Originally posted by humy
You apparently know nothing about servicing air conditioning and refrigeration systems.
….We still have not made a pump that can evacuate all air from a [b]system
So I take it you mean an “ air conditioning and refrigeration systems” by “
system “. Well, I wasn’t talking about conditioning nor refrigeration systems either.
...[text shortened]... and that does NOT include virtual particles else we are simply not talking about the same thing.[/b]You forgot an intermediary step: The cryopump. Vacuum is something I know a great deal about, having been in this field for over 30 years. The cryopump removes air by literally freezing the molecules as they come into an activated charcoal cold head cooled down to 10 to 12 degrees Kelvin (just a few degrees above absolute zero) and like the roach motel, the molecules check in but they don't check out, getting totally stuck somewhere on the huge surface area of the charcoal. Eventually there are such a low number of molecules there is chaotic flow and it's a matter of statistics since now the mean free path to collisions gets longer and longer.
THEN you can zap the rest with UV, and BTW, the UV gets the molecules hidden in the somewhat porous nature of the stainless steel walls, no matter how much electropolishing you do the surface still stores a certain amount of molecules and the UV helps to drive them out.
The vacuum level on the moon is something like 10E-18 torr. That is about ten orders of magnitude lower than what my sputtering machine or ion implanter can do. I have on VERY rare occasions seen vacuum in the minus 9 region but that is with an extremely tight system where there are a lot of VCR fittings as opposed to O rings, like Buna N or Viton. They both diffuse a small but measurable amount of atmosphere directly through the rubber stuff of the O ring. The only certain seal is the conflat seal, a copper gasket squished down between two crimping seals held in place with a bunch of bolts. VCR fittings are used for small shafts and they work well.
I see really dumb stuff, like the machine I am presently refurbishing at work, an MRC sputtering machine, where they have a capacitance manometer for reading in the millitorr roughing vacuum range using a VCR fitting but the flange that actually contacts the vacuum system has an O ring! Kind of silly. Just another O ring would have worked just fine. A bit of overkill.
But in practice, the best even the big boys get at Cern is something like 1E-14 torr, something like that, 10,000 times dirtier than the atmosphere level of the moon.
For one thing, they have this humungusly energetic particle beam slamming around and when it tries to go in a circle some of that beam will inevitably keep going straight and slam into the inner walls of the accelerator and that adds to the general background vacuum. It takes something like 2 months to get that bird down to the minus 14 level with no beam slamming around inside.
Even the level of vacuum on the moon isn't all that great from a zero vacuum level, where there are zero particles, something you can't have even a million light years away from the milky way in the depths of intergalactic space. Even there you will find a few molecules in a cubic meter of space.
There is just too much crap floating about in space, clouds a million light years in diameter in intergalactic space, nebulae in galactic space, and the local clouds in our own interstellar region.
It's amazing we can detect neutral hydrogen clouds in space! They can't usually even be imaged with visible light telescopes but can be seen in microwave frequencies and sometimes in IR.
The Big Bang Theory Wrong?
06 Oct '13 19:3413 edits
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