Tuesday, December 4, 2012

On Martian Spiders, Ice Spiders, the Namibian Desert and Remaining Open-Minded.

"The essence of the Liberal outlook lies not in what opinions are held, but in how they are held: instead of being held dogmatically, they are held tentatively, and with a consciousness that new evidence may at any moment lead to their abandonment. This is the way opinions are held in science ..."
http://en.wikiquote.org/wiki/Bertrand_Russell#Chapter_1:_Philosophy_and_Politics
http://tinyurl.com/cm3fnpp
These words ring as true today as when they were originally penned by philosopher Bertrand Russell circa 1950. 

It is incumbent upon scientists of all caliber to hold ideas tentatively rather than dogmatically. When new evidence comes to light, it is incumbent upon the scientist to evaluate the new information to the best of their ability and, where necessary, discard or re-evaluate those ideas upon which the new information may have bearing.

A good scientist must remain open-minded toward new ideas and remain willing to have his outlook changed, should new evidence require it. This may include strengthening one's opinion that an idea is correct or, alternately, certainty may fall by the wayside as plausible alternative explanations come to light.

It is such an alternative line of inquiry that shall be brought up in this entry (though no definitive answers are yet to be had), with respect to the geological features native to the south pole of the planet Mars, affectionately nicknamed "Martian spiders."


A number of hypotheses have been forwarded over the last decade with respect to how they form, including analogies with living systems such as plants (due to similarity to Fibonacci branching seen therein) or Banyan trees (courtesy of speculation by Sir Arthur C. Clarke). Though many such thoughts have not been borne out by more detailed observations.

The current model in vogue in astrogeology circles seems to involve the notion of icy geysers, despite the fact that no such geyser has ever actually been itself observed. Granted, such a geyser would likely be composed of gases and dust too fine to resolve from orbit, even with the wonderful HiRISE (High Resolution Imaging Science Experiment) instrument. But, that hasn't stopped conceptual artists from running with the fanciful ball:

Artist's impression of hypothetical geysers on Mars.


The notion behind "Martian geysers" is that a layer of solid frost forms over the surface during the Martian winter months. Then, during spring, solar heating causes the surface under the CO2 frost to heat up before the overlaying frost itself heats up, building pressure via sublimated CO2 until the surface frost cracks and a geyser of CO2 and surface material is ejected and blown about by the wind.

Early on, low resolution images were touted by some as being confirmatory images of geyser jets and their shadows:

Screen capture from a larger HiRISE image.

While it seemed convincing to some at first glance, even a cursory perusal of HiRISE images quickly disabuses one of such notions:

Zoomed in screen capture of the above region.

Extreme close-up version of the above region.

It becomes readily apparent that such features are, in point of fact, nothing more than v-shaped fans of surface material with dissimilar albedo (brightness, or the lack thereof) either defrosted or simply overlying the layer of frost. Possibly both, if dust from a small defrosted area were blown into a v-shape by the wind and proceeded to be warmed by insolation and thusly defrost the surface immediately below it.

There are, of course, problems with the 'geyser' model, and models of the 'Martian spiders' generally.

Why should such geysers create radial filamentary ravines? Why not just a large circular crater or some other form? Why are the 'Martian spiders' located only at the south pole of Mars and not formed equivalently at the north pole? Why are streaks and fans of material created in other regions without creating 'spider' formations in the surface materials? Why do the filamentary channels of the 'spiders' sometimes appear to flow uphill 'against gravity'? Why do the ravines sometimes appear to run along ridges or avoid depressions? There seem to be a number of anomalous features not well explained by most popular models.

A more radical suggestion has been offered by proponents of the Electric Universe hypothesis. [1][2][3] That is, that the aforementioned 'Martian spiders' may share something in common with electrically created Lichtenberg figures:


"Lichtenberg figures ... are branching electric discharges that sometimes appear on the surface or the interior of insulating materials. They are named after the German physicist Georg Christoph Lichtenberg, who originally discovered and studied them."
http://en.wikipedia.org/wiki/Lichtenberg_figure

"Lichtenberg figures may also appear on the skin of lightning strike victims. These are reddish, fernlike patterns that may persist for hours or days. ... A lightning strike can also create a large Lichtenberg Figure in grass surrounding the point struck. These are sometimes found on golf courses or in grassy meadows."
http://en.wikipedia.org/wiki/Lichtenberg_figure
As noted on Wikipedia, lightning has been responsible for creating many lovely Lichtenberg figures on golf courses and such:

Lightning strike to a golf course.

Lightning strike to another golf course.

Lightning strike(s) to yet another golf course.

In fact, compared one to the next, there is a certain undeniable similarity between 'Martian Spiders' and Lichtenberg figures:



'Martian spiders' and Lichtenberg figures both seem to display a fractal-like branching and self-similarity. The aforementioned self-similarity is visualized in this graphic from the Tesla Mania web site:


That said, a very similar fractal-like character can be seen in some river systems or dry features attributed to past river systems. Take for instance this feature in the Saudi Arabian desert, as compared to the above Lichtenberg figure:

Saudi Arabian desert vs. electrical Lichtenberg figure.


While it begs the chicken-vs.-egg question of "which came first the rivers or the riverbeds," that's a debate for another day.

We can go as far as to say that discharges on the surface of or internal to insulators are not unknown in the sciences. In fact, surface discharges are briefly covered in Anthony Peratt's textbook Physics of the Plasma Universe (recently reprinted by Springer-Verlag):

"4.6.1 Surface Discharges"

"Surface discharges are produced by large electric fields that develop between the surface and subsurface layers in a dielectric materials as a consequence of energetic charged-particle deposition. For example, when space craft dielectrics are exposed to bursts of kiloelectronvolt particles during magnetic substorms, the particles penetrate a few micrometers to a few millimeters, building up field strengths which may be of the order of hundreds of kilovolts per centimeter. A schematic representation of this is shown in figure 4.18."

"If the material is a conductor or a semiconductor, a conduction current will flow in response to the charge deposition and will effectively neutralize the field. If the material is an insulator, the space charge will build up at a rater faster than the local relaxation time, and the associated electric field will increase. When the field reaches a critical value that depends on the material, surface smoothness, and porosity, a surface discharge will occur. This is a problem that often occurs in laboratory pulsed-power and, in fact, is a limitting constraint on how much power can flow in laboratory transmission lines. Figure 4.19 illustrates the "[Lichtenberg] figures" recorded just below the surface of an acrylic transmission line spacer. Voltage breakdown at dielectric interfaces nearly always results in the formation of these dendritic-type streamers."

Figure 4.19. [Lichtenberg] figures recorded on the surface of an
acrylic insulator used in a terawatt pulsed-power generator.
"Surface discharges will also occur on natural dielectrics in the solar system when these surfaces are exposed to large fluxes of energetic particles. This condition can be found, for example, where magnetospheric currents interact with the surfaces of the giant planets and their satellites."
If one wishes to see the formation of a Lichtenberg figure in acrylic (an insulator), one need only watch the video from the folks over at Tesla Mania. It's almost mesmerizing watching all the secondary flashes after the main discharge, as pockets of internal charge redistribute themselves.

Returning to the subject at hand, it would seem that there are several ways that fractal-like, branching, filamentary features can be created.

In fact, another process capable of creating such features is known by the name of diffusion limited aggregation:
"Diffusion-limited aggregation (DLA) is the process whereby particles undergoing a random walk due to Brownian motion cluster together to form aggregates of such particles."

"The clusters formed in DLA processes are referred to as Brownian trees. These clusters are an example of a fractal."
http://en.wikipedia.org/wiki/Diffusion-limited_aggregation
Below is an image of a Brownian tree created in a computer simulation whereby a 'seed' is placed in the center of the 2D space and other 'particles' are allowed to 'randomly walk' until they move to a position adjacent to the 'seed,' or adjacent to another 'particle' connected to the 'seed' or subsequent branches at which point they stop moving and become part of the overall 'structure':

Diffusion limited aggregate with seed at center.

Clearly, it bears a not-insignificant visual resemblance to Lichtenberg figures and likewise to 'Martian spiders.'

Perhaps more germane to the discussion of the so-called 'Martian spiders' than the Saudi Arabian desert comparison (above) may be the desert region around Koes, Namibia:


Here we see a great many systems of dendritic channels converging on many central points. Not entirely dissimilar to the 'Martian spiders.' So, perhaps there *is* an Earthly analogue after all? It definitely bears further investigation... The standard description of these features is that they are drainage features.

When one zooms in on a 'Martian spider' one sees that it is typically a large mass of filamentary / dendritic channels pointing inward toward some central point (possibly a depression?):




However, there is at least one more method of creating filamentary, branching, fractal-like formations that bears further investigation. It's also native to our own planet, thus accessible for observation. But, I'm guessing not many astrogeologists moonlight as snow-shoers or cross-country skiers. So, they can be forgiven for never have heard terms like 'slush hole,' 'spider hole,' 'ice spider' and 'ice octopus.' But perhaps they should still get acquainted? If only to rule out one more interesting anecdotal candidate...

So, what are these features?
"As soon as it snows on top of ice, that creates a force pushing down on the floating ice.  All ice, including perfectly safe thick ice naturally cracks day and night, expanding and contracting with changing air temperatures.   When the ice cracks water can rush up through the crack on top of the ice but under the insulating snow, and form slush pockets.   These slush pockets can become very broad, sometimes covering entire lakes under the snow, and they are a hazard to travelers."
http://wintertrekking.com/safety/overflow-slush/

"Slush hole:  A hole created by water flowing up through an ice sheet, almost always as a sheet is being depressed by a snow fall. They are the are the formation phase of what become [octopus] patterns when they freeze."
http://lakeice.squarespace.com/glossary/

"[Octopi] are frozen patterns associated with water flow up through the ice and into an overlying layer of snow/slush."
http://lakeice.squarespace.com/glossary/
Put simply, a slush hole is a hole in lake or river ice through which water has welled up from below, usually due to snow over-burden pressing the ice sheet downward, creating a slushy spot. This can be a hazard for cross-country skiers, sledders, snow-shoers, hikers, etc.

A slush hole.
However, in addition to just creating a slush pocket, upwelling water can also infiltrate the snowpack, wicking up into and melting it.

A slush hole with long dendritic flow channels.
When the water melts the snowpack, it often does so in a dendritic pattern. It may also be that as snow melts it simply flows down hill toward the nearest low point and perhaps does so in rivulets that melt dendritic pathways. When it creates such dendritic patterns, it's termed a 'spider hole.' Here's a video showing one up close:


What can happen thereafter is that the meltwater refreezes and you end up with frozen channels in a dendritic pattern. In some cases, you can then also have deposition of additional snow or rain and some melting and/or refreezing. The end result are features typically called 'ice spiders,' 'ice octopi' sometimes also 'stars' or 'crabs.' A sampling of 'ice spiders' found around the web are included below, for reference:

http://www.flickr.com/photos/ezra/5759639/
http://www.flickr.com/photos/76798588@N00/95825175/






http://www.flickr.com/photos/pallo/135039466/
http://www.skridsko.net/skridskonet/bild/bild-v.asp?id=38009
Clearly, some of these features also compare reasonably well to 'Martian spiders.'



Is it possible that, at some point in Mars' past, Mars may have had water, which could have eroded the surface in some fashion? Perhaps. Though there are potential problems with this solution, not least of all that the channels of Mars's 'spiders' seem to sometimes flow uphill against gravity as well as downhill. We can't very well invoke 'novel physics.' Can water's propensity toward 'wicking' (capillary action) account for this apparent motion against gravity? Or is even that an insufficient solution?

Is it possible that these figures were created by geysers of sublimating CO2 and entrained dust? Perhaps. Though that model has its own problems. Why do other defrosting regions not display the same filamentary dendritic channels, despite similar topography and similar CO2 frost? Why are the 'spiders' confined to the southern polar region and seemingly completely absent from the northern pole?

Is it possible that, at some point in the past, Mars was scarred electrically with Lichtenberg figures? Perhaps.

But, one supposes the take away message is that there are no hard and fast answers. It would seem that many different processes seem to be proposed for and/or capable of creating dendritic features. 

A 'Martian spider'

A lightning scar to a golf course.
The desert around Koes, Namibia.
An 'ice spider.'
So, we must be willing to keep an open mind, to hold opinions tentatively and not dogmatically as well as to allow ourselves to reassess existing hypotheses in light of additional data presenting additional avenues of inquiry. It may be that this new avenue does not pan out. That wouldn't, of course, mean it was a 'bad' idea. It would simply mean that it was possibility that didn't pan out. And we should be willing to give all possibilities a shot, even if only to rule out one more contender.

Friday, April 27, 2012

Dark Days For "Dark Matter"

A central pillar of the Standard Model has taken a shellacking this month. Two separate studies have come out contra "dark matter." If this central pillar falls, the entire house of cards may collapse under its own weight.

So, what is "dark matter?"

"Dark matter" or "missing mass" is an abstract concept that came out of the failure of gravitational cosmology to account for certain observations of objects in space.

"The idea of dark matter was born at Caltech in 1933 ... In observations of a nearby cluster of galaxies named the Coma cluster, Fritz Zwicky calculated that the collective mass of the galaxies was not nearly enough to hold them together in their orbits.

"He postulated that some other form of matter was present but undetected to account for this 'missing mass.' Later, in the 1970's and '80's, Vera Rubin similarly found that the arms of spiral galaxies should fly off their cores as they are orbiting much too quickly."
http://www.spacedaily.com/reports/How_We_See_Dark_Matter_999.html

Essentially dark matter is an error bar on the Standard Model of [Gravitational] Cosmology. We can calculate how much mass is needed, gravitationally speaking, to hold galaxies and such together. We can then observe galaxies and other objects in space across the range of the electromagnetic spectrum from radio up through gamma rays and assay whether or not the actually observable mass of the objects matches up with theoretical predictions.

Simply put: the observable matter in galaxies is insufficient to account for their characteristics.

There are, thus, two options:
  1. Consider the gravitational models falsified and move on to a different theory.
  2. Forgo falsification and invent a new theory or substance to salvage the gravitational model.
 Option two leads down a path paved with "dark matter." Basically, invisible, unobservable material is hypothesized then sprinkled liberally wherever the math says there's not enough mass, but there should be. In effect it is an error bar on the gravitational model, telling us precisely how much mass is 'missing' (under the assumption that gravitational theories are correct, despite observations having falsified them).

Don't worry, it gets weirder...

Not only is the stuff invisible, in order not to throw off other theories, it also only interacts gravitationally with other matter.
"Dark matter neither emits nor absorbs light or other electromagnetic radiation, and so cannot be seen directly with telescopes."
http://en.wikipedia.org/wiki/Dark_matter

That is, it doesn't emit electromagnetic radiation (the aforementioned EM spectrum, from radio up through gamma rays) and neither is it influenced by electric or magnetic fields. But, one supposes this shouldn't be surprising since it is, at its heart, only a mathematical kludge.

But wait, it gets weirder!

Despite dark matter not interacting with the known electromagnetic forces, some theorists want to shoehorn in some kind of electromagnetic-like force anyway, but one specific to dark matter.
"...just like ordinary matter couples to a long-range force known as 'electromagnetism' mediated by particles called photons,' dark matter [may couple] to a new long-range force known (henceforth) as 'dark electromagnetism,' mediated by particles known (from now on) as 'dark photons.'"
http://blogs.discovermagazine.com/cosmicvariance/2008/10/29/dark-photons/
It's difficult to tell whether these folks are just pulling our legs or they're actually serious. Though, the fact they've submitted a paper on the subject seems to imply the latter.

So, okay, say for a moment that we accept the premise that dark matter exists. We don't. But let's say we did. This should be a testable theory.

And, testing it, some scientists are (in various ingeniously clever and indirect ways, keeping in mind we can't directly observe dark matter since it doesn't emit EM radiation or interact with electric or magnetic fields and we still have no idea how gravity itself actually works at the most basic physical level).

But, before dark matter has even been experimentally confirmed, scientists have already started incorporating it into other theories and applying this new tool to other fields of inquiry, building up a rickety structure of beliefs and assumptions all resting on this now load-bearing pillar. Reification is a dangerous thing. Once you start believing a thing is real, you stop questioning its reality and it becomes an unquestioned (even if also unproven) assumption, often mistaken for a "fact."

Recently, some scientists tried calculating how often WIMPs (Weakly-Interacting Massive Particles; one "dark matter" candidate particle) impact the human body. They predicted about "once a year," but in working through the problem they came up with something closer to "once a minute."

But, as such things go, their results have tons of assumptions, not least of which being that dark matter is abundant everywhere, including here. A reasonable assumption, considering that upwards of 23% of the mass/energy of the universe.

But, wait a minute... What's that? Breaking news! Two studies released in the past month have offered tentative refutations of dark matter based on actual observations of local space (in the Sun's and the Milky Way's neighborhoods). And one experiment here on Earth appears to be offering null results (that is, no evidence of "dark matter").

Earlier this week, scientists released the results of a survey of the Milky Way's local cosmic neighborhood. The press release had the following to say:
"'Once we had completed our analysis, a new picture of our cosmic neighbourhood emerged,' says Pawlowski.

"Team member Pavel Kroupa, professor for astronomy at the University of Bonn, adds 'We were baffled by how well the distributions of the different types of objects agreed with each other.' As the different companions move around the Milky Way, they lose material, stars and sometimes gas, which forms long streams along their paths. The new results show that this lost material is aligned with the plane of galaxies and clusters too. 'This illustrates that the objects are not only situated within this plane right now, but that they move within it,' says Pawlowski. 'The structure is stable.'

"''In the standard theories, the satellite galaxies would have formed as individual objects before being captured by the Milky Way,' explains Kroupa. 'As they would have come from many directions, it is next to impossible for them to end up distributed in such a thin plane structure.'"
http://www.ras.org.uk/news-and-press/219-news-2012/2118-do-the-milky-ways-companions-spell-trouble-for-dark-matter
If the observations stand up to scrutiny, the Standard Model has a hard time explaining them with the current dark matter-centric theories. Team members put the situation thus:
"Our model appears to rule out the presence of dark matter in the universe, threatening a central pillar of current cosmological theory. We see this as the beginning of a paradigm shift, one that will ultimately lead us to a new understanding of the universe we inhabit."
http://www.ras.org.uk/news-and-press/219-news-2012/2118-do-the-milky-ways-companions-spell-trouble-for-dark-matter

The question is, will he paradigm actually shift or will additional 'fixes' and 'patches' be added, order to save the oft-falsified theory?

A week or two ago, a different paper was released showing that observations of local objects in the Sun's neighborhood (stars, dust, gas) account well for their motions via gravity, with no room for any extra "dark matter."

The press release puts the implications bluntly:
“The amount of mass that we derive matches very well with what we see -- stars, dust and gas -- in the region around the Sun,” says team leader Christian Moni Bidin ... “But this leaves no room for the extra material -- dark matter -- that we were expecting. Our calculations show that it should have shown up very clearly in our measurements. But it was just not there!”

"Despite the new results, the Milky Way certainly rotates much faster than the visible matter alone can account for. So, if dark matter is not present where we expected it, a new solution for the missing mass problem must be found. Our results contradict the currently accepted models. The mystery of dark matter has just become even more mysterious."
http://www.eso.org/public/news/eso1217/
That is, no mass is "missing" from our local neighborhood. Ergo, no dark matter is required to explain the motions of objects in local space, despite the Standard Model's expectations that it should be there. As they say, galaxies "certainly rotate faster than the visible matter alone can account for," gravitationally speaking. Their results "contradict the currently accepted models" and "a new solution ... must be found."

In fact, this revelation has implications for detection efforts here on Earth. Even if dark matter exists, if there is none in our local neighborhood, it'll be a lot harder to detect.
"The new results also mean that attempts to detect dark matter on Earth by trying to spot the rare interactions between dark matter particles and “normal” matter are unlikely to be successful."
http://www.eso.org/public/news/eso1217/

But more likely it won't be detected because, well, it's 'just not there.' It's a figment of the over-active imagination of astrophysical mathemagicians.

But, that brings us to the 'testability' requirement of theories and the experiment currently being run here on Earth to try to detect dark matter: Xenon 100.

It got some press back in the day (2012) when it released preliminary results from its first 11 days of operation.
"Now, a third experiment called Xenon 100, which its makers say is even more sensitive than the other two [DAMA & CDMS-II], has failed to detect the impact of any dark matter particles, casting doubt on the earlier results. 'Dark matter particles continue to escape our instruments,' says Xenon 100 spokesperson Elena Aprile of Columbia University in New York."
http://www.newscientist.com/article/dn18839
However, there was a modicum of backlash against the Xenon 100 results, but the team has continued on undeterred, preferring their results to speak for themselves.

Appropriately enough, the team published a new paper in 2011 regarding the results of 100 days of Xenon 100 data. Their conclusion:
"In 100.9 live days of data, acquired between January and June 2010, no evidence for dark matter is found."
http://arxiv.org/abs/1104.2549
 So, at 100 days, the results are the same as they were at 11 days. "No evidence for dark matter is found."

In all, it seems that dark matter is on the shakiest of footings and current research is not bearing it out. The question, again, is whether the repeatedly falsified model will finally be thrown out... Time will tell.

It is suggested that researchers follow-up, embrace and extend the fully electrodynamic Particle-in-Cell (PIC) simulations carried out by Los Alamos plasma physicist Anthony Peratt back in the 1980's, showing that galaxies can and should be explained in terms of the ubiquitous electrically conductive plasma permeating the universe. Starting from an electrodynamic point of view, galaxy rotation curves come directly out of the simulations, no dark matter required.

Astrophysicists need to move on from one of the weakest forces (gravity) to one of the strongest forces (electromagnetism), and acknowledge the electrodynamic nature of the universe as a whole.

We already know that we live in a so-called "magnetic universe." But, then again, we also know from whence springeth magnetic fields. Magnetic fields are generated by electric currents.
"...steady electric and magnetic fields cannot generate themselves. Instead, they have to be generated by stationary charges and steady currents. So, if we come across a steady electric field we know that if we trace the field-lines back we shall eventually find a charge. Likewise, a steady magnetic field implies that there is a steady current flowing somewhere. All of these results follow from vector field theory (i.e., from the general properties of fields in three-dimensional space), prior to any investigation of electromagnetism."
http://farside.ph.utexas.edu/teaching/em/lectures/node37.html

"...all steady magnetic fields in the Universe are generated by circulating electric currents of some description."
http://farside.ph.utexas.edu/teaching/em/lectures/node35.html
If we live in a magnetic universe, more fundamentally, we live in an electric universe. Live it, love it, deal with it.

So, lets dispense with the pixies and fairy dust and get down to the business of determining what actually runs the universe. Answers are at hand, if we're courageous enough to slaughter a few sacred cows in the process.

Monday, March 26, 2012

Lasers Shine Light on the Electric Universe

All roads lead to one inevitable conclusion: As electric currents produce magnetic fields, any magnetic fields we observe must be produced by electric currents. New research using lasers shows that even where shock waves and magnetic fields correlate, it is an electric current loop that generates the magnetic field.

Science marches blindly onward. The time has come to remove the blinders and explore our Electric Universe.

Galactic magnetic fields have been a thorn in the side of gravitational cosmology for the better part of a century. Where do they come from? How did they get there? Why do they persist? Why didn't gravitational cosmology predict them? Why are Hannes Alfvén's predictions almost always prescient? (Okay. Ambiplasma may have been a garden path. We can accept that. Nobody's perfect.)

Simply put, those who espouse gravitational models of the universe seems to willingly put on blinders to the efficacy of the electromagnetic field in explaining the workings of the universe. Hopefully this blog serves to peel back the veil ever so slightly.

The current leading contender for 'how galactic magnetic fields got there' in the gravitational universe are so-called magnetic 'seed fields,' unexplained small-scale fields that somehow get whipped up and amplified into bigger fields through 'dynamo action.'
"Scientists believe that galactic magnetic fields are generated from weaker seed fields. These seeds are then amplified via a dynamo mechanism, in which the rotation and turbulence of the galaxy’s interstellar medium – the gas and dust between stars – acts to reinforce the original magnetic field."
http://www.cosmosmagazine.com/news/5222/lasers-shine-light-galactic-magnetic-fields

But, how did the 'seed fields' get there? Magic? God put them there when He created everything from nothing? Man put them there when he mathematically created everything from nothing (the Big Bang)?
"However, this mechanism doesn’t explain how the seed fields themselves come into being."
http://www.cosmosmagazine.com/news/5222/lasers-shine-light-galactic-magnetic-fields

Since electric currents are not generally permissible in a gravitational universe (they either don't exist at all, don't exist on the largest scales or don't do anything of consequence, depending who you ask), some other method of creating magnetic fields must come into play. Seemingly, the only other way of generating high-energy events is collisions (banging things together).
"One of the proposed methods for creating seeds is via shock waves..."
 http://www.cosmosmagazine.com/news/5222/lasers-shine-light-galactic-magnetic-fields
So, when all else fails, it seems 'shock waves' are invoked to get things going. Though, why 'shock waves' should be expected to generate magnetic fields isn't entirely clear, other than the fact that something has to do it.

I wonder, does a bullet flying through air produce a magnetic field? It certainly generates a shock wave. I suppose it might be an interesting experiment... Though, it's outside the scope of this blog.

To test the hypothesis, scientists have created a shockwave in the lab using a high-power laser.
"[A] pulsed laser was directed at a small carbon rod inside a chamber filled with helium gas [to mimic an explosion] ... This explosion created a shock wave ahead of the expanding material. As the shock wave moved through the plasma in the chamber, a current loop was created, which in turn generated a magnetic field."
http://www.cosmosmagazine.com/news/5222/lasers-shine-light-galactic-magnetic-fields
As expected, the shockwave generated a magnetic field. Indirectly. The shockwave generated a current loop (an electric current), which in turn generated the magnetic field. This process is known as the 'Biermann battery.' Now, the Biermann battery effect was what they were looking for. So, kudos for that... But the worry is that now science will put its blinders back on and ignore the middle man (electric currents), claiming that 'shock waves generate magnetic fields, enough said.' Too often this kind of pseudo-pedagogical oversimplification is what creeps in.

We should be cautious to always remember the causal chain of events. Yes, a shock wave can lead to a magnetic field, but only through the generation of an intermediary electric current and not through any other action. In the end it is the electric current that produces the observed magnetic field.

So, really what they have confirmed, once again, is that electric currents are the sole source of magnetic fields in the universe (as was pointed out in the initial post of this blog). A shock wave is merely one method of producing an electric current.

It is, thus, still the contention of this blog that where magnetic fields are observed in the universe, we must work backward and ask what electric current systems are driving them.
"Electric current can be directly measured with a galvanometer, but this method involves breaking the electrical circuit, which is sometimes inconvenient. Current can also be measured without breaking the circuit by detecting the magnetic field associated with the current."
http://en.wikipedia.org/wiki/Electric_current#Electromagnetism
Magnetic fields are diagnostic for electric currents. By observing magnetic fields we can infer that a current is present and determine characteristics of that current. This holds just as true in space as it does here on Earth in the lab. For instance, astronomers recently announced the strongest electric current observed thus far in the universe flowing in the jet of galaxy 3C303.

The scientists testing the shockwave hypothesis, however, caution that shock waves are not the only method that has been proposed for generating magnetic 'seed fields.' Other hypotheses includes stars or other objects 'casting off' their magnetic fields into interstellar space. Such a 'casting off' is nonsense, since magnetic fields cannot be 'frozen in' to plasma as has been repeatedly claimed by astronomers (Don Scott).

Unmentioned is the assertion decades ago by Hannes Alfvén that galaxies should be expected to possess magnetic fields owing to the fact that they are electrical structures not dissimilar to a unipolar inductor. If this is so, then so-called 'seed fields' would be an unnecessary artifice, as the electric currents flowing in and around a galaxy analogous to a unipolar inductor would be the only source required to account for the observed magnetic fields.

Perhaps some day soon, we can dispense with the need for 'seed fields' altogether and move to a fully electromagnetic explanation of the ubiquitously observed magnetic fields throughout the universe. So ubiquitous are they, in fact, that a number of mainstream publications have alluded to the fact that we live in a "Magnetic Universe."

But, what is a "Magnetic Universe" if not a second order "Electric Universe" wherein the cart has been placed before the horse?
"Underpinning all this is a serious problem: we simply don't know what created this cosmic magnetism, or how it has maintained its strength over billions of years ... We don't [know] when or how the first magnetic fields were generated, or how they have stayed so strong and ordered over billions of years. "
http://www.cosmosmagazine.com/features/online/4248/the-magnetic-universe
If we can agree that "electric currents are the sole source of magnetic fields in the universe," as was also put forth in the initial post of this blog, then we should also agree that any such "Magnetic Universe" must more fundamentally be an "Electric Universe." Steady magnetic fields arise from steady electric currents. Changing magnetic fields arise from changes to the underlying currents. Thus, if we see that magnetic fields in the universe persist and remain stable, we must also assume that the feeder currents also persist and remain stable.

That currents exist and do things of interest, must at this point become relatively non-controversial. It's time to acknowledge that obvious fact and move forward with our newer and more complete tool set. Where we see magnetic fields, we should seek to determine the underlying current structures.

Perhaps our universe is more readily knowable than we had heretofore dreamed? Galactic unipolar inductors, filamentary nebulae compressed by electromagnetic forces, high energy impulsive events driven by exploding circuits, and so on. All knowable, all testable hypotheses given a more complete understanding.

Thursday, February 16, 2012

"Pinch" Me, I'm Dreaming of "Magnetic Slinkies!"

Silly metaphors require silly titles. Hopefully today we can sort out some astrophysical silliness and come to a better understanding of what is going on from an electrical standpoint. The silliness in question is the "magnetic slinky" that has been metaphorically associated with a molecular cloud in Orion. Put simply, a better physical explanation is the "plasma pinch."

In my introductory post, I exegesis-ized the relationship between... Yes, okay, I know exegesis-ized isn't a word! Sheesh! Fine, I elaborated (some might prefer belabored) the relationship between magnetic fields and electric currents. Hopefully we're all on the same page by now:
"Electric currents are the sole source of magnetic fields in the universe."
Today, we seek to put that notion into practice with a real-world example. Moreover, let's add another bit of electrical physics to the mix.

The topic I want to recap today is an oldie but a goodie. In 2006, astronomers discovered what was subsequently coined a "magnetic slinky" encircling a molecular cloud in Orion. 

But, what does that even mean? Honestly, by itself, not a whole heck of a lot. It's a pretty bad metaphor. Essentially, what was being described is the approximate shape of magnetic 'field lines' encircling the long axis of the molecular cloud. In a later post, I'll cover why we should move away from the concept of talking about 'field lines' (they don't actually exist).

But, again, what does the discovery actually tell us about what's going on? For that I'll actually grab a slightly better quote from the press release:
"The magnetic field lines are like stretched rubber bands; the tension squeezes the cloud into its filamentary shape."
Ahh, action words! Something happened. Finally, we're getting somewhere! Though, the metaphysics is still terrible, since magnetic 'field lines' do not exist thus cannot have 'tension' and cannot 'squeeze' anything. But at least we have some idea now of what has been observed. Something is causing the compression of the molecular cloud into a filamentary shape. It's a start...

So, what do we know? We know there's a 'cloud' out in space. We know that a magnetic field is involved. We know that the cloud is being compressed. We know that the magnetic field is implicated somehow in compressing the cloud.

So, what's actually going on?

Let's back up and head back to the basics. We've already said that magnetic fields are produced by electric currents, because electric currents of some character are the sole source of magnetic fields in the universe.

When a current flows, a magnetic field is generated around it. It can be visualized as a straight line (current, I) surrounded by concentric circles (magnetic field, B).
But, this universe is messy and things are never quite that simple. When a current flows and generates a magnetic field, the magnetic field can also interact back with the current that created it, constricting the current. As the current is constricted the magnetic field increases.
Original Caption: Fig. 10: Physics of the Z-pinch: A current (orange) generates a magnetic field (blue), which causes the current to pinch inwards along the axis by way of the Biot-Savart F = I × B force. This amplifies the magnetic field and accelerates the pinch, heating the plasma and causing it to radiate X-rays (red).
http://www.stanford.edu/~rhamerly/cgi-bin/Ph240/Ph240-2.php#sec4
This feedback continues until magnetic pressure reaches equilibrium with the gas pressure in the compressed conductor. This is known as the 'pinch effect.'

Are there any accessible examples of the pinch effect? Yes. But we'll get to those in a moment.

First let's back up one more time and discuss discharge regimes. In a plasma, there are three basic regimes. One might call them 'intensities' of discharge.
  • Dark Discharge
    This regimes is termed a dark discharge because although a current flows, generally, the discharge remains invisible to the eye.
  • Glow Discharge
    The glow discharge regime owes its name to the fact that the plasma is luminous. The gas glows because the electron energy and number density are high enough to generate visible light by excitation collisions.
  • Arc Discharge
    Beyond the glow discharge is the arc discharge regime. Particle energies and current density are higher. The increased current produces an associated increased magnetic field which pinch the current into a filamentary shape. Arc discharges are also known to emit copiously across the electromagnetic spectrum.
So, are there any examples of the pinch effect? Yes!

In the glow mode, one need look only as far as a novelty 'plasma lamp' or 'lightning globe' as they are affectionately known:


Discharge streamers emanate through low density ionized gases (plasma) from a central electrode, compressed into filamentary forms by way of the pinch effect.

In the arc discharge regime, we can easily point to lightning:


The discharge channel is clearly compressed into a filament with a very small radius. Lightning also emits brightly in the visible range and indeed across much of the EM spectrum from radio to x-rays.

Now you know! The pinch effect can be reasonably easily understood and is useful for understanding several relatively mundane processes here on Earth. But, what about in the cosmos at large?

It is this author's opinion that what's good for the goose is good for the gander. What holds true here on Earth in the lab and in nature should also apply to the cosmos. so, we come full circle back to the original inquiry: the molecular cloud in Orion.

To recap what we know: there is a filamentary cloud of material; it is being compressed into its filamentary shape; magnetic fields are involved somehow.

We also know that magnetic fields find their genesis in electric currents and can be visualized as field lines wrapped around the central axis of the current.
Original caption: The Orion Molecular Cloud superimposed on the Orion constellation, with the orange star Betelgeuse at the top corner and Rigel at the bottom. The inset shows the Slinky-like coils of the helical magnetic field surrounding the filamentary cloud. (Credit: Saxton, Dame, Hartmann, Thaddeus; NRAO/AUI/NSF)
Diagram shows azimuthal magnetic field (B)
as concentric circles around central current (I).
So, based on what we know of the nature of magnetic fields and the pinch effect, do we have enough information to make an anecdotal case for a hypothesis on what's really going on here? I think we do.

An electric current flowing along the length of the filamentary cloud would generate a magnetic field azimuthal to the cloud (wrapped the short way around the filament). Such a magnetic field could interact back with the current flowing through the cloud causing it to 'pinch' or compress into the observed filamentary shape. Not unlike the filamentary tendrils observed in a plasma lamp (above).

Thus, rather simply, we can back-infer from the magnetic field of the filament, its shape and the implication that the magnetic field is involved in compressing the cloud into its filamentary shape that there is a plausible possibility that a current is flowing there, which would reproduce the features observed.

Would the solution be as simple as drawing a line down the middle of the "magnetic slinky" along the long axis and labeling it (I) denoting a current flowing there (as an analogy to the current [I] vs. magnetic field [B] diagram, above)?

I suggest that it is incumbent upon astronomers to perform some follow up observations and/or modeling to investigate this simple, testable proposition. Moreover, if this hypothesis is found plausible or even probable in this instance, this observation and hypothesis could easily be applied to a number of other structures demonstrating filamentary shapes and strongly associated magnetic fields.

Another pertinent example that jumps to mind is the "Strongest Electrical Current in the Universe" recently derived from observations in an extremely similar manner (by first observing Faraday rotation indicating the presence of a magnetic field then modeling the system to determine the characteristic of the current driving it).

One wonders somewhat emphatically whether all similar jets (such as the "largest stellar jet" stretching over 400 trillion kilometers recently found in the Large Magellanic Cloud or Herbig-Haro objects, generally) may share common features, including an electrical character heretofore not widely acknowledged.

I'd love to see a rigorous investigation with the potential to investigate this very simple hypothesis.

If the above examples are tackled and an answer in the affirmative is obtained, perhaps this hypothesis can then be extended to the investigation of the entire filamentary cosmic web of stars, galaxies and galaxy clusters.

Are any astronomers brave enough to undertake a rigorous voyage of discovery into this wild new frontier? The exploration won't be without its challenges. But the bounties may far outweigh the perils.

Wednesday, February 15, 2012

Exploding Circuits: A New 'Magnetic Reconnection'?

Has a minor update about ongoing plasma research just confirmed a decades old idea about the physical origin of 'magnetic reconnection'? The notion of 'snapping' and 'merging' magnetic field lines may be a thing of the past, replaced by an old theory: exploding electric circuits (exploding double layers).

Breaking news promises to revolutionize our understanding of such processes as magnetic substorms and solar flares wherein an unknown process (commonly referred to as 'magnetic reconnection') releases vast amounts of energy very quickly. And by revolution, I mean that it promises to take us a step backward.

"Wait, backward? How can that possibly be a good thing?" you might ask.

Well...

It's a long story about a quiet row in astrophysics that nobody likes to talk about... But, this is my blog, so "out with it!"

There is an unstated or very quietly stated assumption in astrophysics that electric currents can't exist in space (except when they're shown to exist by actual observations; how embarrassing!), or if they do exist they don't do anything of note (well, okay, there's that one jet that's the largest electric current in the universe; "but other than that, what's electricity done for me lately?"). And even if electricity does do interesting things out there, gravity is still king so n'yah!

Unfortunately, this notion has straight-jacketed astrophysics, astronomy, magnetospheric physics, heliospheric physics, etc. In terminology, if nothing else. It's a rather queer situation. Astronomers will tell you they 'factor in electric currents,' on the one hand, and then they'll couch things in terms of 'magnetic reconnection' in such a way as to make you think they have no clue about how electricity and magnetism work, on the other..

Why is this bad? Well, there's the notion of the 'pseudo-pedagogical concept.' Why are you giving me a blank look? Ohh right... Not a philosopher. Okay, in layman's terms, sometimes when one starts using a certain set of terminology and ideas to refer to something else (as a sort of analogical placeholder), one starts believing that the placeholder one has invented is equivalent to the actual thing one was referring to and stops thinking in terms of the original idea at all.

So, what is 'magnetic reconnection?' Up until today, it was pretty fair to say 'nobody knows.' That is, in this particular case, a certain formalism has crept in whereby astronomers and astrophysicists seem to prefer talking in terms of magnetic fields and magnetic field lines.

Although some of us think it's bad, it's also somewhat understandable. Here's why: 1) magnetic fields are easier to detect. 2) Magnetic fields can be easier to work with mathematically.

So, it's certainly easier (if lazier) to talk in terms of the thing we can 'see' and treat mathematically with less effort.

But, getting back to the question of 'what is magnetic reconnection,' it arises out of the observation of certain events in space. In particular, 'magnetic reconnection' is a process of interest in solar flares and the magnetic substorms in our magnetosphere that spark the auroras. What we see is that during substorms, the magnetic field changes in particular ways. At the same time vast amount of energy are released very quickly. The relationship between the magnetic field changes and the energy release is what is not well understood and underpins the idea of magnetic reconnection. We'll return to that in a moment.

Now, a magnetic field is visualized using magnetic 'field lines' kind of like the ones you see with bar magnets and iron filings. Though in the case of field line diagrams the lines serve a specific purpose: denoting magnetic field strength and direction. They are a visual tool and that is all.

That brings us to another problem: reification.

I know, another philosophy word. Basically, it means taking some abstract thing and making the mistake of thinking it's a real thing.

In this case, it seems that some astronomers and physicists have goofed and think that 'field lines' are real. They are not. They are lines on a page. There is not a material object (such as a thread, wire, rope or sheet) in 3-dimensional space corresponding to that line. The line merely represents the strength and direction (sometimes thought of as a 'vector') of the force felt by a charged particle placed at that location in the field. Nothing more or less.

So, they've associated observed energy release with observed magnetic field topology changes (changes in the shape of the field lines) and have come to the conclusion that it's the magnetic 'field lines' that are doing something, and in the process energy is released. That is, 'field lines' are thought to be 'twisting,' 'coiling,' 'breaking' and 'reconnecting.' In point of fact that is not even possible, because they do not exist. Morever, magnetic fields are solenoidal (continuous). What does that mean? It means, for one thing, that field lines are ALWAYS drawn as complete loops (except where they run off the page, and then only if the same number of line return to the page as left the page) and cannot 'break,' let alone then 'reconnect' without violating Maxwell's equations.
"...fields are solenoidal: that is, they never begin or end..."
http://farside.ph.utexas.edu/teaching/em/lectures/node35.html
But, there are still observations for which to account... And, account for them we must if science is ever to progress to completion. So, where does that leave us?

We know that magnetic field topology changes and we know that copious energy is released at approximately the same time. But we also know that field lines do not exist and can't break or reconnect. This should also give us a clue that field lines are not themselves a primary mover and shaker. It's hard for things that don't exist to do much of anything. Nonetheless things get done... 

So, how do we reconcile this conundrum?

While magnetic field lines do not exist, they are helpful visual aids to determine properties of that which does exist, namely magnetic fields (keeping in mind that magnetic fields are actually the expression of a force felt between electric currents).

Hopefully you have already read my very first post. If not: stop what you're doing; don't read any further; read that post first. I'll wait. I'm not going anywhere. I'm just a blog post.

Okay, now that we're sure you've read that, my next statement should no longer come as a cognitively dissonant shocker:
Electric currents are the sole source of magnetic fields in the universe.
To quote myself further:
As electric currents produce magnetic fields, any magnetic fields we observe must be produced by electric currents.
Heady stuff, I know! Simple and to the point... Shocking! And we haven't even gotten to the 'A' material yet...

The above reiterated, the bent of the suggestions in the remainder of this post should not be entirely surprising. Hopefully, it's just pretty cool science.

Let's get to the cutting edge research now and then suggest a better metaphysics to replace the tired old dog known as 'magnetic reconnection'!

In the plasma physics lab (as opposed to 'in a giant supercomputer simulation with 30 adjustable variables'), researchers (Moser & Bellan) have studied the physics of jets (electrical discharges) in plasma in order to ascertain the what, when, where, why and how of 'magnetic reconnection.'
"As in all electrical currents, the flowing electrons in the plasma jet generate a magnetic field, which then exerts a force on the plasma. These electromagnetic interactions between the magnetic field and the plasma can cause the jet to writhe and form a rapidly expanding corkscrew. This behavior, called a kink instability, has been studied for nearly 60 years..."

"The jets in the experiment formed 20-centimeter-long coils in just 20 to 25 microseconds. [Moser] also noticed tiny ripples that began appearing on the inner edge of the coil just before the jet broke--the moment when there was a magnetic reconnection."

"...after months of additional experiments, they determined that the kink instability actually spawns a completely different kind of phenomenon, called a Rayleigh-Taylor instability. A Rayleigh-Taylor instability happens when a heavy fluid that sits on top of a light fluid tries to trade places with the light fluid. Ripples form and grow at the interface between the two, allowing the fluids to swap places."

"What Moser and Bellan realized is that the kink instability creates conditions that give rise to a Rayleigh-Taylor instability ... The plasma tries to swap places with the trailing vacuum by forming ripples that then expand--just like when gravity forces a heavy fluid to try to change places with a light fluid underneath."

"While the coil created by the kink instability spans about 20 centimeters, the Rayleigh-Taylor instability is much smaller, making ripples just two centimeters long. Still, those smaller ripples rapidly erode the jet, forcing the electrons to flow faster and faster through a narrowing channel. 'You're basically choking it off,' Bellan explains. Soon, the jet breaks, causing a magnetic reconnection."
http://media.caltech.edu/press_releases/13496
This research puts the answer to the 'magnetic reconnection' mystery squarely back into the court of plasma physics.

Basically, what they're saying is that there is a large-scale electric current flowing. That current produces its own magnetic field. If the current and its self-magnetic field are inhomogeneous, an instability can develop (the kink instability; literally, a kink develops in the current filament). Additionally, a smaller-scale Rayleigh-Taylor instability can develop that causes the primary current to 'pinch' (self-constrict) and 'neck off' (similar to what happens in a 'sausage instability' where a current may self-constrict at many locations along its length making it look a bit like Bratwurst links; don't eat it!). In the end, this 'pinch' can completely disrupt the current.

You'd think that would be where the story ends. That's certainly where that article ends. But this post continues a little further. Read on valiant listener! I implied a solution and I'd hate to disappoint.

What happens when you disrupt such a circuit? Is it like a light switch? Not necessarily...

Here I'll turn to an esteemed colleague, Don Scott, who had already some time ago turned his steely electrical engineering eye toward the notion of 'magnetic reconnection' in an old post of his own, wherein he quotes Nobel prize winner Hannes Alfvén:
"'In the case of the instability leading to the extinction of the current, it should be remembered that every electric circuit is explosive in the sense that if we try to disrupt the current, a release of the whole inductive energy at the point of disruption will occur.' - H. Alfvén, Cosmic Plasma, Reidel, Holland, Boston, 1981, p.27."

"Alfvén extrapolated his findings about terrestrial power lines to the study of magnetized cosmic plasma. In the case of the disruption of an electric current within such a plasma, he said, 'If the current disruption is caused by an instability in the plasma, the inductive energy in the circuit will be released in the plasma. … The disruption of a current through a plasma is often caused by a double layer becoming unstable.'"

"Astrophysicists ignore Alfvén's work. They attempt to arrive at a de novo explanation for the release of such energy by embracing the notion that the motion and interaction of magnetic field lines is its root cause. They expound on the (basically false) idea that magnetic fields are 'frozen into' plasma, and by moving and breaking, these lines carry the plasma along and spew it out into space."
http://www.thunderbolts.info/thunderblogs/archives/descott08/021608_reinventing_the_wheel.htm
So, it would seem that the disruption of a current in plasma isn't quite the same as flipping a light switch. Rather, when the circuit is disrupted, the inductive energy of the circuit explodes out of the point where the circuit is broken.

It is here that we find our impulsive energy release at the same time as the apparent change in the shape of the magnetic field. When a circuit is broken, there is an electrical explosion. Sometimes the explosion of a double layer of separated electrical charges is involved.

In fact, a mechanism such as this was proposed as far back as 1986 or even earlier:
"According to Bostrom (1974) and Akasofu (1977), an explosion of the transverse current in the magnetotail gives an attractive mechanism for the production of magnetic substorms (see Fig. 11). Bostrom has shown that an equivalent magnetic substorm circuit is a way of presenting the substorm model. The onset of a substorm is due to the formation of a double layer, which interrupts the cross-tail current so that it is redirected to the ionosphere."
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19870013880_1987013880.pdf
Although a double layer may not always factor in, the notion of a current disruption and its attendant energy release has apparently circulated for some time. It seems the idea's time has finally come.

The sequence of events appears (in this instance), to this author, to begin with an electric current (as it should since magnetic fields are involved). At some point the current filament develops an instability such as a kink instability. Beyond that the Rayleigh-Taylor instability develops, causing the current to pinch, neck off and break the circuit. At the point of the break in the circuit, the entire inductive energy of the circuit pours out impulsively. Since the underlying current system has changed and a new impulsive event occurs, it would naturally follow that the 'field lines' denoting the magnetic field shape and strength must be redrawn.

Finally, we can return to a valid causal metaphysics based on real-world entities doing things they are well-known to do in the lab (and we should expect no less in space). We now have a pretty good understanding of what's going on. Currents flow. Currents can become unstable. Instability sometimes breaks the circuit. An electrical explosion may occur at the point of the break in the circuit (not unlike the electrical arcs that happen occasionally at power substations). Magnetic fields change when the underlying current system changes. 'Field lines' do nothing.

'Magnetic reconnection' is dead! Plasma physics hath killed it. Long live plasma physics!

Many kind thanks to Bellan and Moser for this innovative work, even though they have never heard of me (to my knowledge, anyway) and have in no way sanctioned or approved this post. So, if anyone must take the blame for this, I shall happily bear full responsibility for my own contributions and pass on responsibility to Don Scott and Hannes Alfvén those portions which I have borrowed in good faith...