© HozTurner

Having watched the interesting new documentary posted by the Thunderbolts Project and personally found the qualitative arguments and observations rather compelling, I decided to take a look at what critics of the EU comet theory have put forward.

I'll leave the polemics aside and get straight down to the objections put forward by the likes of "RealityCheck" and "Tim Thompson".

CLAIM 1. 
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Cometary density vs Asteroid density apparently shows that comets cannot be defined as rocky bodies (http://forums.randi.org/showpost.php?p=4832138&postcoun~). He cites the following papers as apparent evidence for this objection:-

http://adsabs.harvard.edu/abs/2009MNRAS.393..192Shttp://ads~http://adsabs.harvard.edu/abs/2006LPICo1325...76WThe papers are behind a pay-wall but reading the Abstracts from the first two, I get the impression that non-gravitational influences were used to assist in density calculations in the first paper. In the second paper, we have the following Abstract:-

"In July of 2005, the Deep Impact mission collided a 366 kg impactor with the nucleus of Comet 9P/Tempel 1, at a closing speed of 10.2 km s-1. In this work, we develop a first-order, three-dimensional, forward model of the ejecta plume behavior resulting from this cratering event, and then adjust the model parameters to match the flyby-spacecraft observations of the actual ejecta plume, image by image. This modeling exercise indicates Deep Impact to have been a reasonably "well-behaved" oblique impact, in which the impactor spacecraft apparently struck a small, westward-facing slope of roughly 1/3 1/2 the size of the final crater produced (determined from initial ejecta plume geometry), and possessing an effective strength of not more than Y¯=1 10 kPa. The resulting ejecta plume followed well-established scaling relationships for cratering in a medium-to-high porosity target, consistent with a transient crater of not more than 85 140 m diameter, formed in not more than 250 550 s, for the case of Y¯=0 Pa (gravity-dominated cratering); and not less than 22 26 m diameter, formed in not less than 1 3 s, for the case of Y¯=10 kPa (strength-dominated cratering). At Y¯=0 Pa, an upper limit to the total ejected mass of 1.8×10 kg (1.5 2.2×10 kg) is consistent with measurements made via long-range remote sensing, after taking into account that 90% of this mass would have stayed close to the surface and then landed within 45 min of the impact. However, at Y¯=10 kPa, a lower limit to the total ejected mass of 2.3×10 kg (1.5 2.9×10 kg) is also consistent with these measurements. The expansion rate of the ejecta plume imaged during the look-back phase of observations leads to an estimate of the comet's mean surface gravity of g¯=0.34 mms (0.17 0.90 mm s-2), which corresponds to a comet mass of m=4.5×10 kg (2.3 12.0×10 kg) and a bulk density of ρ=400 kgm (200 1000 kg m-3), where the large high-end error is due to uncertainties in the magnitude of coma gas pressure effects on the ejecta particles in flight."

So in essence they are saying that the ejecta plume behaviour and profile corresponded to a cometary structure that is considerable porous in nature, and thus also low in density. Here is another quote from the paper:-

"the the observed ejecta plume consisted of billions of tiny ejecta particles, each one following its own ballistic trajectory under the influence of Tempel 1's gravity field, and as such, the lateral expansion rate of the collective ejecta plume is also a function of the comet's gravityfield (Melosh, 2001). When coupled with a shape model for Comet Tempel 1 (Thomas et al., 2007), a reasonable gravity
estimate for Tempel 1 also permits an estimate of the comet's
mass and bulk density."
(Full paper can be read here: http://www.eas.purdue.edu/richardson/Papers/jerichardson_IC~)

Thus, in essence the critics are saying thatcometary density profiles cannot simply regard them as the same in origin and nature as that of meteors. The nature of the dust plume from Deep Impact, while showing interesting persistent glows after the impact - seems to fit that of an impact into a dusty low density surface. So they claim.

He also claims that frozen gases are part of the composition of comets

CLAIM 2
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EDM machining processes cannot be responsible for the jets observed on cometary nuclei (http://forums.randi.org/showpost.php?p=5020451&postcoun~). Apparently this is so because heating of the material by EDM would cause material to scatter in all directions. Also apparently there is no dielectric material in place that could account for discharges. No EDM sparks are visible in cometary nuclei, just white-out spots. 

NASA also carried out a temperature map of Comet Temple 1 and found no EDM hot-spots:-
http://deepimpact.umd.edu/gallery/jpg/Temperature_Map.jpg

The hottest spot observed was directly under the sun at 329 Kelvin. I think this thermal map is problematic, at least - for the EU. 

CLAIM 3
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That the EU's analysis of Deep Impact is flawed and that the impact caused "5 million kilograms" of water to be lost from the comet. The impact zone apparently kept "outgassing" for 13 days after the impact.

Here's a quote from the BBC article referenced:-

"Swift's X-ray Telescope (XRT) saw the comet continue to release water for some 13 days after the initial event, with a peak five days on from the collision.

X-rays provide a direct measurement of the colossal amount of water thrown out as a result of the impact - the Earth-equivalent volume of about 100 Olympic-sized swimming pools."
http://news.bbc.co.uk/1/hi/sci/tech/4871934.stm

Thus apparently the comet was composed of porous layers of dust and ice, and not rock.

CLAIM 4
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Apparently, the lack of "X-ray bursts" as well as lack of varied emission down to the level of radio-waves from comets show that there is no electric arcing on the surface. There is no radiation signature or profile of lightning that one normally detects from other astral bodies.

Tim Thompson states:-

"You casually overlook the fact that all of the X-ray emission that we do see is readily & easily explained by other processes, while being simultaneously inconsistent with arcing, or particle acceleration in a plasma sheath. We see narrow line emission at specific charge exchange energies verified by controlled laboratory experiments. Acceleration of electrons in a plasma sheath will not produce that kind of narrow line emission. We see broad band thermal X-ray emission that easily fits the known spectral energy distribution (SED) of thermal electron-neutral bremsstrahlung. Bremsstrahlung is what you get when electrons are slowed & stopped by a resisting medium and has a different SED from electrons accelerated in a plasma sheath."
http://forums.randi.org/showpost.php?p=4832138&postcoun~

There is also laboratory evidence cited in the thread where scientists demonstrate the X-ray production resulting from high velocity electrons colliding with the gases found in cometary coma's:-
https://www.llnl.gov/news/newsreleases/2003/NR-03-06-02.html

CLAIM 5
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Voltage potentials are too small to produce EDM cathode arcing (http://forums.randi.org/showpost.php?p=5061330&postcoun~). He cites a paper titled "Electric Fields and Cold Electrons in the Vicinity of Comet Halley" by Harri Laaks. It seems they used a Langmuir Probe too to guage the e-fields.

CLAIM 6
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Asteroids with cometary orbital eccentricities exist (in large numbers) that do not have the behaviour of comets that EU would expect (http://forums.randi.org/showpost.php?p=5061286&postcoun~).

Also there is the issue of "extinct comets":-
http://en.wikipedia.org/wiki/Extinct_comet

I am sure there have been several more objections to the Electric Comet theory that, to my knowledge - have not been addressed in detail 

Having said that, I would still like to know how volatile frozen compounds and gases could erupt from the surface of a comet beyond the orbit of Jupiter. I don't think any of the JREFer's have addressed this, albeit I don't think it's enough to falsify the mainstream theory just yet. There are some plausible explanations here:-

http://books.google.co.uk/books?id=bf-OU0x8cugC&pg=PA29~

Mind you, I think it is time that we realised that the Electric Universe could do with a lot more effort behind us in terms of answering legitimate questions from our critics. I could be wrong, but this is my impression after experiencing a veritable onslaught of criticism even after my own work.

One of the main issues that needs to be addressed is the issue of nucleus temperature determined via direct infrared measurements (not via interpretive inference). Here is a higher resolution image:-

http://origin-ars.els-cdn.com/content/image/1-s2.0-S0019103~

As one can see, the bright spots where the EU has typically attributed arc discharges do not exhibit any + temperature anomalies. Here is the paper from which the image was derived:-
http://www.sciencedirect.com/science/article/pii/S001910350~

The images of the cometary nuclei were taken via the usage of the High-Resolution Instrument with onboard IR (infrared). Specs here:-
http://deepimpact.umd.edu/tech/hri.html

Already, senior people from the Thunderbolts Project have responded me claiming that there might be something wrong with the IR resolution used to examine the comet.