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Old 18th August 2009, 05:27 PM   #284
Reality Check
Penultimate Amazing
 
Join Date: Mar 2008
Location: New Zealand
Posts: 26,873
Exclamation The EC assumption of EDM machining does not produce jets

EC universe:
Sol88 quoted Wal Thornhill:
Quote:
The dust and gases that form the comet''s tail are not evaporated by the heat of the sun, but instead are electrically 'machined' from the nucleus by cathode arcs. Laboratory examination of cathode arcs shows that they jump around on the cathode surface, removing surface material in jets to form small circular craters. The industrial process of Electric Discharge Machining (EDM) uses this feature to erode a surface to accurate depth. To the naked eye, the EDM surface looks remarkably smooth. However, when viewed at high magnification, the peculiarities of the machined surface become clear. The tendency for the cathode arc to erode one high point then move to the next high point tends to generate chains of flat-floored craters. The finished surface appears as if someone used a circular cookie cutter to produce extended depressions and channels with scalloped edges. Variations in arc current will produce a layered or terraced effect both within craters and between adjacent craters.
No mention of jets or how EDM machining produces them.

Real universe:
Jets cannot be produced from EDM machining of "high points" on comets. The heating of the surface to machine it will cause material to escape in all directions. So there will be fans not jets. This will happen even if the "high point" is a flat surface.

To get jets in the real universe the EDM would have to happen at the bottom of pits or craters. By definition the walls of pits and craters are higher than their bottoms. The EDM will always happen at the "higher point". Therefore no jets.
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