possible explanatory mechanism" he presents in his book. In the years since, he has apparently done nothing to develop it, or to test it.

However, what Scott ignores is that if a conducting fluid (or solid, or gas) moves through a magnetic field, it generates an induced current which feeds back on the original field.  This force will also feedback on the conductor motion.  But if the conductor is getting energy from another source (thermal, hydrodynamic, etc.), this feedback loop can operate for a significant amount of time (i.e. a generator or dynamo action).

IV: Magnetically stored energy
Dr Scott never uses Equations 4-10 and they are not related to any measurable quantity of an EU model which Dr. Scott presents.  These equations are not used to derive any measurable quantity in the paper.  Are they only there for decoration?  What field energy is needed?  What is the current density or electric field measured in the configuration and how does it relate to an observed astrophysical quanity?

VI. Magnetic Fields that Reverse Polarity
Regardless of the direction of the main driving current coming into the Sun, the eleven-year reversal of the magnetic loops can be explained by transformer action as shown above.
Models of stellar dynamos do this (MSFC), where some initial magnetic field combined with conductive fluid motions driven by other energy sources (in the stellar case, thermal energy from nuclear reactions) set up a feedback mechanism that can maintain a reversing global magnetic field so long as there is enough energy to drive it (see Dynamo Models of the Solar Cycle).  These models are being run on commercial-grade desktop computing equipment giving actual numerical predictions we can compare to measurements (see a data-driven visualization of a solar dynamo model).  Where is the EU equivalent?

Dr. Scott's model suggests the solar cycle is not driven by processes inside the Sun, but by external processes driven by a mechanism which he does not define. 

How are these external processes setup?  
Do they form naturally?  If so, how?  

Dr. Scott's model merely moves the problem to be solved from inside the Sun to some ill-defined location and mechanism outside the Sun.  How does this improve the situation?

Nor is there any mention of the origin or driving energy of this external current. 
using the joint European Space Agency (ESA)/NASA Solar and Heliospheric Observatory (SOHO) spacecraft, they had discovered ‘jet streams’ or what they called ‘rivers of hot, electrically charged gas’ (plasma) flowing beneath the surface of the Sun. They also found features similar to trade winds that transport this ‘gas’ below the Sun's surface. Flows of electric charges such as these are, by definition, electric currents.
Because the definition of plasma is neutral or 'quasi-neutral', not all plasma flows qualify as electric currents.

I find no mention of usual EU claim that Sun's energy comes from external electric current, though figure 3 implies it.
Note: Comments that DIRECTLY address the points in THIS post are favored.  Since there will be a post on each of the five papers in the EU 'Special Issue', comments more relevant to one of those other papers should await that specific post.

Sunday, May 20, 2012

Electric Universe: Peer Review Exercise 2

This is the second of five posts devoted to providing a more professional peer-review of the "Special Issue" of the Bentham Open Astronomy Journal (BOAJ) devoted to Plasma Cosmology and Electric Universe (PC/EU).  While BOAJ claims to be a peer-reviewed journal, we'll see in the upcoming posts that the quality of the peer-review process for this issue was very questionable.  Each of the articles exposed in these reviews exhibit many fundamental errors in physics (especially electromagnetism) and astronomy.  Many of the unchallenged mistakes are at levels which could be identified by an undergraduate physics student or possibly even a competent EE undergraduate.

Review report by W.T. Bridgman and Nereid.

Quotes from the article discussed are in blue

Article Reviewed:
On Gravity-centric Cosmology and the Implications of a Universe Awash with Plasma
by David B. Smith
"It is a fact that major "theories" of popular cosmology and its Standard Model have not been tested because they cannot be"
This statement has been repeatedly demonstrated as false.  The solution to many cosmic-scale problems often provided solutions that were subsequently demonstrated in earth-based experiments (Astronomy as an 'Unprovable' science, The Cosmos in Your Pocket).  By Smith's standard, in 1956 there was no laboratory evidence that you could launch a satellite into orbit.  Those who designed the launch trajectory used the same gravitational theory they used to predict planet locations with no other evidence than its success in predicting planetary trajectories.
"they are not plasma scientists and they often have only limited training in electrical engineering principles."
Actually, a number of astronomers have a very good understanding of electrical engineering.  They must often build their own instruments from scratch.  In the 1700s, they built their own telescopes.  In the 1800s they built their own spectroscopes.  CCDs were being wired up to telescopes for astronomy in 1976, long before digital cameras were generally available (link).  Today, a surprising number of astronomers are in shops with hands-on participation in the design and construction of new instruments which must fly on satellites.

I have yet to find even one of the EU 'theorists' who has used their data, or theories - or anyone else's data or theories - to build or manage satellites or instruments in space.  EU 'theorists' have demonstrated no competence in space science.

Electrical engineering principles do not violate known laws of physics - such as conservation of charge, conservation of energy and Maxwell's equations.  Examination of EU models reveal that they violate these principles routinely.
"The gravity-centric theories offered as explanations for the mysteries we observe in the universe and which underpin the Standard Model cannot be tested experimentally, though computer simulations flourish. On the other hand, plasma cosmology is based on sound plasma physics as developed in the laboratory and much of which has been tested both with experiments and in advanced plasma-based computer simulations. Due to better scientific capabilities and understanding today, a solid body of evidence supports credible alternative explanations for what we observe in space. This requires us to reconsider our assumptions."
Full-scale plasma simulations (plasma modeling) do not support Electric Universe claims.  Yet cosmic phenomena can give clues to other processes that CAN be tested in the laboratory and have.
"Cosmos in your Pocket."
"confirmation of ubiquitous magnetic fields throughout the cosmos has forced theorists to acknowledge their existence, yet they still largely ignore the electric currents which must be associated with these fields." 
False.  Electric and magnetic fields, and even currents, have been known in astronomy as far back as the early 1900s.  I have documented many of these facts.

2.3 The Cosmic Microwave Background 
"One of the problems with CMB theory is that IF it is the most distant thing we can see, (a remnant of the Big Bang) then we should observe the silhouettes of galaxy clusters and other major cosmic structures imposed on this image, which we do not [5]"
Correlation tests generate some disagreement due to the assumed simple gas profile of foreground galaxies in tests.  The effect is seen in WMAP, but at a level much less than expected from cluster models and X-ray data. Lieu et al (2006) used an isothermal temperature profile which is way too simple a model for what we know about gas temperature profiles in galaxy clusters.  The issue was followed up in Komatsu et al (2011) and then again by Lieu et al (2010).  In the followup, they conclude that a large part of the deficiency is due to a non-thermal process, in this case inverse-comptonization, redistributing some of the flux into the ultraviolet.  Among their conclusions is "For nonthermally, active clusters the anomaly does not impact negatively on the cosmological origin of the CMB."

Where is the skymap showing the electromagnetic emission (radio and microwaves) of all the current streams needed to power the stars and galaxies in the Electric Universe model?
"Radio astronomy data now reveals that what astronomers call CMB radiation from the far edge of the visible universe, is actually likely to be electromagnetic noise occurring in our own cosmic neighborhood."
However, radio astronomy data reveals that the CMB cannot be local - indeed it must be distant - because the expected number of 'point sources' (i.e. distant galaxies and quasars) are seen, by WMAP (e.g. Bennett et al. 2003), Wright et al. 2008). This would be impossible if the CMB were foreground to these point sources. Further, the two sources Smith cites - [6, 7] - clearly acknowledge that their proposed "local 'radio fog'" does not have the same distribution of energy, by wavelength, as the observed CMB.

2.4. Redshift = Recessional Velocity
"Another example (Fig. 2) shows a highly redshifted quasar which is observed to be in front of low redshift and visually opaque galaxy NGC 7319 [12]"
If you are considering galaxies with larger redshifts 'in front of' lower-redshift galaxies, take a close look at this Hubble Image
Full ACS Field of NGC 1309
and answer these questions:
  • Are the tiny spiral galaxies in this image tiny foreground galaxies, or distant background galaxies?
  • How do you tell?  What is the mechanism to objectively make the distinction?
More info at Halton Arp's Discordant Redshifts.

The only way a galaxy or star cluster can be opaque is if the stars are so crowded their disks overlap to a distance observer, or there is sufficiently thick dust to obscure the starlight.  Dust is very good at attenuating starlight (but not x-rays or radio), so dust-choked regions of a galaxy can be nearly opaque. They certainly produce reddening. So star-burst galaxies, star-forming regions, and the nuclei of classical spirals (i.e. not lenticulars) are often - but not always! - good for dimming background objects.

Consider this image of NGC 6752.  The center looks opaque.  But take a look at higher resolution with Hubble and you see the gaps between the stars.  In many cases, the stars exhibit larger sizes and overlap in images due to a combination of diffraction effects and light being scattered in film or CCD pixels.

Also note that we are in the galactic disk of our own Milky Way galaxy.  If the galactic disk were opaque, we would not be able to see out to the distant cosmos.  Note that some of Smith's compatriots in Australia have been able to successfully observe a galaxy that is seen through the plane of our own galaxy (Circinus Galaxy).

Section 2.9. Thermonuclear Theory of Stars

Quoting C.E.R. Bruce:
""[The Sun's] photosphere has the appearance, the temperature and the spectrum of an electric arc;"
Again, evidence based on 'looks like' or pareidolia (Wikipedia). But the relevant physical questions are:
Solar spectrum from NOAO
  • Where is the electric arc spectrum that looks like the solar spectrum?  I've yet to find an electric arc spectrum that has the same spectral lines and intensities as the solar spectrum (see image).
  • What is the configuration of the arc-generator (volts, amps, gas composition, etc.) that generates the matching spectrum?
Without these details, the claim is indistinguishable from being made-up.

Mr. Smith repeats the common EU claim of an external power source for Sun, yet provides no prediction of the particle flux and energy which has been examined (see My test of one of EUs solar models).  A satellite engineer who read Scott's "The Electric Sky" pointed out that if these fluxes actually existed, they would kill satellites and astronauts.  Satellite engineering requires accurate understanding of the space plasma environment.

This claim also touches on many of the exact same claims as in "The Electric Sky", etc.  Yet nowhere does it provide testable solutions to their own problems
  • Where does the energy come from to drive the charge separation that generates electric fields?
  • What maintains the currents?
  • How do z-pinches with cylindrical symmetry produced spherical, or oblate spheroid stars?  One would expect stars to be prolate spheroids if the electric force was so much stronger than gravitational or inertial forces.
EU solar models fail on very fundamental laboratory physics - as basic as conservation of energy and conservation of particles (since by definition they rule out major contribution from nuclear reactions).

Section 2.10 Neutron Stars and Pulsars
- Claims that neutron stars cannot exist because
"Experiments show that neutrons cannot stay together and remain stable, and we know that individually they will decay into a proton and an electron within 15 minutes."
Yet multiple neutrons exist in nuclei and are stable.  Why is that?  The mechanism of the Fermi level works for nuclei and neutron stars.  Neutrons in a neutron star are not 'free', they are bound by gravity.

2.11 Comets as dirty snowballs
"Their surfaces display sharp relief, not what one would expect from melting ice, " 
Nonsense.  Has Mr. Smith ever actually observed melting snow and shapes that form due to non-uniform heating and melting?  I shoveled plenty of dirty snow for Snowmageddon & Snowpocalypse and enjoyed the many odd shapes formed as it melted and refroze with the day-night cycle.

The ambiguity between comets & asteroids has been known before Thornhill & Talbott
Some of these papers point out even earlier sources. 
"that there would be a double 'flash' consisting of a powerful electric discharge event prior to a very large impact event which would be more explosive than expected, and that radio communication would be interrupted." 
Only very weak x-ray enhancement was detected from this event so claims the impact produced an electric discharge are suspect.  Emissions were delayed and consistent with charge exchange between the solar wind and outgassed simple molecules.
Where is the reference of the double flash before the impact and radio interruption?

"The spacecraft did find the first evidence of surface ice on the surface of a comet instead of just inside a comet."
Temple 1 is an inner solar system comet that has lost a large fraction of its volatiles due to more time spent near the Sun.  A lower fraction of volatiles for such objects is not unreasonable.

Section 3.4-3.5
Fig. (16). PIC galaxy simulation, simplified and colored. No dark matter required.
The model just requires a current stream (a "Dark Current"?) that is somehow undetectable?  That these currents always emit at some wavelength, usually radio or microwave, is the reason "dark current" is a archaic term no longer used in modern plasma studies.  We have instruments that can detect this type of emission. 

Peratt's own predictions to build the Cosmic Microwave Background with these filaments failed totally with COBE and even more so with WMAP.  The PIC technique for plasma simulations are well known and many PIC simulations demonstrate how EU claims do not work. 

Section 3.6
"In a gravity-only environment there is no plausible mechanism for creating such jets and the powerful magnetic fields and radiation as intense as is seen here."
False.  (see Electric Universe: Measurement of the Electric Current in a Kpc-Scale Jet).

Section 3.7: Supernovae and Nebulae
"It is not yet understood why supernovae in faint galaxies should fade faster (relatively) than those in bright galaxies."
Where is the reference for this, or is this a misstatement of the phenomenon noted here: Estimating Distances to Far-away Galaxies, that "slow faders are bright, quick faders are faint".  These refer to the SN themselves, not the galaxies they are in.
"If supernovae are the result of a gravitationally bound object exploding into a vacuum, they should be spherically symmetrical." 
False. Not if the stars are rotating in which case you expect an oblate spheroid with more cylindrical symmetry.

SN 1987A produced the neutrino flux expected for an SN at the mass and distance of SN 1987:
So the relevant questions for EU are
  • How does a z-pinch produce a neutrino flux?  By what reaction path?  What experiment verifies this?
  • Based on the proposed EU model, what is the neutrino flux for the current EU postulates for SN 1987A?
3.8 Earth Lightning and Weather
"The hexagonal 'storm' on Saturn's north pole shown in Fig. (20) is also very difficult to explain under any theory, but at least we do observe hexagonal morphology in relation to plasma discharges."
The web article is Saturn's Strange Hexagon Recreated in the Lab.  Note Gmirkin's 'rebuttal' in the comments, but the many of his arguments apply to the EU 'explanation' as well.  EU seems to only invoke the superiority of laboratory experiments when it suits them.  Here are the original papers: 
and a follow-up demonstrating a similar result in simulations

Most of EU's 'successes' come from regions where astronomers have suspected electric fields at play for decades before the EU crowd got involved (such as the work by many magnetospheric missions such as THEMIS, etc.).  See 365 Days of Astronomy podcast (and more details at 365 Days of Astronomy: The Electric Universe).    By not citing the long history of earlier work, it appears EU advocates are trying to steal credit for the work of these earlier researchers.

Where is a reference to a PIC or similar plasma simulation (other than Peratt discussed above) that matches an EU prediction NOT already covered in areas where astronomers have known about electric fields for years?  A successful PIC simulation of the Electric Sun model would fit this requirement.

While standard cosmology openly discusses the areas still under research (Dark Matter, Dark Energy) EU is suspiciously silent on the far more serious deficiencies in their own allegedly superior alternatives:
  • No synchrotron radiation from current streams, either for Peratt galaxy model or for powering stars.  How is a 'Dark Current' with properties that make it undetectable (not verified in the laboratory), better than Dark Matter which is being actively sought?
  • Where are the generators for these cosmic currents?
  • What is the energy source for these cosmic generators?
  • Where did these cosmic scale electric generators come from?  Aliens?  A deity?  Natural formation?  How?
  • While electromagnetism is stronger, it is also attractive and repulsive while gravity is only attractive.  Large accumulations of like charges blow apart due to mutual repulsion.  How can large charge accumulations form in the first place without some external energy source?  Where does that energy source come from?
EU proposes to replace something as simple as a difficult to detect particle (dark matter) with a set of cosmic-scale electric generators.  How is this a simpler solution?  Without an answer to these questions, EU begins to have more in common with a perpetual motion machine!

Note: Comments that DIRECTLY address the points in THIS post are favored.  Since there will be a post on each of the five papers in the EU 'Special Issue', comments more relevant to one of those other papers should await that specific post.

Sunday, May 13, 2012

Electric Universe: Peer-Review Exercise 1

This is the first of five posts devoted to providing a more professional peer-review of the "Special Issue" of the Bentham Open Astronomy Journal (BOAJ) devoted to Plasma Cosmology and Electric Universe (PC/EU).  While BOAJ claims to be a peer-reviewed journal, we'll see in the upcoming posts that the quality of the peer-review process for this issue was very questionable.  Each of the articles exposed in these reviews exhibit many fundamental errors in physics (especially electromagnetism) and astronomy.  Many of the unchallenged mistakes are at levels which could be identified by an undergraduate physics student or possibly even a competent EE undergraduate.

Review report by W.T. Bridgman and Nereid.

Quotes from the article discussed are in blue.
Article Reviewed:
Editorial: Some Initial Thoughts on Plasma Cosmology
by Jeremy Dunning-Davies

The claim that astronomers ignore plasmas and electric effects has been repeatedly documented as false (see 365 Days of Astronomy: The Electric Universe).  Of all Electric Universe (EU) claimed 'successes' for electric fields in space, I have yet to find a single one whose history can actually be traced to an origin among EU supporters.  In my research, I've even been surprised that some things I thought had originated with legitimate researchers, such as Hannes Alfvén, were, in fact, analyzed in far more detail by others before Alfvén (see Electric Universe: Measurement of the Electric Current in a Kpc-Scale Jet).  Perhaps the only legitimate researcher that could be claimed an EU supporter might be Birkeland, perhaps if his original motivation had been inspired by the writings of George Warder (Wikipedia). 
"the electric universe ideas are supported by much computer modeling".
This statement suggests that the upcoming articles will provide real details of this claim.  However, what we'll find is the same reliance on the Peratt galaxy model - and nothing else.  The Peratt model has failed enough tests that even Peratt has done no development on it in over ten years (see Scott Rebuttal. II. The Peratt Galaxy Model vs. the Cosmic Microwave Background)

In fact, beyond the Peratt model and these five BOAJ articles, I have yet to find a single quantitative model, computer or otherwise, that can be tied back to an original idea by EU supporters.  The great majority of models which EU supporters try to claim as theirs can be traced back to the history of electric fields in astronomy, such as those documented above.

The statement also conveniently ignores the far larger body EU ideas which are NOT supported by computer modeling.  The only 'supported' models fit a few observations, but fail on more critical observations (such as the Peratt model).  I have summarized some of these failures in Challenges for Electric Universe 'Theorists'.

"... a great many laboratory experiments being performed to help establish plasma properties [4]"
Indeed they have. What Dunning-Davies conveniently (and cynically?) ignores is the fact that a huge number of such experiments have been performed - and their results published - since 1992, when Peratt published his book ([4] is Peratt's book). To take just one example, the report from this 2010 Workshop on Opportunities in Plasma Astrophysics referenced dozens of laboratory experiments and published quantitative, plasma physics-based, models describing astronomical phenomena.

None of the Electric Universe evidence presented by Thornhill, Scott, and Smith is based on models that generate quantitative predictions, predicting the measured flux of photons or neutrinos, or the spectral lines shifts due to magnetic fields, as is done in regular astrophysics.  We have never seen substantive quantitative predictions from EU 'theorists' or supporters.   

"the Hubble image of the planetary nebula NGC6751 looks remarkably like the view down the barrel of a plasma focus device"
EU 'evidence' relies on  the 'look' of the object to the human eye and brain giving their evidence more in common with pareidolia (Wikipedia) than any objective standard.   The obvious related physical question is 'where is the evidence for the generator and supporting hardware needed to drive such a plasma focus device?'  Are we to believe that these devices form naturally?  If so, how? Perhaps they were built by a gigantic alien species?  But we'll never get a viable answer from EU advocates.  This EU claimed 'solution' does nothing but generate more questions, questions which should be able to answered easily, directly from a quantitative description of such devices.

Dunning-Davies claims that neutrinos:
"respond only weakly to massive objects such as stars and galaxies but form an extended atmosphere which, for example, refracts light around the Sun from distant stars and this offers an alternative explanation for the so-called gravitational bending of light" 
yet provides no reference and certainly no experimental evidence for this process.  This mechanism is also in contradiction to Thornhill's claim about Dark Matter (Thornhill, BOAJ 2011, v4, pg 193).

Dunning-Davies mentions Tony Peratt's simulations, but does not mention the inability to detect the synchrotron radiation expected from Peratt's currents, predicted by Peratt himself (see Scott Rebuttal. II. The Peratt Galaxy Model vs. the Cosmic Microwave Background).
"the whole purpose of this collection of articles is to draw the attention of a wider audience to the possible importance of electromagnetic effects in cosmology."
As will be pointed out in coming reviews, these articles are so riddled with fundamental errors in astronomy, electromagnetism, and plasma physics, that their net effect will more likely be damaging to the existing REAL work in electromagnetic effects in the cosmos.

Note: Comments that DIRECTLY address the points in THIS post are favored.  Since there will be a post on each of the five papers in the EU 'Special Issue', comments more relevant to one of those other papers should await that specific post.

Sunday, May 6, 2012

Electric Sun: Another Problem with Heliospheric "Drift Currents"

I've pointed out a number of fundamental flaws in various 'electric sun' models based on very fundamental considerations of conservation of energy and particles (Electric Cosmos: The Solar Capacitor Model. I). 

One of the popular excuses Electric Universe (EU) 'theorists' presents in an attempt to circumvent these issues is invoking some population of low-energy electrons ("Drift electrons") that allegedly solve the energy transport problem.  This electron population also somehow manages to be totally undetectable by in situ instruments (see Electric Cosmos: The Solar Capacitor Model. III).

In this post, I'll explore another implication of a high electron density in space.  This property is utilized in a wide variety of science and technologies.

Irving Langmuir explored waves in plasmas (see Oscillations in Ionized Gases) back in the late 1920s and defined a quantity called the plasma frequency (see also wikipedia: Plasma waves & Waves in Plasmas).  When electrons in a quasi-neutral plasma are displaced from a strictly neutral configuration, an electric field is setup by the displacement that creates a restoring force.  This force pulls the electrons back to a more neutral configuration with the ions.  The electrons are easier to displace in this configuration because they are much lighter than the ions.  By the time the electrons are pulled back so the net density is zero, they have sufficient speed to overshoot the neutral configuration.  This process repeats if the electrons don't loose too much energy in the process through collisions with ions and other electrons, and this is an oscillation.  It's simple to show that the natural oscillation for a given electron density is

This plasma frequency also influences how electromagnetic wave propagates through a plasma.  Electromagnetic waves with frequencies below the plasma frequency are strongly absorbed by the plasma.  If the wave propagates at an angle that is not perpendicular to the plasma interface, the waves can also be reflected or refracted.   Frequencies above the plasma frequency can propagate through the plasma, but can be subjected to attenuation and dispersion - which changes their amplitude and speed as they propagate through the plasma.

Here we plot the plasma frequency of electrons (solid black line) and the plasma frequency of protons (dashed black line) in frequency and particle density space, marking the region in (density, frequency) space where electromagnetic waves cannot propagate.  I've also marked the electron density range corresponding to the Earth's ionosphere (10^4 - 10^6 electrons/cm^3). 

There is an important caveat to the graphic.  The no-propagation region applies to waves penetrating a plasma occupying a region very large compared to the wavelength of the electromagnetic waves.  Since the plasma actually attenuates the wave, it can propagate a distance into it.  This means that very low frequency (very long wavelength) radio waves can penetrate the ionosphere when the wavelength is large compared to the thickness of the plasma region.

From this plot, we see that electromagnetic waves with frequencies less than about 10 megahertz cannot propagate through the ionosphere without significant distortion.  These lower frequency ranges are historically known as the short-wave radio band (wikipedia) (covering 1,800kHz - 30Mhz), and the AM broadcasting band (wikipedia).  Due to ionospheric refraction, electromagnetic waves in the lower end of this frequency range can propagate long distances around the Earth by 'bouncing' off the ionosphere.

For radiowaves to reliably propagate through the ionosphere, as one needs for space travel, higher frequencies are needed.  The very first satellite, Sputnik 1 (wikipedia), broadcasted at 20MHz, just a little above the plasma frequency for the ionospheric electron density.  Modern satellite communication uses the Ku band (12-18GHz) (wikipedia), in the microwave frequency range.  These waves run into problems propagating through plasmas with densities higher than about 10^11 electrons/cm^3.

We see from the plot, that the fact that satellites in space can communicate at these frequencies places a firm upper limit on any possible population of 'drift electrons' in the solar system.  To continue this bogus claim of drift electrons, EU 'theorists' must deny much of the laboratory evidence  on which they hang their claims.

Some EU 'theorists' might try to argue that this effect does not apply in a neutral plasma.  Yet a neutral plasma has been where this phenomena has been theoretically analyzed and tested experimentally.  The only time it doesn't apply is if the ions and electrons are bound (which means it is at best a regular neutral atomic/molecular gas and no longer a plasma) and the electric field of the electromagnetic waves is not strong enough to ionize the atoms.  In a plasma, electromagnetic waves will act on electrons & ions relatively independently, and the charged particles will move in opposite directions in response to an electric field of the wave.  With  ions over 1800 times more massive than electrons, they accelerate in the electric field much more slowly.  The net effect is that the electrons move in response to the field while the ions remain largely at rest.

In an upcoming post, I'll explore some other implications of the plasma frequency.  One of the applications is that it can be used to analyze the electron density in regions.  This effect has been used to probe the electron density of the solar corona and is regularly analyzed in GPS signals for computing the signal time delay when propagating through the ionosphere.

Tuesday, May 1, 2012

The USA Science & Engineering Festival DC (2012)

I did not originally have plans to write up on my visit to the USA Science & Engineering Festival, but there was so much cool stuff that I was feeling particularly inspired.  Maybe it will help me get back into blog-writing after some of the heavy load from work and home in recent weeks.

The event was held in the Washington DC convention Center in downtown DC.  This was the first time I'd ever been to an event at this venue - apparently the last time I was in this area of DC, it was still under construction with nothing but a giant hole in the ground.
A view of the showroom floor.
The exhibit floor was huge.  One of the vendors even had a small jet aircraft on the showroom floor.  Markings on the plane indicated it was from the Air Force Thunderbirds squadron (wikipedia).

When we first arrived (about 11AM), there was already a very long line for something which turned out to be a line to get signatures from one of the special guests, Bill Nye (wikipedia).

There were loads of displays covering robots and robotics, technology, physics, astronomy, chemistry, mathematics biology, medicine, even the social sciences.  Many of the displays encouraged visitor participation, with things like people running through (on?) a tub of a non-newtonian fluid (wikipedia) and angular momentum demonstrations with bike tires and rotating platforms.  Various space and automotive technologies were displayed, virtual reality simulators covering everything from flying helicopters to Daedelus-style personal flying.

Since my own Ph.D. was in nuclear astrophysics, I had to check out the very cool exercise sponsored by the Facility for Rare Isotope Beams at the University of Michigan, (link) where they were simulating nuclear reactions using nuclei built of colored magnetized ball-bearings.  They would assemble a 'nucleus' with these parts (I had carbon-12), then use gravity and a tube to guide your 'nucleus' to collide with another in a plastic tub.  They'd collect the fragments and identify what components came out.  This group is apparently responsible for the Rare Isotope Rap (YouTube). There was also an intriguing nuclei card game (link) nearby at the booth of the Joint Institute for Nuclear Astrophysics.

There was also a vendor that builds those fantastic wind turbine systems.  I asked one of the spokespersons for the company an engineering question - these turbine systems are so large and act like gyroscopes, I wondered if they dealt with the torque created on the system due to the Earth's rotation.  The spokesperson was kind of surprised by the question, speculated that the effect might be small, but I'm not so sure.  It is possible that the forces created by small changes in wind direction might totally overpower the effect, but over time the load might show up as uneven wearing on some of the components.  They say they will certainly ask some engineers when they returned to their offices.

In addition, a number of other science 'celebrities' were in attendance.  The Mythbusters (link) presentation attracted such a crowd that it created quite a bottleneck in the middle of the showroom. 
Jamie Hyneman is barely visible on the big screen
We skipped that one since we'd seen Adam & Jamie the previous month when they were on tour (link).  Mayim Bialik (of "Big Bang Theory", wikipedia) gave a very well attended talk about her life from acting to science and back to acting.
Mayim Bialik speaks to her fans
The NASA section was significant, but far from the largest section of the showroom floor.  Many current and planned missions had booths there.  I got to meet Camilla, the SDO mascot (blogspot), only weeks after her recent trip into space (NASA).

I also got to meet Pamela Gay of AstronomyCast, 365 Days of Astronomy, and StarStryder, promoting a new citizen science project, CosmoQuest.  We had met at DragonCon in 2009 but we've only casually crossed paths at an AAS meeting since then.

I ran into a number of others whom I knew from other professional meetings.  I even got to 'fly' a portable planetarium show.

By 5PM, we were approaching exhaustion, so we enjoyed a dinner at  local seafood restaurant and headed home. 

A wonderful event and I hope they can continue doing it.  It would be even better if they could expand these events around the nation.  They didn't have stuff like this available when I was growing up in a small farm town.

Credits: All of the photos here were taken by myself or my wife.